Think Snow, Tweet Snow !!!

Friday, December 28, 2012

Looks at least 6 for Saturday night into Sunday and cold through January 5

And suddenly, its been a great start to the 2012-2013 ski season. Nothing like 20 inches to erase a few bad memories. As mentioned via twitter and I am sure in every other available forecast, more snow is on the way. This system is also organizing in the lower Mississippi Valley and will ultimately be centered near the Virginia tidewater before venturing off into the Atlantic, just south of the tip of Cape Cod. Such a trajectory typically either gives central and northern Vermont a glancing blow and sometimes nothing at all. With this system, there will be a decaying low pressure center north of the coastal low that should allow the frontogenetics (I literally just made that up), to be relatively favorable for a healthy period of snow. It should all start around the time of last tracks Saturday and should continue through the evening. My morning on Sunday, most of the heaviest snow will be over, but occasional terrain induced snow showers will continue throughout the day. If all things go according to plan, we could get an additional 6-plus inches with 4-6 of those inches before first tracks time Saturday.

After Sunday we have roughly a week to enjoy the fruits of our hard earned labor. During this period, we expect a polar vortex to take a run at New England. Not every day will be bitterly cold but some very cold air will make a charge at the region for at least a short period, probably very late next week. It will also be pretty chilly Sunday with temperatures in the teens while a biting wind thanks to our departing storm sends wind chill readings below zero. Monday afternoon temperatures will be a little more comfortable as winds subside. With the polar vortex approaching, it is unlikely that any major snow producers will venture this far north. Instead, weaker disturbances rotating through this PV will bring chances for lighter snows. The first such disturbance will arrive Monday night and may be good for an inch or two by Tuesday.  The next will arrive either later Wednesday or Thursday and will mark the edge of the coldest weather the region has seen since February of 2011. Again any snow will be on the lighter side but temperatures will plummet later Thursday with readings perhaps getting well below zero by Friday and struggling to get above zero during the day. The chill should continue into part of next weekend before abating somewhat Sunday or Monday. I seem to remember that squeaky snow on my ski's when it gets really cold in Vermont but it's been so long since we have experienced some real chill I have almost forgotten that sound !

For those later arrivals to the blog, we have discussed how a ridge in the east-central Pacific ripped apart the first half of December in spite of some otherwise favorable high latitude blocking conditions. I have nicknamed this feature the "evil empire" since it successfully destroyed the winter of 2011-2012 and continues to be pervasive to a lesser degree this winter. I am very sorry to report that this feature will once again rear its very ugly head by next weekend and this spells trouble for the middle of January. We might be able to get through about January 7th or 8th before we start facing the consequences, but face them we must at least for a short time. The feature will temporarily force the trough into the western U.S. and will produce another succession of painfully strong Pacific systems. This will force the arctic cold into a temporary retreat and allow for a period of mild weather between the 8th and 15th of January. Ensembles are split on how all this evolves and I was encouraged that the European forced the Pacific ridge back toward Hawaii quickly and perhaps this would limit any damage.

Lets enjoy this stretch while we can though !

Thursday, December 27, 2012

Amazingly, no adjustments needed to our 15-25

Pretty remarkable actually considering the frequency at which mother nature likes to throw its knuckle balls. Mind you, a knuckler could still be thrown. The National Weather Service issued blizzard warnings for northeast Indiana and northwest Ohio Wednesday and a vicious dry slot cut down snow accumulations quite drastically as if to mock the forecast. Us powder hounds have suffered enough in the past year and we are in no need of any mocking. Sure, we too could get a "lull" in the storm during the day Thursday and snow accumulations might be a little lower as a result. The last cycle of model guidance remained consistent however and still indicates well over a foot of new snow on the mountain by the end of the ski day. If your headed up to the mountain Thursday and Friday, make a few turns for me.

We need to do a more complete update Thursday detailing the Saturday storm which is expected to give us a glancing blow but perhaps a light accumulation.

Monday, December 24, 2012

Bring It !!! 15-25 inches Thursday and Thursday night !!

