Snow on the ground and sub-zero temps has finally put Vermont in the spirit of the season and we should continue with this theme through the upcoming week. A brutally cold arctic air mass has begun its descent into western and central Canada and will ultimately grip much of the northern third of the U.S. this week. The southward push of cold however will not occur without a fight and this sets the stage for a sharp temperature gradient that will set up between the 35th and 40th parallel (that's old school for latitude). This temperature gradient will help carve the pathway for what appears to be two pieces of Pacific energy capable of delivering powder to MRG.
The first weather system marks the advance of the large southward advance of aforementioned arctic air and it will arrive later Tuesday. Of course, we already have very cold air gripping the region and it will gradually loosen its hard grip ahead of the arrival of Tuesday's system. By midday Tuesday, temperatures will warm to within a few degrees of the freezing mark and it will be the thickening clouds that slows the warming. Precipitation will then start as a wintry mix before going to all snow Tuesday night into early Wednesday. The low pressure center responsible will track directly over northern Vermont thus placing the best snow accumulations over Quebec. MRG should in the end do OK with a few inches to show for itself by Wednesday when blustery and very cold weather should reemerge across the region.
A second system late Thursday into Friday will have plenty of cold air to work with but will be a bit moisture starved. We should be able to squeeze a few inches of fluff out of this before cold air is re-enforced for the last time before an uninvited pattern change begins to take root. Thankfully these changes will not have an adverse impact on the weekend of the 21st and 22nd which I would expect should still be a winner. Very cold air will still be in place on Friday along with a few inches of fresh snow and the northward push of milder air will be fueled by a weather system capable of delivering additional and potentially significant snows to interior New England Saturday. I will wait for the next update to provide a bit more clarity on that.
Beyond next weekend is when the big trouble begins. The big personality characteristic so far this winter has been a very tight and very powerful jet stream in the mid-latitude Pacific. Unfortunately we will see this reemerge again and in a very bad way as much of the energy will be focused on the Pacific Northwest and Canadian Rockies. This will allow for a strong upper ridge to develop across southeastern Canada and New England. It is the kind of feature that can produce both record warmth and rain both of which are probable between the 23rd and 27th of the month. With these changes still a week away there are still a few outs but its not worth holding our breath right now.