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Friday, December 29, 2017

Will the caboose produce ? And what does that mean ?

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. 


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.  


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



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.

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.

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.

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.

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.

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.

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.

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.

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.





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.