Think Snow, Tweet Snow !!!

Tuesday, December 30, 2014

Winter read to take a tight grip on Vermont for the next 10 days

Winter is back and should have a clear reign over interior New England over the next 10 days. Temperatures should get very chilly even by New England standards but there should be some snow along with this pattern coming a couple of different ways. In the short term, the dry forecast I put out a few days ago should actually get thwarted by disturbance rotating through the Hudson bay embedded within the polar jet. Not much moisture with this feature but clouds and some light snow should overspread the region New Years Day and continue into part of Friday January 2nd. The snow could amount to 1-4 inches and will be of the "very fluffy" variety. Arctic high pressure then takes a very temporary grip on the region Friday night into early Saturday and sets the stage for our next precipitation producer Saturday night into Sunday.

The upcoming weekend storm continues to look significant and though we have narrowed the outcomes of this considerably there remains some small uncertainty regarding the final track of this storm. The main area of low pressure could travel anywhere between extreme southern Quebec and Massachusetts. There are other questions relating to the evolution of this storm as it interacts with the Atlantic coast as there most always is. That all being said, I am relatively confident that some significant snow should impact northern Vermont early Sunday, accumulate several inches and then possibly change to a sleet/freezing rain mixture and possibly not. I don't think the region has to worry about the "R" word anymore though coastal cities should see that almost exclusively. The possibility of a 8-16 inch powder-fest still exists though and hopefully this outcome wins the day and gets 2015 off to a positive start.

Very cold weather is expected to take direct aim at New England next week thanks to the full force of the Polar Jet. We haven't seen the ole PJ in a while actually and it should although we were hit with some chilly weather in these days after Christmas, it will pale in comparison to some very sub-zero temperatures that should impact the region next week. The cold weather will re-build across the region Monday and then a reenforcing blast of arctic air should send readings to their lowest point of the season so far sometime during the middle to later part of next week. Now the interesting part of this story relates to this reenforcing blast of cold and what kind of disturbance might be responsible for this. There have been hints of some potent PJ energy capable of churning up a storm for New England at some point next week. The Euro showed this 12/29 but took it away 12/30 but I mention it since I believe it's worth watching.

Beyond next week we still have to concern ourselves with the ongoing battle of the arctic cold verses the warm discussed in the last update. A upper ridge in the southeast will be prevalent and will push occasionally very mild air in our direction and this is expected to occur again around the time of the 10th. If the southern branch of the jet, remains strong enough, it should be able to break this ridge down and keep the weather interesting as opposed to mild for the middle of January.

Saturday, December 27, 2014

Holiday Update - The Longer Version

Time for a long version and a bit more detail on what should be an interesting upcoming period across interior New England. We are finally coming to the end of a stretch of relative warmth. Fortunately, it wasn't record warmth but it came at an inopportune time and we are in need of some replenishment. I can't promise any of that in the short term I am sorry to say but we will see a return to winter-like temps following just about a tenth of an inch of rain Saturday night or early Sunday. It will then turn chilly with temperatures well below freezing through pretty much all of the upcoming New Years week. With the exception of a few flurries here and there, it will also be precipitation free.

Although arctic air will make a very profound descent on North America this week, it's continued presence across the U.S. beyond the 2nd across much of the U.S. including New England will not go unchallenged. The jet stream in the Pacific will remain relatively loose for a time, and we will have the support of some high latitude blocking which is expected to start in the Yukon and retrograde more to the Bering Sea. Let it be known that I would certainly prefer any high latitude blocking as opposed to none, but the position of this particular block in the jet stream will be west of a perfectly ideal location. Arctic air will thus have to contend with a upper ridge over the Southeast U.S. which will invariably want to push milder temperatures up the Eastern Seaboard.

There are nothing wrong with such challenges I will point out. This is how storms get churned up and often how very good periods of snowfall can occur across interior New England but it's always a close call and sometimes we end up with rain or ice. This is the very scenario that confronts us on or around the time of January 3rd, which will be the day, or close to the day when our next significant precipitation-producer arrives. The initial low pressure center is likely to pass to the west of New England but we could see a couple of things in spite of this. 1) We could see the storm transfer it's energy to the coast and save the region from another partial meltdown. 2) We could an extended period of overrunning snow before any change to sleet or ice or the dreaded rain. 3) We could still see the track of this storm shift south and east a bit more yielding a much more favorable result for the Vermont high country.

