A few spots found their way to -20 on the last Friday of 2017, making it one of the colder December nights in recent memory. We are basically in the middle of the current cold wave and are now anticipating two additional surges of arctic chill before temperatures are allowed to moderate somewhat. Though the lack of a holiday thaw was a welcome change, we could obviously use a bit of natural snow to go with it. Unfortunately, I can't promised much this holiday weekend, just some light snow Friday afternoon, amounting to about an inch. The PV will simply be too much on Saturday and Sunday especially in northern Vermont. Southern Vermont will likely see some more light snow Saturday from a decaying Clipper system but the underlying theme will continue to be the cold weather with readings struggling to get above zero by day and well below zero at night. More of the same is expected for Sunday night and Monday and although the snowbelt areas in New York state will continue to get snow, Vermont should stay mostly dry. Flurries are possible Monday but the layer of instability is too shallow to allow for any substantial terrain/lake snow in the high country.
So now to the real question on everybody's mind - will the caboose produce ? And what the hell does that really mean anyway ? When I heard that saying years ago, it referred to the last in a series of amplifications in an arctic pattern and the tendency for that final surge of cold weather to produce a storm before jet stream relaxes. Is this really a thing ? Yes, but it's not a hard and fast rule by any means. The combination of very cold air and the relative warmth in the Atlantic is the magic that produces the big snows in our neck of the woods but as evidenced by the current weekend, when the jet stream is too strong, nothing happens. As the jet begins to relax, even a little, often times it's enough to open the "storm door".
The January 4th scenario is an interesting one since it involves subtropical energy over the
Bahamas getting sucked into digging polar jet energy and a clipper system. For a big storm to materialize, the polar jet will need to carve out a near bowling ball type structure. The Euro and Canadian models were all over that Thursday but the Thursday overnight models flipped around and the storm vanished. I wouldn't write the storm off yet however since this is a complicated interaction and may require a few more days to reach any certainty one way or another.
This "final" amplification ensures that bitterly cold air remains in place across the region through first full weekend in January. Tightening in the jet stream across the Pacific will cause the polar jet to retreat but only somewhat. It's been pointed out by several weather sources that the coldest air in the world is clearly centered over North America. It will take a lot more than a neutral EPO/AO to dislodge this impressive area of arctic chill and neutral is about as adverse as it will get. That said, I envision a noticeable temperature moderation after January 6th, but arctic air will remain available. The most disconcerting aspect of the outlook between Jan 6-16th is the re positioning of the ridge/trough axis with the trough centered closer to the front range. This is great for snow starved Colorado but does raise the potential for ice/rain event somewhere in that time frame. I don't see an extended thaw right now however and I would expect a few chances for new natural snow.
Friday, December 29, 2017
Tuesday, December 26, 2017
Snow potential diminishes over the next week as very cold/very dry air consumes Vermont
Still feeling some lingering frustration regarding the shortcomings of our recent Christmas storm. No it wasn't what we had hoped in a couple of different ways. First of all, it happens. Weather is inherently unpredictable and only somewhat less so than it used to be. The element of surprise and the tangibility of that surprise is what keeps the science interesting. Secondly, worse things will happen, like getting totally shut out of a predicted storm or getting 6 Christmas thaws in a row. The trailing clipper system associated with the storm was a much drier storm than forecast models suggested. Locations across the Midwest did quite well but the system dried out as it progressed eastward and many areas didn't live up to expectations. The coastal system, developed and intensified mostly as anticipated but its area of precipitation was quite compact and only grazed the northern half of Vermont. The dry air behind the system was very evident and reduced the lingering snow shower activity to nearly nothing and thus we have been sitting high, dry and very cold.
A good old fashion Polar Vortex will smack the state twice over the next week and produce the most extended, most intense chill since February of 2015. My guess is that over 50 percent of our time over the next week will be spent below the "zero" threshold. Wednesday's high of approximately 5 degrees will be one of the warmer days. Most of Thursday and Friday will be sub-zero and low temperatures both mornings will range between -10 and -15. The effects of the winds will be the strongest Wednesday/Thursday and will subside Friday.
The incoming 2nd PV will be associated with a much larger jet amplification and we've been watching this for a while since it presented the opportunity for a sizable east coast system. That opportunity still exists but the PV looks strong enough and far enough south to suppress most of the action. Though I wouldn't eliminate the chances for snow entirely Saturday, I've seen enough of these situations to remain on the cynical and somewhat pessimistic side. PV's typically, though not always, crush snow chances in Vermont. Usually, there is too much jet energy aimed in the wrong direction to allow a storms impact to reach interior New England. In addition, the shallow and highly stable chill that's often associated with these weather situations puts a lid on the lake/terrain snow. So I'm thinking mostly dry this holiday weekend with some sunshine and occasional flurries. Blustery conditions will return and it will remain very cold with temperatures generally in the single numbers by day and sub-zero at night.
The effects of the cold wave will continue through the middle of next week and it should remain on the dry side thanks to the strong aforementioned dome of high pressure. Changes in the Pacific in the form of jet stream tightening will shift the pattern and force arctic air into retreat mode by the 5th-7th of the month (the first full weekend in January). As of now, this "retreat" appears to be a partial one as opposed to a drastic one. Blocking at high latitudes is expected to disintegrate but indices won't stray too far from neutral and arctic cold will thus be available though its impact will not nearly be severe. Unless this changes it could prove to be just what the doctor ordered. We want the jet to relax a little, especially in January, but not too much to allow a thaw. There are indications that precipitation returns to the region as well after what we think is an extended stretch of dry weather.
A good old fashion Polar Vortex will smack the state twice over the next week and produce the most extended, most intense chill since February of 2015. My guess is that over 50 percent of our time over the next week will be spent below the "zero" threshold. Wednesday's high of approximately 5 degrees will be one of the warmer days. Most of Thursday and Friday will be sub-zero and low temperatures both mornings will range between -10 and -15. The effects of the winds will be the strongest Wednesday/Thursday and will subside Friday.
The incoming 2nd PV will be associated with a much larger jet amplification and we've been watching this for a while since it presented the opportunity for a sizable east coast system. That opportunity still exists but the PV looks strong enough and far enough south to suppress most of the action. Though I wouldn't eliminate the chances for snow entirely Saturday, I've seen enough of these situations to remain on the cynical and somewhat pessimistic side. PV's typically, though not always, crush snow chances in Vermont. Usually, there is too much jet energy aimed in the wrong direction to allow a storms impact to reach interior New England. In addition, the shallow and highly stable chill that's often associated with these weather situations puts a lid on the lake/terrain snow. So I'm thinking mostly dry this holiday weekend with some sunshine and occasional flurries. Blustery conditions will return and it will remain very cold with temperatures generally in the single numbers by day and sub-zero at night.
The effects of the cold wave will continue through the middle of next week and it should remain on the dry side thanks to the strong aforementioned dome of high pressure. Changes in the Pacific in the form of jet stream tightening will shift the pattern and force arctic air into retreat mode by the 5th-7th of the month (the first full weekend in January). As of now, this "retreat" appears to be a partial one as opposed to a drastic one. Blocking at high latitudes is expected to disintegrate but indices won't stray too far from neutral and arctic cold will thus be available though its impact will not nearly be severe. Unless this changes it could prove to be just what the doctor ordered. We want the jet to relax a little, especially in January, but not too much to allow a thaw. There are indications that precipitation returns to the region as well after what we think is an extended stretch of dry weather.
Sunday, December 24, 2017
Christmas storm is set to deliver 8-16" for MRG followed by addional fluff for Tuesday
Christmas storm is set to deliver for Mad River Glen and surroundings. Say what you want about the freezing rain Saturday, not ideal, but it did manage to solidify the best December snowpack in over a decade. A healthy dose of snow now should yield some beautiful holiday skiing and mother nature is set to provide it. Snow should begin just before dawn and Vemonters, most of them, will be waking up to a steady if not heavy snowfall creating a classic white Christmas scene. I mean, I've become so accustomed to Xmas thaws I am not sure I can even call it "classic". As discussed, the storm represents the merging of a surface wave along a slow moving front well to the regions south and a advancing clipper system to our west. It will ultimately go "bomb's away" in the Gulf of Maine, but move quick enough to keep snowfall totals under 2 feet. Vermont should put up some good snowfall numbers regardless with a burst of heavy snow during the midday hours pushing totals to 8-16 inches by days end. MRG's late opening will allow half of that snow to have fall before getting skied on, so don't' get too punchy on egg nog cocktails and get yourself lined up before noon.
Lingering instability should keep flurries and snow showers around Monday night into Tuesday. It looks like a pretty good set up for additional lake/terrain induced snow especially north of MRG. The snow will become extra fluffy and total another 3-6 inches in this time frame but I would expect some bigger additional totals farther north. Once the unmodified arctic air seeps into the region from the north Tuesday night into Wednesday, the snow will shut off for the most part and it will simply be cold, very cold. Readings will hover in the single numbers Wednesday and struggle to get above zero Thursday. Thanks to the deep fresh snow cover, overnight readings will be at least 10 below and perhaps 15 below. Winds will diminish Friday and temperatures will modify slightly (single numbers).
The 29th and 30th of the month (Friday and Saturday) continue to look like a time frame where a significant east coast snow storm could take place. As we advance through time, it looks more and more like arctic cold from a rather intense polar vortex will simply overwhelm the pattern and keep most of the precipitation to our south. Still worth watching to say the least because the potential weather system still involves a dynamic clipper system that could at least produce some light snow. PV's are difficult however, they have the capability of really drying things out in northern New England so I don't want to discount that possibility.
The cold air will make one more big charge around the New Years holiday and keep the region well below normal through at least Tuesday Jan 2. There have been hints of another storm around New Years day associated with the big jet stream amplification but we should probably keep longshot odds on this one for now. The pattern will gradually relax after the 2nd and this should open the door for additional snow even if the concept of a "bigger storm" falls flat. After Jan 7, the tightened Jet in the pacific will likely force arctic cold into "retreat mode" but "retreat" is a loose term and yet needs to be quantified.
For now enjoy the Christmas storm
Lingering instability should keep flurries and snow showers around Monday night into Tuesday. It looks like a pretty good set up for additional lake/terrain induced snow especially north of MRG. The snow will become extra fluffy and total another 3-6 inches in this time frame but I would expect some bigger additional totals farther north. Once the unmodified arctic air seeps into the region from the north Tuesday night into Wednesday, the snow will shut off for the most part and it will simply be cold, very cold. Readings will hover in the single numbers Wednesday and struggle to get above zero Thursday. Thanks to the deep fresh snow cover, overnight readings will be at least 10 below and perhaps 15 below. Winds will diminish Friday and temperatures will modify slightly (single numbers).
The 29th and 30th of the month (Friday and Saturday) continue to look like a time frame where a significant east coast snow storm could take place. As we advance through time, it looks more and more like arctic cold from a rather intense polar vortex will simply overwhelm the pattern and keep most of the precipitation to our south. Still worth watching to say the least because the potential weather system still involves a dynamic clipper system that could at least produce some light snow. PV's are difficult however, they have the capability of really drying things out in northern New England so I don't want to discount that possibility.
The cold air will make one more big charge around the New Years holiday and keep the region well below normal through at least Tuesday Jan 2. There have been hints of another storm around New Years day associated with the big jet stream amplification but we should probably keep longshot odds on this one for now. The pattern will gradually relax after the 2nd and this should open the door for additional snow even if the concept of a "bigger storm" falls flat. After Jan 7, the tightened Jet in the pacific will likely force arctic cold into "retreat mode" but "retreat" is a loose term and yet needs to be quantified.
