Think Snow, Tweet Snow !!!

Monday, March 30, 2009

Lack of snow in March ended a good season a bit early

Temperatures did not stray from normal that dramatically with the exception of a few days. The lack of snow however in a month that is traditionally quite snowy in Vermont was a bit startling. In the end less than 15 inches of snow fell if my math is correct and the one big storm early in the month slalomed around the state for the most part hitting coastal cities as opposed to the interior. Interestingly, March of 2007 had some warm weather in the back half of the month but two big storms, a couple of feet of terrain enhanced snow and a nice stretch of spring skiing is a striking contrast to the last 30 days. There is more warm weather and more rain on the way for this week, a byproduct of the pattern which is causing massive problems in the northern plains which began as flooding and is now evolving into an epic late-winter week with one blizzard set for March 31st and another huge snow event during the upcoming weekend. Both systems will produce rain at MRG as both storms track well into Quebec.

As far as you back country and Tuckerman's enthusiasts are concerned I would act fast and dodge the rain drops if you want to ski down to the base. The upper part of Tucks will be fine and should get a burst of winter during the middle part of April as the pattern appears as if it will turn both unstable and a bit on the chilly side. I will do one more final wrap on the season but if this is your last SCWB read then have a good summer and stay safe !!

Saturday, March 21, 2009

Winter has been undergoing a slow fizzle but may crash altogether next week

We have experienced an amazing stretch of early spring weather. Lots of sunshiny days, lots of dry weather, lots of days where temps are above the all important 32-mark. There has been plenty of mud also on the dirt roads as the snow pack very slowly erodes over the Vermont high country. It has been a slow erosion since the pattern is still supporting some relative cold. It hasn't amounted to winter-like cold but it has, for the most part, served to provide for some cool nights. The cold will be reenforced Sunday and it will be done via the side door as a front crashes southward out of Quebec. There will be some snow that falls as this occurs although most of it will be farther east and the instability will not be strong enough to support a sizable terrain-induced accumulation. Flurries and snow showers will continue sporadically from late in the day Sunday through early Tuesday but accumulations will be minimal.

Temperatures will climb above the freezing Saturday afternoon and perhaps for a short time Sunday before remaining below freezing through most of Tuesday. After that, temperatures will turn mild and will do so very decisively. The pattern by late next week be driven by the PNA which will turn negative and favor a more active and cool scenario in the west. Mild weather will flood the northeast and should provide some great spring skiing while the snow lasts. I am not sure if we can survive the milder temperatures however and in spite some cooler weather that might follow during the last few days of the month it might be too little too late.

Wednesday, March 18, 2009

A week later, a lot of spring later, still some cold to come but little snow

Recent days have not been nearly as cold as I would have expected but overall it has been brilliant. An amazing stretch of sunshine and warm afternoons that is really quite rare around these parts in March and I am told quite favorable for the maple syrup trade. The skiing is great also particularly in the afternoons in the high spring sun softened snow.

Following the rain showers Wednesday, colder weather will again re-emerge across the Vermont high country Thursday on blustery northwest winds. The upper trough responsible for the return to cold will become situated off the Atlantic Coast and the northwest flow in the jet stream is typically a stable scenario for the state where terrain induced snow will be tough to come by. Friday will be a relatively chilly day with temperatures struggling to exceed the freezing mark and we could see some light snow on Saturday as the second in the series of off-shore jet amplifications occurs. In the end though the new snow will amount to very little. Sunday will simply be a chilly and blustery day by March standards with temperatures up around freezing in the afternoon and well below freezing at night. Snowfall for the weekend will amount to 2-3 inches at best and a trace at worst.

Temperatures will modify quite rapidly as the often do in March early next week. The region will start to lose the support of the favorable winter teleconnections and by the middle of the week spring weather will dominate the playing field again and snow cover will continue to gradually erode. It is quite rare to see the first 18 days of March go by with less than 5 inches of snow and it has been years since I have seen such tranquillity in a normally volatile month but there is simply not that much fight in winter right now aside for a few chilly days.

The end of next week should feature another rain event and a bit of uncertainty thereafter regarding the nature of the airmass that follows. The american model suggests a return to seasonable or even below normal temps while the european argues for a continuation of relative warmth.

Wednesday, March 11, 2009

Cold weather returns but snowfall through the weekend will be a struggle

The remnants of a what was once a viciously cold arctic air mass in western Canada will make its long expected arrival Thursday but stability parameters are too high right now to support much measurable snow. Tomorrow marks the beginning of what negative NAO has produced in terms of a weather pattern. The trough in the jet stream will re-position itself in the east through the weekend, weaken slightly, and then strengthen significantly into next week as all three major teleconnection indices briefly fall into the favorable category before turning mixed again by the 18th of the month. The cold however will be of the dry variety and will be accompanied by healthy amounts of sun on Thursday, Friday and at least part of Saturday. Afternoon temperatures on Saturday should finally respond nicely to the sunshine and will creep above the freezing mark during the afternoon and will thus soften the base a bit.

