Early weekend storm has inched warmer but still has snow potential while we maintain hope for pattern the last two weeks of January

 Our outlook requires some adjustments for both this week and for the rest of January and there are two items (one specific and one more general) I want to highlight. Although the clouds have arrived to Vermont as expected, the outlook for our potential late week/early weekend storm has evolved and is in need of a reexamination. The 2nd more general item involves the nature of the pattern as a whole which needs some additional discussion. Though we can be confident about the availability of some garden variety cold air, I've become less confident about the storminess. We had a very active pattern for much of December even though the results were less than ideal. In January however, the southern branch of the jet stream has become less robust and models have been over advertising potential storms with the case in point being the weakening storm system moving toward the southeast coast as of Monday. 

The nice run of sub-freezing temperatures will continue across the high country through at least Wednesday and prevailing cloudiness will produce some on and off light snow but it will be pretty inconsequential. The best chance for a few inches will be from Stowe northward throughout this period and the best chance for any sunshine appears to be Wednesday afternoon. This brings us to the interesting but evolving late week and early weekend forecast. 

A ferocious area of storminess now impacting the Pacific Northwest will progress into the northern plains by late Wednesday and ultimately begin to carve out a very amplified jet stream across the eastern half of the country. This amplification is projected to progress a bit more slowly and set up a bit farther west. It is NOT evolving into another Christmas 2020 debauchery but it is a warmer looking system for much of interior New England overall and we will have to wait another day on any snowfall. That said, the situation continues to evolve and additional changes are likely. For now the slower evolution of this weather situation makes Thursday a bit cooler with a slight chance for some wet snow, Friday drier with temperatures hovering at or above the freezing mark and Saturday very interesting. The precipitation will arrive early Saturday with marginal temperatures and may begin as some rain. The midwest storm will be spun out and occluded by this time and this will mitigate if not eliminate the risk of a rainy meltdown but what transpires along the coast. It will be a powder keg at this time and if something can hit the ignition switch, that would be how the forecast changes substantially from here. For now I would anticipate that any mixed precipitation Saturday morning will turn to at least some snow later in the day. The question is how hard does it fall and how long does the accumulating snow last.  Temperatures will spend Sunday in the 20's accompanied by blustery conditions and at least some snow flurries. 

We hope Sunday marks the beginning of will be an extended period of colder temperatures. Initially, these colder temperatures appear very garden variety consisting of daytime temperatures in the 20's and overnight readings in the single numbers or teens. This is certainly cold enough to support snow but when does it come ? Models have been teasing Vermont with hypothetical storms all month but mother nature has yet to deliver much. This gives me a chance to address a question posed a few posts back regarding the prognostications this winter which indeed have been tougher because of the fickle nature of the southern branch of the jet stream. It spent much of December defying expectations and playing a more dominant role in the region's weather (especially the big nor'easter in the middle of the month), but has been weaker than model expectations for much of this month and this has allowed for the quieter period of weather. It is not typical during a La Nina winter for a prevalent "Pineable Express" and we appear to be heading into a more typical La Nina set up late this month. We will not see the split flow in the jet stream we saw earlier this winter and will instead see a consolidated firehouse type jet stream in the north Pacific with storms crossing the country from there. The energized negative AO and the SSW event that proceeded it will bring some arctic air onto the playing field though bitterly cold temperatures are still not expected.  Storms originating from the southern branch of the jet stream are less likely however after Saturday and snowfall will likely have to come from clipper systems or mid-latitude storms of a north Pacific origin. We have a few chances for both however with snowfall possible at least twice during the week beginning Jan 18 (MLK day). I should mention however that this type of pattern does allow for the inland runner and ensembles are hinting at that possibility around the 21st/22. Its possible, but the -AO/NAO makes such an outcome less likely in spite of what happened on Christmas.