Models continue undulate somewhat on the track of Thursday's nor'easter. For the record, I will absolutely not conform to The Weather Channel's efforts to name winter storms as the National Hurricane Center does with hurricane's. This is a silly crusade and one that I hope will die an early death. Last night we saw a cycle of model runs that actually did take the storm over New Hampshire and thus brought a layer of above freezing temperatures into Vermont. The recent two model cycles however and the information I am most comfortable with right now, has the storm strengthening over the lower Mississippi Valley Christmas Day, move into the Ohio Valley Christmas Night and then transition toward the Atlantic Coast, ultimately tracking between Boston and Cape Cod by Thursday December 27th. This is the ideal track for most of the Green Mountains, and although this storm is not predicted to be the intensity of Valentine's Day of '07, this strengthening to about 992 mb while the '07 storm was sub-980 mb, it will nonetheless be a big hit for MRG and much of the surrounding area.

The details are subject to some minor adjustments but the information we have suggests that snow will start just after midnight Thursday and begin accumulating in earnest by daybreak. At first tracks time on the 27th, we should have a few inches on the slopes while snow falls 1-2 inches per hour. Winds should be rather blustery at the summits Thursday, blowing from the northeast through much of the day. With any storm, there are variations in the intensity of the snowfall but the bulk of heaviest precipitation could certainly result in snowfall rates upwards of 3 inches or more. The concern with this event has always been a potential change to sleet or freezing rain. That risk for the mountain is now minimal but this critical line will not be far. The big east coast cities of New York and Boston will mostly be rain and cities like Rutland, Lebanon, Albany and Concord could see snow change to sleet and then rain. It looks to be another event where the place to be is north and in the mountains, somewhere such as MRG, which from what I hear, had a nice opening day Christmas Eve.

The snow could continue into part of Thursday night but should be over or taper to flurries by Friday with a total accumulation of 15-25 inches. This is not a forecast for valley locations so no emails from readers in Rutland that only got a slushy 6 inches. There won't be much time to worry about snow totals anyway since by then we will be watching a second weather system, and another potentially significant one. This second system, another southern branch product, will grab some moisture out of the gulf and track toward the Atlantic Coast Saturday. Right now it appears this storm will track further southeast, reaching the Virginia tidewater Saturday night. From here, the storm could either take a trajectory aimed more out to sea or turn northward toward the Cape. Either case would mean more snow for the northeast but the latter means another round of big snows for central and northern Vermont.

The pattern could yield one more big hit just after the new year as well leaving the mountain in fantastic shape in the early part of 2013. Around the time of January 5th is where I start to get nervous since there are threatening indications of a turn to more zonal flow. It's Christmas however and I am in no mood to discuss those things. Enjoy the holiday and stay safe !!


Friday, December 21, 2012

Potential December 27th storm looking better and better

The winter of 2012-2013 has gotten off to an inauspicious start to say the least and this is on the heels of one of the worst winters in the history of MRG. Can we finally get an extended period of winter now after another undeserved period of rain Friday ? Yes !!

The next 10-14 days will be as winter-like as anything the mountain has seen since February of 2011. Snow showers and a few snow squalls Saturday from the slowly departing occluded swirl should yield between 2-8 inches depending on the elevation. Anything that falls on the mountain, will do so on top of the few inches of the very dense concrete or conglomeration of half melted but now frozen snow. This is effective stuff actually when it is actually at the bottom and not on top. Sunday looks like a drier day than it did a few days ago which has been the exception in a weather pattern that has produced lots of precipitation of all varieties. And yes, there is plenty more to talk about and it all stems from an active southern branch and a pattern that will ultimately evolve into a more classic split-flow scenario (at least for a time). There are lots of goodies under the Christmas tree in such a regime. The first is a storm that is likely to bring its goodies further south on Christmas Eve/Christmas Day unless there is a late 100 mile shift to the north. It is a weaker weather disturbance and it precedes a much more potent weather system later in the week.

The storm that deserves all the attention and most of the discussion should strike the region in some fashion around the time of December 27th. It is a low pressure center that will efficiently suck moisture out of the Gulf of Mexico and proceed northeast, eventually evolving into a ferocious noreaster. There is a fresh supply of cold air with this storm and since its formation is farther south and east, it will not prematurely amplify before interacting with the Atlantic Coast. The one critical question that remains is the track. There has been a loose consensus amongst the models to allow this system to travel just inland and this would bring above freezing air well into southern New Hampshire and perhaps threaten parts of Vermont. The storm is still 5 days out so a shift 50-100 miles southeast or northwest could make all the difference. Either way, the result appears to be a net very positive and potentially a significant amount of snow, our biggest in a while.