The re-amplification of the trough in the east will begin to occur Sunday as an impulse in the jet drops due south out of eastern Canada. This will be the first of two powerful March jet impulses in a span of a few days. These types of disturbances are very common in March and can often stir things up rather efficiently and produce some big snows. This system unfortunately will drop southeast in a trajectory that will make it nearly impossible for a big storm to develop. We can expect a flurries and snow showers Saturday night and Sunday evening but a light accumulation is about the most that can be expected. The above freezing temps from Saturday will turn to temps of the below freezing variety Sunday.

Chilly but not uncomfortable temps will continue to grip much of New England through Monday as the second of the aforementioned jet disturbances dives south out of the western Great Lakes. This upper air system brings with it more potential as far as big snow is concerned as it will carve a very deep trough along the east coast by the middle to later part of next week. There is all sorts of disagreement on specifics but the potential for an east coast storm is there for now. Good chance it also goes out to sea but this folks is what March madness is about. I am sure we will see a few interesting twists and turns regarding next week. We do now it will stay relatively chilly through most of the week and we shouldn't lose much of the base that remains.

Much of the key features in the long wave pattern will be pushed eastward, again the result of a slight re-arranging of our teleconnection indices. A good chunk of the country will warm by March 20th but whether or not this warmth reaches New England and eliminates our chances for new snow remains a question. There remains a chance with the continued downstream blocking in the jet stream, that conditions remain cold across the northeast.

Sunday, March 8, 2009

Some wet snow for Monday, rain on Wednesday and then winter regains control of Vermont

The National Weather Service has a headline today talking about the "weakening La Nina". We did see sea surface temperatures throughout the winter drift into the La Nina category for a time but it was about half the strength of the La Nina in 2007-2008. Not inferring anything about the National Weather Service but headlines can be subjective and I like to include the quantitative part as a way of providing the proper context. Vermont is losing snow pack but is managing relatively well in a very adverse longwave pattern. MRG will have to endure some rain Sunday night but it may not amount to much. Furthermore, dewpoint temperatures are falling as drier and cooler temperatures build across the region. Drier air in particular has the impact of lowering the wet bulb temperature or the temperature at which 100 % humidity can be achieved. By early in the day Monday, precipitation at most elevations will be snow. Valley locations up through the MRG base can expect mostly a wet snow Monday but higher elevations could see a bit of powder which is a pleasant and somewhat surprising development since we are still in the middle innings of a relative thaw. Accumulations will vary based on elevation ranging from 4-6 inches at the summits to a wet inch or two on the valley floors.

Rain and ice Tuesday night into Wednesday
Monday's snow will be followed by a dry and seasonable March day. Since temperatures will climb above the freezing mark and winds will be light, skiing or any other outdoor activities will actually be rather pleasant. The tranquil conditions will not last however. The NAO is turning sharply negative and a strong cold front stretching southward from an advancing storm system will approach the region Tuesday night. Precipitation may begin as a some ice but is likely to change to a period of rain Wednesday before colder temperatures arrive.

Powder, when can we get some ?
To make use of this upcoming chilly change we will need the powder and Thursday and Friday both appear powder free unfortunately. By Saturday a jet impulse responsible for providing some cold air reinforcement may bring a light accumulation of snow but a big weekend accumulation is unlikely. Though the pattern will turn colder the mean position of the trough axis will actually be off the east coast. This makes it tough on storms as they are not given the chance to strengthen along the coastline before they are swept out to see. Precipitation is thus confined to terrain-induced events and the random bomber, clipper or mauler that might sweep southeastward with limited moisture. March however is an unstable month. You can do a lot with a little. The strong winter winter jet stream is still present in March but surface temperatures are warmer thus reducing stability. Little and often very benign looking events can turn noteworthy and we will have to keep our eyes open for that beginning this weekend and persisting into next week.

Looking way out in the 10-14 day time frame, the ensembles show evidence of a split flow scenario with energy flowing through the southern rockies, advancing east across the plains and eventually into some of the colder temperatures along the east coast. This is our next chance of something sizable but it woudn't occur until sometime in between the 18th and 23rd of the month.

Friday, March 6, 2009

Rain and warm temps in the short term but winter's return is less than a week away

It is not a very exciting short term forecast and hardly worthy of another update. Friday's milder weather would be nice if we can get in on the sunshine but that may not happen until later in the day. Over the weekend, the real spring-thaw will be confined to the mid-atlantic and southeastern United States while Vermont will be in no-man's land, or stuck in the middle of a broad south to north temperature gradiant. The winter-like cold will have retreated deep into Canada and as moisture arrives from the southwest it will fall as rain. Steady precipitation is probably not going to begin until after the ski day Saturday (although we may get a shower early). This particular weather system has an elongated zone of overrunning that will extend across half of the country Saturday night. This will mean light rain into Sunday morning before the area of moisture sags south and seasonable temperatures settle into the region.