For now enjoy the Christmas storm
Friday, December 22, 2017
A very active stretch of weather begins with snow->ice and then Xmas snow and hopefully more snow after that and hopefully even more snow beyond that
We've officially entered a very active stretch of winter weather at Mad River Glen. The mountain got a big, cold dose of overrunning snow Friday and the 2nd wave associated with this big temperature boundary brings its moisture to the region Saturday. Many forecast sites including NWS suggests temperatures make a big climb beyond the freezing mark tomorrow. I don't see that, but we could a pretty wild inversion during the day with temperatures at the summits near freezing while readings stay in the 20's in the valley locations. The ice situation looks like this. Precipitation should be pretty light in the morning, perhaps just a bit of freezing drizzle, but the heavier stuff should start to impact MRG by midday and icing could be significant. By the end of the day, most areas will have a rather glazed snowpack with 1/4 to as much as a 1/2 inch of ice.
A weak area of high pressure will build across the region Saturday night and will help to make Christmas Eve the rare dry day in an otherwise very active weather week. It won't last long however as the third and final wave of low pressure is ignited along the same temperature boundary that produced the prior two. The storm will form across the central Appalachian Mountains but merge nicely with a clipper system traveling through the Great Lakes at the same time. The nexus of the two systems will create a nice looking inverted surface wave that will ultimately strengthen into a nor'easter off coast of Maine. It won't produce a historic snow but it looks better than a stocking stuffer. Snow should begin late on Christmas Eve and continue into Christmas morning with temperatures supporting powder throughout. Looks like a 6-12 incher right now but instability should linger into Monday Night and Tuesday allowing for the possibility of additional snow to fall.
Very cold and very dry arctic air will eventually eliminate the snowfall by Wednesday but expect brutally cold temperatures with readings generally in the single numbers during the day (Wed - Fri) and 10 below at night. This airmass won't be the type that modifies over the unfrozen Great Lakes, it will attack us directly and smack us with the "unmodified" cold.
This brings us to the end of the week and another intriguing weather set up. The possibilities have already been outlined but the specifics remain unknown. That said, the weather represents a classic massive east coast snow setup around the 29th and 30th of the month which would be Friday and Saturday of the New Years Holiday weekend. Large, cold dome of high pressure to the north, low pressure to the south ready to ignite along the relative warmth of the Atlantic Ocean. There's a chance any storm could remain to our south but they're enough forces in the ambient weather pattern, the remnants of a jet stream ridge along the southeast U.S. coastline, to help steer this storm along the yellowbrick road to glory. Stay tuned !
Cold weather is locked in through New Years weekend and if you are to believe the various ensemble simulations, through the first week of 2018. Even as the cold lingers, there are signs of changing fundamentals particularly in the Pacific Ocean where the jet stream is expected to tighten. It could be our first taste of an "evil empire" but the effects of this appear to be way out on horizon, like after January 6th or so. Until then, we should continue to add up the new snow and enjoy what could be the best start to a ski season since dare I say 2008-2009 or perhaps even 1995-1996 (the first year of the MRG coop).
Have fun and stay safe out there in all the varying forms of weather.
A weak area of high pressure will build across the region Saturday night and will help to make Christmas Eve the rare dry day in an otherwise very active weather week. It won't last long however as the third and final wave of low pressure is ignited along the same temperature boundary that produced the prior two. The storm will form across the central Appalachian Mountains but merge nicely with a clipper system traveling through the Great Lakes at the same time. The nexus of the two systems will create a nice looking inverted surface wave that will ultimately strengthen into a nor'easter off coast of Maine. It won't produce a historic snow but it looks better than a stocking stuffer. Snow should begin late on Christmas Eve and continue into Christmas morning with temperatures supporting powder throughout. Looks like a 6-12 incher right now but instability should linger into Monday Night and Tuesday allowing for the possibility of additional snow to fall.
Very cold and very dry arctic air will eventually eliminate the snowfall by Wednesday but expect brutally cold temperatures with readings generally in the single numbers during the day (Wed - Fri) and 10 below at night. This airmass won't be the type that modifies over the unfrozen Great Lakes, it will attack us directly and smack us with the "unmodified" cold.
This brings us to the end of the week and another intriguing weather set up. The possibilities have already been outlined but the specifics remain unknown. That said, the weather represents a classic massive east coast snow setup around the 29th and 30th of the month which would be Friday and Saturday of the New Years Holiday weekend. Large, cold dome of high pressure to the north, low pressure to the south ready to ignite along the relative warmth of the Atlantic Ocean. There's a chance any storm could remain to our south but they're enough forces in the ambient weather pattern, the remnants of a jet stream ridge along the southeast U.S. coastline, to help steer this storm along the yellowbrick road to glory. Stay tuned !
Cold weather is locked in through New Years weekend and if you are to believe the various ensemble simulations, through the first week of 2018. Even as the cold lingers, there are signs of changing fundamentals particularly in the Pacific Ocean where the jet stream is expected to tighten. It could be our first taste of an "evil empire" but the effects of this appear to be way out on horizon, like after January 6th or so. Until then, we should continue to add up the new snow and enjoy what could be the best start to a ski season since dare I say 2008-2009 or perhaps even 1995-1996 (the first year of the MRG coop).
Have fun and stay safe out there in all the varying forms of weather.
Wednesday, December 20, 2017
Steady snow Friday, no thaw Saturday and a Christmas Storm that looks more and more promising
Yesterday's update seemed rather inadequate in light of the rapidly evolving weather situation going into the holidays. There's a ton of new information that should help us pin down a few key forecast details in the short term, get us all jacked with lofty expectations for Christmas Day and then speculate as to how long we can keep this going. This is one of the better updates I HAVE EVER GIVEN so by all means, blame the messenger, it's a terrific time to do so.
Winter is re establishing itself across Vermont as of Wednesday and the airmass responsible for this will continue to strengthen its grip on the state Wednesday night and Thursday. Though discredited for several days, this airmass is a very effective one since it will dam itself east of the various northeast mountain ranges by Friday morning which helps to enhance the overrunning precipitation that is anticipated for Friday. This is one of the more important details to clarify. There was dissension within the ranks of model info for a time but not really anymore, snow begins around 7 am Friday and should fall steadily throughout the day. Temperatures will also be colder than people are anticipating, remaining in the low teens throughout the day and into the evening. Lets be entirely unequivocal, Friday is a powder day with 6-10 inches of the good stuff falling by the evening. Some of the best forcing associated with this initial wave of moisture will clear the area Friday night and the snow will become less intense.
Things brings us to our next important detail. NO THAW ! Don't think it happens, not anymore. Temperatures will make a push into the 20's Saturday and any snow turns to freezing drizzle and eventually we are likely to see some freezing rain. Models have obviously evolved very quickly on this upcoming weather situation so it begs the question, does the evolution continue ? More simply, can we get rid of all the ice in this forecast Saturday ? Not impossible, but still not probable. I would still expect a glaze atop of Friday's snow.
Oh Christmas Storm, Oh Christmas Storm, what tidings bringest thou ? This is very tricky storm to pin down and still is, but one gets the feeling the Euro is starting to lock in on this sucker, a potential 1-2 footer for interior New England and the Adirondacks beginning Sunday night and persisting through most of Christmas Day. Canadian is on the snow train also predicting the same for Christmas Day. Here's the caveat though, the polar jet is a ferocious animal and it has a tradition of crushing these systems. The Christmas storm will start as a wave along a front only slowly pushing east this weekend. A small change in the way the incoming polar jet interacts with this boundary could have profound consequences on this storm. It's looking better and better but remember, one run of models can give you lots of snow and the very next day they can take it all away. I'd say our chances for big snow Xmas are just north of 50 percent as of late Wednesday.
Still got big cold in the outlook for the middle part of the holiday week. A blanket of snow could set the stage for readings of 10 below or more on one or two nights before the arctic air is allowed to modify. Still expect the cold weather to sustain through New Years weekend with the possibility of another storm around the time frame of December 29th and 30th.
Winter is re establishing itself across Vermont as of Wednesday and the airmass responsible for this will continue to strengthen its grip on the state Wednesday night and Thursday. Though discredited for several days, this airmass is a very effective one since it will dam itself east of the various northeast mountain ranges by Friday morning which helps to enhance the overrunning precipitation that is anticipated for Friday. This is one of the more important details to clarify. There was dissension within the ranks of model info for a time but not really anymore, snow begins around 7 am Friday and should fall steadily throughout the day. Temperatures will also be colder than people are anticipating, remaining in the low teens throughout the day and into the evening. Lets be entirely unequivocal, Friday is a powder day with 6-10 inches of the good stuff falling by the evening. Some of the best forcing associated with this initial wave of moisture will clear the area Friday night and the snow will become less intense.
Things brings us to our next important detail. NO THAW ! Don't think it happens, not anymore. Temperatures will make a push into the 20's Saturday and any snow turns to freezing drizzle and eventually we are likely to see some freezing rain. Models have obviously evolved very quickly on this upcoming weather situation so it begs the question, does the evolution continue ? More simply, can we get rid of all the ice in this forecast Saturday ? Not impossible, but still not probable. I would still expect a glaze atop of Friday's snow.
Oh Christmas Storm, Oh Christmas Storm, what tidings bringest thou ? This is very tricky storm to pin down and still is, but one gets the feeling the Euro is starting to lock in on this sucker, a potential 1-2 footer for interior New England and the Adirondacks beginning Sunday night and persisting through most of Christmas Day. Canadian is on the snow train also predicting the same for Christmas Day. Here's the caveat though, the polar jet is a ferocious animal and it has a tradition of crushing these systems. The Christmas storm will start as a wave along a front only slowly pushing east this weekend. A small change in the way the incoming polar jet interacts with this boundary could have profound consequences on this storm. It's looking better and better but remember, one run of models can give you lots of snow and the very next day they can take it all away. I'd say our chances for big snow Xmas are just north of 50 percent as of late Wednesday.
Still got big cold in the outlook for the middle part of the holiday week. A blanket of snow could set the stage for readings of 10 below or more on one or two nights before the arctic air is allowed to modify. Still expect the cold weather to sustain through New Years weekend with the possibility of another storm around the time frame of December 29th and 30th.
Tuesday, December 19, 2017
A little mild weather and rain late Saturday but Christmas forecast continues to improve and includes plenty of cold weather
Lots to discuss today with it being a busy finish to 2017 weather-wise and a certainly a busy part of the ski season given the upcoming holidays. Generally the news today is pretty good. The mild weather Tuesday was tame relative to many thaws we've experienced the past few years and we hope there's only one brief additional difficult window to get through before another extended stretch of winter begins.