I think this will be a ongoing battle through around the middle of January. Cold weather fighting it out with an occasional mild push of air. Each of these air mass clashes though should bring the chance for a storm and some wintry precipitation to the region. It's hard to fathom this particular pattern lingering too long into January. A ridge across the southeast U.S. is not something that is typically very prevalent during any kind of El Nino, even a weak one. It will be interesting to see how this all evolves, but given the presence of arctic air, I would surprised if we end up with little or nothing to show for all this by January 15th.

Friday, December 26, 2014

Holiday update - Just the short version

Been a little tough to do a full update the past few days so my apologies for that. I can do a short version right now and a longer version tomorrow. We have some light rain to contend with early Sunday after one more mild day Saturday. It then turns colder but unfortunately, no Pre-New Years storm. The next big precipitation producer will likely come during the weekend after New Years. Arctic air will be battling it out with a strong upper ridge in the Southeast. It's a close call right now between mixed precipitation or snow so I am hoping for a bit more clarity tomorrow when we do a subsequent and more comprehensive update.

Monday, December 22, 2014

Through the holidays and beyond

Through most of this December, Northern New England has been one of the few places east of the Mississippi to actually enjoy some assemblance of winter. This remains true as of early in the Christmas week. Temperatures have begun their rise over a large expanse of the country but readings remain below freezing under clouds across much of the Vermont high country. This is about the only good thing I can say in the short term. It is not very advantageous to be anywhere in the east during the Christmas holiday, Vermont included.

Moisture from a piece of the approaching storm system will arrive Monday night as some snow, accumulate a few inches then turn freezing drizzle or some freezing rain during the midday hours Tuesday. Some locations are indicated to get above freezing during the day Tuesday but I think much of the mountain can hang on to 32 F for most of the day. Models do indicate a more organized area of rain, arriving Tuesday night which will likely fall as some rain in most places and freezing rain in some.

A massive surge of mid-layer tropospheric warmth is expected to arrive by Wednesday morning. Most of this air will remain a couple thousand feet above the surface and it could provide one of those rare situations where the summit of Mt Washington out does all the valley locations on temperature. Even the summit of General Stark could warm to near 40 by late Christmas eve before valley locations do the same by early Christmas morning. There is no avoiding the rain however. It will remain sporadic through early Christmas eve then turn heavier during the day. I am hoping the temperature inversion will keep the winds down since high winds combined with high dewpoints and rain can eat away at snow very quickly. Models do indicate a small window of time early Christmas day when some of the excessive mid-level warmth could mix down to the surface allowing temperatures to surge (perhaps as high as 50). This would occur just as some of the better frontogenetics are pushing through the region allowing for the possibility of very heavy rain and even a thunderstorm. The pain should be over with by later in the day on Christmas and temperatures will fall back toward the freezing mark by the 26th.

The overall weather pattern is expected oscillate quite violently over the next several weeks. A loosening of the jet in the Pacific combined with the development of the large upper level ridge over Alaska and the Yukon will support a turn toward colder temperatures. The arrival of the cold in Vermont will have to wait until the 28th (both Friday and Saturday following Xmas could see readings sneak above freezing still). The combined presence of Arctic air in the days before New Years along with a trough position in the middle of the continent does provide an inviting open door for a substantial winter weather event around or just before New Years Day. Medium range models have gone back and forth on this; but in this update, it is a small island of hope in a sea of bad news.

The Madden-Julian Oscillation or MJO is what has many in the meteorological community talking over the last few days. At least as it pertains to weather as we head into January. I don't want to get too bogged down talking about the phenomena, but to put it as simply as I can, the MJO describes a cycle of convective thunderstorm activity near the Indian Ocean. There are several phases of the MJO and each phase can have an impact on the Jet Stream in the Pacific, how loose or tight it is and whether or not we will see an evil empire. The MJO has been very disappointing this month. It spent a number of days in adverse phases for us and has since proceeded toward neutrality without fully rotating toward favorable phases. By early January, it is now expected to move back into treacherous ground for us. This is a big reason why some of the ensemble guidance has allowed the cold pattern to flop just after the New Year. We don't have total agreement on some of this but there are enough indications to suggest that the cold will retreat again in early January. If it's a modest retreat, we can still hold out hope for some snowfall but a full retreat could put a hurting on us again. We shall see.

