Sunday, January 31, 2021

Strong early Feb nor'easter set to deliver a foot or more of snow to Mad River Glen Tues/Wed

 It happened again ! The northward shift has occurred and hopefully will continue to occur over the next day and the MRV is once again in play for a decent snowfall Tuesday into Wednesday. Though this doesn't appear to be a setup capable of producing epic snowfall, its certainly good enough for the folks at the NWS Burlington office to issue a winter storm watch for their portion of the state (Albany covers portions of southern Vermont and they have done the same). Meanwhile, a healthy dose of sunshine will help temperatures recover Sunday from the -10 to -15 degree morning and we won't be contending with the bitterly cold wind chills. 

One thing we can make very clear is that Monday is dry in northern Vermont even as the storm is raging closer to the NYC metro. A few hours of early sunshine is even likely before clouds advance into the region in the midday hours. Temperatures will again start below zero but rise well into the 20's with light winds. The setup for the upcoming storm is somewhat unique because of the departed polar jet and the very closed off upper air pattern underneath the blocking in northern Quebec. This combination translates into a slow motion scenario where snowfall is slowly advancing northward. Be patient, the snow will arrive but it will take a little time. Furthermore, the slower movement will keep the snow falling (albeit at a lesser rate) through Wednesday. 

The fun begins late Monday evening with snow advancing methodically northward maybe even slightly west of northward. The overnight hours should (Monday night) should feature several hours of decent snowfall rates capable of delivering 6-10 inches to MRG by early Tuesday. I would love to be able to advertise more but the storm appears a bit stretched out by the time snowfall is impacting Vermont. What I mean by this is that the primary are of precipitation will become pretty dislocated from the main surface feature, driven mainly by a closed off upper air pattern. This very much reduces the risk the epic two footer and likely means that after some decent snow very early Tuesday, we are seeing intermittent light snow during the midday and afternoon hours and an additional 1-3 inch accumulation. This still makes for a pretty incredible day on the hill in spite of what we expect to be some pretty gusty northeast winds. Those lighter snows will continue Tuesday night into Wednesday as winds become more favorable for terrain/Champlain enhanced material. This should be enough to push 48 hour snowfall totals (ending Wednesday evening) over a foot.

Beyond Wednesday the outlook continues to trend colder. We may even get through the Friday push of milder temperatures without any major thaw while possibly adding a light accumulation of snow. A 2nd push of milder temperatures continues to be indicated for Sunday/Monday but even this looks weaker and may fail to produce a stretch of above freezing temperatures of any significance. It is not impossible to conjure up new snow in this time frame as well given the right set of circumstances. All that said, the threat for non-snow type precipitation in the period beginning Friday Feb 5 and ending the 8th remains. Arctic  air is then likely to return for a few days between the Feb 9-11 which certainly did not seem especially likely a week or so go.

Friday, January 29, 2021

Models keeping most snow from early next week nor'easter south of Vermont but we've seen this movie before

A very cold and blustery Friday at Mad River Glen was made better by the addition of a few inches of snow. It was a very shallow layer of instability that produced that snow but it was enough to push the monthly total to 40 inches and make for a very wintry landscape as temperatures plummeted below zero. Though temperatures are expected to be well below zero again early Saturday morning, but sunshine should bring readings closer to 10 during the afternoon and although winds will continue to be a formidable 10-20mph (a little stronger at the summits), this isn't quite as strong as Friday. Winds will continue to abate for Sunday and temperatures will continue to moderate (closer to 20 during the afternoon) making for an excellent high visibility end to the weekend. 

Most of us are likely focused on the early next week time and the potential for a big nor'easter. We've got a pretty good sample size of model data for Friday with most (except for the Canadian GEM) keeping the bulk of the snow south of northern Vermont late Monday into Tuesday. At face value, models aren't shutting the state out of snow but are keeping totals fairly minimal. Additionally, the trend, at least right now is to keep the storm more subdued and farther south. This would undoubtedly be a more disappointing outcome in a setup loaded with potential but the path is hardly shut. This narrative has played itself out numerous times in northern Vermont and some of our best events over the last 20 years have occurred from storms that were forecast keep snow mostly south of the region 3-4 days out. Early March 2001, Valentines Day 2007, Ides of March 2017 all played out this way and the late northward shift wasn't an accident. Storms that undergo a dramatic intensification upon interaction with the relative warmth of the Atlantic Ocean remain a challenge for medium range forecast models to get a handle on in spite of many improvements over the past two decades. When the right conditions present themselves, storms often end up stronger, more dynamically robust and track farther north and west, often preferring to hug the natural baraclinicity (temperature gradient) of the coastline as opposed to tracking more innocently out over the ocean. No this doesn't automatically but early next week is a scenario where it could happen, especially with a retreating polar jet stream. With that in mind, I still view the general outlook similarly to a few days ago. There's a chance most of the snow from this storm stays south and we get a 1-4 inch outcome and there is a chance for a late northward shift in the forecasted track of this storm and an outcome including more than a foot of snow. And one more thing about the northward shift, they tend to happen within 48 hours of the event (see the December nor'easter) and we remain 72-96 hours from the event. Stay tuned. 