A colder push of weather will be accompanied by snow showers and maybe a squall or two Tuesday night. The snow will only amount to a few inches and accumulations will generally be confined to the high country, but winter will be back with temperatures in the 20's Wednesday along with a chilly wind. The Rocky Mountains have gotten off to a difficult start this winter with balmy temperatures and a glaring lack of snow. Resorts in both Utah and Colorado will pick up a bit of snow Wednesday and this represents our next storm and in this particular case, our next concern. Fortunately, a healthy area of cold will continue to build across the region Wednesday night and allow temperatures to plummet back into the single numbers and subsequently remain in the teens on Thursday. This airmass will provide a nice foreground for an approaching system that is not poised to track in a favorable direction. The result is what I think might be a healthy overrunning thump of snow late Friday and Friday night. As of late Tuesday, it looks like much of this snow falls very late in the ski day Friday, Friday night and into early Saturday before changing to freezing rain/drizzle early Saturday. Temperatures will remain in the teens through Friday and are likely to be in the 20's early Saturday. Powdery turns are possible early Saturday before the ice begins in earnest. Several inches of snow are possible but I can't say that I have the timing or the exact amounts of snow nailed down. I could use another day or two on that.
Milder air will slowly make its northward push Saturday and the aforementioned ice will turn to a bit of rain. Temperatures will make climb toward 40 but will have a limited window to do so before colder air arrives by the morning of Christmas Eve. Arctic cold will be beating against a rather stubborn ridge in the jet stream - positioned just off the southeast U.S. coast. The front marking the advance of the arctic cold will thus remain active and capable of generating a 2nd east coast weather system in time for Christmas Day. As this is happening, extremely cold arctic air will make a giant southward advance. It all makes for a rather delicate situation. It won't take much to move this potential Christmas storm offshore and it also won't take much for the cold to be somewhat delayed and allow for precipitation to be something other than snow. For now, snowfall on Christmas Day appears to be a legitimate possibility as opposed to a far-fetched one and within a few days, we should be able to pin this storm down as well.
Coldest air of the winter season so far will consume the region after Christmas and send temperatures well below zero. There might even be a day between Tuesday and Thursday where readings fail to break 10. Snow showers and squalls are possible Tuesday although the intensity of the arctic air will likely limit available instability. I expect the cold to persist through the New Years holiday however thanks to the blocking structure which is expected to drift westward very slowly across the Alaskan Peninsula and the EPO which will keep the Pacific loose and friendly. The setup looks conducive for another big east coast system around December 29th and 30th but it is very early and there have been only occasional hints of such an outcome right now.
A colder push of weather will be accompanied by snow showers and maybe a squall or two Tuesday night. The snow will only amount to a few inches and accumulations will generally be confined to the high country, but winter will be back with temperatures in the 20's Wednesday along with a chilly wind. The Rocky Mountains have gotten off to a difficult start this winter with balmy temperatures and a glaring lack of snow. Resorts in both Utah and Colorado will pick up a bit of snow Wednesday and this represents our next storm and in this particular case, our next concern. Fortunately, a healthy area of cold will continue to build across the region Wednesday night and allow temperatures to plummet back into the single numbers and subsequently remain in the teens on Thursday. This airmass will provide a nice foreground for an approaching system that is not poised to track in a favorable direction. The result is what I think might be a healthy overrunning thump of snow late Friday and Friday night. As of late Tuesday, it looks like much of this snow falls very late in the ski day Friday, Friday night and into early Saturday before changing to freezing rain/drizzle early Saturday. Temperatures will remain in the teens through Friday and are likely to be in the 20's early Saturday. Powdery turns are possible early Saturday before the ice begins in earnest. Several inches of snow are possible but I can't say that I have the timing or the exact amounts of snow nailed down. I could use another day or two on that.
Milder air will slowly make its northward push Saturday and the aforementioned ice will turn to a bit of rain. Temperatures will make climb toward 40 but will have a limited window to do so before colder air arrives by the morning of Christmas Eve. Arctic cold will be beating against a rather stubborn ridge in the jet stream - positioned just off the southeast U.S. coast. The front marking the advance of the arctic cold will thus remain active and capable of generating a 2nd east coast weather system in time for Christmas Day. As this is happening, extremely cold arctic air will make a giant southward advance. It all makes for a rather delicate situation. It won't take much to move this potential Christmas storm offshore and it also won't take much for the cold to be somewhat delayed and allow for precipitation to be something other than snow. For now, snowfall on Christmas Day appears to be a legitimate possibility as opposed to a far-fetched one and within a few days, we should be able to pin this storm down as well.
Coldest air of the winter season so far will consume the region after Christmas and send temperatures well below zero. There might even be a day between Tuesday and Thursday where readings fail to break 10. Snow showers and squalls are possible Tuesday although the intensity of the arctic air will likely limit available instability. I expect the cold to persist through the New Years holiday however thanks to the blocking structure which is expected to drift westward very slowly across the Alaskan Peninsula and the EPO which will keep the Pacific loose and friendly. The setup looks conducive for another big east coast system around December 29th and 30th but it is very early and there have been only occasional hints of such an outcome right now.
Sunday, December 17, 2017
Pre-Xmas thaw looks brief and outlook for the holiday week appears colder
The season at MRG is officially underway as the snow continues to fly. More of the good stuff is expected on Monday as mild air makes a significant push toward the region. Though it may commonplace in our circles to cast negative aspersions on a "mild push of air" it is often a very effective way to produce snow. I don't expect Monday's "overrunning" snow to produce epic powder, but 2 or 3 inches is likely along with temperatures in the teens and 20's. This mild air will make a brief interlude into the region on Tuesday. Temperatures will sneak above the freezing mark for a few hours at the base of the hill but will likely stay below freezing above 3000 feet or so. Elevations sensitive rain/snow showers should impact the region during the afternoon before colder air changes all precipitation to snow Tuesday night. By Wednesday, temperatures will be back in the 20's and snow showers should freshen the mountain with a few new inches.
The bigger and more important questions obviously involves the upcoming holiday weekend and beyond. We certainly have some concerns. Though we are unlikely to come out victorious in every one of what should be a few intriguing weather situations during the last 10 days of 2017, we could still actually do quite well and score at least one big snow before the new year. We have the excellent fundamentals mentioned in prior posts such as the loose Pacific Jet and ridge/block across the Alaskan peninsula and we are also dealing with the byproducts of what is now a rather stable La Nina. The pattern will amplify as it should as we approach the holiday weekend and arctic air will come cascading southward into the United States. This initial amplification will occur too far west however and allow a storm to cut up through the eastern Great Lakes around the time of December 22 and 23, a Friday and a Saturday. We should see some snow from this system intially and then some ice and then it looks more and more that a period of rain on Saturday along with above-freezing temperatures.
As this is happening a very strong arctic high pressure center will build across the western two thirds of the country and advance east. Some very cold air is likely to build across the area around the Christmas holiday but the ridge across the southeastern United States is expected to be persistent enough to keep the mild air close along with the a general area of storminess. It's a muddled weather picture and is likely to change but there are indications of a 2nd significant storm Chistmas Eve or Day. With colder air on the playing field, precipitation is more likely to stay frozen though nothing is set in stone.
Arctic air is then shown to overwhelm the pattern in the days following Christmas and the outlook thus appears colder on Tuesday and Wednesday. Can we generate another storm later in the week ? Absolutely. It typical La Nina fashion, the ridge across the southeast will encourage any storminess to track a bit closer to us than it would otherwise in such a pattern. Though models aren't showing any hard evidence of big snow around New Years weekend as of Sunday morning, one is certainly possible along with the continued presence of cold air.
The bigger and more important questions obviously involves the upcoming holiday weekend and beyond. We certainly have some concerns. Though we are unlikely to come out victorious in every one of what should be a few intriguing weather situations during the last 10 days of 2017, we could still actually do quite well and score at least one big snow before the new year. We have the excellent fundamentals mentioned in prior posts such as the loose Pacific Jet and ridge/block across the Alaskan peninsula and we are also dealing with the byproducts of what is now a rather stable La Nina. The pattern will amplify as it should as we approach the holiday weekend and arctic air will come cascading southward into the United States. This initial amplification will occur too far west however and allow a storm to cut up through the eastern Great Lakes around the time of December 22 and 23, a Friday and a Saturday. We should see some snow from this system intially and then some ice and then it looks more and more that a period of rain on Saturday along with above-freezing temperatures.
As this is happening a very strong arctic high pressure center will build across the western two thirds of the country and advance east. Some very cold air is likely to build across the area around the Christmas holiday but the ridge across the southeastern United States is expected to be persistent enough to keep the mild air close along with the a general area of storminess. It's a muddled weather picture and is likely to change but there are indications of a 2nd significant storm Chistmas Eve or Day. With colder air on the playing field, precipitation is more likely to stay frozen though nothing is set in stone.
Arctic air is then shown to overwhelm the pattern in the days following Christmas and the outlook thus appears colder on Tuesday and Wednesday. Can we generate another storm later in the week ? Absolutely. It typical La Nina fashion, the ridge across the southeast will encourage any storminess to track a bit closer to us than it would otherwise in such a pattern. Though models aren't showing any hard evidence of big snow around New Years weekend as of Sunday morning, one is certainly possible along with the continued presence of cold air.
Thursday, December 14, 2017
Still wintry for at least a week but thaw is possible around Xmas
Arctic air controls the state and has helped to make for some beautiful wintry scenery and a few good ski days as well. Vermont in particular will in fact be one of the most wintry states in the country over the next several days. Opening day has been officially moved up a day to Friday December 15th. It will be a chilly start with temperatures just below zero degrees. Some early sunshine will help boost readings back into the teens but clouds should be on the increase ahead of a polar disturbance in the jet stream. This disturbance will spread some light snow into the the mountains Friday night and re enforce the arctic chill for the weekend. There are a few hours where atmospheric profiles (and wind direction) are very favorable for lake//terrain enhanced snow at MRG. This would occur right around opening on Saturday and would fall in addition to the light snow Friday night. I am going to take a stab and say 3-6 inches of snow by midday Saturday but forecasting the lake/terrain induced stuff is a challenge so that range is a rather soft one (though I would be quite surprised if we end up with less than two). Conditions should dry out late Saturday followed by a bluebird Sunday with readings climbing up near 20 in the afternoon after a sub-zero start.
There was some talk and some Iphone forecasts suggesting snow during the middle of next week. I think our best chance for a decent accumulation comes from the warm advection induced precipitation Monday. It doesn't look more than a few inches but it does look powdery. Tuesday looks like a day where some warm air could sneak into the region. Don't think rain is very likely but temperatures could certainly push past the freezing mark in the valleys and challenge that same mark on the lower mountain. After this "relaxation" in the pattern, colder air will retake control of the state and more terrain/lake induced snow is possible Tuesday night into Wednesday.
Ok, now moving on to the Christmas weekend where tons of very tough questions need to be answered. Hemispherically speaking, there are going to be some encouraging fundamentals or teleconnnections anchoring the weather pattern, the biggest of which is a block over the Alaskan Peninsula. That said, the crest of this block is setting up a bit further west than we would like it. It will leave Vermont in a war zone of airmasses. Though we could win a battle or two and I fully expect we will, we could also lose one. The pattern amplifications during the current week and to some degree next week will favor Vermont ski country but these will shift westward by Christmas Eve. As a result I expect a series of storms to track right at the state. A reasonable expectations right now as that we get some snow and wintry weather from one and rain and a thaw from another. Hard to pinpoint exact dates but the first such system should come within a day of Christmas Eve with another a few days after that. The situation is obviously fluid. I am not married to particular scenario and fully expect the outlook to shift around a bit.
There was some talk and some Iphone forecasts suggesting snow during the middle of next week. I think our best chance for a decent accumulation comes from the warm advection induced precipitation Monday. It doesn't look more than a few inches but it does look powdery. Tuesday looks like a day where some warm air could sneak into the region. Don't think rain is very likely but temperatures could certainly push past the freezing mark in the valleys and challenge that same mark on the lower mountain. After this "relaxation" in the pattern, colder air will retake control of the state and more terrain/lake induced snow is possible Tuesday night into Wednesday.
