Rapidly retreating arctic air and angry Pacific to bring a very mild week of weather to Vermont

Arctic air continues its end of 2022 North American retreat and temperatures across all of New England are poised to soar. Model data is suggesting a dry day Friday with a layer of clouds assisting at maintaining an inversion that would mitigate the warmth and the wind. I think this can be true for a chunk of the day, but even a small period with a break in the overcast will allow the excessive surge of mid-level warmth to mix down to the surface and allow temperatures to exceed 50 in valley locations and at the base of Mad River Glen. These temps along with the near 40-degree dewpoints will soften snow conditions and this should continue into Saturday when temps continue to hover in the 40's even during the morning. The rain is coming for the weekend as well and its just a matter of timing it at this point. Several hours early in the day Saturday should remain dry but the risk for rain increases during the afternoon and and we should expect to get wet before the end of the ski day. The heaviest rain can then be expected Saturday night followed by colder windier day Sunday with precipitation becoming a wet snow across the high country though  it appears to be too light to amount to anything of significance. 

The jet stream in the Pacific has decided to end 2022 in an especially angry mood and the results are not good for Vermont snow lovers. Across a corridor of the western United States, the results have been a lot better. Tahoe has had an incredible month but the recent storm saw rain even as high as 7000 feet. Mt. Rose is a cool family owned Nevada mountain and also has the luxury of having much of its skiable terrain above 9000 feet. Almost 170 inches of snow has already fallen at Mt Rose this season with more on the way. Utah and much of Colorado have done extraordinarily well this week and have enjoyed cool temperatures and excellent snow throughout this month. The mood  of the jet in the Pacific  is expected to improve over the coming week, but not soon enough to prevent another big surge of east coast warmth toward the middle of next week. Almost everything appears a bit quicker as of today verses some model indications a few days ago but that hasn't shifted the overall theme of the outlook for next week; in fact, the warm surge looks warmer and may result in record breaking temperatures (60 degrees in valley locations) across New England with a wind and rain event quite possibly wiping out much of our snow after Wednesday. I use the term possible because there's a more intriguing possibility emerging following the big warm-up and a period of rain that appears impossible to avoid. Could low level cold in Canada make a southward push out ahead of a lagging wave of flow pressure and induce a late week snow event late next week (Jan 5-6)? Slight chance for now but not yet likely.

As mentioned teleconnection indices all turn mildly favorable even before my targeted turning point date of January 10 save maybe for the NAO which as of today is indicated to remain just a little positive through the foreseeable future. For the time being however, longer range models are struggling to pull arctic air back into North America. There is evidence of some ridging in the arctic regions above the northeastern Eurasian continent and this feature would be capable of pulling arctic air back into the northern half of North America (most of Canada), but models are yet suggesting this feature to be strong enough to do this in a large scale way. Even without the presence of large scale amounts of arctic chill however, operational models over the past few days have indicated the return of winter weather between January 9th and 16th which is about as far out as we can see. As mentioned, a softer January pattern with a limited polar jet might be bad for snow along the New England and Mid-Atlantic coasts but is not terrible for interior and elevated areas which can be dominated by dry stable air in such an environment. We will need some time to recover after this stretch of warmth, but it continues to look at least a little promising for the final 3 weeks of January.

Hideous stretch of winter weather expected across interior New England for the start of 2023, but improvements are visible beginning around January 10

At the very least, it is good to see a lot terrain open not only at Mad River Glen, but throughout the northeast. We've had many Christmas periods with "practice slope only" situations at least at MRG so I am happy to see we've cleared that bar without too many problems. Unfortunately we have to face some irritating music over the next 10-14 days as arctic air is forced into a deep retreat. I can guarantee a lot of above-freezing temperatures through January 10th and not a lot of natural snow. I was hopeful that we could avoid excessive amounts of snow eating rain and wind but the rainfall part appears to be an increasing concern right at New Years. As lousy as this seems however, one can already see improvements way out on the horizon and the last 21 days of January should see much better results than the first 10.

High res model data is indicating just a bit of warm-advection or overrunning snow Wednesday morning. Enough for a 1-2 inch fluffing, most of this before the ski day begins. As the ski day winds down, we may see clouds give way to some blue sky and temperatures that approach the freezing mark. In comes the mild for Thursday with temps soaring above the freezing mark and into the 40's across many low lying areas. Clouds are likely to keep the wind lower and temperatures from getting too excessive. This also applies to Friday and Saturday though I am concerned breaks in the overcast will allow mild southwesterly breezes to mix the atmosphere and allow afternoon temperatures to approach 50 in some spots. Through Saturday, we can certainly confine any rainfall to the "light" and very "sporadic" category. On New Year's day, a Sunday this year, we are seeing more evidence of an organized storm system. This low pressure area is indicated to  track over Lake Ontario which is certainly not the worst kind of inland runner ever, but we will have entirely voided ourselves of cold weather by this point and a cold rain is about all that we can expect with much of it falling on the first day of 2023. 

Temperatures are expected to remain well above normal beyond New Year's day although readings will cool down, mostly during the overnights on January 2nd and 3rd. We then can expect another big surge of mild weather as the first full week of January progresses and likely some additional rain just before or during the weekend of January 7th and 8th. In total, 3 days of 50-plus temperatures are my best guess for this upcoming 12-day mild stretch.