We've got a comfortable day or two sandwiched in between the potential storm early next week and a potential thaw around February 5th and 6th. Again, model data is indicating a potential path through the threat of milder temperatures in this period but a storm is expected to pass well north and west of interior New England creating some challenging obstacles not excluding the possibility for a little rain. Ensemble data diverges as we get to the 8th and 9th of the month with the American simulation showing a quicker return to colder weather while European/Canadian shows yet another threat for a mild surge early in this 2nd full week of the month. More generally, I've been a bit more encouraged with the teleconnections over the past few days and I think an extended torchy period is unlikely even if a one day thaw is unavoidable.


Wednesday, January 27, 2021

Bitterly cold Friday/Saturday and huge storm potential for early next week

 The overunning snow Tuesday night was a little disappointing but our run of winter weather continues and will continue in the MRV at least for the next week.  There's much to unpack in this update including the coldest weather of the season so far and the big storm potential for next week. Meanwhile, we should see some stiff winds on Thursday along with some snow flurries but temperatures will hover in the teens on the mountain making it the warmest of the next 4 days. 

We haven't had much bitterly cold arctic air this season. Much of that resulting from the persistent jet stream blocking over the Davis Strait/Labrador Sea/Hudson Strait area. A "mini-me" polar vortex will squeeze its way underneath that feature late Thursday into Friday and bring the wind and bitterly cold temperatures to New England; in fact, Vermont will be pretty close to ground zero with the intensity of the chill. Temperatures on the mountain will hover within a few degrees of zero Friday with 20-40 mph winds producing dangerous wind chills. Saturday's temperatures will be similar but the wind won't be quite as strong. Sunday will feel a lot nicer with temperatures recovering into the teens and calm winds. 

Thinking back on my years following weather, which spans over a generation now, I can't think of a much better set up for an east coast storm than the one early next week. The "mini me" PV will supply the cold early in the weekend but the polar jet will retreat quickly leaving a modifying arctic air mass over New England late on Sunday into early Monday. Meanwhile a strengthening storm system will progress east from the central plains Saturday and ultimately begin to consolidate energy near the North Carolina coast later Sunday. Now here is where the fun begins. There is no polar jet to speed this thing along or drive it offshore; instead, this storm will tunnel underneath the blocking in northern Quebec allowing for what could be fireworks display along the east coast that could last days. Now many of the medium range models over the past two days are keeping the storm south of Vermont, but how many times have we seen this movie. To put it simply, if you account for some of the inherent biases in the models 5-6 days out, we are in a pretty spot right now. Looking at the recent run of the Euro from Wednesday afternoon, I started to feel like it was late February 1969 - a period I did not live through in Vermont but wish I did. So lets stay positive and watch this sucker over the next few days, knowing that it could miss us but also knowing that this is the type of storm capable of producing 2-4 feet of snow in a particular location. I am actually pretty sure it will do that somewhere, but very uncertain as to the location. 

Temperatures are expected to modify even as the continues to rage and the risk of a thaw continues late next week. If anything, that risk appears to have lessened somewhat and there appears to be at least a chance we can find a way through to the weekend of February 6th and 7th unscathed. Starting to think of this winter as the tall man stalemate in tennis. You know, when neither player can break the others 1000 mph serve and the match goes on and on and on. In this case its the Pacific Ocean jet stream and the high latitude blocking going at it. The latter has looked more formidable over the past few days and has helped to neutralize a longer range outlook that appeared to be moving in a milder direction about 4-5 days ago. Whatever the analogy, I'll take it so long as the results are good. 

 

 

Monday, January 25, 2021

Next 8 days look both snowier and colder so I am not sorry for any bad forecasting

This is one of those updates where I get to take much of what was in the last update and throw it in the trash. A perfectly enjoyable mission however since all of the very important changes are positive. Though we still have a threat of some milder temperatures late next week, the next 10 days looks much snowier and even days I was convinced would be dry, now look powdery. Even in the warmer longer range outlook, there are some positive developments that will likely prevent it from getting too mild for too long. 

Happy to report that I did get Monday right. Beautiful sunshine and still a little bit of wind but not nearly as blustery as the past weekend, particularly Saturday. That sunshine will be with us again early Tuesday with even calmer winds but clouds will advance into northern Vermont by the afternoon and snow will begin falling out of those clouds Tuesday evening. In yet another example of a storm system shifting northward, this one comes as a result of a temporarily dominant southeast ridge in the jet stream which will allow temperatures to climb well into the 70's across Georgia and portions of the Carolina's. None of that mild air will intrude on our New England winter but the push of warmer temperatures will be felt in the form of overrunning snowfall. 2-4 inches of snowfall by first tracks time Wednesday with an additional 1-3 inches during the day. A powder day is thus the result since temperatures should hold steady in the 20's Wednesday. 

A northwest wind should allow snow flurries through Wednesday night but a the formation of a major storm east of Cape Hatteras should quickly cause precipitation over New England to diminish and allow some sunshine to return Thursday. This brings us to our next change - the polar vortex, or at least a piece of one. In another surprise, a piece of stronger arctic chill will jam its way underneath the persistent block in the jet stream over the Hudson Strait. We will begin to feel the effects of that late Thursday with temperatures dropping from a high of near 20 early in the day to below zero Friday morning. Blustery winds and bitterly cold temperatures will then be the story for Friday with readings only in the single numbers a wind chill values well below that. Winds of near 10-20 mph will continue into this upcoming Saturday with temperatures recovering into the teens and then Sunday should feel much nicer with minimal winds and temperatures in the 20's. Both weekend days should feature healthy amounts of sunshine although that could change. 