Ok, now moving on to the Christmas weekend where tons of very tough questions need to be answered. Hemispherically speaking, there are going to be some encouraging fundamentals or teleconnnections anchoring the weather pattern, the biggest of which is a block over the Alaskan Peninsula. That said, the crest of this block is setting up a bit further west than we would like it. It will leave Vermont in a war zone of airmasses. Though we could win a battle or two and I fully expect we will, we could also lose one. The pattern amplifications during the current week and to some degree next week will favor Vermont ski country but these will shift westward by Christmas Eve. As a result I expect a series of storms to track right at the state. A reasonable expectations right now as that we get some snow and wintry weather from one and rain and a thaw from another. Hard to pinpoint exact dates but the first such system should come within a day of Christmas Eve with another a few days after that. The situation is obviously fluid. I am not married to particular scenario and fully expect the outlook to shift around a bit.
Tuesday, December 12, 2017
Got one in the bag, more is on the way but lots of uncertainty in the outlook going forward
Our first significant snow has successfully blanketed the region Tuesday and more is on the way. We should expect to see additional snowfall through a good party of Wednesday along with blustery conditions and temperatures generally in the teens but it does not appear to be the greatest case for terrain/lake snow at MRG. There's only a shallow layer of low level instability over northern Vermont Wednesday and some wind shear above this unstable layer. That said there is plenty of lingering moisture. 2-5 inches Wednesday on top of the 10-14 Tuesday and Tuesday night should bring storm totals to a foot or more though snow conditions at the summits will be pretty wind blown thanks to strong northwest winds.
A series of small weather systems will keep most of the snow action to the south Thursday and Friday. Temperatures will be quite cold and possibly find their way below zero for the first time this winter season on Friday morning. Readings will only rise into the teens both Thursday and Friday. Temperatures will moderate on Saturday, opening day, and some snowfall will return from a rather benign looking weather feature. A few inches is certainly possible on Saturday.
Uncertainty rises rather quickly after Saturday. Models are having a difficult time wading through the specifics of a pattern that is expected to relax Sunday/Monday and then re amplify Tuesday and Wednesday. There are varying scenarios being advertised and for now I prefer what appears to be the colder one. Dry arctic air will re establish control of Vermont's weather Sunday ahead of a mild push of air and a weather system Monday. Snow or a snow to ice situation should accompany this milder push of air which and its yet to be determined how substantial this precipitation event might be. Colder air then re establishes control of the regions weather Tuesday into Wednesday and some terrain/lake induced snow is possible as this happens.
Ensembles continue to go back and forth for Christmas week. This is turning out to be a very difficult forecast. Conditions in the Pacific will flirt with adversity in the middle of next week but the EPO is expected to slide back into negative territory as mentioned in the last update. A loose jet (negative EPO) in the Pacific is a very critical component in keeping arctic air a part of the weather picture across New England and many other places. In addition, a nice looking Omega blocking feature in the jet stream is still the expectation across Alaska. The position of this feature is very critical. If it sets up shop too far wet across the Alaskan Peninsula it could invite a push of warmth along the east coast. If block is positioned along the Alaskan/Canadian border, Vermont will be very wintry, cold and possibly snowy. I think Vermont has a good chance to be on the wintry side of the action but I'll admit it's a little closer than I would like it be.
A series of small weather systems will keep most of the snow action to the south Thursday and Friday. Temperatures will be quite cold and possibly find their way below zero for the first time this winter season on Friday morning. Readings will only rise into the teens both Thursday and Friday. Temperatures will moderate on Saturday, opening day, and some snowfall will return from a rather benign looking weather feature. A few inches is certainly possible on Saturday.
Uncertainty rises rather quickly after Saturday. Models are having a difficult time wading through the specifics of a pattern that is expected to relax Sunday/Monday and then re amplify Tuesday and Wednesday. There are varying scenarios being advertised and for now I prefer what appears to be the colder one. Dry arctic air will re establish control of Vermont's weather Sunday ahead of a mild push of air and a weather system Monday. Snow or a snow to ice situation should accompany this milder push of air which and its yet to be determined how substantial this precipitation event might be. Colder air then re establishes control of the regions weather Tuesday into Wednesday and some terrain/lake induced snow is possible as this happens.
Ensembles continue to go back and forth for Christmas week. This is turning out to be a very difficult forecast. Conditions in the Pacific will flirt with adversity in the middle of next week but the EPO is expected to slide back into negative territory as mentioned in the last update. A loose jet (negative EPO) in the Pacific is a very critical component in keeping arctic air a part of the weather picture across New England and many other places. In addition, a nice looking Omega blocking feature in the jet stream is still the expectation across Alaska. The position of this feature is very critical. If it sets up shop too far wet across the Alaskan Peninsula it could invite a push of warmth along the east coast. If block is positioned along the Alaskan/Canadian border, Vermont will be very wintry, cold and possibly snowy. I think Vermont has a good chance to be on the wintry side of the action but I'll admit it's a little closer than I would like it be.
Sunday, December 10, 2017
First significant snow Tuesday/Wednesday and I am starting to like the Christmas outlook
Got a few inches in the bag and should have plenty more to come in the coming days and even weeks. I'll readily admit that at the time of the last blog update, there was legitimate concern that this entire pattern might flop around Christmas Eve. Just in the last 36 hours or so, there have more definitive indications that the jet stream in the Pacific Ocean, though tightening slightly next week, will loosen substantially right around Christmas Day sending the EPO index back into more favorable negative territory. The 6-year consecutive stretch of Christmas thaws is thus in jeopardy but not yet eliminated (eliminating it now would obviously jinx it and ensure 60 degree weather by the 26th).
First thing is first however, a significant storm system on Tuesday. Was surprised on Sunday to see the National Weather Service in Burlington lower accumulations (2-4")for Tuesday and only advertise the event as "light snow". Perhaps it reflects some lingering uncertainty regarding the nature of the event. Though models have zeroed in on snowfall Tuesday, the storm's eventual strengthening or "bombing" in the Gulf of Maine remains a question. Both domestic models seem a little less bearish on the "bombing" than foreign counterparts. Sorry about the puns, it's just the way the sentence came out. Even without significant downstream strengthening, we will see more than 2-4 inches.
Snow should begin around daybreak Tuesday and for a time, should fall moderately and perhaps heavily for a few hours. I think the strengthening in the Gulf of Maine will be more substantial and though I think snowfall might taper to flurries by late Tuesday afternoon, 6-10 inches should be the expectation for high country locations like Mad River Glen. Snow will re intensify Tuesday night and continue as snow showers Wednesday as some of the coldest weather of the season so far builds across the area. There has been lots of talk about big time lake effect snow Wednesday because of the thermal situation around the Great Lakes. This applies to Lake Champlain as well and snow showers and squalls should be the result providing the mountains with additional accumulations. I am going to retain a little caution and suggest 8-16 inches over the two day (Tuesday/Wednesday) period but my gut wants to say 10-20". I'll leave both forecasts out there for now and let the chips fall where they may.
Temperatures will be in the teens and single numbers Wednesday and Thursday and we expect the east coast to get impacted by another clipper system later Thursday into Friday. Lots of uncertainty persists regarding this situation and snowfall is possible over a broad area but not guaranteed for anyone. The European model has been relatively consistent in its assessment that the storm and its snow will remain to the region's south but this model has its miscues over the last few weeks so it will be worth watching.
The pattern is expected to relax around the weekend of the 16th and 17th though cold weather will fight to remain in place across interior New England. Will a mild push of air coupled with a storm system late in the weekend bring another wintry weather situation to Vermont ? Could we see a limited stretch of above freezing temperatures ? Several possible outcomes here but either way, we should see colder weather return by Tuesday December 19th and persist through the middle of next week.
The longer range was already discussed but to reiterate, I was very encouraged to see varying ensembles suggest a weakened Pacific Jet as we head toward Xmas weekend. In addition, there are indications of a full fledged Omega blocking structure in the jet over Alaska and this more or less guarantees the presence of arctic air for New England and plenty of other places.
First thing is first however, a significant storm system on Tuesday. Was surprised on Sunday to see the National Weather Service in Burlington lower accumulations (2-4")for Tuesday and only advertise the event as "light snow". Perhaps it reflects some lingering uncertainty regarding the nature of the event. Though models have zeroed in on snowfall Tuesday, the storm's eventual strengthening or "bombing" in the Gulf of Maine remains a question. Both domestic models seem a little less bearish on the "bombing" than foreign counterparts. Sorry about the puns, it's just the way the sentence came out. Even without significant downstream strengthening, we will see more than 2-4 inches.
Snow should begin around daybreak Tuesday and for a time, should fall moderately and perhaps heavily for a few hours. I think the strengthening in the Gulf of Maine will be more substantial and though I think snowfall might taper to flurries by late Tuesday afternoon, 6-10 inches should be the expectation for high country locations like Mad River Glen. Snow will re intensify Tuesday night and continue as snow showers Wednesday as some of the coldest weather of the season so far builds across the area. There has been lots of talk about big time lake effect snow Wednesday because of the thermal situation around the Great Lakes. This applies to Lake Champlain as well and snow showers and squalls should be the result providing the mountains with additional accumulations. I am going to retain a little caution and suggest 8-16 inches over the two day (Tuesday/Wednesday) period but my gut wants to say 10-20". I'll leave both forecasts out there for now and let the chips fall where they may.
Temperatures will be in the teens and single numbers Wednesday and Thursday and we expect the east coast to get impacted by another clipper system later Thursday into Friday. Lots of uncertainty persists regarding this situation and snowfall is possible over a broad area but not guaranteed for anyone. The European model has been relatively consistent in its assessment that the storm and its snow will remain to the region's south but this model has its miscues over the last few weeks so it will be worth watching.
The pattern is expected to relax around the weekend of the 16th and 17th though cold weather will fight to remain in place across interior New England. Will a mild push of air coupled with a storm system late in the weekend bring another wintry weather situation to Vermont ? Could we see a limited stretch of above freezing temperatures ? Several possible outcomes here but either way, we should see colder weather return by Tuesday December 19th and persist through the middle of next week.
The longer range was already discussed but to reiterate, I was very encouraged to see varying ensembles suggest a weakened Pacific Jet as we head toward Xmas weekend. In addition, there are indications of a full fledged Omega blocking structure in the jet over Alaska and this more or less guarantees the presence of arctic air for New England and plenty of other places.
Friday, December 8, 2017
Let the December snowfest begin !!
Certainly a few rather important updates this morning and most of them are pretty darn positive as far as new snow is concerned in Vermont. So this Saturday storm is now "a thing" in the parlance of our current times. I need to be shamed somewhat for dismissing the possibility a few days ago. Models have such a difficult time dealing with fronts that so often linger around the Atlantic Coast. I've described the coastline as a "tinderbox" which it is, but a major consequence is that if models miss even slightly on one wave of jet energy, errors accumulate exponentially and 48 hours later the forecast picture is hardly recognizable. The wave of energy in question is causing snow in some rather unusual locations across Dixie. Its more of a disorganized but still rather significant conglomeration of moisture as of Friday but by Saturday it will have evolved into a garden variety coastal low pressure system. Snow will be falling across the Mid Atlantic and spread into southern New England during the morning hours.
