Lots of stuff to sort out as we head toward the Christmas holiday and as of early Thursday morning, we are beginning to get some better clarity on the coming weekend. There is a lot to cover and could make the update seem a bit long-winded but bear with me. Unfortunately, the mountain will have to play some defense against a weather pattern that wants to push very mild temperatures into New England. Barring a late inning change, we have have to endure some less than ideal stuff (Perhaps we should call in the 2013 vaunted Red Sox bullpen or David Ortiz for some heroics) Arctic cold will put up a massive big fight on our behalf to maintain some control on our weather; in fact, by Sunday I can almost envision one of those epic battlefield scenes in a movie as the appropriate metaphor for the clashing of these air masses. The big consequence of all this is of course, a lot of weather.
A decaying wave of low pressure will provide the region with the initial taste of precipitation Friday. The boundary responsilbe for the upcoming warm push will reach central and northern Vermont but will stall during the day and precipitation is likely going to be a wintry mix, starting as snow and going to a sleet/freezing rain mixture. At some point we could get a period of plain rain also but at least on Friday, this problem will be minimal. Mountains such as Jay Peak and points north will be positioned north of this aforementioned boundary and are likely to get mostly snow and minimal sleet/freezing rain from Friday's more benign system.
I expect some occasional light freezing rain/drizzle or some light rain or drizzle but much of the day Saturday will just feature clouds and some areas of fog. As this is happening our bigger storm will move out over the southern plains, gather moisture from the Gulf and begin to head northeast toward the eastern Great Lakes. Since the last update, models have suggested that this storm will deepen (strengthen) quicker and track farther north right into the heart of the St Lawrence Valley. This will put the onus on a potent artic high pressure center in northern Quebec to dam whatever is left of the cold air across interior New England, a challenging task considering the track of this storm. There is time for some late inning changes, and even a slight shift south in the trajectory of this strorm could have a serious impact impact on the results. As it stands now however, a major of intrusion mild air between 5,000 and 10,000 feet in the atmosphere takes out the possibility of snow. The inversion is so strong in fact, that it could create a situation where many of the summits on the Green Mountain chain are noticeably warmer than valley locations. It could, during a significant part of the precipitation event, be the difference between ice or plain rain.
Precipitaiton over the mountain becomes more intense Saturday night and there is a threat for some serious icing if temperatures are at or below the freezing mark. It is very close call but since we are anticipating 1-2" of liquid precipitation, the icing situation could rival anything we have seen in the last decade or so if temperatures stay below freezing. If the storm would track over Vermont, it would open the door for more sleet with is a much more ideal early season scenario since it would provide a big anchor to our early season base. Although this is still a remote possibility, I think the more likely scenario is freezing rain or rain. Even this less than ideal situation should not become a complete debauchery, temperatures across most of the mountain should stay in the 30's, mostly in the low 30's so although there will be some melting, it will not be a total melting. The rain or ice should end during the afternoon Sunday and temperatures will gradually return to normal by Monday afternoon along with some some snow flurries.
The Christmas holiday week will feature a cold day Christmas Eve followed by moderating temperatures Christmas Day and the 26th. This could go one of two ways at this point. Around the time of the 26th, we could see a weaker storm system, maybe even a clipper, spread some light snow into the region ahead of what should be a reenforcing shot of cold weather very late next week or into the the last weekend of 2013. We could also see something more along the lines of what the recent European model indicated which was a more organized storm system another round of a wintry mixture of snow sleet or freezing rain. After a glance at the ensemble data, i didn't get the sense that the Euro solution was a true representation of the model conensus so I would expect that the 26th is our next chance for at least a light accumulation of plain snow followed by colder temperatures on the 27th.
There are signs around the new year that the Arctic Oscillation will finally turn negative but this will compete somewhat with the evil empire in the Pacific. We saw a lot of this in 2012-2013 and the results are all over the place. For the time being though, the upcoming weekend represents the only major elongated threat of above freezing temperatures and in the end, temperatures may not get above freezing by too much.