There also could be more where that came from as there are some indications of a follow-up snowfall around the time of the 30th and below freezing temperatures through the early days of 2013. For now, the blog will stay focused on our potential December 27th event. Hopefully it is worthy of such focus.

Wednesday, December 19, 2012

After some rain Friday, snow for the weekend and maybe some more next week

The mountains hung in there Tuesday and in the end really didn't see too much rain. With the additional snows Tuesday night, Mad River Glen is dare I say, a winter wonderland just without the skiers. Attention now shifts to the big storm set to brings its bag of goodies by Friday morning. I have some good news to report with this system but just as they like to say "all politics is local", all news is also relative. I set the bar pretty low with last night's update so lets see if we can raise it a bit.

This very powerful storm system will get pretty wound up across the Midwest Thursday bringing heavy snow, gales, and even severe thunderstorms as far north as the Ohio Valley. The storms early and very deep amplification does not bode well for interior New England and as has been mentioned already, warm marine air from out over the Atlantic will flood the region Friday morning. If precipitation starts as snow late Thursday night, it will go over to rain Friday and we could even hear thunder once or twice. So where is the good news you ask ? We can't do much about the slice of warm Atlantic air but models do show this storm evolving very quickly and thus occluding very quickly. By late afternoon Friday or into the evening, colder temperatures will gradually become re-established over the mountain and we should see a quick change over to snow. In the end, the rain and above freezing temperatures will probably persist for roughly 6 hours. A swirling occluded system, such as this, will make the storm appear like a poor man's hurricane by Friday night on satellite imagery and the center of circulation will gradually make its way into the Gulf of Maine by Sunday. The slow movement and instability associated with this storm should allow for occasional snow between Friday night and Sunday morning. Snowfall could be significant before its over, perhaps upwards of a foot or more across the upper half of the mountain.

There is another storm system that should garner plenty of discussion. For one, it could be very significant. Secondly, the likely time-frame is right after Christmas, traditionally one of the most popular times to make a few or several turns. By Christmas Eve, polar air, of a weaker intensity will cover a broad area of both the Upper Midwest and New England. Meanwhile the next in this continuing series of storms will organize in the southern plains, gather moisture from the Gulf of Mexico and proceed northeast around Christmas day. This system will have more cold air to work with than the preceding few storms but questions and uncertainty remain. The main concern involves another potential premature amplification across the center of the country. Would this happen the result could include precipitation other than snow. Other questions regarding the organization, timing and track of this feature could also hold a lot of sway on the eventual forecast. I am cautiously optimistic, but its early so lets just see how things play out.

There are conflicting indications as we heard toward 2013. There are indications that the evil ridge in the west-central Pacific migrates back to the east and starts creating more mischief. Both major ensemble packages do suggest a trend back toward warmer temperatures just prior to the New Year. At the same time, a succession of recent European Ensemble runs have trended toward a negative AO just before the New Year and have also allowed some of that ridging to extend into the Yukon in northwest Canada. If we can keep the ridge axis in the Pacific west of Hawaii and finally get some ridging in western Canada, it would produce a very ideal split flow scenario full of storminess and Arctic chill. Lets end the discussion on that and hope for the best


Monday, December 17, 2012

Wet weather for Tuesday and again Thursday night

As expected, heavy precipitation is advancing northeast as below freezing temperatures gradually get scoured out of most of Vermont. Forecast atmospheric cross sections through the day Tuesday reveal that temperatures will simply be too warm to support snow in most locations and instead will see rain with some occasional sleet mixed in. The above freezing layer will hover close to the surface and should extend up between 3,000 and 5000 feet. This means that some of the high summits could still see some wet snow through the day tomorrow but even in these elevated locations, temperatures could challenge or exceed the freezing mark. Precipitation will become less intense and more sporadic Tuesday evening and night but also turn to snow as temperatures slowly move back toward the freezing mark.