The forecast picture for Vermont has changed profoundly as a result. We expected Saturday to be dry and quite possibly feature a good bit of sunshine. Though we may see the sun very early on Saturday, most of the day will be cloudy and snow should arrive by mid-afternoon. Across SE New England, this has become a very significant snow event and accumulations across a sliver of eastern Massachusetts could reach the 8-14 inch category. Snow will be on the lighter side across the Mad River Valley but still fall at a rather steady rate for several hours and total 3-6 inches by Sunday morning. The situation is still very fluid and models have been trending toward a stronger system and a farther west storm path. If this continues, accumulations would obviously be higher.
The storm Saturday will swallow much of the energy from the Midwest clipper we discussed a few days ago. That said, snow showers and even snow squalls are still likely on Sunday yielding some additional accumulations and leaving us feeling rather wintry as temperatures hover in the high 20's and then drop into the lower teens Sunday night. A weak area of high pressure will try and build across the region on Monday but flurries remain possible particularly in the morning.
I advertised "50 percent" or a "coin flip" on a big storm for Tuesday into Wednesday of next week. This probability looks closer to 80 percent as of Friday. Some disagreement persists relating to the track and timing of the event but the concept of a bombing New England/Gulf of Maine clipper system appears to be a universally accepted outcome. The clipper will spread its snow into Vermont Tuesday morning if all goes according to plan and the storm would strengthen. The disagreement mostly revolves around the track of the storm and would certainly impact overall snow accumulations and the positioning of dry air but not the overall forecast of snow. Accumulations could still wind in the modest 4-8 inch category if the American/Canadian model is correct in its assertion that the track of the storm is right over or even north of the state, but storm totals could reach a foot or more if the European solution is right and the storm path is closer to the southern New England coastline. Think we could probably iron out all those uncertainties within two days.
Bigger surge of cold weather arrives on Wednesday as the snow tapers to flurries. Though temperatures might be in the 20's Tuesday night, we should see readings in the teens for much of the day and drop into the single numbers by Thursday morning. There are some additional snow possibilities later in to the week and into the weekend for a variety of reasons. The pattern is then expected to relax somewhat on Sunday Dec 17th into the early part of the following week but the AO will remain a very dominant player on a continental level (negative AO) and cold air should remain available across New England even if temperatures modify substantially further south. A storm system is certainly possible in this time frame as the temperature gradient between the warm and cold intensifies.
We should see another good southward surge of cold weather just prior to the Christmas holiday weekend and I am ready to suggest that the 20-23rd of the month will be on the wintry side. Can we break this 6-year streak of a Christmas thaw. Certainly possible but those horses are not in the barn quite yet.
The forecast picture for Vermont has changed profoundly as a result. We expected Saturday to be dry and quite possibly feature a good bit of sunshine. Though we may see the sun very early on Saturday, most of the day will be cloudy and snow should arrive by mid-afternoon. Across SE New England, this has become a very significant snow event and accumulations across a sliver of eastern Massachusetts could reach the 8-14 inch category. Snow will be on the lighter side across the Mad River Valley but still fall at a rather steady rate for several hours and total 3-6 inches by Sunday morning. The situation is still very fluid and models have been trending toward a stronger system and a farther west storm path. If this continues, accumulations would obviously be higher.
The storm Saturday will swallow much of the energy from the Midwest clipper we discussed a few days ago. That said, snow showers and even snow squalls are still likely on Sunday yielding some additional accumulations and leaving us feeling rather wintry as temperatures hover in the high 20's and then drop into the lower teens Sunday night. A weak area of high pressure will try and build across the region on Monday but flurries remain possible particularly in the morning.
I advertised "50 percent" or a "coin flip" on a big storm for Tuesday into Wednesday of next week. This probability looks closer to 80 percent as of Friday. Some disagreement persists relating to the track and timing of the event but the concept of a bombing New England/Gulf of Maine clipper system appears to be a universally accepted outcome. The clipper will spread its snow into Vermont Tuesday morning if all goes according to plan and the storm would strengthen. The disagreement mostly revolves around the track of the storm and would certainly impact overall snow accumulations and the positioning of dry air but not the overall forecast of snow. Accumulations could still wind in the modest 4-8 inch category if the American/Canadian model is correct in its assertion that the track of the storm is right over or even north of the state, but storm totals could reach a foot or more if the European solution is right and the storm path is closer to the southern New England coastline. Think we could probably iron out all those uncertainties within two days.
Bigger surge of cold weather arrives on Wednesday as the snow tapers to flurries. Though temperatures might be in the 20's Tuesday night, we should see readings in the teens for much of the day and drop into the single numbers by Thursday morning. There are some additional snow possibilities later in to the week and into the weekend for a variety of reasons. The pattern is then expected to relax somewhat on Sunday Dec 17th into the early part of the following week but the AO will remain a very dominant player on a continental level (negative AO) and cold air should remain available across New England even if temperatures modify substantially further south. A storm system is certainly possible in this time frame as the temperature gradient between the warm and cold intensifies.
We should see another good southward surge of cold weather just prior to the Christmas holiday weekend and I am ready to suggest that the 20-23rd of the month will be on the wintry side. Can we break this 6-year streak of a Christmas thaw. Certainly possible but those horses are not in the barn quite yet.
Wednesday, December 6, 2017
Trying to make sense of a wintry forecast
Depending on when you read this, we are about to start or have just started what we hope to be our first extended stretch of below freezing temperatures. We should see our first flurries Wednesday evening and night but snowfall will be minimal by the looks of things, may take a few days before amounting to anything significant. Snowfall will mostly be confined to the Great Lakes Thursday in the traditional snowbelt areas. That said, we expect a band or two of snow to make it over the Adirondacks and get slight boost from the warm waters of Lake Champlain. This should be enough to whiten the mountains around the Mad River Valley but the best snow Thursday appears to be from Stowe northward to Jay where I would expect a few inches.
Snow prospects for the weekend did not move in the direction that I would have preferred. Moisture and energy associated with a nearly stalled front off the Atlantic coast will linger too close to the coastline though not close enough. I referred to this the other day as "baroclinicity" and it often becomes the focal point for moisture and storms. Unfortunately, when energy is consolidated just off the Atlantic coast as is the case this weekend, the weather will remain quiet across interior New England and devoid of snowfall. We are in fact between two systems Saturday with the energy offshore representing one area of storminess and clipper across the Great Lakes concentrating snowfall well west of Vermont. Decaying moisture from this clipper system will finally reach Vermont later on Sunday or Sunday night bringing what I would expect to be our first light accumulation to the region but the bigger possibilities are laying in wait and may at that point be consuming most of our attention by the end of the weekend.
The storm situation in question involve the Tuesday-Wednesday time frame or December 12th and 13th. The pattern will relax somewhat in the wake of the passage of the late weekend clipper but as this is happening, the jet stream will be gearing up for another, even bigger amplification. We don't have any southern branch jet energy to work with but a series of shortwaves will accompany this next incoming surge of cold weather. Can any of these shortwaves be the match that lights the fuse ? Models, all of them, have been erratic and inconsistent in answering this question. The European model had a classic Gulf of Maine bomber on the run released Tuesday afternoon but it was not shown Wednesday morning. The American model seems to be back and forth on this question every 6 hours. The lack of consistency in the operational model runs simply reveals the uncertainty regarding this storm at this juncture. The ensembles, as of early Wednesday, continue to suggest strong hints of a significant snow for all of interior New England. My interpretation ? It's a coin flip - 50 percent.
Even if we end up on the wrong end of this "50 percent", we should be on the receiving end of at least some lighter snowfall. We should get some of this as early as Monday the 11th thanks to a weak area of overrunning moisture and then some additional snow Tuesday from the clipper. Modestly cold air follows for Wednesday and Thursday of next week and then we have the possibility of more snow on Friday December 15th and into the weekend.
The longer range looks about the same as it did several days ago. Though the PNA appears as if it wants to relax as we approach the Winter Solstice the AO will remain decidedly negative and there are no glaring indications of jet tightening in the Pacific though this situation will bear watching in the days to come.
Snow prospects for the weekend did not move in the direction that I would have preferred. Moisture and energy associated with a nearly stalled front off the Atlantic coast will linger too close to the coastline though not close enough. I referred to this the other day as "baroclinicity" and it often becomes the focal point for moisture and storms. Unfortunately, when energy is consolidated just off the Atlantic coast as is the case this weekend, the weather will remain quiet across interior New England and devoid of snowfall. We are in fact between two systems Saturday with the energy offshore representing one area of storminess and clipper across the Great Lakes concentrating snowfall well west of Vermont. Decaying moisture from this clipper system will finally reach Vermont later on Sunday or Sunday night bringing what I would expect to be our first light accumulation to the region but the bigger possibilities are laying in wait and may at that point be consuming most of our attention by the end of the weekend.
The storm situation in question involve the Tuesday-Wednesday time frame or December 12th and 13th. The pattern will relax somewhat in the wake of the passage of the late weekend clipper but as this is happening, the jet stream will be gearing up for another, even bigger amplification. We don't have any southern branch jet energy to work with but a series of shortwaves will accompany this next incoming surge of cold weather. Can any of these shortwaves be the match that lights the fuse ? Models, all of them, have been erratic and inconsistent in answering this question. The European model had a classic Gulf of Maine bomber on the run released Tuesday afternoon but it was not shown Wednesday morning. The American model seems to be back and forth on this question every 6 hours. The lack of consistency in the operational model runs simply reveals the uncertainty regarding this storm at this juncture. The ensembles, as of early Wednesday, continue to suggest strong hints of a significant snow for all of interior New England. My interpretation ? It's a coin flip - 50 percent.
Even if we end up on the wrong end of this "50 percent", we should be on the receiving end of at least some lighter snowfall. We should get some of this as early as Monday the 11th thanks to a weak area of overrunning moisture and then some additional snow Tuesday from the clipper. Modestly cold air follows for Wednesday and Thursday of next week and then we have the possibility of more snow on Friday December 15th and into the weekend.
The longer range looks about the same as it did several days ago. Though the PNA appears as if it wants to relax as we approach the Winter Solstice the AO will remain decidedly negative and there are no glaring indications of jet tightening in the Pacific though this situation will bear watching in the days to come.
Saturday, December 2, 2017
A few days away a big stretch of winter and maybe a week away from significant snows
It might be a little mild out there but early December is early December. Its always very dark and typically there isn't a lot of snow on the ground. We expect that all to change within the next week or two and we are going to try and zero in on some details but it's still a challenge as we remain several days away from a significant snow.
After a series of sub-freezing nights, we can expect about a 48 hour stretch of above freezing temperatures (somewhat less than that above 2500 feet) beginning Monday afternoon and persisting through Wednesday afternoon. The front marking the end of the thaw will also mark the beginning of a new and very improved pattern. The front will also bring a few hours of modest rainfall to the entire state Tuesday evening along with 45-50 degree temperatures. The rain is all done by Wednesday, the above freezing temperatures are done by Wednesday evening and away we go.