Friday, December 19, 2014

Join the movement ! Sign the petition ! Keep the warm air out !

If there seriously was a community-action type movement, I would certainly put a sign in my yard. I even wonder if I made a tee-shirt "keep the warm air out" and sold them at the Mad River Glen general store, would they sell. They should this week..

I am certainly a little disappointed at Santa Claus for the partial Christmas debauchery that models are currently indicating for the mountain. Especially for a week that showed such promise a week ago only to turn so horribly wrong the last few days. The model consensus has moved away from the "Midwest hurricane" which was indicated a few days ago. This would have a more dire scenario with, warm air, rain, wind, and high dewpoints dealing the mountain a crippling blow heading into the New Year. The period of 40-plus warmth and rain appears limited to a smaller window now but needless to say it will still do some damage.

In the very short term, we will get a chance to dry out this weekend. Limited sunshine and a higher ceiling should allow for better visibility. Temperatures will also remain below freezing through Monday. Part of our "How the Grinch Stole Our Snow" story next week involves how a storm which originally seemed to destined to be a big east coast hit Sunday/Monday, has fizzled to nothing (Monday looks entirely dry) and how all the action now is confined to the massive mid-continent jet amplification which will have a clear dominance over the battlefield.

As of now, there appear to be a few pieces to the Christmas storm and although this is still hardly ideal, it is better than the alternative as I had mentioned - the bomb/hurricane looking system over the Midwest. The first wave brings it's moisture into interior New England Tuesday; in fact, temperatures at that point might still be able to support snow for a time before going to some freezing rain or drizzle. If the storm conglomerate remains a conglomerate, the near freezing temperatures will put up some resistance and we will avoid any substantial melt-off through early Christmas Eve. After that though, the region will see a tremendous surge of both Atlantic Ocean moisture and air and this will allow readings to climb into the upper 30's. The rain could be heavy and be accompanied by wind - it won't be pretty. There are indications on some of the medium range models that temperatures spike into the mid-40's, though I am still holding out some hope that we remain in the 30's, partially limiting the damage.

With the trough amplification occurring much farther west than we would have preferred and the upper air energy associated with this storm drifting north into eastern Canada late next week, it will actually take a bit of time to chill the mountain down again. Wrap around moisture might be able to sweep back into Vermont by the 26th but snow will be limited and valley temperatures might remain above freezing. There is a second weather system that should come out of the Rockies late in the week which could bring mixed precipitation or snow to the region around the time of the 27th. Hopefully this begins our road back.

We still expect the emergence of a jet stream block over Alaska and a loosening of the jet in the mid-latitude Pacific. Eventually, even the NAO is expected to make a run into negative territory. This will support the presence of cold arctic air across much of the country including New England. There has been a trend in recent days to shift the main thrust of this arctic air westward allowing the east coast to be more in a battle zone of air-masses. This works fine for us since it usually means storminess, and we will need that after the Grinch steals our snow Christmas eve.

Wednesday, December 17, 2014

Potential Christmas storm looking more like a "meltdown"

I almost felt that we had some authentic "mojo" this year, the chaos of New England weather can put the kibosh on those good vibes very quickly. I sincerely wish I had better news for the Christmas holiday but I don't today. We knew it was going to be a stormy week, a week with some potential but it looks today like mother nature could take us to the woodshed.

In the short term the mountain will be fine. Snow on Wednesday night into Thursday will amount to 3-6 inches and we will temporarily rid ourselves of the dreary dampness. Bluer skies should arrive Friday will be accompanied by seasonable temperatures and this will be followed by a fantastic visibility day Saturday, again with seasonable temperatures.  By the end of the weekend, we could see some clouds move into the region but even Sunday should be precipitation-free.

All the action comes during the upcoming Christmas week. There are still two weather systems worthy of mention but the 2nd will hog most of the headlines. The first will do a slow lollygag along the Gulf Coast this weekend and try and gather some energy as it reaches the Atlantic Sunday. I had much higher hopes of this system honestly, as did many others in the meteorology community. For now however, it appears this storm will struggle to attain any significant strength and although it will proceed up the east coast Monday it will only bring limited moisture into New England early in the week. I am not giving up entirely on this system but current indications are for a limited accumulation if anything at all.