If all those changes aren't enough to digest, I've got a big finale consisting of the potential for a big storm early next week. Just getting a piece of that polar vortex early in the weekend is enough to slow the advance of milder temperatures and as the polar jet retreats late in the weekend, it will create a inviting stage for  a winter storm Monday. Models have been hinting at something for a few days actually but the last few cycles of model data suggest more cold air on the playing field. Long way to go still and this outlook could go many directions but I like the direction we are headed now and hope it continues. 

And yes, the trend in the longer range outlook still does include the threat of some milder temperatures but some interesting developments do accompany that. The persistence of the -AO would be the generalization you could make. We've talked about the importance of having that index counter the negative impacts of an agitated Pacific jet stream which it has continuously this winter. More specifically though, ensembles are again showing a block in the jet stream north of Alaska with a possible result consisting of arctic air flooding much of western Canada and parts of the western parts of the United States. Though that doesn't help Vermont directly and immediately later next week, it may eventually if the effect of all this is to push the persistent blocking over the Hudson Strait eastward back to Greenland. That is way off in the distance however and I am having enough trouble getting the next 6 days right.

Saturday, January 23, 2021

Cold but dry week follows lingering snow showers Saturday but risk for warmer temps rises in early Feb

 Two  short-lived snow squalls were about all MRG could muster on Friday; which, when considering how well southern Vermont performed was a little disappointing. Fortunately, the snow did return late in the evening and will set the stage for what should be an outstanding day of skiing Saturday. We are in the "take no flurry for granted mode" with several cold but dry weather days on the way this week and the threat of a thaw on the rise in early February. 

The coldest stretch of days we've seen in 2021 begins on Saturday and those 10-15 degree temperatures will feel a lot of colder thanks to gusty northwest winds. Flurries and snow showers will continue for a good part of Saturday thanks to that wind direction and we could see a light accumulation on top of what fell Friday night. More sunshine can be expected Sunday but with similar temperatures and only a little wind. 

Our cold weather will remain in place for the upcoming week but the jet stream will be steering storms south of interior New England. The biggest jet stream feature in North America is a block located across northern Quebec and the Hudson Strait (connecting the Hudson Bay to the Labrador Sea). Two storms will tunnel underneath this blocking feature but this results in a very dry scenario. The presence of both these storms will shut off opportunities for snow showers though it will allow for several days of sunshine. Temperatures will remain stuck in the teens on Monday but rise into the 20's during the afternoons in the Tuesday to Friday time frame. Snow from the first area of storminess could get as far north as southern Vermont Tuesday night into Wednesday but that is about as good as we are going to do. 

 Our best chance for snow after January 23rd will likely come from some type of warm advection type scenario on the last weekend of the month. This comes ahead of a rising threat for a thaw during the first 5 days of February. Though it looks like the negative AO will remain in place in early February, the jet stream in the Pacific simply will not relent this year. In addition to forcing a retreat of our limited supply of arctic chill, it will likely focus storminess on the western US. With the help of the -AO we still have a chance at avoiding multi-day stretch of warmth or significant amounts of unfrozen precipitation but the risk has certainly gone up.

Wednesday, January 20, 2021

More snow late Thursday into Friday followed by a week of dry, chilly and at times blustery conditions

 If we could only bottle winter weather like this. The best week of the season continues to deliver Wednesday. As I begin this blog post, heavier snow showers continue from Waterbury north to Smuggs and as we turn those winds to a more northwesterly direction, we can expect some of that activity to impact MRG and Sugarbush (likely around midday). It will be a race to beat the drier air however which should clear all of the convective activity away by evening and set the stage for a chilly near zero degree overnight. 

The week culminates with the approach of another clipper system Thursday.  Like many clippers, this system contains plenty of jet energy but not plenty of moisture. I think we can make the most out of the whole situation however with light snow arriving in the afternoon Thursday and persisting into the evening. By early Friday, the snow shower setup arrives and improves as the day moves along. 1-3 inches are likely from the light snow late Thursday and Thursday night and another 2-5 inches is likely during the day Friday, particularly at the peak of diurnal instability, Friday afternoon. 

Our weekend weather is dry and cold and should feature at least some sunshine both Saturday and Sunday. Though new snowfall isn't likely over the weekend, we can expect a small amount Friday evening and night as an extension of the activity Friday. In addition to the cold temperatures of near 15 Saturday we can expect some very gusty winds of up to 30-40 mph at the summits.  Sunday looks a touch colder on temperatures and just a touch less windy though certainly far from calm. 

