Wednesday, January 4, 2017

Winter returns to Vermont but just not in a big way, at least not yet

Our first big storm of 2017 didn't produce the epic powder we would've liked but it came back from the dead to help solidify what is already a decent foundation. Colder air is in the process of enveloping eastern North America and  well below freezing temperatures are ready to dominate the region for a stretch of several days. This particular outbreak of arctic air will fall a little short of the one which impacted Vermont in December but not by too much. Unfortunately we are still contending with some problematic variables in the outlook beyond a week and although we might continue to find some narrow pathways through the "thornier looking thickets" it would be nice if we could improve our spectrum of possibilities for a stretch of time.


In the short term we have some snow. Not as much as we might like, but the occasional bursts of snow from terrain enhanced snow showers on Wednesday night into Thursday and Thursday night is likely going to produce a couple of inches. My best guess is for 2-5 inches in this time frame with the highest amounts above mid-station. That said, the snow might organize into some streaming bands from Lake Ontario which leaves open the possibilities for some lucky bigger totals.


The period beginning Friday and stretching through the weekend to Monday looks chilly but generally free of substantial snowfall. The polar jet is pushing what was once a promising looking stationary front well to our south. This boundary of airmasses will be the catalyst for one snow producing system on Friday across the Mid-Atlantic and then another bigger coastal system that will impact parts of the Virginia Tidewater Saturday. Cape Cod might get in on this action Saturday night but the pattern will become too overwhelmed by cold weather to allow this storm to have an impact on a broader part of the northeast.


This brings us to next week and multitude of forces that will be counteracting each other during what looks to be another tenuous period for Vermont ski country. We have talked about the negative PNA which has been focusing the cold weather and snowfall on western North America. If you want proof of that, take a look at some of the epic snowfall totals from Tahoe over the next several days from two successive winter storms. Some of the models are suggesting upwards of 5 feet for the Sierra. The Wasatch will perform quite admirably also. Cold weather and snow across the west can spell trouble across the east and it has on a few occasions already. Interestingly however, ensembles are also keying in on a large blocking ridge which will develop over the Bering Sea and migrate over Alaska. This feature appears substantially larger in stature over the last two days and it will help to flood most of Canada with arctic cold and keep it there through the week. Will this feature help to keep arctic air in Vermont through next week ? The 2nd of the two big Tahoe storms will make its way across the country during the middle of the week and make an attempt at tracking up through Canada. The big Alaskan blocking feature will need to help force this system southward and keep the arctic cold entrenched over Vermont.


The negative PNA is indicated to finally weaken and breakdown just beyond the midpoint of January. High latitude blocking is also expected to diminish however and the polar jet is shown to retreat somewhat across all of the United States.  The ensembles at face value show much of New England to have a warmer than average look but not excessively warm. Cold is expected to reassert some minimal control over the region late next week and a weaker weather system might bring some snowfall to the region just prior to the MLK holiday weekend.