After that is when our headache might begin. The 2nd in the series of southern branch features will follow closely on the heels of the first, but the 2nd will make it's eastward progression just as a major piece of Pacific energy is cascading southeast out of the Northern Rockies. This is an extremely unfortunate turn of events if it were to play out this way. The two systems will phase in the middle of the country, way, way too far west for our liking. A storm will thus explode in the Ohio Valley and Great Lakes region and the storm could be strong enough to suck extremely warm air from the Atlantic Ocean through all New England and even deep into Quebec. There could be wind, high dewpoints and a lot of rain, all of which contribute to the dreaded meltdown which we really wouldn't want. I am seriously calling for a lifeline on this, especially since the list of ingredients could have produced some exceptionally positive results if we could simply mixed all this stuff together a little differently.

Is there a way out ? Please ! It was such a resounding statement from two of the major computer models today that I am cowering in fear right now. I hate rain on Christmas anyway and I double hate it when it's melting snow. Yes though, I will keep the slight possibility of a way out. My hope right now is that the southern branch feature can haul ass early next week, get well out in front of the trailing Pacific energy and thus allow for a later amplification. The storm in that case might be able to jump to the coast before exploding and flooding us with warm air. If your planning to ski on Christmas day or just beyond, my advice would be to join me in prayer in that regard.

The trend toward a colder pattern, anchored mostly by the emergence of blocking across Alaska and the Yukon and a much looser Pacific jet remains on track around Dec 27-28. The new "colder" pattern could also be accompanied by more storminess as there remains indications of split flow in the jet. We should be able to keep this going through the early part of January as well so at least we have that.

Monday, December 15, 2014

Evolving weather pattern will bring back the cold while storm potential continues

Though it may be categorically "above-normal", a thaw it has not been. Temperatures have generally remained below-freezing on the mountain and the deep snow has so far held its ground. The next storm system will bring its precipitation to the mountain Tuesday night and we still expect temperatures in the lowest 5,000 feet to be very marginal. This being said, models are only allowing these "marginal" temps to get to about 34 or 35 which keep the door open for mixed precipitation as opposed to plain rain. The summits might be able to keep the precip-type completely frozen. This system is eying the St Lawrence Valley as it's favored track but it will make that important jump to the coast during the day Wednesday and in doing so will allow the lower troposphere to cool enough to support some snow. What does fall later Wednesday into Wednesday night will be of the terrain-enhanced variety and could accumulate 2-5 inches by first tracks time Thursday.

There is lots to talk about today including some potential storms and some big-picture changes that will have a profound impact on MRG weather as we head toward the end of 2014. In spite of all the snow, the pattern has not been anchored by favorable teleconnection indices and the jet stream in the Pacific has been much too tight for my liking allowing the EPO index to remain positive. Over the next 7-10 days, the jet in the Pacific will loosen dramatically, a ridge will establish itself over Alaska and the Polar jet will make it's presence known. The country as a whole has seen very limited amounts of cold over the first two weeks of December and MRG has had a very limited supply to work with during the last two recent snow events (though we managed to come out on top anyway). After Christmas, this will be very different, cold will cover much of the country, New England included, and so long we can keep the southern branch of the jet stream active (which is legit question), things will get very interesting.

Actually things are already interesting and this refers back to our last discussion a few days ago. There are two systems of note and one or both or none could have a significant impact on the region between the 21st and 26th of the month. The first is a strong southern branch system, yet another in this El Nino winter, which will progress across part of the country by the 20th and then attempt to make a northeastward turn as it heads toward the Atlantic Coast. Models over the last three days have produced a variety of results regarding the outcome of this system. As of Monday afternoon, the consensus of information actually allowed the storm to simply move out over the ocean and remain a non-event for most of New England. I bring it up however because it is hardly game-over with this system. The polar jet will remain rather uninvolved in the weather pattern through the 21st and thus the door is open for this thing to make critical northward turn. I wouldn't at all be surprised to see models sing a different tune on this storm either tomorrow or the next day.

