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Monday, March 30, 2015

Snowfall still possible this weekend but much milder air will win control for a time late this week

The month of March is concluding and I have been admittedly discouraged with how the weather has played out. Plenty of relative cold throughout the month has kept temperatures 5 degrees below average but organized storm systems were scarce and many locations were only able to score 30-50 of their respective normal melted precipitation totals. Though I don't want to be one to complain, especially after a relatively successful winter, any March featuring cold of this intensity is somewhat wasted if the snow isn't falling.


The sour mood is also a result of the evolving outlook for the rest of the week and the weekend. After some snow on Monday, a clipper system will move southeast through the eastern Great Lakes Tuesday but its moisture will entirely miss New England and much of Tuesday, Wednesday and Thursday will be precipitation free. Temperatures will be on the cold side of seasonable between Tuesday and Thursday morning, generally staying below freezing even during the day and falling into the teens at night. By Thursday afternoon milder air will make a push into the region and temperatures should make a push toward 40 degrees.


As of late last week, it appeared as if Vermont and much of New England would be ground zero for a battleground of airmasses and weather conditions. A healthy area of cold remains across much of Eastern Canada while a building upper ridge across the Mid Atlantic and Southeast U.S. will allow mild air to expand and push north. All this happening as an activated jet stream pushes at least one big organized storm system into the plains and ultimately toward New England. Unfortunately, it appears as if the warm weather will mostly win out, particularly late this week. Thursday will feature temperatures near 40 followed some rain Thursday night. Friday will then follow with some of the mildest weather in quite some time, perhaps as high as 55 degrees before a front arrives Friday night. There are still some signs of a 2nd piece to this storm system, though in recent days this system appears weaker and less threatening. Still, at least we have chance. The potential storm appears more like a wave along the eastward moving cold front. This wave will hopefully be a little strong and perhaps evolve into a rain to heavy snow situation for Saturday April 4. At the very least the push of colder temperatures will ensure another wintry period of weather lasting through Monday April 6th with some snow from a disturbance possible on Sunday April 5th.


Beyond April 6th, the ensembles are strongly indicating the development of a much warmer pattern across much of the Ohio Valley and Mid-Atlantic States. This will certainly help the growing season commence in those areas. Vermont and much of Northern New England will be on the northern edge of this developing pattern and at times we will see the effects of this and at times colder air push the milder air southward again. I do expect some serious thawing though in the period beginning April 7th through the middle of the month, perhaps enough to end the ski season at MRG.



Thursday, March 26, 2015

Some interesting possibiliites for the first weekend in April

It's got a little wet out there during the middle of the week but cold weather is in the process of reestablishing its grip on the region. A light accumulation of snow Friday morning accompanies the turn to colder weather and the deep trough responsible for this latest round of chill will also help ignite an offshore storm Friday night into Saturday. This system will stay well east of Cape Cod but dynamics will allow for some snow across southern New England through much of the day Saturday. Not much is expected across interior New England except for the continuation of flurries and perhaps an additional inch following the few inches received Friday. Temperatures will remain below freezing for much of the weekend, but sunshine will help boost readings at least close to the freezing mark by late Sunday afternoon.


There is lots of weather to talk about in the days and weeks that follow. Much, but not all of it appears wintry. Two clipper systems are lined up and ready to deliver some goodies early in the week. The first should deliver a decent 2-5 inch snow to the mountain Monday. We are a bit limited on available cold air so the snow could be on the wetter side at the base of the mountain but should remain powdery from the mid-mountain to the summit. Models are arguing about the 2nd clipper which has been showing some potential on recent runs of the Euro while other models are confining much of the precipitation activity to the south of Vermont. The early part of the week won't be especially cold but should not allow for significant thawing with readings climbing into the 30's during the day and falling into the 20's at night.