We can speak to the weather for the last week of January with a bit more clarity today and its really an extension of the weekend. Dry and cold and at times pretty windy. Many of the general ideas proposed by the ensembles several days ago appear to be looking pretty good as we get a bit closer to the forecast period. We won't see any of the bitterly cold temperatures or even get a taste of the arctic cold currently gripping portions of Siberia, but a less substantial area of arctic cold will make its way on to the playing field beginning this weekend and grip northern New England through most of next week. Most importantly though, the position of the mean trough over the western North Atlantic, well underneath the island of Newfoundland and east of Bermuda places Vermont in a dry zone of weather. The biggest weather producing system will impact portions of the east coast Monday and Tuesday but the jet stream is likely to steer the moisture well south and east of the our state. Worth watching as always but I am very doubtful. We are thus left with cold, dry and windy weather through at least Wednesday, a calmer day Thursday and the chance for some light snow Friday. Temperatures which will finally reach below normal territory this weekend will continue to be through most of next week with readings between 14-22 for highs and within 5 degrees of zero for lows. 

Aside from marking the arrival of a new President, Inauguration Day also offers us the first real chance to glance into early February. The pattern continues to look less arctic with the persistently irritated and agitated Pacific jet stream forcing a retreat to some of the arctic chill next week. Blocking in the jet stream across northern Quebec will also help keep it very mild in eastern Canada placing us in a more tenuous but not hopeless situation as we enter February. Fortunately, the negative AO will not leave our side and will give us the opportunity to take something positive away from the first 5 days of February.  We can expect more active weather at the very least, but will to retain at least a minimal amount of chill.

Monday, January 18, 2021

Outstanding upcoming week of winter weather in Vermont even as overall outlook trends toward less cold

January 2021 has earned a place in the weather section of my memory files. After this past weekend, temperatures are almost 8 above average, yet it has barely been above freezing above 2000 feet. The high country has also procured close to 30 inches of snow but more notable is a particular form of weather that we haven't seen so far this month. No, I am not going to say it because I've been around long enough to know what that will likely do. 

Our snowy weekend is going to be followed up with more exceptional winter weather this week. The snow showers from the weekend have continued into MLK Monday. This snow will taper off and give way to a minimal amount of sunshine Monday afternoon and the clearing sky will set the stage for a more typical Vermont January overnight with temperatures falling off to near 10 degrees. A push of arctic air, the first of 2021, will approach on Tuesday and a disturbance accompanying that airmass will bring clouds and more snow to northern Vermont late on Tuesday. Most of Tuesday will actually feature decent visibility (the first such day in a while) even as the clouds increase throughout the day. It will be a light snow most of Tuesday night but as winds shift and become northwesterly early Wednesday, we'll have a small window where heavier snow showers can occur. It all adds up to a terrific ski day Wednesday with 2-5 inches of new snow and temperatures  hovering in the teens. 

It's an illustration of the benefits of a colder but not overwhelmingly arctic January weather pattern in Vermont. Aside form the obvious challenges of outdoor activities when its 10 below, the proximity of a stronger polar vortex this time of year can stabilize the lower troposphere while suppressing much of the storminess. After another break in the snow late on Wednesday that will extend into a chilly Wednesday night, a clipper system will spread clouds into Vermont and bring more light snow beginning Thursday afternoon. Not only are we likely to see another small 2-4 inch accumulation by Friday morning, but the passage of the storm will provide another extended opportunity for snow showers, Friday afternoon into Friday night. The largely unfrozen Lake Champlain should make a nice contribution as winds shift later Friday. We can expect a cold upcoming weekend and blustery on Saturday but readings will only be slightly below average (teens on the mountain). That and another few inches of new snow Saturday morning will ensure another winning weekend. 

We've been going with the theme all month that the pattern is generally favorable for snow but has been non-arctic for January standards and that appears as if it will continue. I had anticipated the coldest week of the month in late January with more arctic air on the playing field but the jet stream blocking which has been amazingly entrenched across the Labrador Sea and Hudson Strait next week has acted as a roadblock to any arctic air venturing across the pole from the Eurasian continent and this is now expected to continue. We still expect dual troughs across North America, more or less one on each coast but the stronger of the two is expected to eventually be in the Pacific Northwest, while the east coast trough is again, less arctic. The outlook for next week is thus less cold obviously but its also less dry with a storm track that could deliver for us around the 25th or 26th of the month. The -AO has been old reliable for us, especially this month but ensembles do show it weakening around the turn of the month. I don't want to see too much of this since the AO has been a vital ally fighting off what has has been a persistently agitated Pacific jet stream. 

Very little to complain about for the next week so try to enjoy it if you can !

Friday, January 15, 2021

Snowy weekend incoming across the high country !

Model data has been playing some Ring Around The Rosie over the past 24 hours but we still have a clearing picture of how this will play out. This is a tough weather situation for a model or a human to get a handle on since the precipitation producing low pressure center has yet to form and temperatures in the lowest 5000 feet of the atmosphere are so close to freezing, that differences of a degree can make all the difference. 

If your sitting below 1000 feet, you might not be too excited with the forecast this weekend and I wouldn't blame you. Mixed precipitation, rain and maybe a sloppy accumulation on grass is not especially exciting. For the base of MRG (around 1700 feet) and upward, the forecast for snow holds and accumulations could be quite significant. The low pressure center in question will eventually form, strengthen and track right up through the Upper Valley. Temperatures are predicted to be rather marginal, ranging from about 32-34 degrees in the lowest 5000 feet of the troposphere. If you push that air up a mountain though, it will cool just enough to make the critical difference and that's what I think happens when precipitation commences around dawn Saturday. Temperatures will range from about 33 degrees or so at the base to maybe 29 or 30 at the summit which will make the snow a bit gloppy in nature. We can also expect near gale force east winds at the summit which, as some of you know is not a good wind direction for the single chair. That wind will actually subside later in the day and ultimately shift to a more westerly direction for the duration of the weekend. As for precipitation, we could see a pretty decent thump of snow during the midday hours. If I am correct with my assumptions about an elevation sensitive storm, 6-12 wet inches will be the end result. That said, if a period of rain or sleet (less likely) impacts elevations up to 2500 feet or above, it will hold accumulations down. We are very likely going to get a piece of the deep moist plume of this storm however even a gloppy accumulation can be put to good use as far as establishing a decent base is concerned. 

