Winter getting closer to a full return follwing extended thaw

The corn horn has been echoing through the Vermont high country this week as temperatures have surged and in almost every case, bested expectations. Valley locations saw 60-degree readings and the hills saw readings surge into the 50's. If you like the warm, soft snow, you basically have one more solid day to enjoy it Saturday. We have weather system approaching and this will bring a very well-defined line of rain, perhaps even a thunderstorm to the region but the ski day is expected to remain mostly dry with the exception of a few sprinkles. Strong southerly breezes will help push temperatures into the 50's again.


I expect a quick half inch of rain Saturday night beginning within a few hours of 8 pm. Interestingly, the latest model data has trended a bit toward a more anafrontal system which means the incoming cold will undercut the area of moisture. This will allow for a brief window where snow is possible starting around midnight and persisting for 1-3 hours. 1-2 inches  of snow and a return to sub-freezing temperatures will greet the Mad River Valley Sunday morning but temperatures should again climb above freezing in low lying areas as the cold weather isn't particularly intense. At the summits, I'd expect temperatures to remain below freezing throughout Sunday and this will certainly make a difference regarding the condition of the snow above 3000 feet.


Beyond Sunday, the outlook has trended more wintry and the period beginning March 2nd through around March 12th looks especially intriguing. I was reviewing Arctic Oscillation (AO) data through the early part of the season and noticed that since December 1, there has been only 1 period where the index went negative. It explains the lack of mid-latitude cold especially across the southern part of the United States. The only period where the index went negative was during 10 days in the early to middle part of this month during the period where the mountain received its multiple feet of snow. The second such period is likely to begin in early March and persist another 10 days or so. This will for a time be combined with the dip in the EPO (which is not expected to last) and the establishment of a nice blocking feature that appears fairly broad over the Bering Sea area. Winter will thus make a return to Vermont and I expect things to get exciting for a time.


Interestingly, the storm I have been especially disappointed with for several days. The one expected to consolidate over the Rockies early next week does not look nearly as organized or as consolidated on the models today. This means that the recent spring-fest might be over and sooner than expected with no return to excessive temperatures around the changing of the month. Precipitation could arrive as some snow on Tuesday February 28th although temperatures are likely only capable of supporting wet snow. Most of the model data does show a mixed bag of precipitation and even some rain before precipitation ends during the day Wednesday but this is a drastic improvement over what appeared to be another round of 50 degree temperatures and rain which was shown two days ago.


Colder and more legitimate arctic air is then expected to filter into the region by later in the week and that's when things could get interesting. The pattern is expected to remain relatively stormy thanks to  a multitude of intense looking systems that will impact British Columbia. These storms, and I expect there to be a few of them, will cross the Canadian Rockies and encounter the presence of the polar jet. Things could go array with one of these storms and warm Atlantic Ocean air might ruin a nice end game but if this happens at all, I'd expect it to be isolated to one event. What appears more likely right now is for some East Coast fireworks and a big snow producing system, at least one and maybe more, sometime in the time frame between March 2nd and 12th. Models are painting a variety of pictures on how it all might play out but lets just keep it simple and say that that there are multiple storm possibilities and expand on details later this weekend.