The cold air is expected to make another temporary retreat during the later part of the week while activity in the jet stream begins to enhance. Initially, the storminess will be focused on the west but much of this activity is expected to move across the country by very late in the week and the weekend. Models have been digesting this information and spitting out varying solutions in this 7-10 day time frame but a hazy picture that includes two sizable looking weather systems is beginning to emerge. A potential first precipitation producer strikes the region with limited cold air and is likely to result in a period of rain for the mountain in the Thursday to Friday time frame. Some very interesting possibilities exist for the 2nd system over the weekend thanks to the presence of a fresh supply of colder temperatures and an amplifying trough in the jet stream over the eastern U.S. You just get one of those feelings that the winter will not leave us until sending one more memorable storm. I keep waiting, but such an event has yet to materialize. The potential is certainly there during the first full weekend of April but it remains more than a week out and several key details need to be sorted out before any promises are made.


Cold should linger through about April 6th or 7th before more spring thawing commences.

Tuesday, March 24, 2015

Milder air trying to find an open road to Vermont but cold air will remain a force into April

Some chinks in the armor are finally starting to appear in the winter 2015 frigid and snowy reign.  This in spite of a incredibly cold stretch of recent days when, over a 48 hour period, readings failed to break 20 degrees. Generally speaking, the pattern is expected to remain cold, supported mostly by a large ridge jet stream level ridge over the northeast Pacific Ocean and Alaska. This ridge is expected to gradually lose some intensity and migrate westward in the first week of April allowing some tightening of the Jet Stream in the Pacific and a less supportive EPO index for cold and snow across New England. The cold however will remain a prominent force in the short term and a less persistent part of the medium and long term weather picture as well.


In the short term, a temperature moderation will ultimately lead to a 36-48 hour thaw. A two-faced system in the Rockies will approach and do so with a rapidly eroding area of cold. The first area of low pressure will move northeast through the eastern Great Lakes Wednesday allowing milder air to encompass the region by Wednesday evening. Light rain and a few pockets of freezing rain are possible Wednesday evening along with temperatures in the 30's. On Thursday the jet stream will amplify ahead of a 2nd area of low pressure. This storm will have the ability to gather more significant amounts of moisture from the Gulf of Mexico before its northeastward ride toward new England. With the pattern more amplified and the cold scoured out of New England by Thursday morning, the day is shaping up to be mild, wet and certainly melty. Temperatures may approach 50 during the day at low elevations and 40-45 at the summits. The rain on Thursday could also be heavier for time amount to almost a half inch of liquid. Much colder air will slowly advance back into the region Thursday night into Friday and the snowflakes should be flying through most of the day Friday. A light accumulation is possible Friday but it doesn't look like anything more than that right now.


Both weekend days look chilly and generally sub-freezing even at the low elevations. Flurries could linger into Saturday morning but the afternoon into Sunday appear dry and Sunday in particular should feature sunshine and some excellent visibility. A clipper system will approach Sunday night and brings the next real chance for snow. This particular system looked more vibrant on the models a few days ago and models are currently showing that this clipper will fail to fully re-amplify the pattern going into the early part of next week (the last two days of March). Still, a few inches is likely out of this and the month is likely to finish out on the chilly side with a continuation of mostly sub-freezing temperatures on the mountain.


By April 1, much milder air will begin competing for control of the weather in New England stemming from some of the changes discussed in the opening paragraph. Ensembles are still indicating that the cold air will win most of the battles but the center of this cold will retreat into Canada allowing for a sporadic very spring-like day. The southern branch of the jet stream is responding to what appears to be a strengthening late season El Nino. This means that in spite of the weakening cold, the right set up could still bring a late and very big winter storm to Vermont in early April.

Thursday, March 19, 2015

Spring 2015 will really struggle to dent the deep New England snow through early April

A southern branch storm system Friday and southeastward moving Clipper Saturday will miss a chance encounter by a day. If we could have gotten these two storms to fall in love, it would have been bombs away and some big weekend snow. Friday's southern stream system has some moisture but will track well south of Cape Cod and some snowfall will make it into southern Vermont Friday, we shouldn't expect anything significant at MRG. The high march sun angle will work to push the mountain up toward 30 degrees in spite of some cloudiness.