As bad as this all seems however, the month does not appear to be a complete loss and the torch seems temporary. The Pacific is certainly angry for a time forcing the retreat of arctic air in North America but the EPO index never attains "evil empire" status and the storminess at the lower latitude regions in the Pacific will ultimately break down the ridging in eastern North America. Other teleconnection indices are also expected to improve with some soft indications of ridging in western North America as we approach my turning point date of January 10th. Even a few days prior to said date, every major teleconnection index turns mildly favorable but it's the PNA or some ridging in western North America that will be critical in allowing eastern Canada to finally get some winter and for New England to have better access to colder weather. Even as cold in western North America has been earning headlines and snow/wind has paralyzed Buffalo, eastern Canada has been very warm most of this month. Ice expansion in the Hudson Bay had a strong start November but has been crippled by continuous warmth in eastern Canada and this large body of water remains not entirely frozen as of Boxing Day. A frozen Hudson Bay does not have the impact of modifying arctic airmasses and is another reason why January and February are materially colder in Vermont than December.

Cold weather over Christmas expected to yield quickly to several days of mild above-freezing temperatuers around the New Year's holiday

The skiing was beautiful early this past week, but as I watch Buffalo record its 36th consecutive hour of blizzard conditions I can't help but think that we have once again performed an epic reversion to our December mean. This point is underscored when looking at weather conditions for the next 7 days. The storm December 16th was beautiful and we had a few days to enjoy it, but then somehow managed to get ravaged by rain and widespread power outage producing winds while the strongest December arctic cold shot in years envelops much of the eastern two thirds of the country. We have a lot of water in that remaining quite encrusted snow pack but it is poised to get tested by a good round of El Torchy over the New Years holiday and an early January period that appears quite balmy. 

Through Wednesday December 28th, conditions across interior New England continue to appear to be chilly. A "caboose" type disturbance in the polar jet is in fact going to impact Vermont with some clouds and light snow late Monday into early Tuesday and this snow is capable of producing a few inches though there are no indications of anything more than that. Clouds from the strong push of milder temperatures could again bring a period of snow to the MRV Wednesday but there are also indications that this could remain north of us allowing southwesterly flow to warm temperatures beyond the freezing mark. The 1-4 inches of snow Tuesday is the best mother nature is capable of in what appears to be a lousy upcoming period beginning on December 29th. 

If you simply take a snapshot of the raw teleconnection indices over the next 2 weeks, they don't look all that terrible; in fact, they appear to be pretty neutral. This serves as good justification for suggesting that the excessively mild weather we appear clearly earmarked for won't persist through most of January. That said, the period around New Years just looks atrocious for winter weather lovers. The jet stream in the Pacific appears ready to get really angry for a time. After January 10th, this setup could produce a few decent storms, but for a time the pattern will simply align for excessive warmth in New England and much of eastern Canada while arctic air goes into a deep retreat to start 2023. Weather systems could bring a period of rain to Vermont in the New Year's holiday time frame, but there continues to be a lack of evidence suggesting heavy or widespread rain. The warmth is different story where temperatures are expected to exceed the freezing mark every day from December 29th through January 2nd with at least 2 of those days possibly seeing temperatures above 50 below 2000 feet. The above normal temperatures are expected to continue after January 3rd though there are indications of a jet stream that could potentially support snowfall producing storms after January 5th.

Powerful storm to bring both snow, rain and wind to northern Vermont and mild weather looms larger for New Years weekend following a cold Christmas

There's obviously a lot of weather out there and much to discuss with upcoming storm, a powerful cyclone that will prove to be challenging given its impact on one of the bigger travel days of the year. Across much of Vermont, wind is the primary concern. New England sees some of the worst storms in the country yet much of our electricity remains distributed through the vast network of above ground wires which are very vulnerable in a storm such as this one especially when older trees or tree limbs come down. Please keep that in mind during the day tomorrow whether your plans include travel or hunkering down at home. 

Obviously this isn't the ideal storm for snow in northern Vermont given the track and the early amplification in the middle of the country. That said, model data has moved away from some of the worst outcomes and a sizable front-end thump is now expected beginning around midnight Friday.  Some of the data out there is suggesting as much as 6 inches while more conservative indications (and better in my opinion) points toward 2-4. By daybreak Friday, temperatures will have inched above the freezing mark and precipitation will become rain. For a time the rainfall will be steady as opposed to heavy and I think most of the high winds gusts will remain above the surface and protected areas and valley locations. Summit locations won't be so lucky where winds could even reach hurricane force by the middle of the day Friday. The high wind and a 1-2 hour burst of heavy rain is likely during the midday or early afternoon period when, even in valley locations, gusts could reach 50 mph. Wind has a propensity to eat at snow along with rainfall so it is my hope that we can limit both forms of weather to a limited window. Temperatures will start Friday in the 30's, spike into the 40's briefly and then tumble back toward the freezing mark as it gets dark Friday evening with a period of snow likely between 5- 8 pm. Standing, slushy water certainly could freeze quickly and the snow is expected to be heavy enough to accumulate another 1-3 inches before conditions dry out later in the evening. 

