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Wednesday, April 22, 2015

MRG season ends but late April snows set to begin

The MRG season came to an appropriate finish this past week and weekend with a corn-fest. One might have intuitively expected that winter was finished given the several days of 60-degree weather we experienced but winter only just preparing for a late April encore performance. The show begins Wednesday night April 22 with rain at the very low elevations and snow above 2500 feet. The culprit for all this is an expanding upper level ridge encompassing most of central and western Canada. The remaining cold air at the poles will thus descend on the eastern two-thirds of the United States causing more than a week of unusual late April chill and in some locations, additional snows. Interestingly, the weak weather system responsible for the initial burst of rain and snow Wednesday night will strengthen, slow and ultimately get sucked west by a strengthening eastern U.S. upper trough. I think of these systems as “Maritime Stallers” since the storms travel to the Canadian Maritimes but then fail to make any additional eastward progress. The last several years have seen a scarcity of such events but they should be more common and are often very fruitful. They bring pockets of instability, moisture from Lake Champlain in addition to their own decaying areas of moisture to the Green Mountains and the slow moving nature of these weather systems can allow the results to “pile up” quite nicely.

Snow showers should impact even valley locations across Vermont later Thursday, Friday and into early Saturday. Some occasional dustings in the Valley should melt with sporadic sunshine. In the high country however, the snow will be more persistent fall occasionally quite hard. Between the snow Wednesday night and the additional snows late Thursday through early Saturday, accumulations in the highest locations could be well over a foot. The snow might be wet in nature late Wednesday but the airmass poised to invade Vermont is very chilly and the snowfall will be powdery above 2500 feet on Thursday and Friday.

Temperatures will moderate somewhat over the weekend as we watch a series of spring “cut-off” low pressure centers impact the eastern part of the nation. The first will entirely miss New England over the weekend and will bring a cold rainfall to the Mid-Atlantic. The 2nd next week might have a serious impact on the entire East Coast. There won’t be much cold air left by that point, but the storm could still bring some high elevations snows to the Green and White Mountains.

I am working on an end of season wrap-up that I wanted to keep separate from this update. Didn’t want readers to be looking at a late April update for the next 6 months.

Tuesday, April 14, 2015

Spring has arrived in Vermont though winter might give an encore late in the month

It took quite a while but as of mid-April, winter is rapidly receding and spring has arrived. Temperatures are likely to fall back under the freezing mark for a few short hours both Wednesday and Thursday mornings but plenty of sunshine will boost readings into the 50's during the afternoons. The El Nino might have failed in its effort to have much of an impact on the winter but it has strengthened over the last month and has helped to invigorate the southern branch of the jet stream this month. The consequences of this could prove interesting late in the month when a large upper level ridge is expected to reemerge over the Yukon and parts of Alaska. In the meantime, which covers the rest of the MRG season, weather conditions are expected to remain quiet.

Energy in the weakened polar branch of the jet stream will deliver some clouds Friday but aside from an isolated shower or occasional sprinkles, weather conditions should remain mainly dry. For Saturday and even into Sunday, the MRG grand finale, the weather remains uncertain. There is a large and moist weather system in the middle part of the nation that may or may not get kicked eastward. The European and Canadian models holds most of this wet weather off until April 20 and 21st while the American GFS model suggests we get wet over the weekend. I tend to think the GFS is moving things along too quickly in this time frame so I am inclined to believe the drier outlook. That being said, even the drier scenario allows for an unsettled day Saturday with scattered showers and perhaps some high elevation wet snow showers. Once the dust settled on this argument, I'll tweet out some final details.

If we get another round of wintry weather, an entirely feasible possibility given the evolving weather pattern, we probably don't see it until after April 23rd or so. By then the mountain is expected to be closed. I'll provide some details on any such excitement in a subsequent post which will also include our annual seasonal weather summary. Part of me wants to continue past the weekend  but a bigger part is blogged out this season and is ready to refuel for next season.

Friday, April 3, 2015

5-10 inches of glop Saturday morning could turn somewhat powdery as temperatures drop

If one is to forecast based simply on model derived "precip-type", the mountain will get thumped to the tune of up to a foot of snow between midnight Saturday and midday Saturday. The weather service isn't quite buying that however and I am a bit skeptical myself. It's a key question however, if the changeover occurs quickly due to the intensity of precipitation, MRG will do very well, scoring upwards of a foot of snow by late morning. I tend to think the changeover to snow will be a bit slower and thus accumulations will be in the 5-10 inch category. Snowfall will be wet and gloppy overnight but could turn powdery as temperatures above the mid-mountain fall to sub-25 by around 8 AM Saturday.

There are two additional changes for light snow from weaker disturbances or areas of moisture. One Sunday morning could result in an additional 1-4 inches. Another later Monday is more of the overrunning warm advection variety and could result in a few more inches.

Wednesday, April 1, 2015

Quick Saturday thump looking more likely

Though the weather has been generally sub-freezing through much of the month of March it will start becoming quite choppy in early April and some slow thawing is certainly on the horizon. In the short run, we finally have a moisture endowed weather system to talk about. A two-faced storm system with the first piece bringing a big mild push of air into the region. Some rain will arrive Thursday night and it will remain mostly cloudy and mild through Friday with temperatures in the 40's and 50's throughout the mountain. Models are currently confining a lot of the rain to the south of the mountain Friday which would turn out to be quite fortunate if your planning to do some spring skiing. I would not rule out a period of rain however during the day, at least not yet.

A strong cold front advances toward New England Friday night along with the 2nd piece of this storm. For a time it will remain a relatively weak low pressure center, but it will have a healthy amount of moisture and it will bring this moisture northeast out of the Plains as cold air descends southeast out of Canada. The storm will then strengthen very early Saturday and bomb off the New England coast later Saturday. Precipitation may remain rain for a few hours Friday night and then change to snow early Saturday around dawn. If the storm can deepen quickly Friday night, the snow could potentially be heavy for several hours and accumulate 6-10 inches by midday Saturday before tapering off during the afternoon. If the storm is slow to mature, we will be stuck with lighter snows.

Weaker disturbances are likely going to bring the mountain some additional snowfall Sunday or Monday or both. Needless to say it will be quite chilly in this period as well. Temperatures will fall back to sub-freezing levels by Saturday morning and will later turn blustery in the wake of whatever snow falls. Sunday morning will feature temperatures in the teens and limited sun will only bring afternoon readings to 30. By Tuesday, some thawing will recommence but the weather hardly appears delightful. A slow moving storm system in the middle of the country is likely to bring an expansive area of clouds to the central and eastern part of the country. Vermont will likely be on the north side of a nearly stationary temperature boundary and temperatures will remain mostly in the 30's as a result. Occasional rain and in places, some ice is also possible. If this entire conglomeration of weather can be further south, we might be talking about some snow but i would not count on it right now.

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.