With that part of the forecast transcribed, I can now move on to the even better part. The Sunday-Monday period is the best terrain enhanced snow set up we've had all year and this snow, on the mountain will be powdery even if valley locations hover above the freezing mark Sunday. The initial thump of wet snow on Saturday may be followed by a period of drier weather before these snow showers commence sometime Saturday night and continue through Sunday. The wind direction isn't ideal for MRG/Sugarbush and is better for locations farther north, but the moisture and instability are there regardless and I expect a decent additional accumulation of 3-6 inches on the mountain by late Sunday. That wind direction is expected to become more northwesterly Monday providing an additional window for snow showers, at least while the instability remains. Overall, this is a pretty good holiday forecast so long as you get yourself out of the valleys. 

The snowfall doesn't end on Monday either. A clipper-like disturbance accompanied by a weak push of arctic air will bring snow back to Vermont Tuesday night followed by the coldest day we've had this month on Wednesday with temperatures struggling to get past 10 on the mountain. We then arrive at the less certain part of the forecast period, late next week. The question involves the presence of absence of a significant east coast storm and that question revolves around how much sub-tropical/southern branch jet energy/moisture wants to involve itself into this colder pattern. Looking at the models it appears to be a here today, gone tomorrow type situation which means I can't say anything conclusive. I can say this though, even without a bigger storm, some new snowfall is likely from another unphased clipper-like storm. 

The end of the month continues to look chilly but a bit drier. The mean axis of the trough appears likely to set up over the western Atlantic Ocean leaving us on the less active flank of this jet stream feature. We would have to rely clippers, maulers and screamers out of Canada in this scenario but things can change beyond 10 days. 

Wednesday, January 13, 2021

Storm this weekend is no home run but looks better overall for natural snow in northern VT as pattern sets up to lock in cold weather for a few weeks

Using the Mt Mansfield snow stake as the official northern Vermont measuring stick, snowpack continues to run well below average as we enter the middle part of January. It's been mild in a relative sense as well, with temperatures about 5 degrees above average. So far though, its been 5 harmless degreese since temperatures across the northern Vermont high country have stayed below the freezing mark for the first 13 days of 2021. Over the next few days, we can expect some of that above freezing air to creep up the mountain side during the days but not by much and our attention will be fixed on the weather situation for Saturday which should bring our first substantial new snow since the New Years holiday. 

A very potent jet impulse is expected to dive southeastward out of the Canadian prairies and spin up quite a storm across the upper midwest Thursday into Friday. This storm will spin up and ultimately spin itself out, occluding and weakening as it turns east and then northeast. This process will carve out a beautiful trough across eastern North American setting the stage for our weekend weather situation. Just a little spark is all we need along the Atlantic Coast and a spark is what we are expected to get with a storm forming along the Delmarva and moving northeast and inland over southern New England. The speed at which this storm strengthens or bombs is the critical question at this point. A quicker strengthening might result in a bit more warm air and some mixed precipitation for us at the start but will yield better result at the finish with a foot or more of snow by midday Sunday. I am relying on the recent European run which shows some modest strengthening as the storm approaches Vermont but has yet to fully mature as a consolidated coastal system. Though changes are possible, this scenario would allow snow to begin before dawn and fall quite steadily for several hours into midday before drier air shuts off precipitation for a while later in the afternoon. A nice added bonus is what appears to now be a better setup for snow showers Saturday night into early Sunday winds shifting north of west allowing for a better moist feed from Lake Champlain which will already enhance some backlash moisture from the then departing storm. It's not easy set of details to sort through and some changes can be expected but a low end of 6 inches for Saturday and Sunday is what I am expecting. Temperatures will be closer to the freezing mark Saturday making the snow, especially at low elevations a little wetter, but whatever falls Saturday night and Sunday should be powdery but windblown. Temps for Sunday should remain in the 20's but the effect of the 20-30 mph winds will make it feel sub-zero. 

A weaker clipper system is expected to approach for MLK Monday but this system is expected to be weakening and much of the snowfall, what little there is, will be south and west of Vermont.  There are also some hints of some light snow in the middle of next week but it appears the storm to watch arrives late in the week. Interestingly, models are showing a more robust sub-tropical feed of moisture into this system after I declared the southern branch essentially dead in the last post. Ensembles are not so certain about all that but it does appear like we are in a pretty good firing line late next week for something. This would be followed by a chilly weekend on the 23rd and 24th with snow showers and snow flurries possible. 