The incoming cold airmass is not expected to hit New England particularly hard compared to some other areas. Temperatures will stay confined to the teens Saturday after bottoming out in the single numbers in the morning. Winds will remain high enough to produce wind chills well below zero but actual temps should rebound back into the 20's both Sunday and Monday afternoons. Unfortunately, the southwest flow bringing the cold back to Vermont is also a relatively dry wind. Lake effect snow will hit the snowbelt regions but the snow shower activity should remain minimal through Monday and expect to see decent amounts of sunshine accompanying the wind through the weekend. 

Fully expect the colder temps to persist through Wednesday 12/28,  but the weather pattern is expected to take a bad turn later in the week and allow mild air to make a big push northward prior to New Years weekend. I've yet to see indications of any big rainfall but there are hints of temperatures that could reach or exceed 50 for a 2-day stretch. As of Thursday evening the current weather pattern doesn't even seem inclined to give us a goodbye kiss with a system capable of producing a few inches of snow as the pattern softens and arctic air retreats. This often happens in these type of situations and though it's worth watching, nothing is indicated for now late next week. I will reiterate that fundamentally speaking, the pattern doesn't look capable of supporting several weeks of this but the North American continent is expected to lose its arctic air which is typically a challenging obstacle for natural snow.

A short-lived thaw with some heavy rainfall Friday afternoon followed by a chilly Christmas weekend

 If there was any type of trend to convey regarding our upcoming Friday storm it would be "less bad". It's really no consolation however because "bad" is bad. We've had worse thaws around Christmas both in duration and intensity. This one will feature a little over 12 hours of above freezing temperatures and a small window where temperatures approach 50 along with a burst of heavy rainfall. By Friday evening the rainfall is done and temperatures will again support snowfall if we can get any. 

A friend at the National Weather Service made an interesting point to me the other day. He suggested that sometimes the presence of a polar jet can at times have a detrimental impact on a promising storm track. Jet stream impulses with in a polar jet are more dynamic and have the power to amplify storms so ferociously that they are unable to make a clean transition to the coastline and will run up through the Great Lakes sucking warm air into New England. This case would certainly underscore the point although arctic cold is an important ingredient for snow producing storms on the east coast so its presence is important though I suppose it needs to be the right kind of presence. 

After several days of sub-freezing temperatures atop last week's two foot snow storm, the big push of warm air should initially bring a period of snow to northern Vermont very early Friday morning. I like to refer to this warm advection snow as a "front end thump" but unfortunately it won't be much of a thump. A few hours of snowfall before dawn and a few inches. At daybreak on Friday temperatures will be moving past the freezing mark and any wintry mix will become mostly rainfall. Models are beginning to sort out the ugly details which include only a few hours of heavy rainfall sometime between noon and 5 pm. This is a very strong storm and I expect the high winds to remain off the ground until late on Friday when we will see wind gusts of 30-40 mph in the valley's and upwards of 50 near the summits. If there's been a positive trend over the past day or so it involves the possibility for some anafrontal precip Friday evening in the form of snow. The drop in temperatures is expected to be very dramatic and capable of flash freezing some standing water late Friday evening. By Saturday we should see some intervals of sunshine, a cold southwesterly wind along with snow flurries. If the flow was better or more northwesterly, we might have snow shower activity of more significance, but this southwest flows confines the heavy snow showers to areas like Jay Peak over the weekend. The arctic outbreak is substantial for the Ohio Valley, Kentucky Tennessee and even areas further south though short-lived. In Vermont however, the cold is very garden variety with high temperatures in the teens on the mountain and morning temperatures in the single numbers. Expect some ugly wind chill values Saturday to go along with those teens and this will only very slowly improve Sunday into Monday. 

Most of the holiday week following Christmas is expected to remain sub-freezing in Vermont but the pattern is expected to undergo some material changes with the polar jet and its associated arctic air gradually retreating. A softening pattern can create the opportunity for storminess along the east coast and there are hints of this on the Euro/Canadian models on Tuesday or Wednesday of next week. We should more clarity on how realistic our snow chances are in this time frame within the next 48 hours or so. 

After Wednesday the Pacific is expected to really intensify and the entire North American continent outside the southwest U.S. is expected to see moderating temperatures. As bad as the Pacific appears for a few days, and as detrimental as that is for the buildup of cold across North America as a whole, I've seen worse January weather patterns. Both the NAO/AO are expected to remain on the favorable side of neutral and even the PNA index (a measure of ridging on the western North America) isn't all that terrible. Remember, by January, we don't want to be overwhelmed with arctic air as that can really dry things out at our latitude. We would prefer a stormy pattern with a bit more available arctic cold than what's indicated. So the pattern at face value doesn't look great at the start of '23 and quite terrible if you want snow along the coast or in NYC and points south, but there's room for some hope in Vermont.

Forecast models Mr. Grinching potential big storm on Dec 22-23 (Thur/Fri) shifting track west and bringing ice/rain into forecast picture

We certainly got a terrific result with the storm both Friday and Friday night with two feet falling over the high country and some additional snow showers and flurries on Saturday. Though we are in the middle of a very favorable weather pattern, there is growing concern with our next storm expected to strike on Thursday December 22nd into Friday December 23rd. We've gotten a couple rounds of model data showing adverse results and we will need to reverse this trend very quickly to save a storm setup that appeared loaded with potential for several days. I'll discuss the details two paragraphs down but needless to say it has been very disappointing watching where forecast simulations have trended the last few days. 

