The late surge of warmth on Sunday has our snow encrusted yet again and when combined with the outlook for much of the rest of February, my Valentines Day spirit leaves something to be desired. A ferocious ridge in the mid-latitude eastern Pacific will induce a fast flowing west to east jet stream south of Alaska. Not only will arctic air be forced into retreat mode across eastern North America, but the pattern will take on a classic "negative-PNA" configuration which focuses all the cold weather and much of snowfall on the Intermountain West while large portions of the eastern United States experience spring-like warmth. Models have been and continue to be extremely slow picking up the intensity of the pattern which largely stems from the stalling MJO and problems resolving the behavior of the jet stream in the Pacific generally. There's simply no denying it now however, the upcoming pattern is a very challenging one and is almost certain to deliver Vermont its third consecutive February with temperatures 3 or more above average. Barf !
Seasonable temperatures and sunshine will prevail for Tuesday and temperatures will remain winter-like through Wednesday morning before "El Torchy" makes its first February visit to Vermont. The warm push will not bring any new snowfall to the region prior to its arrival; instead, southwest winds Wednesday afternoon will bring temperatures into the 40's in many areas and 30's across the high country. This initial round of warmth, which is now expected to persist through early Friday doesn't appear to be associated with heavy rain or high dewpoints which are two ingredients that eat snow like we might eat fried green beans after a long day at MRG. We will however have one relatively windy day Wednesday, 48 hours of above freezing temperatures in many areas and some light rainfall Thursday, Thursday night and early Friday.
Arctic cold is set to return for a time beginning midday on Friday and a sagging front responsible for the colder weather does offer a few more hopeful possibilities. The most likely outcome is that some light rainfall early Friday gives way to a sharp turn toward colder temperatures accompanied by a few significant snow showers. Though the window is brief, the set up for lake/terrain induced snow showers is pretty good across the Mad River Valley Friday evening as it stands right now and a few inches is a reasonable expectation by early Saturday. Then there is the Tom Brady hail mary possibility for Friday. This would involve Friday's potential precipitation producer becoming an anafrontal wave with undercutting southeastward advancing cold inducing a changover to steady and significant snowfall. Models don't show this now and thus it has the distinction of being a Tom Brady hail mary.
Our upcoming holiday Saturday is sunny and chilly, hopefully with a few new inches of snow and this is followed by a cloudier Sunday with temperatures making a run at the freezing mark by the afternoon. By Sunday, milder air will be gathering across the southern and central parts of the country and preparing to make another massive push northward. We could see some precipitation, even the more frozen type prior to its arrival, but unfortunately, it will be very difficult to keep the milder air away from the state for a good chunk of the holiday week. The mild push stems from what is expected to be an amplifying jet and a huge dump of cold across the western United States. We can get somewhat saved if the jet turns out to be flatter. Though this remains a possibility, it seems to be a deteriorating one as more and more model data continues to support the negative PNA configuration mentioned above. Mild weather would thus reach the state Monday, Presidents Day which would be one of up to 3 or 4 above freezing days next week. Rainfall is also possible. The forecast isn't solidified yet and there have been 2 or 3 other potential thaws that have been thwarted this winter but the fundamentals look worse and worse.
Out further in time is the potential development of a block in the jet stream over Greenland. Though this would help push the jet stream southward again and possibly allow the month to finish with a flourish, ensembles continue to push the positive impacts of this feature out further in time.