With the exception of the Carolina coastal areas, much of the east coast has been enveloped in a stretch of cloudy, rainy mild weather; basically, my least favorite form of winter weather. Vermont experienced a bit of mild weather as well on Monday but yet again, we've managed to stay on the wintry side of the action from a latitudinal standpoint. This trend is actually going to continue for the rest of this week it appears, though it remains a close call regarding the upcoming storm Wednesday night into Thursday morning.
All the rain and mild weather along the east coast is the result of a train of Pacific-based impulses that have managed to draw on subtropical moisture out of the Gulf of Mexico. Unfortunately, it is not the result of the more preferable split-flow pattern where a true southern branch of the jet stream can blend its moisture with an involved and dynamic polar jet stream. The jet stream in the Pacific continues to have a very consolidated look and Vermont weather weather enthusiasts will have to manage the situation according. Fortunately, there is some cold air to be had, and it continues to sit over eastern Canada and mitigate the northward influence of a strong southeast ridge in the jet stream. All of this might put us in the sweetspot Thursday morning. In the meantime, a weaker wave of low pressure will slide south and east of us along the southern New England coastline. If this were a stronger, more dynamic system, moisture and snowfall might reach much of Vermont, but this is a very weak system and precipitation, most of it being rain, will largely miss the state with the exception of the very southern most areas. Once the system clears the region, a weak area of high pressure will build across the area Tuesday night following another day cloudy but dry 28-33 degree day over the high country. Some areas over the northern green's can expect snow showers late Tuesday night into early Wednesday, but most of Wednesday will be dry and at least somewhat sunny. Temperatures on Wednesday will continue to be mild, reaching the 30's and upper 30's over valley locations.
Thursday's storm originates out of the Gulf of Mexico and will thus bring plenty of moisture into the Ohio Valley and eventually into New England. There is some available cold air on the playing field but much of it arrives in the later parts of the storm. When precipitation arrives late Wednesday night, temperatures will be marginal and we will need an optimal storm track to keep our local atmospheric cross section below freezing. The consensus of data suggests the storm will track in a relatively optimal way (though not perfect), tracking just north of NYC to central Mass and off to the NH seacoast. If we can keep this track, MRG is just far enough north to support a mostly snowy setup. The snow might be a little we at first, especially at lower elevations, but cold arriving on Thursday will lower temperatures and allow the storm to finish on the powdery side. Accumulations would be in the 6-12 inch category. Temperatures are then expected to plummet Thursday night and Friday will begin with sub-zero readings.
It's a classic northern New England temperature roller coaster for the holiday weekend. The airmass on Friday is probably the season's coldest so far and it will land on us while we are enveloped in our deepest snowcover of the season. Friday will be a blustery day with dangerously cold wind chills at the summits and actual temperatures struggling to break zero. Winds will subside Friday night and allow temperatures to reach -15 or so by Saturday morning. A strong dose of February sunshine will allow readings to recover well on Saturday to a more manageable 10-15 above along with minimal wind. Sunday will feature more clouds and a bit more wind but it will be milder with readings up in the 20's. The push of warmer temperatures Sunday should also increase the chances for some snow though it remains difficult to say if any of that snow falls during or after the ski day.
Honestly, I am a bit concerned about the upcoming holiday week as a whole. This very marginal weather pattern which consists of very minimal amount of arctic air support and a strong, consolidated Pacific jet stream will present us with more challenges next week. This aforementioned jet strength in the Pacific weakened just enough these past few days into this week but is forecast to strengthen this weekend and allow for an already formidable east coast ridge to gain further strength. Might we find a way through all of this ? sure, we can hope, but there are two trouble spots next week and this makes the odds more difficult from a big picture standpoint. One possible rainy thaw comes either late Monday or Tuesday while another one threatens a few ski days later in the week. It is quite possible that one or both storms in question track more favorable resulting in winter weather or significant snow but there's cause for concern and my guess is that we get hit with at least one rain event in the 5 day period beginning Monday and ending Friday.
I can't promise a drastic improvement in the pattern after that but the PNA will provide us with a bit of support around the time of Sunday February 23rd thus allowing the east coast ridge to weaken and offering a bit more hope for the last full week of the month.
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