Up until Thursday we continue our stretch of sub-freezing temperatures on the mountain and readings will actually inch toward the colder side each day with high temperatures up near 30 on Sunday and then dropping into the 20's Monday, Tuesday and Wednesday and perhaps only low 20's for a while on Thursday with morning temperatures in the single digits. Westerly flow on Sunday is capable of producing a few flurries and light snow showers but the setup will improve Monday with snow showers enhancing in the afternoon as winds become more northwesterly. Models are not indicating much of an accumulation and I would not expect one in the valley, but the mountains, General Stark, Lincoln, Mt Ellen could see a few inches. Tuesday and Wednesday don't appear to be totally bluebird but both should feature the most sun out of any of the days during the upcoming week. 

So I've been reading my nearly 2 year old daughter The Grinch That Stole Christmas and she doesn't seem to very fond of Christmas Trees vanishing up the chimney. As far as I am concerned however, old Mr. Grinch can have my Christmas Tree just don't give me a highly amplified inland cutting storm capable of flooding me with warmth. This is what's been happening to Vermont year after year and the curse seems to have taken on a special life of its own by defying a blocked weather pattern late in 2020 and yielding a Christmas Rain and threatening to do that again with the upcoming storm on the 22nd and 23rd. But before we all start crying in our beer (I've already kinda done that), keep in mind that we are working with more substantial amounts of cold air both on the front and especially rear flank of the storm. Even if the very dynamic low pressure center in question were to track over Syracuse, northern Vermont would be capable of procuring a decent front end thump of powder, limit the the freezing rain/rain period and receive some back end wrap around oragraphically enhanced snowfall Friday evening into Christmas Eve. If this were indeed the absolute downside of possibilities, I wouldn't feel too bad about the less than ideal situation. Late on Saturday evening, both the Canadian (GEM) and American GFS ensembles seemed to support such a scenario. That said, there have been several operational models released over the last 24 hours that have been suggesting the polar jet injection is just a steroid that simply over amplifies the whole setup, too early and too far west. The European model from this afternoon flooded much of eastern Ontario and all of Quebec with warmth and had the best snow over Madison, Wisconsin. As I mentioned, I've seen a few iterations of this on operational models run over the past 24-36 hours but fortunately the aggregated consensus of data has not yet been advertising anything that dire. 

I mentioned the other day how difficult it is for medium range models to get a handle on winter storms when a polar jet gets involved. The arctic, and the jet stream that brings it operates at a different speed and small changes in that speed can mean very different results. We are 5-6 days from this event and I continue to expect some additional changes. Highly amplified storms can be fun when the track of the storm is right, but in this case we would prefer a slightly flatter less robust storm. It's not looking promising we can keep the ice or rain out of the forecast picture in this setup given where data has been trending, but we still have some limited time to salvage the situation. 

Additionally, we still have several days of garden variety arctic chill in the wake of this storm though amazingly, after all the hype surrounding this weather pattern on social media, most of interior New England won't see any sub-zero readings from this. Parts of the deep south will see some impressively cold temps for a day or two thanks to the core of the cold getting pile-driven toward the Gulf Coast by this storm. The cold will come quickly and go rather quickly however and is unlikely to create too many problems outside of the winter storm's primary impact zone. As far as additional chances for snowfall after the 22-24th, nothing specific is showing up, but I expect the weather pattern to soften and this process typically allows for another storm to materialize. In this case it would allow our next chance to arrive in the time frame just before New Years. 

Beyond that there are clearer suggestions of a push toward a milder pattern with a tightening Pacific jet stream and a more zonal weather pattern. There are indications on the ensemble data of continued storminess which is encouraging as far as snow potential is concerned. By January we don't want a weather pattern to overwhelm us with arctic cold and thus a little mild can still produce decent results while a complete torch is something we would obviously no part of. 

Storm to bring 15-25 inches Friday and Saturday to areas above 1500 feet with another possible storm lurking late next week

With each new piece of data, I've become more impressed with our upcoming event. Just a perfect type of storm to get the season started. As I mentioned yesterday, this isn't a "bombs away" situation or a storm capable of reaching any kind of historical strength as far as nor'easters go, but the weather pattern has created an ideal set of circumstances for this and it reminds me a little of the setup we had prior to getting clobbered with 4 feet of snow in late February of 2010. 

We continue to be working with an airmass that wasn't especially cold to begin with and has gradually become rather stale through the week. This allowed temperatures over valley locations Thursday to approach 40 degrees. It's a good thing our coastal low is establishing itself nicely Thursday and will track along the southern New England coastline because an inland runner would flood the region with warmth with little resistance. Fortunately, no inland runner is expected and we have a healthy, slow moving plume of moisture which should bring snowfall to the region by daybreak Friday. What is particularly impressive is the deep moist layer of southeasterly fetch or flow of air, which when rammed against the spine of the Berkshires and Green Mountains, enhance snowfall rates and bring some very impressive snowfall totals above 1500 feet. The warmth will make the snow consistency wet over valley locations and if you reside in a western shadow of a mountain range, you are in a big screw zone. Over the years, I've seen some wild snow shadows in these aforementioned regions and I think this is a really amplified case where areas just west of the big Green Mountain spine (thinking of you Middlebury, Bristol, Hinesburg and Underhill), will see limited gloppy snow and mild above freezing temperatures. Fortunately, most of us don't make turns in these areas (though some of you might) and if you stay above 2000 feet the results will be very good and considerably more powdery. The best part of this event is the extended stretch of time this pivoting area of moisture will sit over our area. This is just outstanding and should allow moderate to heavy snowfall to continue well into Saturday. It's this facet of the storm which will allow accumulations to reach 15-25 inches over the high country with a gloppier 10 inch snow expected in the valley and less in areas west of the Green Mountains. Folks always ask me about wind and though this is not an especially strong storm, it does have a healthy and deep easterly gradient as I mentioned. This means winds will be substantial Friday but slacken a bit Saturday while shifting 180 degrees and becoming westerly.