Potential storm #2 will impact the region around Christmas as cold air invades a large swath of the plains and Rocky Mountains. There is legitimate concern that the pattern could initially amplify too far west and allow any storm to ride into the Great Lakes but it's early and their are lots of moving parts here. Incoming polar jet, southern stream energy and changes in the pattern at a big picture are level are all going to have some impact.

Friday, December 12, 2014

Mild air won't dent us too much over the next few days so lets discuss more interesting stuff down the road

The big nor'easter has left MRG sitting pretty on December 12th with a terrific base to work of off. Hopefully as many of you as possible were able to make it out for opening day, the earliest in a decade if memory serves. To provide some perspective, I remember years where no one has been up the single until mid-January

Although flurries will continue through Saturday, we are entering a brief drier and milder stretch of days. I say mild but the relative "warmth" will merely consist of a few comfortable above-freezing afternoons Sunday, Monday and Tuesday and when I say "above freezing" I am talking mid-30's. All three of these days should feature some great visibility as well which the mountain hasn't had since Monday. If there is a upcoming concern, it involves a potential weather system that is expected to swing through the region Tuesday night. Temperatures will be quite marginal and we may see rain or mixed precipitation. There is a Great Lakes low pressure center with this system that is likely to pass to our west but it is possible that the storm makes a jump to the coast. If it does this quickly, and the coastal system can intensify quickly, it could keep precipitation mostly frozen and even allow for a few inches of snow before more seasonable below freezing temperatures are ushered back into the region later in the week.

There are two very visible, and very intriguing looking southern jet disturbances that have been on many of the recent ensemble runs over the past two days or so. They begin a progression across the southern part of the country late next week and move into Texas by the weekend of the 20th/21st. Meanwhile, the pattern fundamentally will begin to take on a different shape. The blowtorch across Canada will subside and this should start to open the door for colder weather to enter the weather picture (although I don't think this really happens until after Christmas). The system in Texas next weekend will need some help, a wingman so to speak. If a disturbance, either Pacific or Polar, can come and provide a little assistance, this could again wind up being a significant east coast system in the days prior to Christmas. The same goes for the 2nd disturbance which should trail the first by a few days.

In short, with the threat of a big warm-up now mitigated, we can now focus on what could wind up being a very exciting period around the days of the Christmas holiday, with all this occurring after an early open and 45 inches of snow which has already fallen this month. I'll talk more about some of the longer range stuff come this Sunday when we could perhaps have a clearer view at particulars.

Wednesday, December 10, 2014

Snowflakes are back and they should start to pile up

Beautiful looking swatch of moisture rotated back into interior New England and ultimately Vermont Wednesday afternoon bringing heavier precipitation back to Vermont. The light freezing rain and sleet changed back to some snow and this should continue into Wednesday evening as the lower troposphere continues to cool; in fact, we should see less and less sleet/freezing rain and more and more snow as the hours go by.

The decaying surface low pressure center will drift, ever so slowly, toward the Canadian Border tonight into tomorrow. The various conveyors of moisture currently on radar won't be as pronounced allowing select locations to get lucky while others are less than lucky. Still, we should begin seeing some good terrain enhancement tomorrow which should persist through Friday and then taper to flurries or very light snow Saturday. Hopefully opening day ! Additional accumulations beginning now and ending by early in the day Saturday could easily be a foot.

We still have a few above-freezing afternoon's to contend with beginning Sunday and ending Tuesday but the end of next week appears categorically cooler or normal.

Tuesday, December 9, 2014

Heavy snow overspreads the Green Mts Tuesday but will it continue ?

Just a quick update...

Good moderate to heavy snow is falling across the Green Mountains as of early evening Tuesday. We need this to keep up because the snow is falling through a small but very marginally above-freezing layer in the atmosphere. Would not at all be surprised to see some sleet and freezing rain mix into the snow later this evening. It could be a bit of a back and forth battle during the overnight depending on the intensity of the precipitation. The heavy stuff will come down more as snow while the light stuff will be more of a sleet/freezing rain mixture. By Wednesday morning, most of the heaviest precipitation will be over with and we will see sleet, freezing rain or even some plain rain for much of the day. I really do think total accumulations (5-10 inches) will be held down by the mixing but we will see a very healthy water equivalent out of this which means we have a great foundation to build on.