The initial blast of cold will have modified substantially before reaching New England and is taking the scenic root across the Ohio Valley. We can still expect flurries to commence by later Wednesday and continue into Thursday though I am skeptical about accumulations amounting to much. The real question relates to the lingering baraclinicity (a fancy word for temperature boundary) that will remain just offshore. It won't take much to ignite a coastal system on the 9th/10th which is why I described the environment to be a "tinder box" in a tweet the other day. Opinions vary on the viability of storm but Vermont has some optionality. We can get a dose of snow from a potential coastal system which would more likely be Saturday or receive a potentially greater gift if a dymanic clipper system becomes the dominant feature and produces both synoptic snow and lake/terrain enhanced snow Sunday. Can't guarantee anything this early but if I were a betting man, I would take the "over" on at least 6 inches by the end of the weekend.
Not too many changes to the longer range outlook as of the weekend which is a "no news is good news situation". The pattern looks excellent, propelled mostly by a very negative Arctic Oscillation and a big assist from a positive PNA. Another significant "clipper-like" disturbance is likely to bring additional snows to the high country in the Monday/Tuesday time frame ahead of what should be a more significant surge of cold air. Since the air isn't overwhelmingly cold (modestly cold) we get the added benefit of keeping the boundary layer on the unstable side. Particularly intense shots of arctic air can be both very dry and bring a shallow very stable layer to the atmospheric preventing snowfall. All that said, I expect additional snowfall later in the week.
The looming question and I mean the very looming question relates to the Christmas holiday and whether or not this pattern can continue into Christmas week. I can promise good things until about the Winter Solstice but patterns such as this are often interrupted during La Nina years and do not typically last a month or longer. There aren't any ominous signs way out on the horizon but lets be cautious for now.
After a series of sub-freezing nights, we can expect about a 48 hour stretch of above freezing temperatures (somewhat less than that above 2500 feet) beginning Monday afternoon and persisting through Wednesday afternoon. The front marking the end of the thaw will also mark the beginning of a new and very improved pattern. The front will also bring a few hours of modest rainfall to the entire state Tuesday evening along with 45-50 degree temperatures. The rain is all done by Wednesday, the above freezing temperatures are done by Wednesday evening and away we go.
The initial blast of cold will have modified substantially before reaching New England and is taking the scenic root across the Ohio Valley. We can still expect flurries to commence by later Wednesday and continue into Thursday though I am skeptical about accumulations amounting to much. The real question relates to the lingering baraclinicity (a fancy word for temperature boundary) that will remain just offshore. It won't take much to ignite a coastal system on the 9th/10th which is why I described the environment to be a "tinder box" in a tweet the other day. Opinions vary on the viability of storm but Vermont has some optionality. We can get a dose of snow from a potential coastal system which would more likely be Saturday or receive a potentially greater gift if a dymanic clipper system becomes the dominant feature and produces both synoptic snow and lake/terrain enhanced snow Sunday. Can't guarantee anything this early but if I were a betting man, I would take the "over" on at least 6 inches by the end of the weekend.
Not too many changes to the longer range outlook as of the weekend which is a "no news is good news situation". The pattern looks excellent, propelled mostly by a very negative Arctic Oscillation and a big assist from a positive PNA. Another significant "clipper-like" disturbance is likely to bring additional snows to the high country in the Monday/Tuesday time frame ahead of what should be a more significant surge of cold air. Since the air isn't overwhelmingly cold (modestly cold) we get the added benefit of keeping the boundary layer on the unstable side. Particularly intense shots of arctic air can be both very dry and bring a shallow very stable layer to the atmospheric preventing snowfall. All that said, I expect additional snowfall later in the week.
The looming question and I mean the very looming question relates to the Christmas holiday and whether or not this pattern can continue into Christmas week. I can promise good things until about the Winter Solstice but patterns such as this are often interrupted during La Nina years and do not typically last a month or longer. There aren't any ominous signs way out on the horizon but lets be cautious for now.
Thursday, November 30, 2017
Big pattern shift poised to bring multiple weeks of cold and snow to Vermont ski country
Wish the blog could start this way every year ! Though the month of December will begin on the mild side, a very decisive drop in the Arctic Oscillation index over the next week to ten days teamed with a large upper ridge in western North America (+PNA) should bring a December weather weather extravaganza for at least two weeks. We haven't seen a set up this good in December since 2010 and though it will be difficult to pinpoint the best days for "powder", we will get our share over what I expect to be a 2 week stretch of favorable weather beginning December 7th.
A series of rather "blah" days will kick off the month of December. Temperatures will remain mostly below freezing at night and get close to or slightly above freezing during the days. Sunshine will be limited and skiing in Vermont will likely be confined to the usual early season arteries. The early part of the first full week of December will feature a pattern poised to explode. Arctic air will enter the northern Plains and flood the Front Range corridor. As this happens milder air will make its way northward into interior New England. The entire state will likely see an extended almost 36 hour above-freezing stretch accompanied by a few hours of rain later Tuesday. When readings do finally fall back into the 20's late on Wednesday, it will begin what I expect to be a very long stretch of sub-freezing weather and a terrific opportunity to begin establishing what we hope to be a healthy 2017-2018 base.
Though we likely see some flurries late on Wednesday and more snow showers Thursday, significant snowfall might wait until at least at least the weekend before reaching the state. Relating to this upcoming cold pattern, the question relates whether or not we see much of a southern branch of the jet stream. The strength of the building La Nina suggests likely not. We will need a portion of the jet stream in the Pacific to undercut the large ridge in western North America and this kind of thing doesn't usually happen in La Nina years, at least not a lot. That said, we can still see plenty of fireworks along the Atlantic Coast and clipper systems galore. The unusually warm water situated in the Great Lakes and in Lake Champlain actually provide a rather exciting thermodynamic environment when the arctic air attacks. We might start slow, but we will see some terrain enhanced snow and substantial amounts of lake enhanced moisture. There are hints of something along the Atlantic coast during the weekend of the 9th or 10th. Though models were a bit more bearish as of late Thursday (Dec 30th), subsequent runs may very well show some activity and my guess is that our first few significant inches fall over that weekend and perhaps as early as Friday the 8th.
Re enforcing blasts of cold arrive in the December 10th-11th period and both cold and winter weather should dominate the ensuing week through what we hope to be opening weekend on the 16th/17th of the month. A significant storm is possible during this period though I expect that a good chunk of snow falls as a result of a series of smaller systems, clippers and lake and terrain enhanced snow. I'll take it anyway we can get it, should be a great start to the year !
A series of rather "blah" days will kick off the month of December. Temperatures will remain mostly below freezing at night and get close to or slightly above freezing during the days. Sunshine will be limited and skiing in Vermont will likely be confined to the usual early season arteries. The early part of the first full week of December will feature a pattern poised to explode. Arctic air will enter the northern Plains and flood the Front Range corridor. As this happens milder air will make its way northward into interior New England. The entire state will likely see an extended almost 36 hour above-freezing stretch accompanied by a few hours of rain later Tuesday. When readings do finally fall back into the 20's late on Wednesday, it will begin what I expect to be a very long stretch of sub-freezing weather and a terrific opportunity to begin establishing what we hope to be a healthy 2017-2018 base.
Though we likely see some flurries late on Wednesday and more snow showers Thursday, significant snowfall might wait until at least at least the weekend before reaching the state. Relating to this upcoming cold pattern, the question relates whether or not we see much of a southern branch of the jet stream. The strength of the building La Nina suggests likely not. We will need a portion of the jet stream in the Pacific to undercut the large ridge in western North America and this kind of thing doesn't usually happen in La Nina years, at least not a lot. That said, we can still see plenty of fireworks along the Atlantic Coast and clipper systems galore. The unusually warm water situated in the Great Lakes and in Lake Champlain actually provide a rather exciting thermodynamic environment when the arctic air attacks. We might start slow, but we will see some terrain enhanced snow and substantial amounts of lake enhanced moisture. There are hints of something along the Atlantic coast during the weekend of the 9th or 10th. Though models were a bit more bearish as of late Thursday (Dec 30th), subsequent runs may very well show some activity and my guess is that our first few significant inches fall over that weekend and perhaps as early as Friday the 8th.
Re enforcing blasts of cold arrive in the December 10th-11th period and both cold and winter weather should dominate the ensuing week through what we hope to be opening weekend on the 16th/17th of the month. A significant storm is possible during this period though I expect that a good chunk of snow falls as a result of a series of smaller systems, clippers and lake and terrain enhanced snow. I'll take it anyway we can get it, should be a great start to the year !
Monday, November 27, 2017
Lots of analysis, optimism and excited anticipation for 2017-2018, but at the end of it all, temperatures and snow shouldn't be too far from normal
Hope everyone enjoyed their thanksgiving festivities and with those in the rearview mirror, our collective attention turns to ski season and the blog thus returns for another season of prognostications. Those of us following the meteorological world have been watching a few critical variables the last month or so such as a building La Nina, a seemingly non-committal Pacific Decadal Oscillation and an Arctic Oscillation that seems to be very resistant to "negative" behavior. The unrelenting blowtorch that consumed much of later September and all of October generated plenty of consternation but there are reasons for optimism, perhaps not the glowing variety, but enough to expect a fairly solid season in the months ahead.
The state of the El Nino - Southern Oscillation (ENSO) is always at the top of our radar going into a winter season. There are times when the ENSO retreats to relative neutrality, mitigating the impact it might have over a winter and elevating other variables to greater importance. The 2015-2016 situation presented the opposite scenario when a super strong El Nino, a "Super Nino", sucked all the air out of the room and in that particular case, the snow and the cold with it.
In the last several weeks, we have witnessed the ENSO take on a very La Nina look. This wasn't forecast a few months ago proving yet again how challenging it can be to forecast SST trends in the equatorial Pacific. As of early September, the ENSO had really yet to reveal itself but but in the last two months we have seen a decisive trend toward La Nina and in the last two weeks the Nino 3-4 which makes up a broad area of the equatorial Pacific from 120 to 170 west longitude has cooled to 1.1 C below average.
Seasonal SST Animations
A "-1.1 C" La Nina might not be the strongest La Nina, but it's nonetheless significant. If it holds at this level through the winter it will undoubtedly play a role on the weather in eastern North America. In Vermont, we have seen La Nina winter's go both ways. We have seen some huge snow years such as 1970-1971 and 2010-2011 and we have also witnessed some catestrophic seasons such as 1988-89 and 2011-2012. There are obviously several in between. La Nina's produce several obvious impacts such as wet and unsettled weather in the Pacific Northwest and dry and mild weather in the southeast United States. Every inch of latitude is critical, much like it was last winter, for a successful winter weather season. The Mid-Atlantic ski areas in Pennsylvania, New Jersey, Maryland and West Virginia will likely have another challenging year. Farther north however, the season could go either way and given how some of the other variables evolving as of late November, I am inclined to think that our 44 N latitude will serve us quite well, much like it did last year.
The Pacific-Decadal Oscillation (PDO) has a relationship though not a perfect one with the ENSO. The PDO describes the configuration of sea surface temperatures in the mid-latitude Pacific as opposed to the equatorial Pacific and is thus even broader than the ENSO. Rather than explain it further (which I have done in prior years), I'll just provide a link with showing the various positive and negative phases.
PDO Information and phases
I'll note that negative phases have an association with La Nina winters while positive phases often go with El Nino. Though the relationship exists, it is chaotic and a statistical nightmare to try and pin down. The positive PDO was close to a record during the winter of 2014-2015 yet the ENSO was neutral. During that winter, the nature of the PDO was a dominant driver of some of the repeated and particularly intense outbreaks of cold in February.