Sunday appears drier and a little cooler with temperatures hovering in the 20's in the mountains and near 30 in the valleys. As indicated in a prior post, some limited moisture should be able to return to northern Vermont in the form of some snow showers either late on Sunday, Sunday night or Monday though this has gradually appeared less impressive as our Saturday snow totals appear more impressive. The early part of next week then appears somewhat tranquil even as a motherload of arctic air invades western Canada and the pattern prepares to amplify for fireworks late in the week. 

I make no guarantees regarding the potential event on December 22-23. It can be very difficult for models to nail down weather events when the polar jet starts to get involved. It just creates a more chaotic environment and a difficult one to predict with small simulation errors amplifying into larger ones exponentially. That said, ensembles are showing an outstanding signal, 8 days out, for a major nor'easter with this one producing heavy snow, wind and featuring much colder temperatures both during and in the wake of storm. This event could end up out over the ocean and it was even indicated at one point to be an inland runner a few days ago (I highly doubt it at this point), but at the very least it provides an additional opportunity for snowfall prior to Christmas. Speaking of that holiday, it looks both windy and frigid most of the weekend and I will underscore the wind part because I don't think temperatures, though cold (single numbers and teens), will shatter any records. The cold air is expected to linger through the holiday week and I expect another chance at snowfall as the pattern softens and the arctic air either retreats or moderates. I actually expect an additional surge of cold prior to New Years over New England but the pattern overall over eastern North America is indicated to soften. There are hints at a strengthening Pacific Jet around the start of 2023, but I don't consider this a threat to holiday skiing in Vermont.

Snow on Friday begins a beautiful stretch of winter weather that should extend through at least part of the Christmas holiday

Doesn't seem likely that Friday's storm turns into a coastal bomb, but the Green Mountains appear well situated to do about as good as anyone from our upcoming weather event. This storm has already bombed over the northern plains and it is expected to fully mature and occlude over the western Great Lakes by Thursday. Typically, this can spell trouble across New England, but it's the NAO to the rescue with low pressure expected to reform closer to the southeast coast on Thursday, strengthen and then proceed northeast bringing moisture into a widespread swatch of the Northeast. 

Meanwhile the cold dry air has managed to overperform across interior New England early this week allowing us to procure the first round of single digit temperatures this month Monday night. A storm spinning its way in the maritimes has failed to return moisture into western New England but has managed to suck the cloudiness and instability away from Vermont allowing for the bluebird weather. The dry air, will serve us well as moisture arrives Friday morning. We should see an all snow event beginning around daybreak and persisting at varying intensities through Friday evening. Coastal New England snow lovers have been showering love on the American GFS model because it indicates a track which would keep snow further south. I don't for a minute buy that however. We should see that model conform to the rest of model consensus which would keep the best snow and mostly powder snow at high elevations, over interior New England. Even the Champlain Valley which as recently as the weekend seemed earmarked for some rain, appears to be primarily snowier though their snowfall could still be a bit gloppier. As for us, I think this is a solid 10-14 inch event Friday and Friday evening with some additional snow possible later in the weekend which I will discuss below.

We should a break in the snowfall either early or through much of Saturday with some limited sunshine allowing temperatures to creep above the freezing mark in the valley locations though the high country should stay mostly in the 20's. The initial pool of jet stream energy associated with this storm will gradually move over Vermont Sunday into Monday allowing for elevation sensitive snow showers that should persist through Tuesday. I don't love the wind trajectory in this time frame for the MRV and would favor heftier accumulations in this time frame from Stowe and Smuggs northward to Jay Peak but we should be able to procure at least some additional snowfall in this time frame while temperatures remain generally in the 20's during the day. There is some activity in the southern branch of the jet stream to watch for the middle of the week, but there is a stronger signal for a significant storm around Friday December 23rd. A lot of the right ingredients are in place emphasized by a amplifying jet stream and a big surge of arctic chill in the middle part of the country. If nothing else, it sets up the Christmas holiday beautifully with wintry conditions locked in place through at least the 28th of the month. 

There is a beautiful upstream block in the jet stream expected to form north of the Bering Sea. This would correlate to a very intense outbreak of arctic cold across the western two thirds of North America with a burst of intense cold expected for the Christmas holiday along the eastern seaboard. There are indications that the surge of cold would abate somewhat after the 26th but with some remnants of this pattern remaining in place up until New Years. This is the best looking Christmas setup since maybe 2005 which goes back 17 years ! Almost as old as the blog.

