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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.