The PDO has been very non-committal during the autumn months of 2017. The last negative month was December 2013 and though we've gotten pretty close as of October, we haven't quite crossed the "zero" threshold. Whether or not we can turn the PDO negative, it is encouraging to see the PDO index neutral in a "relative" sense. The terrible winters of 1988-89, 1999-2000, and 2011-2012 all had decisively negative PDO's parlayed with significant La Nina's. 2010-2011 featured a positive PDO and was a terrific snow year. The verdict will come in the form of the EPO personality. In the common SWCB tongue, it refers to the prevalence or absence of the "evil empire".
There is one more important element related to the PDO that I did not want to neglect. In the preseason outlook questionnaire that I did for Vermont Ski and Ride magazine I had expressed some concern about a strengthening blob of anomalous ocean warmth in the western Bering Sea and across the Sea of Okhotsk north of Japan. Though somewhat associated with a more positive PDO, the position of this large area of warm water was disconcerting since it was broad enough to potentially tighten the jet stream in the eastern Pacific and discourage ridging in western North America (positive PNA patterns). One could attribute, though not conclusively, the unrelenting blowtorch in October to this Pacific SST configuration. If this area of warmth had maintained its strength through November, it would have profoundly changed the mood of this outlook; fortunately, the area of warmth vanished in a matter of a few weeks. Be it by consequence or by coincidence, the blowtorch ended and November has actually felt like November and a large portion of the month was actually "below normal" in Vermont.
Moving on from our PDO discussion gets us to talk of snowcover expansion. I like to keep this analysis very global or at least hemispheric in nature and though I view snowcover as an important leading indicator, I understand that there are those that don't share that view. With Twitter weather personalities exploding, I have seen the debate over snowcover expansion and its relevance in seasonal forecasting play out visibly on social media. We've had healthy build ups of October/November snow in each of the last 6 years including the last two which preceded mild winters. This has fueled some of the skepticism but proponents of the data such as myself would never argue or attempt to over exaggerate its significance; in fact, I try and make a point to talk it down.
2017 21.17
2016 22.95
2015 21.40
2014 22.88
2013 21.01
2012 20.14
2011 17.34
Average: 18.40
Though ice cover is outpacing 2016 by a significant amount, it continues to run well below average. This is associated with the very discernible long-term trend of receding northern hemispheric arctic sea ice. The interactive sea ice graph (linked below) is one of the most visible displays of the ice retreat. Click on years 40 years ago and compare them to recent years. This kind of trend is scary as its occurring over an incredibly short period of geological time. To say it's an accident or naturally occurring is simply not a reasonable assertion though I wish it were true.
http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
As for the upcoming winter, the healthy expansion of snow in the Northern Hemisphere bodes well the pooling of arctic air masses. It is my belief that the greater the coverage of snow and ice, the greater the ability of arctic air to strengthen efficiently. Speaking slightly more locally, the Hudson Bay is 25-35 percent frozen as of late November which is normal historically speaking but pretty good relative to the last decade. Though the Great Lakes aggregate remains quite warm as a result of the warm fall, the recent stretch of cold has at least chilling down these bodies of water.
Last but not least is our annual examination of "atmospheric tells" with "tells" being poker lingo.This really saved the outlook from going astray last year when there were several bullish indicators suggesting it might be pretty cold yet I suggested, correctly as it turned out, it would be mild. This is not meant to be self-promotional, I busted substantially on snowfall during the Super Nino and I am still trying to figure out how I could have been so blindly optimistic. In spite of some bullish data last autumn, the mild weather during the summer and fall was so persistent and below average temperatures of any significance were so hard to sustain or even achieve that forecasting cold was statistically maniacal. Don't weather patterns change or constantly evolve ? Absolutely. That said, the weather across Vermont and in many other places will exhibit similar patterns of behavior over the course of a season and multiple seasons and such patterns can be foreshadowed in October and November. The back half of 2016 featured a persistently positive Arctic Oscillation (AO) that broke briefly in October (although with very little cold across the continental U.S.) but continued through the winter of 2016-2017. The mild weather ravaged ski seasons from Colorado to the Mid Atlantic during February of this past year and though Vermont also got a big thaw, we were fortunate enough to score big on March snow to save the season.
For much of the last two calendar years, mild air has dominated the U.S. and eastern Canada. 2015-2016 can certainly be attributed to the Super Nino while much of the last year can be associated with the persistently positive AO. The pattern of mild weather has in recent months been somewhat broken. We saw a widespread outbreak of cooler temperatures and a negative AO in August across a wide swatch of the continent. A ferocious blowtorch returned for late September and October but has been broken again in November and so has the positive AO. I'll discuss the shorter term outlook in more detail in a subsequent post but after some mild weather in early December, the northern latitudes look impressively blocked and quite favorable for both colder weather and snow. This is very different behavior relative to the last two years. It may not be enough for me to forecast a cold winter relative to "normal" but certainly colder than the last two seasons by a noticeable amount.
So to summarize, I am cautiously optimistic about the upcoming season. For the third consecutive season, I would have to say temperatures come out on the "above" side of average though not by much and I expect a noticeably colder difference relative to the past two seasons. The strengthening La Nina is a substantial concern as of this posting. If it gets much stronger, we will be dealing with a significant ENSO season and a ridge across the southeast United States could be an overwhelming feature in the weather pattern. Even if we see a relatively stable but moderate La Nina going forward, thaws are still going to be a problem and longer 6-8 stretches of favorable skiing will be unlikely. Our latitude plus what I assume to be the prevalence of arctic air at our latitude should help us immensely on snowfall. In short, I think we perform somewhat similarly to last year on snow, slightly above average, but both ice, periodic rain events and thaws should be expected. I would be surprised if see another thaw consume 3-4 weeks of the winter as it did last February into early March. I'll have an update on the shorter term within a few days. We have some milder weather to get through in early December but the blocking in the weather pattern discussed above should bring winter to Vermont, perhaps in a big way by December 10th making that December 16th potential opening a reality ! Think snow and as always, it's good to be back !
The state of the El Nino - Southern Oscillation (ENSO) is always at the top of our radar going into a winter season. There are times when the ENSO retreats to relative neutrality, mitigating the impact it might have over a winter and elevating other variables to greater importance. The 2015-2016 situation presented the opposite scenario when a super strong El Nino, a "Super Nino", sucked all the air out of the room and in that particular case, the snow and the cold with it.
In the last several weeks, we have witnessed the ENSO take on a very La Nina look. This wasn't forecast a few months ago proving yet again how challenging it can be to forecast SST trends in the equatorial Pacific. As of early September, the ENSO had really yet to reveal itself but but in the last two months we have seen a decisive trend toward La Nina and in the last two weeks the Nino 3-4 which makes up a broad area of the equatorial Pacific from 120 to 170 west longitude has cooled to 1.1 C below average.
Seasonal SST Animations
A "-1.1 C" La Nina might not be the strongest La Nina, but it's nonetheless significant. If it holds at this level through the winter it will undoubtedly play a role on the weather in eastern North America. In Vermont, we have seen La Nina winter's go both ways. We have seen some huge snow years such as 1970-1971 and 2010-2011 and we have also witnessed some catestrophic seasons such as 1988-89 and 2011-2012. There are obviously several in between. La Nina's produce several obvious impacts such as wet and unsettled weather in the Pacific Northwest and dry and mild weather in the southeast United States. Every inch of latitude is critical, much like it was last winter, for a successful winter weather season. The Mid-Atlantic ski areas in Pennsylvania, New Jersey, Maryland and West Virginia will likely have another challenging year. Farther north however, the season could go either way and given how some of the other variables evolving as of late November, I am inclined to think that our 44 N latitude will serve us quite well, much like it did last year.
The Pacific-Decadal Oscillation (PDO) has a relationship though not a perfect one with the ENSO. The PDO describes the configuration of sea surface temperatures in the mid-latitude Pacific as opposed to the equatorial Pacific and is thus even broader than the ENSO. Rather than explain it further (which I have done in prior years), I'll just provide a link with showing the various positive and negative phases.
PDO Information and phases
I'll note that negative phases have an association with La Nina winters while positive phases often go with El Nino. Though the relationship exists, it is chaotic and a statistical nightmare to try and pin down. The positive PDO was close to a record during the winter of 2014-2015 yet the ENSO was neutral. During that winter, the nature of the PDO was a dominant driver of some of the repeated and particularly intense outbreaks of cold in February.
The PDO has been very non-committal during the autumn months of 2017. The last negative month was December 2013 and though we've gotten pretty close as of October, we haven't quite crossed the "zero" threshold. Whether or not we can turn the PDO negative, it is encouraging to see the PDO index neutral in a "relative" sense. The terrible winters of 1988-89, 1999-2000, and 2011-2012 all had decisively negative PDO's parlayed with significant La Nina's. 2010-2011 featured a positive PDO and was a terrific snow year. The verdict will come in the form of the EPO personality. In the common SWCB tongue, it refers to the prevalence or absence of the "evil empire".
There is one more important element related to the PDO that I did not want to neglect. In the preseason outlook questionnaire that I did for Vermont Ski and Ride magazine I had expressed some concern about a strengthening blob of anomalous ocean warmth in the western Bering Sea and across the Sea of Okhotsk north of Japan. Though somewhat associated with a more positive PDO, the position of this large area of warm water was disconcerting since it was broad enough to potentially tighten the jet stream in the eastern Pacific and discourage ridging in western North America (positive PNA patterns). One could attribute, though not conclusively, the unrelenting blowtorch in October to this Pacific SST configuration. If this area of warmth had maintained its strength through November, it would have profoundly changed the mood of this outlook; fortunately, the area of warmth vanished in a matter of a few weeks. Be it by consequence or by coincidence, the blowtorch ended and November has actually felt like November and a large portion of the month was actually "below normal" in Vermont.
Moving on from our PDO discussion gets us to talk of snowcover expansion. I like to keep this analysis very global or at least hemispheric in nature and though I view snowcover as an important leading indicator, I understand that there are those that don't share that view. With Twitter weather personalities exploding, I have seen the debate over snowcover expansion and its relevance in seasonal forecasting play out visibly on social media. We've had healthy build ups of October/November snow in each of the last 6 years including the last two which preceded mild winters. This has fueled some of the skepticism but proponents of the data such as myself would never argue or attempt to over exaggerate its significance; in fact, I try and make a point to talk it down.
2017 21.17
2016 22.95
2015 21.40
2014 22.88
2013 21.01
2012 20.14
2011 17.34
Average: 18.40
Though ice cover is outpacing 2016 by a significant amount, it continues to run well below average. This is associated with the very discernible long-term trend of receding northern hemispheric arctic sea ice. The interactive sea ice graph (linked below) is one of the most visible displays of the ice retreat. Click on years 40 years ago and compare them to recent years. This kind of trend is scary as its occurring over an incredibly short period of geological time. To say it's an accident or naturally occurring is simply not a reasonable assertion though I wish it were true.
http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
As for the upcoming winter, the healthy expansion of snow in the Northern Hemisphere bodes well the pooling of arctic air masses. It is my belief that the greater the coverage of snow and ice, the greater the ability of arctic air to strengthen efficiently. Speaking slightly more locally, the Hudson Bay is 25-35 percent frozen as of late November which is normal historically speaking but pretty good relative to the last decade. Though the Great Lakes aggregate remains quite warm as a result of the warm fall, the recent stretch of cold has at least chilling down these bodies of water.