Data aligning for a solid base-building storm Friday and into the weekend with wintry temps dominating through the early part of the holiday period

A nice stretch of sub-freezing temperatures and a bit of snow and we have liftoff once again for our northern Vermont winter. November was just a tease. For the most part, the weather pattern, though not supportive of bitterly cold temperatures yet, will support a continuation of sub-freezing temperatures, perhaps through the Christmas holiday. It will remain dry for the short term with temperatures in the teens during the overnights and 20's during the day with some stiff northerly winds, particularly at the summits. I've been eyeing the possibility of moisture getting sucked back in the maritimes, a frequent occurrence in these types of weather patterns. Furthermore, we have a favorable snow shower wind trajectory Tuesday and Wednesday with the flow directed beautifully from the longest fetch of an unfrozen Lake Champlain possible. For now, models suggest the atmosphere is too stable for anything, but I would not be surprised to see afternoon snow showers or flurries late Tuesday and perhaps again on Wednesday. 

I've had the urge the post updates on the upcoming Friday/Saturday storm but models have moved in every direction with this sucker over the last few days and a play by play of this action would be dizzying. In short, the blocked weather pattern will do its job and allow this overly mature and occluded monster of a storm in the plains to establish a new center near the southeast coastline. This process thwarts any northward push of air or severely mitigates it across northern New England. We needed this in the worst way with cold dry air in rather short supply by week's end. Though we can't get too definitive about the details yet, my inkling is that most if not all of the precipitation with this storm remains frozen on the mountain with a small opportunity for sleet or freezing rain and yes rain for valley locations and especially Champlain Valley locations. There's quite a bit of snow possible here also with a thump possible on the front end and a deep pool of instability over the weekend providing the opportunity for additional snowfall on both Saturday and Sunday. A few models late last week lit the fuse, phased and bombed this storm yielding a 2-foot outcome for interior New England. That outcome was then pushed south on Saturday and then the ultra-phased bomber has not been shown on successive cycles of model runs Sunday. I wouldn't entirely eliminate that possibility as of yet, but I feel very good about getting a solid base-building snow (8-16") this Friday and into the weekend for the mountains. 

The weather pattern for the upcoming week and through our end of week storm will be dominated by the blocking centered in the Davis strait almost due north of us. As we progress beyond this weekend the weather pattern will take on a different look with the -NAO fading and a new round of high latitude blocking forming closer to the pole north of Alaska in the arctic. This can be a terrific mechanism for transporting bitterly cold arctic air southward and into the United States, but the North American continent will be voided of its core of cold with much of it locked over Siberia. It will be challenging to pull a substantial chunk of that chill over the pole on a massive scale so I continue to favor a garden variety chilly pattern that I think should see additional storms and possibly a very big one right around the Christmas holiday. We are certainly long overdue such a result after experiencing so many recent holiday thaws.

 

A colder and snowier trend has re-emerged in the period leading up to the holiday as we enter a more wintry weather pattern

No warmer trend in this update. I don't particularly enjoy playing that game in the winter and we appear to be done with it for the time being. Additionally, and most importantly, the snow forecast has improved. I wouldn't bet on seeing the the 40 inches of snow yesterday evenings American model advertised over the next two weeks, but when you take that model and the just released European model and incorporate all of it into your possibility spectrum, the potential results improve dramatically. Lets discuss. 

We have a near term (next 5 day) colder trend and one that was needed. There's a small amount of snow to go with that, which, given the current state of the bare ground is very welcome if only for aesthetics.  Friday and Saturday are both bluebird days and sub-freezing across the skiable northern Vermont high country. A subtle jet stream impulse will be crossing the southern Great Lakes region on Saturday as we continue to bask in our December sunshine. It will ultimately energize a new low pressure center in western Pennsylvania and that feature will transition offshore Sunday evening. There is an increasing likelihood that a corridor of moisture will impact some or all of Vermont for several hours and thus bring a small accumulation of snow to the barren ground. We have to start somewhere ! 

In addition to any snow Sunday night, there is a small pocket of chillier temperatures that will get flushed into New England once this storm passes. This allows the first three days of next week to appear colder in the forecast and certainly below freezing across the high country with teens dominating the overnights and 20's during the day. A persistent wind on both Monday and Tuesday will bring wind chill temps below zero as well. Moisture could sneak its way southward from the maritime regions of Canada during this time frame as well but current indications are that this stays east of us. 

The big question next week relates to the storm with a potential impact on Thursday and Friday. I mentioned on twitter that there remains a lot of potential with this sucker. The temperature situation remains tenuous but has moved in our favor a bit on 2 major cycles of model runs. Most importantly, the pattern is there for this to evolve into a big snow producer. There is just a massive pull of jet stream energy with this storm as it matures in the central United States. Normally, the track of such a storm would suck warm air and rain into the region late in the week, but with the downstream jet stream block in place it changes the equation quite significantly. I wish I could lock the just released European model into our forecast but too much could still change. That scenario would have some mixed precipitation change to wet and eventually a more powdery mountain snow that could persist through early Saturday yielding well  over a foot of snow above 2000 feet. A cold rain remains possible however as does a bunch of other outcomes in between. I can say with confidence that temperatures next week won't even closely resemble the disastrous outcome this week. 

