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Saturday, February 28, 2015

A mostly wintry first 10 days of March but a massive warm-up is possible after that

We have brought to a close a totally historic month of weather for Vermont and New England in general. No doubt that the weather experienced by many this month will become legacy, passed along from one generation to the next in its mythic glory. Undoubtedly, the moral of any story will have one common thesis -  "You think this is winter ? This dusting ? This tropical breeze ? You weren't here for February 2015 !! I can just envision some tale like this being told at some dive 20 years from now or perhaps in the shadow of General Stark himself at the pub named after him. The final numbers are almost in for the month including almost 80 inches of snow, an actual temperature average of 5 degrees (13 below normal), and zero above-freezing days. This last achievement stands out in my mind since I consider it very un-Vermont-like and something that perhaps occurs only once a decade or so.

The month of March begins with more snow, which begins Sunday evening and continues through Monday. This is a clipper-like system but it will grab some of the leftover moisture from the big Rocky Mountain system and deposit a chunk of it on the New England. Total accumulations will fall in the 3-6 inch category. Dry, cold weather and sunshine return for Tuesday with temperatures remaining below freezing. Clouds will advance into the region late in the day in advance of the incoming next system. As mentioned in prior posts, this midweek system represents a major push of warm temperatures. And like we discussed in the last update, it doesn't look like much of this warmth will make it to central and northern Vermont. Nonetheless, we will see a plethora of precipitation types beginning in the form of snow late Tuesday night. The snow could accumulate several inches before precipitation changes to a period of sleet and ultimately freezing rain and drizzle. For a short time on Wednesday, I think temperatures will finally climb above freezing allowing for the possibility of just plain liquid rainfall. The opportunity for this will be very short however and the melt off will be extremely limited.

Cold weather grabs the steering wheel again Thursday and should continue to dominate through the first full weekend in March. There are two interesting looking clipper systems that could deliver powdery snowfall in the period beginning March 7th and ending March 11th. I bring this up because any powder we see in this period could be the last for at least a bit. There are now some glaring indications that much of the eastern United States will see a major warm-up as we move into the middle of March. It is possible this pattern is being a bit over-promised by recent runs of the longer range ensembles but it can't be completely ignored either. The pattern in the Pacific has been very loose and extremely favorable for us for nearly 6 weeks now but this is expected to completely reverse with the "evil empire" rearing its head by around March 10. We will, at the very least, see some major changes in the behavior of our weather  starting around the time of March 12th. After this, expect to see several days of "above-normal" temperatures, including readings as high as 50, or even 60. If we can get some sunshine to go along with this warmth, it will make for some great spring skiing on our deep base.

Thursday, February 26, 2015

Light snow very late this weekend but the mountain will have to fend off a major push of mild air next week

Temperatures through the rest of February, will finish just as they have for the rest of the month, very cold. Both Friday and Saturday mornings will be below zero and the strong late February sun will fail to push readings above 20. Dry weather also prevails both of these two days and the combination of sunshine and relatively calm winds will make for some comfortable days on the mountain. Clouds advance back into the region for Sunday and snow begins later in the day. I don't think too much snow falls during the ski day but 3-6 inches is certainly possible during the overnight hours setting the stage for a powdery Monday. The late Sunday system is a clipper which will grab some left over moisture from one of a few big Rocky Mountain systems. This is been an absolutely awful, awful year for skiing out west. It's been warm and dry since January, but the snow this weekend into early next week could be very heavy, amounting to several feet in a few places and should make for one of the better weeks of the season beginning this Friday.

Cold air, of a lesser intensity returns later in the day Monday March 2nd along with sunshine. This is a very different pattern and we are going to get challenged, big time, by a gigantic push of warm air during the middle of the week. Models have been all over the place with the midweek weather system. A few runs yesterday pushed the entire storm well to our south but successive cycles of models (overnight Wednesday and the subsequent cycle Thursday) track a low pressure center well into Quebec later Wednesday allowing mild air to breech the chill which has dominated New England for over a month. Let me go on record by saying that I am skeptical of the recent trend in the models, at least for interior New England. There remains a lot of cold air across the eastern provinces of Canada next week and it will not give way without a fight (not this year anyway). That being said, a storm tracking up toward the St Lawrence valley is looking more likely and this means snow giving way to sleet and freezing rain. The Thursday afternoon run of the Euro suggested 45-degree temperatures and a period of rain and I am not inclined to believe that as of now. A period of icing though is certainly possible and a small period of above freezing temperatures is also possible. Given the model variability, don't be surprised to see additional changes. Though the data didn't trend our way today, it could in future days and a relatively big "all-snow" event is not yet out of the possibility range.