The atmosphere will cool enough Wednesday night for snow to re-commence and continue both Thursday, Friday and possibly into Saturday. The storm will have occluded, essentially meaning that it has reached its final state of maturation and will decay but it will only move very slowly as it does this. This is a set up that favors terrain enhanced snow and we could see an additional 6-12 inches over the 2-3 day period. We won't see the kind of snowfall rates we saw Tuesday evening but the steady light snow should add over the course of 3-days.

Still looking at some milder days late this weekend into early next week. A feared massive thaw is starting to look less lightly as come chillier air will sneak back into the region later in the week.

Monday, December 8, 2014

Variety pack of weather set to hit MRG with mid-week nor'easter

Almost game time with this storm though it's only beginning to take shape as of Tuesday afternoon.  It is a rather unique merging, almost collision of two garden variety weather systems. One, well off the Mid Atlantic coast that will migrate northwestward toward the coast, and another passing rather innocently through the Great Lakes. The two will phase in magnificent fashion Tuesday morning and the fireworks show ensues. Rain and snow will light up the radar screen by Tuesday afternoon and snow should spread into MRG by the middle of the afternoon. Cold arctic air snuck its way into New England Sunday night and will continue a tenuous grip on the region through the onset of precipitation tomorrow. It should get quite fun for a time with huge snowfall rates Tuesday evening into early Tuesday night allowing accumulations to get as high as a foot and very quickly.

The track of this quite powerful nor'easter is expected to proceed to southern New England before becoming nearly stationary. Warm air will thus get sucked around the top side of the storm in counter-clockwise fashion. I expect we will see a lull in the precipitation as this happens, often referred to as a dry slot. Once precipitation does re-commence during the day Wednesday, it is unlikely to be snow.  There are some interesting temperature profiles being shown by some of the shorter range computer models and they run counter to some of my thoughts from the last post. During the day Wednesday, a layer of above freezing temperatures is expected to cover northern Vermont between 6,000 and 10,000 feet. Below that, readings struggle to reach the freezing mark. One would look at this storm and quickly conclude that it is not an "overrunning-style" event but temperature profiles show that type of structure. So instead of a elevation sensitive rain/snow day on Wednesday, it looks more like sleet/freezing rain/rain type of day. Any powder that falls Tuesday evening is going to get a very quick glaze or get mashed up by the sleet.

After a period of the non-snow type stuff Wednesday, temperatures in the lower troposphere should cool enough to support snow, particularly at the high elevations. The storm is expected to occlude by this point and although this eliminates the chance for extremely heavy precipitation. Elevation sensitive snow should be able to persist through Thursday into Friday. I am still hoping that the storm just gets a small second wind while repositioning itself near the coast Thursday. This could allow a period of at least moderate snow Thursday or Thursday night. Whatever does fall Thursday into Friday will be wet at low elevations and only powdery near the summits and accumulations will range from a relatively low few inches in the valley's to upwards of an additional foot near the summits. Because of the sleet/freezing rain/rain situation Wednesday, I highly doubt we will ever have 2 feet on the ground at the end of the storm. We are more likely to get a good 6-12 inch thump Tuesday night which will get compressed Wednesday with another layer of 6-12 inches between Wednesday night and Friday. Classic New England !

I've seen some maps suggesting a widespread 1-2 foot storm for Vermont. This might work for the Adirondacks but I think this is too aggressive for all of Vermont. Don't think we will score those results unless you above 2000 feet but fortunately most of Mad River is.

We still are going to have to contend with a nasty string of mild days beginning late this weekend. The Pacific is not friendly right now with the positive EPO (Equatorial Pacific Oscillation) creating the dreaded evil empire. We will have an active southern branch of the jet next week into the Winter Solstice but with very limited cold air. Expect several above freezing days next week and a day with some plain rain. Unfortunately, the pattern could linger until just before the Christmas holiday.

Saturday, December 6, 2014

Tuesday/Wednesday Nor'easter is happening but expected track shifts west

We're a couple inches closer thanks to some snow on Friday and Saturday and could get very close with a little help from some fortuitous "bomb-o-genesis" Tuesday and Wednesday. Every time a model shows an event like this I think of Bob Weir's solo effort "Bombs Away". The lyrics in the chorus are "Bombs Away (bombs away), I think I am back in love again". Nothing but love for Bob Weir, but it is not one of my favorite songs. I just can't keep it out of my head when a nor'easter shows up and why not. The lyrics are perfectly appropriate in regards to pre-storm anticipation and those lyrics will be a future tweet sometime but just not now. The uncertainty regarding development of this storm has vanished, it will happen and it will be big. Unfortunately, a big snow event at MRG is far from guaranteed. At the least though, the storm will bring some drama and if your a weather enthusiast get ready !