I'll have a more complete update Tuesday evening but there is another intense storm late this week that is destined to impact the region. This system will amplify across the Midwest and over-amplify thus allowing a destructive swath of very warm temperatures to advance deep into New England Thursday night into early Friday. Unless there are some miraculous 11th hour changes regarding this system, the mountain is getting a period of rain, perhaps even a short period of heavy rain and thunderstorms. This is a powerful system that could very well bring blizzard conditions to portions of the Upper Midwest. The silver lining with this storm involves what is expected to be an eventual stalling this weekend over the Canadian Maritimes after the occlusion occurs. This sets the stage for several days of snow showers capable of yielding accumulations over a multi-day period

Saturday, December 15, 2012

Lots of storminess, lots of precipitation types

As they like to say, let the games begin !!! In what should be one of the more active weeks of weather this calendar year, the region will see a bit of everything. The news is not all good but there is certainly plenty of news and after what should be a true roller coaster ride of weather conditions through Christmas Eve, the mountain should be much closer to an opening.

As of Saturday afternoon, there were not too many places in the U.S. that were seeing below-freezing temperatures but interior New England was one of those places. The culprit was a decaying but at one time quite intense piece of Arctic air centered over Quebec. The cold, dry airmass slipped into the region just ahead of the first round of precipitation expected to arrive in the form of snow during the middle of the day Sunday. I know the weather forecasts for Sunday have been all over the map and even as of now, models have yet to agree completely on a precipitation type through Sunday night. Various forecast sources seemed to have formed a consensus (that I agree with)  calling for a period of snow through Sunday night. The snowfall intensity will be mainly in the light to occasionally moderate range allowing for snowfall totals to to be in the modest 2-5 inch range. With temperatures only a few degrees away from the freezing mark, snowfall will generally be wet.

4 days ago, we discussed a second and more vigorous piece of upper air energy which will act as a potent steroid (for lack of a better word) in this whole weather situation. The upper air support, described in the meteorology community as a "shortwave", will commence its impact early Tuesday. Prior to this, the loosely entrenched area of cold weather over New England will continue battling it out with a push of milder weather from the south. The result will be the periodic continuation of either mixed precipitation or snow depending on what package of model guidance you believe. For the most part however, temperatures should stay at or below freezing in spite of whatever precipation falls Monday. This vigorous injection of upper air support will unfortunately begin to tilt the scale of this cold vs warm battle in the wrong direction. This is a situation I discussed somewhat in the previous update. As exciting as some of these amplifications look in a medium range model, and as much upside potential in terms of snowfall they can bring, the lack of a reliable supply of cold air can lead to some lousy results, especially early in the season. In this case, we will see an exploding area of precipitation Tuesday probably get wasted as cold air slowly gets scoured out of northern Vermont allowing for a period of rain Tuesday. This remains a tenuous situation and a few slight changes in the evolution of Tuesday's system could yield a different result. The storms amplification will ultimately allow colder temperatures and some snow to return for Wednesday although temperatures will remain near to just below the freezing mark through Wednesday and into Thursday.

When it comes to weather, it seems everything comes in streaks. It is largely analogous to a baseball player who has hitting slumps and periods when he hits lots home runs in a short period of time. The upcoming period can certainly be described this way. After the the snow, mixed precipitation and rain in the Sunday-Tuesday time frame, another even feistier weather system will move out of the Rockies and into the Plains and Midwest Wednesday into Thursday. This is yet another system capable of amplifying the jet stream in a profound way but do so with only limited cold air and probably do so too early. By Thursday evening, cities like Chicago north through much of Wisconsin could see near blizzard conditions if some of the medium range models are correct, but an amplification so far to the west allows warmer temperatures and rain to again threaten New England for a period beginning Thursday night or during the day Friday. Fortunately this situation is fluid and the ridging in eastern Canada will prevent this storm from tracking too far into the Canadian provinces before transferring some of its energy to the New England coast. This means that rain will turn to snow and snow showers and could persist through the weekend into Christmas Eve with some significant snowfall accumulations and colder temperatures. By the end of all the storminess, there should be a good amount of snow on the mountain and hopefully we have an opening day in our sights.

The end of 2012 should continue to feature temperatures that are in the above normal category but not excessively so. A few runs of the European ensembles have indicated a storm around the time of the 27th and 28th. That weather system is a long way off still but has promise at least as of now. The pattern as a whole should continue to be a ruled by a ridge in the west-central Pacific (near the dateline) and a ridge in eastern or central Canada. This is not the most ideal situation in the world but it is not totally adverse either. We have yet to see anything resembling an upper ridge in the western part of Canada which is necessary for a sustained outbreak of arctic cold and below normal temperatures.