On the general side of things I am a bit more encouraged with the pattern on the whole. Both ensembles are allowing a trickle of jet energy undercutting this mammoth ridge in the Pacific Ocean and this would weaken the potency and the +EPO index somewhat. The feature in the Pacific is one of the dominant forces on the globe but will connect with blocking in the Arctic and the continued presence of blocking in the Labrador Sea. I think this will have the effect of keeping cold weather in our grasp and perhaps allow for a several week stretch of sub-freezing temperatures beginning Sunday and extending into early February. The pattern appears active for the next week with aforementioned storm this weekend and another late next week. If the ensembles are correct by showing a broad area of unsettled weather out west and another trough out over the western Atlantic Ocean late in January, it would be a drier less active setup to finish the month but as I said, it looks quite cold and readings will likely finish the month below average across New England and more broadly across the eastern third of the United States. 



Monday, January 11, 2021

Early weekend storm has inched warmer but still has snow potential while we maintain hope for pattern the last two weeks of January

 Our outlook requires some adjustments for both this week and for the rest of January and there are two items (one specific and one more general) I want to highlight. Although the clouds have arrived to Vermont as expected, the outlook for our potential late week/early weekend storm has evolved and is in need of a reexamination. The 2nd more general item involves the nature of the pattern as a whole which needs some additional discussion. Though we can be confident about the availability of some garden variety cold air, I've become less confident about the storminess. We had a very active pattern for much of December even though the results were less than ideal. In January however, the southern branch of the jet stream has become less robust and models have been over advertising potential storms with the case in point being the weakening storm system moving toward the southeast coast as of Monday. 

The nice run of sub-freezing temperatures will continue across the high country through at least Wednesday and prevailing cloudiness will produce some on and off light snow but it will be pretty inconsequential. The best chance for a few inches will be from Stowe northward throughout this period and the best chance for any sunshine appears to be Wednesday afternoon. This brings us to the interesting but evolving late week and early weekend forecast. 

A ferocious area of storminess now impacting the Pacific Northwest will progress into the northern plains by late Wednesday and ultimately begin to carve out a very amplified jet stream across the eastern half of the country. This amplification is projected to progress a bit more slowly and set up a bit farther west. It is NOT evolving into another Christmas 2020 debauchery but it is a warmer looking system for much of interior New England overall and we will have to wait another day on any snowfall. That said, the situation continues to evolve and additional changes are likely. For now the slower evolution of this weather situation makes Thursday a bit cooler with a slight chance for some wet snow, Friday drier with temperatures hovering at or above the freezing mark and Saturday very interesting. The precipitation will arrive early Saturday with marginal temperatures and may begin as some rain. The midwest storm will be spun out and occluded by this time and this will mitigate if not eliminate the risk of a rainy meltdown but what transpires along the coast. It will be a powder keg at this time and if something can hit the ignition switch, that would be how the forecast changes substantially from here. For now I would anticipate that any mixed precipitation Saturday morning will turn to at least some snow later in the day. The question is how hard does it fall and how long does the accumulating snow last.  Temperatures will spend Sunday in the 20's accompanied by blustery conditions and at least some snow flurries. 

We hope Sunday marks the beginning of will be an extended period of colder temperatures. Initially, these colder temperatures appear very garden variety consisting of daytime temperatures in the 20's and overnight readings in the single numbers or teens. This is certainly cold enough to support snow but when does it come ? Models have been teasing Vermont with hypothetical storms all month but mother nature has yet to deliver much. This gives me a chance to address a question posed a few posts back regarding the prognostications this winter which indeed have been tougher because of the fickle nature of the southern branch of the jet stream. It spent much of December defying expectations and playing a more dominant role in the region's weather (especially the big nor'easter in the middle of the month), but has been weaker than model expectations for much of this month and this has allowed for the quieter period of weather. It is not typical during a La Nina winter for a prevalent "Pineable Express" and we appear to be heading into a more typical La Nina set up late this month. We will not see the split flow in the jet stream we saw earlier this winter and will instead see a consolidated firehouse type jet stream in the north Pacific with storms crossing the country from there. The energized negative AO and the SSW event that proceeded it will bring some arctic air onto the playing field though bitterly cold temperatures are still not expected.  Storms originating from the southern branch of the jet stream are less likely however after Saturday and snowfall will likely have to come from clipper systems or mid-latitude storms of a north Pacific origin. We have a few chances for both however with snowfall possible at least twice during the week beginning Jan 18 (MLK day). I should mention however that this type of pattern does allow for the inland runner and ensembles are hinting at that possibility around the 21st/22. Its possible, but the -AO/NAO makes such an outcome less likely in spite of what happened on Christmas.

Sunday, January 10, 2021

Light mid-week snow foreshadows excicting late January weather pattern

The weekend has been on the blustery side, but the sub-freezing temperatures were accompanied by decent amounts of sunshine. It's been approximately 6 above average for the first 10 days of January but temperatures haven't ventured above freezing above 2000 feet. This of course means good snowmaking for all of Vermont ski country in spite of the continued lackluster amounts of natural snow. 

We can expect more clouds for the upcoming week with snow flurries for Tuesday and some light snow Tuesday night. The southern branch storm currently producing snow in central Texas was a feature we once had hoped could evolve into a big east coast snow producer. Unfortunately, it will meet a rather embarrassing North American fate, moving off the North Carolina coast Monday night, whimpering as it does and confining light rain to a small area of the southeast. 