Talk of more substantial amounts of colder air has again gained steam in the last few days for the period around the winter solstice and continuing through Christmas. As we approach that time frame the consensus has moved toward a pattern dominated by a downstream block to a pattern dominated more by a upstream block positioned over Alaska. This upstream block is a much more effective mechanism for arctic air delivery in general. Still though, I continue to see obstacles bringing the core of bitterly cold air, bottled up over much of eastern Russia across the pole and into North America and I would favor a forecast with chilly (sub-freezing) but not bitterly cold temperatures. That said, I continue to love the pattern for storm potential. The negative EPO or tamed Pacific jet stream sets up beautifully for additional snow producing storms in a very critical point in the ski season. There is no guarantee the stars align, but the odds are better this year than any other Xmas holiday period I've seen this past decade.

Though the trend toward milder temperatures continues for the next 10 days, the pattern continues to have winter weather potential through Christmas

Many of the same ideas will dominate this blog update as rain dominates the weather picture in northern Vermont in the middle of our first week of December. The upcoming pattern continues to have potential on the winter storminess side of the equation, but the cold air which I predicted would under-perform, has under-performed even my low expectations and the forecast for the next 10 days continues to move in a warmer direction. 

With that said, there are a couple of opportunities for winter weather over these aforementioned 10 days. Nothing imminent and certainly nothing we can take the bank, but it's something and we have to start somewhere. Though we won't have snow on the ground, we can a nice stretch of dry weather beginning late Wednesday with sunshine featured on part of Thursday and most of Friday and Saturday. Though the air isn't bitterly cold, much of this period should stay below freezing above 2000 feet allowing snowmaking operations to progress. As expected, a weather system will track well south of the region late Friday and the rain/minimal snow will also stay well to our south. There's been a move on the most recent cycle of models to allow a jet stream impulse to undercut the large blocking structure in the jet stream to our north on Sunday. This feature will have an opportunity to use the relative warmth of the Atlantic to intensify into something on Monday. Precipitation is likely to stay south of Vermont with this guy also, but I am not sure we have total clarity on this potential situation yet. It will evolve and it's worth watching as a potential snow producer for someone early next week. After that a bigger weather system is likely to impact the region later next week. We have gained a clearer picture of this likelihood, but models have been trending farther north and warmer with this storm and at least at this juncture, are not moving the the system underneath the Davis Strait block which is a trajectory storms often take in this weather pattern. I am exercising my constitutional right to remain optimistic regarding a potential storm late next week in spite of current models which will most assuredly shift again. This is a pattern that favors a more optimal storm track and often times we can miss precipitation because we are too far north as opposed to worry about rain.  That said, temperatures continue to appear above average yet still mostly sub-freezing through at least Wednesday December 14th. 

After the potential storm in the later part of next week, the strength of the -NAO starts to recede but not vanish entirely. The emergence of what appears to be some ridging in the Gulf of Alaska would suggest to me the possibility of a better cold air delivery device around the time of the winter solstice (or just before). At face value ensembles are suggesting the potential for storminess more than cold, but most of the teleconnection indices are at least somewhat  supportive of both cold and storminess. I have argued that the cold is being held back by a re-energized Pacific and a negative PNA which is a loose measurement of jet stream ridging strength in the western part of North America. We are expected to at least neutralize this by the 19th while other teleconnection indices remain somewhat supportive of more favorable winter weather conditions. What choice do we have but to wait patiently.

Stormier and more intriguing weather pattern still imminent but cold air remains limited through at least next week

 In the last post, I put some special emphasis on the idea that although the upcoming weather pattern appears favorable for storms, it does not especially favor bitterly cold weather. I've been at odds regarding this point with a few other notable longer range forecasters yet in spite of all that, my own forecast ideas were still too cold for the next two weeks. A blocked pattern supported only by a negative -NAO is typically not all that cold and all that's fine but we need to see some storms and some snowfall to begin moving our ski season in a positive direction. I was hoping we could gain a little clarity as to when we might see some significant snowfall but instead I need to go with the theme that temperatures will remain on the milder side a little longer and east coast storminess capable of impacting Vermont with snow is still likely more than a week out.

In the meantime it's another rain event event Tuesday, Tuesday night and into early Wednesday with temperatures generally in the 30's or low 40's. A few areas could see some freezing rain for a while across the high country, but this appears to be a significant precipitation producer gone to waste. I hope this is the last liquid we see for a while and while it's no guarantee, we have a good chance of beginning such a streak after the rain tapers off Wednesday.

 Drier air will build across the region later Wednesday and encompass the region Thursday but the stiff north to northeast wind will be bringing southward, air that simply isn't that cold. Remember, the jet stream block will be producing a pool of relative warmth over northeast Canada so that source of cold will be lost to us for a while. Still. there is enough cool air in place for the American GFS model to tease us with the possibility of some wet snow on Friday and into the weekend. The smart phone should be promising dry weather for northern Vermont on Friday and into the weekend and I think that's right. Two major ensembles are keeping storminess and all of the either rain or snow south of Vermont and I think the GFS is out to lunch with its more northerly track. Yes, never downplay the possibility of a late inning northward shift but this pattern also doesn't quite favor that kind of magic. 