Tuesday, December 11, 2012

Winter storm speculation begins

Exciting times have finally arrived making the colder weather feel that much more invigorating. Finally, we have storms (plural) to discuss and real winter weather to talk about. Lets also preface some of the details by saying that it is especially nice to see a succession model guidance cycles trend colder and snowier as opposed to what dominated last years SCWB headlines - warmer and rainier or just warmer and warmer.

Over the next five days there will be two important big picture developments. The first and I will say critical, is the westward progression of the "evil empire" in the Pacific. This large and destructive ridge will move west toward the date line and will allow the onslaught of storminess to shift south. The second is the westward movement and enhancement of a large upper ridge, almost a block, across eastern Quebec, Newfoundland and Labrador. Although this combination doesn't necessarily encourage widespread very cold weather, it does promote an active and southern storm track capable of producing moist systems which can ultimately get trapped along the New England coast or in the Canadian Maritimes. This is precisely what we can expect with the weather as we head toward next week. We still have significant concerns regarding the amount of available cold air but we are headed in the right direction and lets hope this continues.

This is a one-two punch scenario with the first system tracking through the plains and Midwest this weekend as cold air across Canada weakens with the remaining chunk settling over Quebec. The building ridge over eastern Canada will allow this lingering cold to ooze south ahead of the approaching initial weather system and it looks for now that potential precipitation should begin as snow Sunday evening the 16th. With several days still remaining before the start of this potential weather situation, a lot can still change, but there are good indications of a healthy moist conveyor with this initial system that could allow for an extended period of light to moderate snows into Monday. Such a scenario would certainly mean the first real significant accumulation of snow for the winter were it to hold.

The second part of the one-two punch is a much more dynamic system and could involve a large east coast amplification Tuesday into Wednesday (18th-19th). I consider this type of system a high risk/high reward event at this point because the potential, given an absolute ideal situation is for a massive snowfall. The risk however is that when such a powerful amplification occurs, with minimal cold air, so close to the warm Atlantic, there is little resistance to the eventual envelopment of warm air and a transition to rain. For now, I will be happy to see this first system evolve in the way it is forecast to evolve right now and hope the powerful ridge in eastern Canada works to flatten out this second storm somewhat,

Aside from the potential over-amplification next week, there are fewer if any threats for warm weather going forward to Christmas. The pattern does not support below normal temperatures but for the most part, respectable temperatures through Christmas day consisting of generally below freezing temperatures, at least in the high country.  

Monday, December 10, 2012

Another week of generally uninteresting weather but what about after ?

The sleet, freezing rain and rain will all be a memory as of Monday evening and this leaves us waiting and hoping for some good news before the holiday. Unfortunately it will not come from the "third wave" of low pressure, which will confine its impact to coastal communities Wednesday. We will see a few days of seasonable temperatures, generally below freezing but no major snowfall. Meanwhile, the cold weather will continue to intensify across Canada and act to freeze the Hudson Bay entirely within a few days - certainly a good development and the earliest freeze since 2007. The "evil empire" or the east-central Pacific Ocean upper ridge however will be the dominant player on our playing field and because of this, the bitterly cold arctic air will be forced more east rather than south and will have a difficult time being a major force in Vermont's weather over the next week.

As indicated in previous posts, another mild push of air will impact the region late in the week and into the weekend. The trend over the last few cycles of model runs has actually been a good one, lessening the intensity of the mild weather during the upcoming weekend and even hinting at a little pushback from colder air in eastern Canada. The concern however relates to the first in what should be a series of storm systems after December 16th. This first storm system is not likely to take a very favorable track and we might do best just hoping for a flatter, weaker storm that comes and goes with little notoriety.  A stronger storm system, like the one the last European model is showing, is likely to bring another round of sleet, freezing rain and rain and perhaps a lot of it.

