Snow, some freezing rain/drizzle expected for Christmas Day and a more promising outlook around New Year's

 There's a lot to unpack in this rapidly Evolving weather situation across northern Vermont and yes I capitalized "Evolving" on purpose for emphasis. It's about to get very cold in the Pacific Northwest, a ton of snow is falling around Lake Tahoe and our friends in Aspen got a little taste of what it's like in a typical east coast ski season - it rained !  A rare occurrence in Colorado above 8000 feet, but it rained for several hours Wednesday evening and night and although it is expected to snow Christmas Eve, wet weather is not something that ski town is used to in any winter month. The system responsible for Colorado's weather will move east quickly and bring Vermont its share of weather on Christmas Day. The details continue to change very rapidly. 

 First of all relates to the timing. The whole event was a question mark a few days ago and was initially pegged as a late Christmas Day, early on the 26th light snow situation.   Precipitation is now expected by dawn on Christmas Day. This is a very disorganized storm and is moving quickly but is expected to get an infusion of moisture from the Gulf of Mexico. Additionally there are healthy low and mid level frontogenetics in place from the strongest area of arctic cold we have seen this season (temps fell close to zero early Xmas Eve in northern VT). In spite of the strong area of surface cold, milder mid level air is expected to chip away and push readings  into the marginal category at around 6000 feet even as it remains sub-freezing closer to our surface. What does this all mean ? Temperatures are close enough to freezing, where it counts, for snow to fall so long as precipitation is heavy enough. When precipitation is lighter, freezing rain or drizzle is possible. Based on some experience I've had with these types of setups, I am going to predict a decent period of snow Christmas morning resulting in a few inches, some light freezing rain or drizzle in the afternoon followed by another period of light snow Christmas night into early Sunday morning the 26th. I think it all totals to about 3-6 conglomeration and I am hopeful that the final inch or two is off the fluffy snow variety. A gentlemen on twitter asked me about the differences between Champlain Valley weather and MRV high country weather and this is one of those instances where we can expect some huge differences. Burlington will get light easterly downsloping winds hurting their ability retain the necessary amounts of low level cold to support snow. Their low elevation will also hold down total precipitation amounts and they will likely struggle to get an inch. Rutland will perform even worse for the same reasons in addition to the fact that they are positioned closer the milder mid-level air. 

We are likely to see more of these marginal situations in the next two weeks with arctic air on the playing field but the southeast U.S. jet stream ridge maintaining a presence and even occasionally surging northward in our direction. Temperatures, especially across the high country, appear to be mostly sub-freezing but it won't guarantee we can keep all precipitation in the form of snow. The next chance for such event appears to be around Tuesday the 28th or Wednesday the 29th with temperatures at critical levels again appearing marginal and varying precipitation types possible. 

There is some decidedly good news involving New Years which appears both colder and potentially snowy across northern Vermont. Models are having a very difficult time dealing with all the fast moving systems and the specifics are therefore very blurry right now but the threat of a thaw appears reduced while the chances for accumulating snow increased in the period between December 31 and January 2. Even with the continued presence of the southeast U.S. ridge the longer range outlook continues to show a decent coverage of arctic air especially over central Canada. Two of the major 3 ensemble packages now indicate a blocking feature in the Chukchi Sea. If this does indeed occur, we will see some very intense arctic chill make a southward push into the U.S. in early January though the focus of this would likely be west of New England. It will mean an interesting start to 2022 to say the least with arctic air likely competing with the southeast U.S. ridge and placing us in the pathway for multiple storms with a variety of outcomes possible.