Saturday's incoming clipper, like many other clippers, is a bit moisture starved. I expect that we should do fairly well considering. Snow should begin in the midday hours and a very healthy looking frontogenetic zone should pass through the region Saturday evening and help induce a heavy burst of fluffy snow for no more than two hours or so. Flurries should continue into Sunday accompanied by blustery winds and some impressive relative chill for March. The accumulating snow will be confined to Saturday afternoon and evening however and should amount to 3-6 inches of fluffiness mostly available for the Sunday ski day. Saturday's temps should climb into the 20's, Sunday's readings however are likely to hover in the low teens with wind chills well below zero. We may have missed out on the potential phasing of the equinox storm but it eventually will phase well downstream of us over the Canadian Maritimes. The storm may get hung up a bit on Sunday into Monday allowing some moisture to wrap itself back into interior New England. There are hints of some accumulating snow across the Green Mountains Sunday night into Monday as a result of this but it may only amount to continuous flurries.


Accumulating snow or no, Monday will continue to feature blustery and very chill weather. Tuesday will be dry and cold with less wind and we should finally see some modification in the temperatures by Wednesday. Models are trying to suggest that a storm will cut up through the eastern Great Lakes later in the week either tracking up through interior New England or well up into Quebec. A mild push of weather will certainly be the result but to what degree. Consensus seems to indicate at least a small period of rain Thursday though this is subject to change.


In spite of the brief period of mild weather, the pattern remains fundamentally cold and should continue to be through early April. The PDO and specifically the nature and intensity of this winter's PDO event has yet to fade. The strong ridge across western North America will thus not get eliminated and will continue to allow relative chill to encompass much of eastern Canada and the northeast U.S. going forward. Cold weather will reestablish itself over New England during the last weekend of March and could very well be accompanied by some snowfall. The cold my lessen in intensity as we move into April but aside from the brief period of melting we might see late next week, we shouldn't see much more through April 4 incredibly. I know the end-of-season MRG coop meeting is slated for that Saturday and there is no reason to think the mountain can't remain nearly fully open then.

Tuesday, March 17, 2015

At least some light snow just prior to and during the upcoming weekend

Most of the rest of the country has enjoyed a round of impressive spring warmth, but Northern New England, which is sometimes the last place to get warm, missed much of the much-above normal temperatures. The highest readings in this nearly 10-day stretch of relative warmth was back on March 10th where it climbed to near 50 degrees and thus, much of the deep snow cover remains over Vermont, even as it melts rapidly across the Great Lakes and Mid-Atlantic states. The melting will now be further slowed as the pattern supporting the relative warmth is replaced by a postitive-PNA jet structure beginning now.


 Still, even with the slow advance of spring in New England, one can feel winter's intensity begin to wane. Much colder air and a few inches of fluffy snow on Tuesday is certainly wintry, but temperatures will stay above the zero-degree line this go round and rise into the 20's during the day. Conditions will be mainly dry Wednesday and Thursday and part of Friday. Moisture in the activated southern branch of the jet stream will allow a weather system to develop off the Mid Atlantic Coast on Friday. This combined with a southeastward advancing clipper system will try and brig snow back into the region just prior to and during the Spring Equinox weekend. Its a little early for exactitudes and there is some upside with the Friday system if it can track farther and west though right now it looks like only a side swiping few inches. The clipper will mark the advance of some very chilly late March temperatures and I expect at least a few inches by late Saturday. Though Friday's temperatures might sneak above the freezing mark, Saturday's should stay in the 20's and will then subsequently fall off into the teens Sunday as a Polar Vortex (spring version) sweeps through Quebec.


Below freezing temperatures but dry weather then prevails in the Monday-Wednesday March 23-25 period though readings could warm back above freezing by late in the week. The strong ridge across western North America is expected to weaken by the weekend of the 28th and 29th and the weather pattern will respond by turning more variable. The days just prior to the weekend could feature a precipitation producer of some sort though mild air will begin to compete for control of the region by then so I can't guarantee snow. Though El Nino has proven to be a rather minimal factor this winter, the pattern in front of us, through perhaps early April may exhibit some El Nino characteristics with the aforementioned activated southern branch of the Jet Stream. I wouldn't mind one more good late-season southern branch humdinger as a grand finale but there is no hard evidence of such an occurrence yet.