Last but not least is our annual examination of "atmospheric tells" with "tells" being poker lingo.This really saved the outlook from going astray last year when there were several bullish indicators suggesting it might be pretty cold yet I suggested, correctly as it turned out, it would be mild. This is not meant to be self-promotional, I busted substantially on snowfall during the Super Nino and I am still trying to figure out how I could have been so blindly optimistic. In spite of some bullish data last autumn, the mild weather during the summer and fall was so persistent and below average temperatures of any significance were so hard to sustain or even achieve that forecasting cold was statistically maniacal. Don't weather patterns change or constantly evolve ? Absolutely. That said, the weather across Vermont and in many other places will exhibit similar patterns of behavior over the course of a season and multiple seasons and such patterns can be foreshadowed in October and November. The back half of 2016 featured a persistently positive Arctic Oscillation (AO) that broke briefly in October (although with very little cold across the continental U.S.) but continued through the winter of 2016-2017. The mild weather ravaged ski seasons from Colorado to the Mid Atlantic during February of this past year and though Vermont also got a big thaw, we were fortunate enough to score big on March snow to save the season.
For much of the last two calendar years, mild air has dominated the U.S. and eastern Canada. 2015-2016 can certainly be attributed to the Super Nino while much of the last year can be associated with the persistently positive AO. The pattern of mild weather has in recent months been somewhat broken. We saw a widespread outbreak of cooler temperatures and a negative AO in August across a wide swatch of the continent. A ferocious blowtorch returned for late September and October but has been broken again in November and so has the positive AO. I'll discuss the shorter term outlook in more detail in a subsequent post but after some mild weather in early December, the northern latitudes look impressively blocked and quite favorable for both colder weather and snow. This is very different behavior relative to the last two years. It may not be enough for me to forecast a cold winter relative to "normal" but certainly colder than the last two seasons by a noticeable amount.
So to summarize, I am cautiously optimistic about the upcoming season. For the third consecutive season, I would have to say temperatures come out on the "above" side of average though not by much and I expect a noticeably colder difference relative to the past two seasons. The strengthening La Nina is a substantial concern as of this posting. If it gets much stronger, we will be dealing with a significant ENSO season and a ridge across the southeast United States could be an overwhelming feature in the weather pattern. Even if we see a relatively stable but moderate La Nina going forward, thaws are still going to be a problem and longer 6-8 stretches of favorable skiing will be unlikely. Our latitude plus what I assume to be the prevalence of arctic air at our latitude should help us immensely on snowfall. In short, I think we perform somewhat similarly to last year on snow, slightly above average, but both ice, periodic rain events and thaws should be expected. I would be surprised if see another thaw consume 3-4 weeks of the winter as it did last February into early March. I'll have an update on the shorter term within a few days. We have some milder weather to get through in early December but the blocking in the weather pattern discussed above should bring winter to Vermont, perhaps in a big way by December 10th making that December 16th potential opening a reality ! Think snow and as always, it's good to be back !
Tuesday, April 25, 2017
Winter 2016-17: A fun ride that at times made us a little nausious
Another season in the books and what a ride it was. A little bit of frustration, a little bit of elation and though certainly not a winter for the ages, we came out alright in the end. The bar was set very low following the Super Nino catastrophe of 2015-2016 and although we tasted some of the same pain that was inflicted upon us in that winter, 2016-17 turned out to be very different and certainly much better. The biggest difference was the elimination of the dreaded snow hole which terrorized Vermont skiers during 2015-16. Vermont was in fact, one of the best places to be for snowfall in the northeast receiving a healthy share of storms and we were reintroduced to a nearly forgotten concept of the Champlain enhanced terrain induced snowfall. I mean, I myself had about forgotten all the pleasures of living in the mountains downwind of Lake Champlain and all of ski country benefited copiously.
The traditional winter ski season at MRG stretches 17-18 weeks starting in early to mid December and ending in early to mid April. During most of this span we were dealing with some pretty tough headwinds. The prevailing pattern was, for a majority of the winter season pretty lousy and temperatures were almost as mild as last season once you crunch all the numbers. For 8 of those weeks, the skiing was incredible. We had two weeks in December, 3 spanning the period in late January into the first half of February and another 3 during the month of March into April fools day. Even during those interludes of terrific winter weather, it wasn’t especially cold except for isolated stretches of a few days. In March, we finally recorded a below normal temperatures month which was the first in two years (during the winter) and remarkably, actual temperatures were lower than February, an occurrence that happens perhaps once in 75 years. For those 8 weeks though , we really brought it. Of the nearly 250 inches of snow that fell this year on MRG, three quarters of it fell in that consolidated stretch.
Going into December, just knowing that we had the Super Nino quashed was reason for optimism. Still the inability to sustain below normal temperatures through the summer and fall in any material way was a legitimate concern and was expressed as such in the preseason outlook. This tendency in fact, held through much of the winter largely because of the Arctic Oscillation which maintained a positive index for over 80 percent of the season. The Arctic Oscillation isn't the be all end all of teleconnection indices but from a big picture standpoint, it is the best overall measure of blocking in the jet stream at high latitudes. It is after all, the blocking, which is the best way to sustain cold across the middle latitude climates. Vermont can still can get cold without it and we did in several instances, but the winter as a whole was very mild and the mainly positive AO would be the culprit before anything else. Without the AO we were dependent on a loose jet in the Pacific and a positive Pacific-North American or PNA index which we only received intermittently. The pattern was in generally speaking dominated by zonal flow and lots of storminess in the Pacific, especially in California. The Lake Tahoe ski resorts think they might be skiing until the 4th of July thanks to the nearly 500 inches of snow that fell over the resorts this winter. The glory in the Sierra Nevada high country however proved to painful for ski areas south of 40 N latitude in eastern North America who suffered through long stretches of mild weather and received very little snowfall the few times it was cold. Vermont faired much better and benefited from the personality of the winter which consisted of more snowfall the farther north you went.
By the first week in December, we knew that our winter would not go the way of 2015-2016. A large blocking feature emerged in the Bering Sea and a relatively tight jet in the Pacific loosened considerably. Snowfall came almost instantly and much of it was the terrain induced variety from Lake Champlain. By December 10th we were blanketed with over 3 feet of relatively fluffy snowfall and were immersed in a elongated stretches of sub-freezing temperatures. It proved to be one of the better such stretches of the season amazingly which is unusual for December. Most of the Vermont ski country was opened for business early in December and Mad River followed with an opening on the 2nd full weekend of the month. The cold air associated with the Bering sea block peaked around December 16th with an airmass that brought temperatures on Mt Washington to –35 F, one of the coldest readings I have seen there in several years. The large Bering Sea block which was the catalyst behind that nice stretch of December weather broke down by the Winter Solstice and at no point during the rest of the winter did we see a large blocking feature of the same magnitude. Rain and ice arrived by the 18th of the month and most of the holiday period was spent in a defensive posture, while snow piled up across the west.
Mild weather continued into the first few days of 2017 and was followed by a widespread outbreak of cold between January 5th and 9th that somewhat snuck up on eastern North America. The absence of any jet stream blocking feature allowed the cold to escape rather quickly before snow of any significance reinvigorated the rather "crusty" conditions. The middle of January didn't feature record warmth but the pattern was dominated by a zonal flow and a powerful Pacific Jet that unloaded an amazing amount of snow on the Sierra Nevada range and other parts of the intermountain west. MRG stayed open and was dangling by a thread for several days during the middle of the month yet maintained a relatively healthy base above 3000 feet that proved useful as time went along. One of the more significant precipitation producing storms of the month impacted the region around the time of the 23rd 24th of Jan. Temperature profiles were marginal and in the end, the mountain ended up receiving several inches of sleet. It was a disappointing result but it laid the foundation for what became an outstanding stretch of winter. It began Thursday the 26th with an elevation snowfall that yielded 6-8 inches and this was followed 5 more inches of the Champlain stuff Friday night and several more inches during the weekend.
The first two weeks of February featured a weakened Pacific Jet, a tenuous ridge in western North America and some of the best skiing of the year in Vermont. The snow piled up rather impressively, not all at once but in several 5-10 powder days. We had a brief several hour period of rain on February 8th but aside from that, the first 17 days of February stayed below freezing and the snow was plentiful. Adding the last few days of January into this 3 week stretch, the mountain received 5 feet of snow between January 26th and February 16th and I remember the mountain declaring for the first time in 2 years "We are 100 percent open"! The best storm in that stretch came February 12th and 13th which was roughly an 18 incher. We got side swiped by another storm later in the week that provided another 6-10 inches and made for some terrific skiing for the first part of the President's Day holiday. Ominous signs loomed however and though I certainly suggested some rough times ahead, I totally underestimated how incredibly bad it became.
The last 10 days of February is often when some of the best skiing is there to be had at MRG. By February 11th , it certainly appeared that the holiday week following President's Day would not feature such conditions. In spite of this, the mild weather appeared like it would be somewhat short lived and ultimately replaced by a more productive pattern to close out the month. What happened was a complete abomination. Some mild weather around President's Day proved only to foreshadow a catastrophically warm period that began on the 21st. Lingering arctic air in Quebec or even a layer of cloudiness couldn’t save us. Mild air fully enveloped the region and not only was every day above freezing, it blew away expectations. Temperatures on the mountain exceeded 50 on 5 different days and when combined with the wind and the heavy rain on the 25th, our deep snow was obliterated.
March 1st featured temperatures 30 above normal and there was legitimate "nail in the coffin" fear. There was the promise of a much more favorable pattern but a very dismissive form of cynicism emanated from the Mad River Glen community. Temperatures were 25 below normal on March 4th but accompanied by plenty of bare ground ! A potential storm during the middle of the first full week of March turned into another mini washout and this was followed by one of the most intense blasts of arctic air of the season March 11th accompanied again by hardly any snow ! At this point however we had our eyes gazed at a storm system poised to blast the northeast corridor with winter weather. It was apparent the storm would be a substantial event quite early and furthermore MRG was certainly in position to be on the receiving end of some of the goodies. That said, models suggested a bigger hit in coastal cities and even an 8-14 inch storm could have fallen short of what was needed to reopen the mountain for business. The SCWB fumbled the football a bit on the intensity of the February thaw, but remained a believer in the potential of the pattern in March and the possibility of getting "bullseyed" by the March 14th event. It was "Game of Thrones" style drama, season 6 to be specific since the rest of the seasons had crap endings. With time winding down on the clock, models shifted the track of the storm 100 miles west and just like that we were free to fly. The March 14th storm started right at daybreak, slammed the Green Mountains with 3 inch an hour snowfall rates during the evening and continued right through March 15 enabling MRG to score 30-plus inches. It certainly ranked as one of the best since the inception of the blog back in 2004. Cold weather continued for several days in the wake of the storm and allowed for skiing enjoyment into the ensuing weekend. Additional snow and another arctic blast around March 22 provided an additional powdery window.
Temperatures warmed somewhat during the last few days of March and into the first full week of April. The snow was slow to melt however and allowed for skiable terrain until the weekend of April 8th and 9th. By the end of the season, snowfall in most areas, particularly in the high country, was above average and I know a few hearty souls continue to make turns with the cornhorn firmly in hand as of late April. I know there were some rough times, but I'll take a winter like this over a few other the blog has presided over. A highly favorable pattern never really seemed to materialize but the marginally favorable ones allowed for 7-8 incredible weeks. Hopefully we can achieve the same type of success in terms of snowfall next season but without the prolonged interruptions. Enjoy the summer folks and sorry for the delay !
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