Our snowfall forecast has not been zeroed out for the week however, we will just have to be a little patient. A slow but steady push of mild temperatures will certainly help, providing an overrunning surface that will help produce some light snow Tuesday night as mentioned in the above paragraph. I would expect this snow to be pretty minimal but a couple of inches are possible from Smuggs northward to Jay Peak by Wednesday morning. A slightly stronger impulse Wednesday night will then bring another chance for light snow and a better chance for a small accumulation in and around the MRV.  Whatever falls, will be followed by one of the milder days of 2021 Thursday with temperatures potentially eclipsing the freezing mark, especially across valley areas. 

There's plenty of details to unpack regarding the overall weather pattern going forward, which, in short, will produce a lot more excitement. We've had the Sudden Stratospheric Warming (SSW) event and the polar vortex disruption which will be marked by the emergence of a block in the jet stream over the Arctic, strengthening the persistently negative AO. There's been some questions however about how arctic the pattern will get over North America and there are many indications that the strongest area of cold will be trapped on the Eurasian continent. It's already been very cold over portions of Asia with Europe expected to get a healthy dose over the next few weeks. Mid-latitude North America will also get cold but likely not bitterly cold which I think is a preferable outcome since most of us are snow hounds first and cold hounds much later if at all. I will discuss my one concern below but I think the garden variety outbreak of cold for the back half of January will be accompanied by several chances for accumulating snow and the first will come well ahead of any arctic air late this week. 

By Friday, temperatures will be well above average and likely hovering at or even above the freezing mark in the morning. Meanwhile the jet stream will undergoing a very intense amplification. Were we to have a decent focusing southern branch feature to go along with this dynamic looking jet stream, we could be guaranteed of some east coast fireworks. I don't see anything like that now but a feisty clipper system could nonetheless have a rather wild interaction with the eastern seaboard and at the very least will bring a bit of wet snow to northern Vermont during the day Friday. Lingering instability during the Saturday and Sunday of MLK weekend will allow for additional snow showers along with temperatures in the 20's. 

We can expect arctic cold to be back on the playing field the last two full weeks of January beginning around MLK day. There are signals of possible storminess around Tuesday, January 19th and then again around the weekend of January 23rd and 24th. My one concern isn't with the availability of cold but rather the continued and persistent strength of the Pacific Jet. It was a concern going into the season because of the sea surface temperature anomaly configuration in the eastern Pacific and has invariably been problematic through the early part of this winter. As the pattern continues to evolve, and the +EPO pattern restrengthens, will much of the cold and unsettled weather focus on the western U.S. ? Ensembles have been suggesting that both the west and eastern U.S. will share in the snow-wealth in this pattern which, as of now is at least encouraging.

Wednesday, January 6, 2021

Sunny and tranquil for the next 5 days and then the fun begins !

We are in the midst of a quieter period of weather in Vermont. Even the clouds have given way to some sunshine and this relative bit of winter tranquility will continue through the upcoming weekend. Temperatures are winter-like but hardly bitter-like and actually it's been pretty nice. Yes, we could use a deeper snow cover but at least we have a little to accompany what should be a nice 5 day stretch of January sunshine through Monday. Meanwhile, the southern branch of the jet stream will produce another rain and snow maker on Thursday and Friday but just not for us. The storm will be well offshore early this weekend but close enough to ensure our stretch of sunny days continues. 

The next chance for snow and weather comes during the middle of next week. If we are to aggregate all the available data as of now, the impact of this storm would again be south and east of us but the drama here has likely just begun. Over the past 24 hours we've had a couple runs of the operational European model show an impact in New England. It's likely a significant storm and the pattern, though not cold, will become pretty amplified by the middle of next week. I wouldn't call it likely that we get a big snow but its at least possible so we should keep watch. 

All of that tranquility in the short term will become a distant memory by late next week as the pattern evolves into what should be a more entertaining form of January weather. We will maintain the negative -AO/NAO combination and the Arctic Oscillation will get a boost from a block in the jet stream expected to form north of Alaska. This combined with the recent Sudden Stratospheric Warming (SSW) event is expected to bring arctic air back to the North American mid-latitudes. And that is not all said the cat in the hat (sorry but I've been reading that story every day to my 2 year old, he doesn't want me to read anything else). Before the advance of any initial offering of polar air, we should get a major amplification of the jet stream around the time of the January 16th-17th long MLK weekend. We could see several outcomes resulting from this but most of them look pretty good for us and should include some new snow and maybe a more organized snow producing storm. 

Arctic air may spend some time fighting for control of the pattern during the January 18th-22nd time frame but i would rather have this as opposed to the polar jet suppressing all of our weather. We also have an unfrozen Lake Champlain poised to deposit some terrain enhanced snow upon the earliest opportunity and that opportunity appears to be on the horizon (possibly beginning MLK weekend). Overall, it looks to be a pretty solid period of winter in Vermont and I am certainly excited for it.