Another temporary round of cold weather is expected to follow for late in the week but the overall pattern is expected to remain. Many will attribute the change to the MJO (Madden Julian Oscillation) which favors a tightening of the Pacific Jet and the dreaded "evil empire". Thus  the European and American ensembles are hinting at another round of warmth around the time of March 9th-13th. Hopefully there is some snow in the period just prior to this around the time of March 6th-8th.

Tuesday, February 24, 2015

New pattern coming for March but more snow shoud be the result at least initially

There is some available energy and moisture in the southern branch of the jet stream this week but the pattern has become very suppressed for the back half of February and many would-be storms are staying well to the south of Vermont. We have managed a dose here and there however though Wednesday's dose will amount to the 1-4 ultra fluff variety. Flurries may continue into Thursday but a gigantic arctic high pressure center situated over the Dakotas will keep a large portion of the northern United States on the drier side for late in the week.

The much-discussed pattern change takes shape for the weekend. After a sunny but cold Saturday, the first day of March should bring more seasonable temperatures, perhaps, dare I say 30. Clouds will also be prevalent later in the weekend  and some snow should fall. The nature of this rather disorganized late weekend weather system remains a bit uncertain but it will be the first of many, in what should be a less cold and much stormier weather pattern for the first 10 days of March.

At least for a short time, the mean position of the upper trough will be located across the western United States. Meanwhile, lingering very cold weather Canada will battle it out an emerging area of warmth across Dixie. I think two additional storms (following the Sunday event) will impact the region as a result of this situation. I can't promise both will be all snow but the first, in the midweek time frame, as a good chance to be mostly snow and quite possible significant snow. This midweek storm will finally deliver the Rocky Mountains a big storm before it exits the west and advances toward us Tuesday. Final track, storm intensity and total snowfall remain unclear but the remaining supply of cold in Quebec paired with the healthy push of warm advection thanks to the warmer south are very beneficial for us typically.

There is some disagreement amongst the models in regards to the strength of the chill that follows the Midweek storm. The American Ensembles argue for a very temporary round of extreme cold late in the week while the European suggests a more garden variety shot. Given the way this winter has played out across New England and given the extent of ice and snow across eastern North America, it would not be wise to bet against a short but extreme outbreak of cold in early March; after all, these things are quite common during this part of our winter. The cold should retreat by the weekend and set the stage for what I think will be the next in this series of storm systems. More on that in a subsequent update. In general however, this new pattern will keep the blog busy talking about all kinds of weather. We have almost completed a historic month of weather across Vermont, one which could rival the cold of February 1934. Though March will likely be a little below normal as well, we will be talking about some above freezing weather days in the very near future thanks both to the emergence of this new weather pattern and also due to March's higher sun angle.

Sunday, February 22, 2015

Cold for the upcoming week but only light snow

We are still expecting a patter change at the beginning of March, but until then, temperatures will remain cold. Unfortunately, it does not look especially snowy. This has been a epic fail for El Nino which, since December, has failed to invigorate the southern or subtropical branch of the jet stream. The southern branch will fail to make a contribution to the midweek weather system which now appears only to be a clipper-like disturbance. The snow will follow another round of bitterly cold temperatures early in the week. Barring a change snow will be on the lighter side and fall mainly Wednesday accumulating a few inches before temperatures turn chilly again later in the week.

The pattern change is as we discussed. Though it will noticeably less cold for the early part of March, I don't see a major thaw or a massive melt down eiter. At some point we will break the incredible streak of sub-freezing temperatures early in the month but it won't be a prolonged break. The new pattern should also include more in the way of storminess. A few Pacific-like storms should cross the country and bring the potential for precipitation. I tend to think this precipitation has a better chance of falling in the form of snow, in spite of the new pattern. We will spend more time discussing this potential in a subsequent update Tuesday.