As we move beyond next weekend, it gets much more interesting. The "evil empire" shifts west allowing the jet stream in the eastern Pacific to weaken and the storm track as a whole to shift south. Meanwhile the ridge and potential block across Greenland should finally give us a long awaited assist. This feature should help to keep the NAO negative and keep things active and intriguing along the east coast. There are indications of at least two major storm systems between the 17th and Christmas Day and one or both could yield some significant snows, at least somewhere. There will be ongoing concern regarding the amount of available cold air by then. Much of what is so available now, will be scoured out of Canada by the 17th so we potentially could use some help in that department.


Thursday, December 6, 2012

Storminess on the way, just not exactly how we would want it

Although not under the most ideal circumstances, there is some very active weather on the immediate horizon. The storminess will stem from what will be a highly amplified jet stream and all the ingredients that typically come with it like mild and moist air from the Gulf of Mexico and Arctic chill from Canada. I was almost expecting that a massive storm would be churned up out of all this; but were that to happen in this set up, it would suck very mild weather deep into interior New England. Instead of one big storm however. this massive baraclinic zone will produce not one, but two and quite possibly three separate storm systems. Cold air is in short supply but it's better than no supply.

The first and weakest of the series of potential weather systems arrives Saturday into a stale and deteriorating airmass. Precipitation will mostly occur early Saturday and will be in the form of rain with a few pockets of freezing rain. As completely useless as this weather system would seem, its passage will help allow some arctic air to jam its way into the Green and White Mountains in spite of a very adverse upper air weather pattern. The cold will arrive late Saturday and will be firmly in place on Sunday as the next system gathers strength in the Great Lakes and tracks toward the St Lawrence Valley. This track, unless it changes, will make it tough for any significant to snow fall when precipitation recommences Monday, but a period of mixed precipitation including a little snow is becoming likely. Ultimately, the mild push of air later Monday could prove to be too much and change all precipitation to rain but we could see some significant icing and if we are lucky, a nice base layer of concrete to build on. I had mentioned the possibility of a third wave in this series. Such a storm would be more of a snow producer Tuesday into Wednesday. Most of the model guidance has downplayed this possibility but the most recent run of the Euro showed some support for this.

Ensembles continue to show hints of another warm up beginning around the 13th of the month and persisting for a few days. The constant pushes of warmth still stem from Pacific ridge or the "evil empire" as we have been calling it. This ridge will migrate westward and set up an interesting dichotomy as we proceed toward Christmas with the PNA and NAO contradicting each other. With the Pacific ridge out of play however, the door will open for Arctic air to make its way into the northern part of the country and for the storm track to get pushed well to the south. In the end, some very positive developments should result. Stay tuned.


Tuesday, December 4, 2012

Weather to remain on the milder side through mid-December

I do not have the news most were looking for 3 weeks before Christmas. The dominant chess piece through mid-December will indeed be the upper air ridge in the mid-latitude Pacific. This will make life very difficult for those of us hoping for some good early skiing this December. I had hoped that other pieces on the chess board might mitigate the pain but we will instead be forced to deal with a few rounds of milder weather, rain and a minimal build-up of snow through the next 10-12 days. This is not to say that wintry weather is completely out of the picture through this period. The storm I had alluded to in the previous post could still provide a bit of that Monday, but that is a best case scenario at this point.

Temperatures should get a little closer to seasonable levels late this week but only for about 36-48 hours. Thereafter, another surge of milder temperatures is expected as the pattern turns more meridional. This essentially means that colder weather advances south across the western half country while the milder weather pushes north across the eastern United States. There will be a rather intense clash of airmasses in between which sets the stage for some very active weather across the Midwest this weekend into early next week. Interior New England could also be a part of this clash if we can get a little push-back from the building cold across Canada. This is a big "if" right now however and I would expect more in the way of rain or perhaps some freezing rain Saturday from the first wave of low pressure. The second wave brings precipitation late Sunday or Monday and could have a bit more cold air to work with but only in a very limited variety. Snow or mixed precipitation is a bit more likely in this period but the models have been trending toward this warmer scenario I have been detailing and we would need to reverse this soon if we were to get any love from this.

Temperatures will turn colder for a brief time during the middle of next week but the pattern will fail to break down. In fact, a vigorous disturbance over the Yukon will drop south and re-invigorate the trough over the western states. This is one of those really unwanted byproducts of what we should refer to as the "evil empire" or the mid-latitude Pacific upper ridge. As a result, we should see another round of milder temperatures between the 13th-16th of the month. After that, there is some evidence that the "evil empire" will migrate northwestward allowing the Pacific Jet to loosen somewhat. There is even some evidence of some splitting in the flow and would thus make it considerably more interesting right around the time of the holiday.