Friday, March 13, 2015

A little wet Saturday but powdery Sunday

The weekend event is not looking to throw us any curve balls, at least not yet. The best "frontogenetics" with this event on Saturday will set up about 100 miles north of us. There are also issues on Saturday with the limited amount of available cold though I believe the frontogenetics is the bigger issue since that is ultimately where the heaviest precipitation will fall. Saturday should feature plenty of clouds and eventually some light rain as temperatures rise into the upper 30's. The wet weather is not expected to persist for too long and liquid precipitation should amount to less than a quarter inch, perhaps less than a tenth of an inch.

Overnight Saturday, colder air, both aloft and at the surface will establish itself over the mountain as the weather system in question reestablishes its position off the coast. A healthier conveyor of precipitation should then move over the Green Mountains by Sunday morning which should be in the form of snow. The snow will continue through much of the day and accumulate 5-10 inches before tapering off Sunday evening. This is a rare instance this winter when areas farther north should see better results from this storm. Jay Peak for example could score well over foot and could see more in the way of snow Saturday. With temperatures in the 20's and several inches of snow on Sunday, Mad River will ultimately be powdery as well.

Sub-freezing temperatures will last through the overnight hours Sunday and then another mild push of air could allow readings on Monday afternoon to approach 40. A fiesty clipper system will put a quick end to the mild air and will mark the beginning of another sustained stretch of below normal temperatures that will begin Tuesday. The aforementioned clipper may bring a little rain to the region and then precipitation turns to snow by Tuesday morning, accumulating a few inches before conditions dry out later in the day.

I expect below normal temperatures to prevail for most of the rest of the month beginning on St Patrick's Day thanks to another charismatic looking PNA structure. In the periods between March 18-23, the storm track appears very suppressed much as it was in late February. A storm might impact the Mid Atlantic States around the weekend of the 21st and 22nd but there is nothing as of now that indicates an impact for interior New England though this remains more than a week out. The final week of March appears a bit more promising in this regard as there are hints of potential storms leading up to April 1.

Wednesday, March 11, 2015

Reports of Winter 2014-2015 demise have been greatly exaggerated

The nationwide thaw and in some locations, a heat wave, finally pushed the mountain above freezing and thus the stretch of sub-freezing temperatures officially lasted about 45 days. Sub-freezing temperatures return to the mountain by Thursday morning and our focus turns to a potentially sizable precipitation producer for the weekend. Got some questions and comments regarding this event and I know some folks have already started sizing up some of the model data for the weekend.

Let me preface all this by saying that the pattern through the weekend remains warm and though we will have some cold air to work with, it will be quite limited especially relative to most of the other events we have seen this winter stretching all the way back to November. I also want to advise caution when looking at those model precip-type maps. The Euro in particular can be extremely bad and can lead many forecasters astray, usually by incorrectly assigning any kind of heavy precipitation as snow. When it comes to precip type, I prefer to look at raw data and then account for model biases accordingly. With this particular event, the consensus of data tries to take the storm into the St Lawrence Valley at least initially. Ultimately however the storm is expected to deepen along the New England Coastline. Such a scenario is not an all snow event even though some recent runs of the American GFS are suggesting such. Precipitation would likely begin as rain or a mix on Saturday and then as the storm begins to deepen along the coast Saturday night, precipitation would become snow and this would continue in some fashion through a good part of Sunday. This is a tricky event with lots of moving parts and the end results could vary based on where one is on the mountain. Right now however, I don't like the idea of an all-snow event and think it could get a little wet Saturday followed by several inches of snow Saturday night into Sunday.

We may get one more semi-warm day next week before winter returns for another significant stretch of March. This is another classic looking PNA-anchored pattern much like many of its predecessors this year. Consistent with much of what we have seen this year, the pattern appears devoid of support from the the AO or NAO. Its been a pretty simple process of simply placing a big upper ridge in the right place across western North America and watch as the cold and snow impact the eastern U.S. persistently. I expect this will occur again and I further expect multiple rounds of big results for interior New England. Being that it is later in the season, I think interior New England could be the favored location for some big events later this month though they are tough to pinpoint as of now.