Thursday, February 19, 2015

Light snow for the weekend, more cold for next week along with some midweek snowfall

Our stretch of sub-freezing temperatures has now extended beyond a month and the snow continues to fall even if not in the largest of doses. Light snow will become mostly flurries Friday along with blustery winds and mostly sub-zero temperatures. The bitter chill continues through early Saturday but temperatures will moderate during the day as any sunshine gives way to clouds in advance of our next snow producer.

This next weekend system appears discombobulated today and though it will keep our potential snow on the lower end, it also nullifies the risk of any mixed precipitation or ice which is something we certainly do not want at this stage in the game. The storm, if you want to call it that, will track up through the Ohio Valley and bring with it a disorganized area of moisture along with it Saturday. The frontogenetics (yeah a big word but I lack a better one) do not support any heavy precipitation up our way but snow will begin Saturday evening and continue off and on into Sunday Morning. I would put accumulations in the 3-5 inch range at this time so certainly enough for a mini-powder day. Most of Sunday will feature flurries along with temperatures in the 20's, which should feel quite balmy no matter what part of the Northeast you are coming from.

More cold dry air envelopes the region Monday, again sending temperatures below zero and perhaps back to -15 by Tuesday morning.  The weather pattern then gears up for another major amplification. It will be the last of such an occurrence for the very distinguished month of  February 2015 and perhaps the last in this very memorable weather pattern. There are hints that a significant storm could be one of the byproducts of all this during the middle of the week but the end result will depend heavily on the amount of available subtropical or southern branch moisture. Models have produced some differing results on this question though we have managed to perform quite admirably even without much involvement from the southern branch of the jet stream. This is surprising since typically it is a characteristic that is more pronounced in any kind of El Nino, even a weak one. I'll take snow anyway I can get it, but we will get potentially a big snow with the help of more subtropical action. Without it, polar jet energy could still bring more garden variety type snows before the next wave of cold overspreads the region late into the weekend through the end of February.

I have been watching the early part of March quite intently since it still appears as if the jet stream configuration will do some major realigning. The super positive PNA jet structure will disintegrate and a large western North American upper ridge will shift into the eastern Pacific Ocean. There are obviously changes that are about the occur simply due to seasonality but the added effects of the shifting weather pattern will certainly result in some very different results for Vermont going into March. Interestingly, the last few cycles of ensemble runs have shifted markedly away from any prolonged thaw and even suggest a continuation of below normal temperatures into early March even if the intensity of the cold is far less than it has been. If we could move into such a regime, it could mean a very interesting start to March. The polar jet would recede, we would see a major warm-up across much of the southern United States while a much more active jet stream brings several storms across the country. Yes, we could get unlucky and get a round of mixed precipitation or rain out of one of these but we could also score a major snowfall. In fact, I think the latter is more likely.

Tuesday, February 17, 2015

Two nice doses of snowfall over the next 5 days and (in case you forgot) more ferocious cold

February 2015 will be remembered for its snowfall but also for the unrelenting cold which has persisted in remarkable fashion since late last month. When all is said and done, the month will go down as one of the coldest February's on record for Vermont and one of the coldest months relative to normal in recorded history. Just incredible stuff.

We have more snow to talk about also. We missed the bulk of the post-President's Day weather system. Most of that snow fell over the Mid Atlantic states and most of it did not fall over southern New England, giving those guys a needed break. The pattern is ready to undergo another in a long series of jet amplifications. This is yet another product of the super positive Pacific Decadal Oscillation. The "+2" index will be etched firmly in my memory as one of the biggest drivers of the persistent cold this year. The polar jet energy responsible for the upcoming "jet digging" will be dynamic enough to allow for an outbreak of light snowfall very late in the day on Wednesday into Thursday. Most of the snow will fall after the ski day Wednesday but enough to make Thursday powdery with 4-8 inches of snow between Wednesday evening and Thursday evening. Another major blast of cold, makes a grand entrance Thursday night and this will ensure that Friday is yet another "mostly sub-zero day" on the mountain. Friday should feature some sunshine after morning show showers or flurries. Wind chills will be 30 below zero in the morning but winds will subside by later in the day and the late February sunshine will make it feel a bit more tolerable.