Sorry about the crap news. It is very east to lose heart especially after a year like 2011-2012 but it's very early and there are plenty of reasons to remain optimistic. If we get another 10 days of lousy weather we might as well get it now because it can be much more disruptive once the season begins.


Saturday, December 1, 2012

Competing forces battle for control of Vermont's weather after the eary month thaw

After a nibble of the white stuff and a bigger taste of some single digit temperatures, the mountain will be forced to endure a significant stretch of above freezing temperatures and some rain. All of this has been in the cards for some time so there is nothing too surprising or alarming. All of the big questions and potential concerns relate to the period beyond Thursday. There are reasons to be optimistic but there are also reasons to be nervous. The weather pattern confronting the region involves many competing variables and which ever one wins the day will largely determine whether or not the mountain can be set up with an early opening.

It's not worth spending significant amounts of time on what amounts to a meaningless thaw. Temperatures should surge into the 50's Tuesday and the combination of mild weather and rain Tuesday night should essentially wipe out most of the snow below 3,000 feet.


More seasonable temperatures and even a bit of terrain-induced snow should prevail later in the week which is where much of the uncertainty exists in our forecast timeline. As mentioned there are competing features on our playing field. The big concern, at least from my vantage point, is that the medium range ensembles are showing the return of the dreaded upper ridge in the east-central Pacific. My personal loathing for this feature has been on full display for well over a year now and my reaction is a mix of both dismay and skepticism. The preseason prognostication mentioned that the ridging in the mid-latitude Pacific has really not been an issue this fall and the disappearance of La Nina certainly discourages its development this year, at least for an extended period of time. Yes, it still could prove to be another tease, but we have to be honest, such a feature works to tighten the jet in the pacific, encourage zonal flow, and all but eliminate the ability of cold air to sustain its coverage of mid-latitude geography over the eastern United States.

There is a brighter side of this possibility spectrum so I hope I have not completely killed the mood. The hemispheric picture consists of much more than a east-central Pacific ridge. In fact, there is clear evidence of ridging in the Jet Stream extending from the Aleutian Islands northward over the north pole and southward to Greenland and the Davis Strait. Essentially, the ridging forms a ring-around-the-rosie encompassing an area of very cold air across Alaska and western and central Canada. The cold has allowed for a rapid expansion of snow and ice across North America as a whole and most importantly for us, the Hudson Bay. Look at the coverage of ice on the Hudson Bay this year compared to the last 5.

2012 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2012/ims2012335_alaska.gif

2011 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2011/ims2011335_alaska.gif

2010 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2010/ims2010335_alaska.gif

2009 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2009/ims2009335_alaska.gif

2008 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2008/ims2008335_alaska.gif

The freezing of this large body of water, and freezing it early is monumental in getting a good build up of cold over eastern Canada so it ultimately can become an asset in our crucial winter weather scenarios.

Cold weather across Canada is not the only reason to be optimistic. The two major ensemble packages largely disagree with one another on how this all plays out by next weekend. The American GFS package depicts a scenario that hinges on the aforementioned Pacific feature. Two additional and significant surges of milder weather are likely in such a pattern which would be dominated by a negative PNA and more minimal high-latitude blocking. The European package paints a much more optimistic evolution which would have cold weather returning by the end of next weekend and remaining in place for an extended period there after. This set-up hinges more on what is indicated to be a negative AO and a broader extended reach of the bitter chill across Canada. Most interestingly, the European also depicts the potential for our first major snow producer around the 10th of the month. We have not seen evidence of such a storm until today we would love to see it.

I thought it was interesting to see how similar this year is matching 1984-1985. November of 1984 was a touch below normal on the east coast (same as this year) but more significantly below across western Canada, much like this year. The December that followed featured cold weather across the U.S. and mild weather covering much of the east coast, much like the GFS ensemble depicts. The ensuing January was then bitterly cold featuring the coldest Presidential Inauguration ever recorded when Ronald Reagan was sworn in for his second term. I am closely watching how this plays out, and whether we continue to follow the 1984 scenario in accordance with the American ensemble or whether we diverge like the European suggests.