Rain Saturday, more rain/snow possible Monday and perhaps another next week
Saturday nights rain will mark the first of three occasions where precipitation will impact central and northern Vermont during this stretch of mild temps. The first two chances at precipitation are from more or less one interconnected system, which, after a dry period Sunday will threaten to bring more precipitation on Monday. Again temperatures will be a shade above freezing although in Monday's case we could see some snowfall on the upper part of the mountains. If you have been lucky enough to distract yourself from some of the dismal economic news and have tuned into what has happened weatherwise across the country you might have noticed the big snowfall totals in the Sierra Nevada mountains and other locations across the west. The unsettled weather has certainly focused itself out there for now and it means a series of west to east moving storm systems, the strongest of which approaches Vermont Wednesday. There are strong indications that this system, like its predecessor will bring a mild air northward as it tracks into Quebec and the result will be another round of rain or perhaps some ice. Fortunately this system will be a quick mover and its passage will mark the return of winter.

Winter's return

The ensemble information from our friends at the ECMWF (Europe) has really amplified on some of the ideas proposed in the last post. There are now overwhelming indications that the NAO will move decisively negative by the weekend of the 15th. When the NAO turns severely negative, an "Omega-block" often forms in the jet stream across Greenland and there is growing evidence in the forecast of such a feature. The feature may in fact become so strong that will extend to the poles and will thus turn two teleconnection indices to the pro-winter side of the spectrum. The weather as a result will swing back to the colder side of normal across New England and a few days between the 13th and 20th of March could very well be much below normal. There is yet to be any glaring signs for a big storm and in the next update perhaps we can identify a few opportunities for powder, but it would to early to venture down that road. For now however it would be fair to assume that winter will make a return and the powder days should join the party.

Wednesday, March 4, 2009

Spring-like temps for the next week to ten days but winter isn't done

And the most deceiving thing about March can be that initial blast of mild temperatures. They can arrive very abrubtly, can last a week and sometimes beyond, and seem to always give the inclination that winter has had its final encore. But rarely is the latter the case. Winter usually makes a comeback and indications are it will again.

The forecast warms
The forecast in the short term however has warmed quite considerably. The pattern appears more amplified than it did a few days ago and the cold and snow will be isolated to the western United States while a strong upper level ridge brings warmth to a huge part of eastern North America. Over the next week temperatures will reach the 70's across many of the same locations that just saw the biggest snowfall of the season Monday. Vermont is unlikely to see temperatures that warm, but high temperatures in the 50's should occur on multiple occasions through the end of next week and this means corned-up spring conditions even at the summits.

Some rain or ice late this weekend and perhaps more rain next week
As far as specifics go, we sould see the cold weather maintain its grip on the region through Thursday. At that time the warm front marking the swing toward the milder temperatures will help induce a period of snow, perhaps enough for a light accumulation. Whatever falls however will be forgotten by Friday as temperatures make a run at 50 with the help of some sunshine. Saturday's temps will start mild but clouds and the possibility of rain late in the day could dampen the spring fever. Saturday's late day rain marks the approach of what appears to be the most organized weather system of the upcoming 10-day period. It will track out of the southern Rockies and into the St Lawrence Valley of Quebec. This storm will be working with very little cold air and it may take more than a change in track to save us from a round of rain or freezing rain either Monday or Tuesday.

Winter makes a return around mid-month ??
Sunday's rain or ice event is likely not the last of the spring intrusion. More mild weather and more rain is likely at some point later in the week. Whatever days turn out to be rain-free and sunny will be the real winners. As the mild weather continues to prevail through next week the NAO index will drop and turn significantly negative. This should utimately lead to another twist in the pattern and a return to winter prior to the St Patty's day. Even the PNA, which will itself turn very negative over the next few days will eventually erode and may turn postive sometime around the middle of the month. History, as I mentioned in the first paragraph, would also suggest that mild periods in March rarely mark the end of winter's demise. My guess is that it returns in a big way for at least a week during the last half of March and yields a few powder days in the process.

Sunday, March 1, 2009

5-10 inches of snow for the first Monday in March

The mountains in Georgia might beat this go round but we got to let them have a few and keep them in the game. Even cities like Atlanta are experiencing some heavy snow and should see an impressive accumulation before it tapers off Sunday evening.

Fine Tuned Details
Heavy snow will fall along and east of the Blue Ridge mountains stretching from the Carolinas north through Virginia as the storm moves off the Atlantic Coast and travels north-north east on a trajectory that will take it just east of Cape Cod and the eastern tip of Maine. Such a track will mean that much of the state of Maine will, for the second time in 10 days, be a storm sweet spot. Vermont will be situated on the western edge of some of the heaviest snow. If the storm could attain some additional strength it would enhance and broaden the zone of frontogentic forcing and mean an extended period of heavy snow across the state. As is, much of the will be of the light or moderate variety and should begin within a few hours of daybreak Monday. The snow should continue through the day and into the evening totaling 5-10 inches. Gusty north winds will blow down the spine of the Green Mountains and this will continue into Tuesday as precipitation becomes snow showers. Temperatures will be chilly throughout holding in the teens Monday and remain closer to 10 on Tuesday.

Temperatures will warm by the end of the week and we may get some wet snow leading into the weekend. Enjoy !!