I referenced the great Nor'easter of December 1992 and there are some similarities with the upcoming storm. That storm also formed without much help from the polar jet and had limited amounts of cold to work with. The storm caused historic coastal flooding that in the last 30 years has probably only been surpassed by Hurricane Sandy. It also dumped 30-50 inches of snow on the Catskills and Berkshires (I can't quite remember how Vermont fared on that one). The lack energy from the polar jet can open the door for warm intrusions of air and a dreaded change to rain but it also means a very slow moving event. These are the very items that need to be discussed with the upcoming storm.

As of late Saturday we are starting to establish a consensus based on data from several medium range computer models. This consensus has actually shifted the track of this very strong storm farther west, particularly Tuesday evening. The European and Canadian model now suggest an inland track that allows the storm to track west of Boston. The limited cold would be at least partially flushed out and the region would have to endure a change to rain at least at low elevations late Feb 2010-style. The American model has been the last arriving guest to the nor'easter party but would suggest the most ideal solution - all snow, all the time at all elevations.

With the European/Canadian blend performing better with this event so far I am inclined to believe the "warmer" scenario which does allow for a period of rain at low elevations. The silver lining has to do with the aforementioned paragraph.  The storm will be a very slow mover and its final phase of maturation, the closing off of the low pressure system or occlusion, it will reposition itself along the coast and could allow for elongated period of light to moderate snow later in the upcoming week.

As for specific timing, precipitation will begin as all snow and become very heavy for a time later in the day Tuesday into Tuesday evening. By early Wednesday morning, warm ocean air would allow low elevations to change to plain rain while snow continues to fall near the summits of the Green Mountains. This type of storm will be incredibly elevation sensitive on Wednesday. By Wednesday night, once the storm begins to occlude, we could see a change back to snow. The snow intensity is unlikely to be heavy and will fall at varying intensities (we could also see a lull in all precipitation) but accumulations could be significant. Even with a warmer track, we still could see 6-12 inches of snow on the front end of this event and another 5-15 inches at the back. The rain at low elevations Wednesday is a "downer" but not an "outer" for this event. Total snowfall could still be over 20 inches, especially above 3000 feet.

Following the storm the region will have to endure a gradual warm-up and what could be some very warm days around the 14th to 17th of December. This is in response to the overall North American retreat of the cold thanks mostly to the severely tightened jet in the Pacific. Around the time of the Solstice the pattern might normalize, thanks mostly to a PNA ridge which is expected to form around that time. The southern branch of the jet though is clearly and very back in business this year.  This is a classic El Nino personality and this means lots of potential storms event with just a minimal amount of cold, very much like the one in front of us.

Thursday, December 4, 2014

Talk of a big storm ignites in spite of a lousy looking weather pattern

In what looks, in the large scale, like a very no-fun weather pattern, Vermonters might be in need of their party hats next week. I don't want to get too carried away but there is, at the very least, a good deal to discuss over the next week. Mad River has yet to open so we will try and keep this concise.

There are now two precipitation producers to talk about, the 2nd of which is the most intriguing but also the most uncertain. The first arrives Friday night and brings the ole variety pack of weather with it. Although a limited supply of cold has been positioned over New England, it will grow stale by late Friday. Precipitation will arrive in the form of snow, accumulate 1-3 inches and then change to freezing rain or rain, depending on the exact location. Model cross sections do show the potential for a return to snow Saturday afternoon or evening after several hours of freezing rain, rain or drizzle. The snow on the back end of this system could again amount to several inches. Hopefully it all makes for a nice concrete slab to build on. Nothing wrong with a good foundation if that's what we get.