 

 



Monday, January 4, 2021

Rain-free outlook remains intact even as midweek snowfall forecast dwindles

The pattern has been so active in recent weeks that its been tough to keep these updates concise, each one feels like a book. Through much of this time, the ball hasn't really been bouncing our way but we did scores some nice snowfall over the weekend and now will have at least a few days to catch our breath and maybe even enjoy a bit of sunshine if we are lucky. The recent storm, now well off the New England coast is tracking well east of expectations a few days ago. Yes, it will become nearly stationary for a time, but this will happen several hundred miles further east than I was hoping. We can expect some flurries Tuesday and Wednesday but the notion that significant amounts of moisture will back its way into northern Vermont was an incorrect one. This type of snowfall is inherently difficult to predict and I am convinced we'd have a better chance of receiving it had I not discussed it at length a few days ago. 

The big picture landscape still appears about the same in spite of the drier short term outlook. A more cooperative -AO/NAO combo is going to keep the storm track further south and ensure a nice stretch of rain-free weather. Over the next 10 days, this pattern will remain relatively non-arctic and mostly consisting of above normal temperatures. Fortunately, this version of "above normal" will mostly consist of below freezing temperatures through about January 15 which means some comfortable ski weather, especially if we can score some additional snowfall. Beyond January 15th, the negative AO will get an additional boost as a ridge is expected to strengthen in the Arctic Ocean north of Alaska. This will likely bring arctic air back onto the playing field for the 2nd half of the month with the polar jet playing a more active role in the region's weather. 

In the meantime, the still somewhat irritated Pacific jet stream is still producing storms and keeping the pattern active. Our next chance at such activity comes Saturday albeit a reduced chance. This storm will likely produce some snow in a few places down south not especially used to seeing it on Thursday and Friday and then proceed to the North Carolina coast Friday evening. The storm is forecast currently to stay well offshore and not be a snow producer for the weekend but it will be the first of what I think will be a few chances to churn up something of significance. Assuming we miss out on Saturday's storm, we will see windy conditions this weekend with a few flurries and below freezing but not bitterly cold temperatures. Speaking of those additional chances for snow or a storm, I think one will come about every 3-4 days meaning the Tuesday January 12th time frame would be the next and then another chance during or just before the weekend of the 16th-17th. 

We've managed to get it pretty white and wintry out there and are probably one good storm short of some pretty good January conditions.

Friday, January 1, 2021

Very positive start to 2021 with accumulating snow expected 4 of the next 5 days

I hope 2021 is off to a good start for everyone ! The snow and mixed precipitation Saturday morning is certainly a big improvement in the MRV and the outlook going forward continues to improve. We will continue to fight an agitated Pacific Ocean jet stream through the middle of January but there are signs that it will weaken somewhat. Most importantly, and there are no two ways about it, this is a blocked pattern at high latitudes. This, more than anything else, gives our beloved ski country the opportunity to avoid rainfall or extended thaws for a period of a few weeks. As we've seen, nothing is guaranteed and the pattern hardly looks arctic, yet, but it does look stormy and the track of these storms appears a lot more favorable and certainly not rainy. 

The southern branch of the jet stream continues to over-perform and in many cases defy model expectations and I am thus watching the Sunday/Monday situation closely. The consensus of all this data shows the heaviest snow falling further south from a modest looking, but strengthening storm expected to move northeast but remained positioned just off the coastline. Given the propensity of these types of systems to track farther north and attain more strength, it will be worth watching until the end. Even without a more favorable track, the storm is likely to benefit the MRV in more ways than one. We can expect to receive a few inches of snow very late Sunday but the storm in question is expected to get trapped underneath all of that aforementioned blocking and I expect this to induce some additional fun during the early and middle part of the upcoming week. 

I am going to take a stab at some of the details even though they are likely to change some. Following what we think is a few inches late Sunday, a still relatively consolidated storm will confine snowfall to eastern Maine Monday leaving northern Vermont with a dry but mostly cloudy day with temperatures just below the freezing mark across the high country. By Tuesday, the same storm will get stuck and be well passed maturation allowing a conveyor of moisture to rotate westward bringing snowfall back to Vermont. This is how northern Vermont gets paid from a snowfall climatology perspective and lets be honest we are owed ! We won't break any records from this snow but it will be a nice dry accumulation and could be continuous even if light, starting some time on Tuesday and extending into Wednesday. 6 or more inches above 2500 feet in this time frame is very realistic and would make this upcoming Wednesday easily the best ski day of the year so far.

And there is yet another storm to be watched for Friday. Models have been taking this potentially large precipitation producer farther south over the past day or two. This is somewhat related to our storm early in the week getting hung up over the Canadian Maritimes. Even if we miss on this guy, we can be ensured of keeping temperatures below freezing through the week. Not too bad in a very non-arctic pattern. 

Speaking of that pattern, I have certainly been a lot more encouraged over the past few days. The nature of the blocking over the Davis Strait/Labrador Sea was disconcerting as of a week ago but this feature appears a lot more cooperative going forward, confining its influence closer to home. A not so insignificant block in the jet stream north of Alaska in the Arctic is a nice added chess piece as well, counteracting the somewhat menacing Pacific Ocean which is also expected to weaken just a touch. The hotter topic in the weather forecasting community as of late is the sudden stratospheric warming (SSW) event which has just commenced over the Arctic. I won't get too tangled in the weeds on SSW but I can certainly recommend following Amy Butler or Judah Cohen on twitter if you want to learn more. These types of events that occur in the stratosphere often foreshadow big southward advances of arctic cold. So yes, the pattern is not especially arctic over the next two weeks, but that is likely to change in the 2nd half of the month.