Much of next week also doesn't look especially cold. Given the lack of arctic air, readings appear more likely to average above as opposed to below normal. Ensembles continue to favor a stormy pattern however and at varying runs of different models have produced all kinds of terrific looking fantasy winter storms. Given the continued presence of an downstream blocking jet stream structure, any east coast cyclone will have the opportunity to intensify and get stuck close to the coast offering up the possibility of several days of precipitation. Just find us a way to get at the moisture and away we go. I would love to provide a few more details good or bad as soon as possible, hopefully with the next post in a few days. 

Looking even beyond next week, there are more encouraging signs on the temperature side of the equation. The signal for the downstream blocking or negative NAO begins to decline after December 16, but as this is happening the upstream support for transporting colder weather from the Eurasian continent improves and the period leading up to the winter solstice might feature a decent round of colder weather. Still looks overall to be more of a stormier as opposed to a cold pattern.

Large -NAO blocking structure over Greenland to produce a pattern loaded with storm potential beginning December 7th

Happy 1st of December to everyone and its an exciting time in the world of weather blogging because it's an exciting weather pattern. Those that may have followed some social media banter may have noticed that I've voiced some disagreement, mainly regarding the interpretations of what might occur in this jet stream structure. It might sound like a "downplay", but its not. We are headed toward a terrific weather pattern for east coast snow but there's been a considerable amount of hype for extreme early winter cold and I've been repeatedly suggesting that this is a misinterpretation. I would reiterate that today. This is a pattern conducive for east coast storms not so much extreme cold. The big picture weather pattern tends to be dominated by the elephant in the room and that elephant will be the formation of a large Greenland jet stream blocking structure, capable of sending the NAO toward a -2 index which in a historical context is quite intense. I do expect some garden variety chill to maintain a grip on much of New England for the two week period beginning next Wednesday 12/7 and persisting at least through the winter solstice but temperatures should stay within a standard deviation of normal (generally ranging from 8 below normal to 2 above). At the very least it should consist of an extended period of sub-freezing temperatures which will allow both natural and artificial snow to accumulate a healthy base. 

There are still a few ugly details to get through, but after yesterday's wind driven abomination, the time left before we begin our extended stretch of winter weather is getting smaller and smaller. I noticed at dusting of snow at MRG Thursday but whatever falls will get obliterated by one final torch this Saturday. We should see a nice day Friday with sunshine and temperatures in the 30's before clouds, milder temperatures and some rain arrive for Saturday with readings besting 40 up on the mountain and 50 in the valley's. It should be the last we see of that for a while. 

Colder air won't completely take over for early next week, but will be involved enough to at least make things interesting for our next weather system on Tuesday December 6th. It doesn't look cold enough throughout the lower troposphere for snow but it does look like it could be cold enough at the surface for sleet and a bit of ice. I don't expect temperatures to venture too far above freezing during the day Tuesday if at all (on the mountain) and drier, colder early season arctic air will then build across the region Wednesday. Tuesday's weather system will be the first to get trapped underneath the building Greenland block. Recall last year when we could never trap systems in the Canadian maritimes and we lost out on opportunities for additional snowfall as a result. This pattern will produce the opposite and will feature storms spinning in the Gulf of St Lawrence/Newfoundland region for days and days. Tuesday's system will do that and although Wednesday might be dry, we could see moisture return later in the week in some form presenting the Green Mountains it's first opportunity for snowfall with the new regime. 

Alright, now I get a chance to talk more about this weather pattern, a blocked weather pattern supported disproportionately by the -NAO or a downstream block over Greenland.  In my opinion there has been an irresponsible level of cold weather hype for this pattern though there is little historical correlation between a weather pattern supported almost entirely by a -NAO and bitterly cold arctic air. Ensemble data really doesn't suggest it either but it has not stopped folks from predicting extreme temperatures. I should expect we see some garden variety below normal temperatures, likely peaking around the 9th and 10th of the month in New England, but I don't think the cold weather will be especially distinctive this month or during this pattern. Storminess ? Now that's a different story. I would never belittle a -NAO, I just think it's misunderstood sometimes. The most defining event of the 21st century so far, Superstorm Sandy struck the northeast and in October of 2012, a month that featured an aggregated -NAO measured at -2 (similar to what is expected in the coming weeks. So, I think the hype is misguided and should be focused on storm potential and not cold and I would not at all want to understate the former in this type of setup. 

How will such a storm happen and when ? That's why weather forecasters get paid the big bucks, to be as vague as possible ! But actually, we can come up with some idea. Though we don't have a ton of support from the other teleconnection indices, we do have a little, particularly in the Pacific where jet stream energy is expected to continue undercutting a ridge trying to establish itself in the north Pacific. Such a feature would allow storms to enter the southern Rockies and then gather moisture from the Gulf of Mexico while the -NAO helps to keep the storm track south. We can add this to what was discussed earlier, the potential for storms and moisture getting wrapped up in the maritimes of Canada and perhaps even getting sucked westward underneath the blocking to the north. It's not out of the realm to see snowfall from moisture entering our picture from regions several hundred miles northeast of us in Canada. It's an atypical situation, but very typical in a pattern like this.  The downside and unusual in December would be for the storm track to remain southeast of us as it has done in months like February of 2010 (until the end). So, stay tuned this could get interesting.