Arctic air positioned in Quebec will then infiltrate the region and become what could be an important ingredient. The big picture view shows the polar jet in full retreat mode next week and although this can be counter-productive, it can also allow open the door for all sorts of interesting things along the east coast. Think about it ! No polar jet and nothing steer some of the bigger Atlantic storms out to sea. So it basically goes like this. A storm will gather strength near the Virginia Tidewater Monday and proceed up the coast Tuesday. Meanwhile, a leftover Pacific disturbance will dive into the Midwest and little provide the dynamite for what should be an explosive storm. A classic noreaster actually, though the coast should be spared of any snow.
The cold air comes compliments of our buddies in Quebec but it will only have a precarious hold on the region. That and the American GFS model continues to take the system out innocently over the ocean. So the possibility of a rain event and the possibility of a total whiff remains a part of the possibility range. This being said, the more I look at this system, the more I think it could produce results. Maybe even big results of the foot or more variety. Totally incredible actually in an otherwise crap pattern. I almost forgot, the timing of all this is pushed back slightly. Precipitation, if it does arrive comes Tuesday and persists through much of the day.

And yes it still remains a relatively unexciting pattern. The jet in the Pacific has tightened and although the teleconnections are generally neutral or slightly adverse for us. Jet energy like that in the Pacific is always problematic. By around the December 14th or so, we could be looking at a thaw or at least a series of above freezing December days. The weather has done a good job of thwarting an otherwise lousy pattern so far. Maybe it continues.

Tuesday, December 2, 2014

El Nino's dark side is revealing itself but Vermont weather still could get interesting

The critical ENSO "3-4" region has jumped to a warm 1.0 as of this past week and although the weather pattern doesn't directly respond to those types of changes, El Nino is making itself known and not in the way I would have wanted. The weather pattern in November more or less picked up where last year left off. A large ridge in the jet stream across Alaska and western North America, a mostly loose jet in the Pacific and extreme cold for November standards over large swaths of both the U.S. and Canada. As the month turned to December, the weather pattern flipped on its head and is now dominated by an entirely different set of weather features. The most critical of these features is a broad expanse of jet energy that has settled into the northern and middle latitudes of the Pacific Ocean. This has tightened the jet stream dramatically and caused much of the arctic cold in North America to make a hasty retreat. There are similarities here to our coined "evil empire" feature (large mid latitude Pacific Ocean ridge) but the two are different for a few reasons. The biggest of which will be the precipitation situation in California. The major impacts will be similar however with much of the eastern United States struggling to have enough cold air to support snow over the next 2-3 weeks. "Much" however is not all and I am hoping Vermont is one of the few exceptions.

We did experience a brief but damaging thaw over the weekend, but the "leftovers", from November's polar vortex have brought winter back to Vermont and a few inches of snow as well. The late part of the current week and the weekend are expected to be high and mostly dry. The one exception would be Saturday where some light snow from a disturbance in the retreating polar jet could grace the region with a very light accumulation. After the weekend and through most of next week, the polar jet will be of little use to us and our eyes will turn to the southern branch of the jet stream and a storm that will ultimately track toward the Carolina coast late this weekend or early Monday. This system will not be inhibited by any polar energy, and moisture from this system could work its way into the region early next week. Do we have enough cold air to support a big snow ? Maybe, but it will be of the stale variety, and this makes the prospects of a 15-30 inch powder-fest a daunting one.

Winter will remain loosely entrenched across the region through the middle part of next week, a few days after our potential early-week storm.  The threat for warm days and even some rain will persist however in this pattern through around the Winter Solstice as much above-normal temperatures dominate much of Canada. If there is a silver-lining, it is that the mean axis of the warmth-producing ridge should set up well to the region's west. I certainly don't expect sustained cold weather in such a set-up, but interior New England is positioned to have the best chance of retaining some sense of winter even as the blowtorch impacts large portions of the rest of the continent.

Some other "housekeeping" items that I want to mention in the update today. The "favorability index" this year will be scrapped. I still like the idea of an index but it proves confusing and most importantly has not been particularly accurate over the last few years. One of the big issues with the index, as it relates to snowfall in Vermont, is the varying degrees of what is optimal. For example, a maxed out negative AO and NAO in January usually means Vermont is in the "shaft" zone for snow but such a scenario can be fruitful very early or very late in the year. What has worked well is the tweets however. Hey, we live in the attention-deficit tech savvy world and the blog should embrace it. We will use twitter more and use complex and unreliable "favorability index" less (I should say not at all). Please feel free to follow and respond on Twitter.