Temperatures will moderate for the upcoming weekend and snowfall is likely as a system cuts from the Southern Plains up through Pennsylvania. The track of this system will force some of the most intense cold out of New England and will also bring overrunning moisture capable of producing several inches of snow later Saturday into Sunday. The eventual nature of this system remains a question mark. In spite of some available moisture, models fail to develop this system into anything of significance and the snowfall would thus be in the "garden variety" category of 4-8 inches. I would not be surprised if expectations change and we are dealing with a more mature storm. We don't want this system to go crazy in the Southern Plains, track to the eastern Great Lakes and flood layers of the New England atmosphere with mild air but I certainly wouldn't mind a 10-plus inch storm. It's a classic New England weather "catch 22". I would have to say, at least as of now, that things look relatively good for at least a light snowfall this weekend.

The jet stream will then re-amplify and ultimately get forced south yet again in the wake of the weekend weather system. This means more cold air and a couple of mainly dry days early next week. During the middle of the week, there is a very good chance for a clipper system followed by what I think will be one more serious blast of cold. We discussed in the previous post about a possible change in the weather pattern around the turn of the month. This still appears very possible as ensembles indicate some serious re-aligning. The biggest change will occur across the Pacific Ocean as the position of the large ridge in the jet stream will shift from western North America to the open waters of the eastern Pacific Ocean. This will make weather conditions more variable for a time in early March although I think a return to the current weather pattern is possible by the middle of the month.

Saturday, February 14, 2015

Tueday's system is getting pushed south by cold onslaught

Snow from the latest coastal New England "humdinger" has begun across the mountains of Vermont. This vicious looking weather system has yet to draw on the warm, moist waters of the Atlantic Ocean but when it does so, it's "bombs away" once again. News cycles around New England are talking about this storm in a seemingly infinite loop so I am not sure how much I can add. The track of this storm however has gradually shifted farther north. Not a lot, but enough to bring moisture into the mountains of Vermont. Snow will on the light to moderate side and the heaviest precipitation will be confined to coastal sections of New England. The entire region will get wind and brutally cold temperatures. Most of the snow across MRG will fall late in the day Saturday and Saturday night. Most of Sunday will feature just flurries, temperatures near or below zero, and wind chills of 30 below and possibly near 50 below at the mountain summits. Total snow accumulations will probably fall in that familiar 5-10 category but the snow will be wind blown, very wind blown, so taking an accurate measurement is impossible.

Both the wind and cold will continue into Monday. Actual temps Monday will be generally between negative -10 and -20 along with wind chills similar to Sunday. We've been watching the Tuesday system all week and I've been under the assumption that the pattern would relax, just enough, to allow this thing to unleash some justice on us. Unfortunately it looks like my assumption was wrong. Can't count anything completely out in a year like this but the upcoming week looks now like a period simply overwhelmed by the ferocity of the polar jet. There is "clipper-type" energy that should approach for Tuesday night into Wednesday and this might draw some limited moisture from the original Tuesday/Wednesday system back into the region. Hopefully we can pull a rabbit out of the hat again but for now expectations should be for a lighter snowfall Tuesday night into Wednesday and light accumulations of 2-5 inches.

More cold is unleashed on the region late Wednesday into Thursday. Snow covered Vermont will have to endure another sub-zero day with wind chills of 20 to 40 below zero Thursday. The cold will continue into Friday although winds might relax just a bit. I thing the overall pattern, a big positive PNA, PDO induced pattern is capable of one big reload during the weekend of the 21st and 22nd. I think a storm will be one of the byproducts of this although models have been all over the  place on where this storm happens. New England is certainly one location that could see some results however. Another round of cold follows around the time of the 22 and 23rd.

Finally, there are some indications of some serious fundamental changes in the weather pattern. Coastal New England needs a break, but I would never wish one on MRG until late April if I had my way. It looks like a possible shift in the phases of the Madden Julian Oscillation (MJO) will result in some big changes in the Pacific. The jet will tighten somewhat and the ridge will shift away from the western North America and focus itself more on the open waters of the vast Pacific Ocean. This should end the polar onslaught and open the door for more  of a variety pack of weather across New England toward the very end of February. Given the ice cover over the Great Lakes and the snow cover across New England, a 180 turn in the weather seems unlikely but we should notice a difference as we head into March. And we are heading toward March and we should notice the higher sun angle as well.