Monday, December 21, 2020

Nightmare before Christmas looking more real, but it does look more promising as we head toward 2021

The two big things we need to accomplish during this holiday period is to get ourselves out of harms way during the potential "night before Christmas" fiasco and then see what we can stir up between December 28-30 which seems to be the next period where we could score significant snow. In the short term, we have southeastward advancing clipper system heading our way but will bring its minimal amount of moisture well south of Vermont Monday night and early Tuesday. We will see some snow flurries and snow showers late in the day Tuesday thanks to the combination of some instability and a favorable flow off Lake Champlain. I actually expect to see a few inches from this but it will be very isolated to the high country late Tuesday and early Tuesday night. Temperatures will remain

The American GFS model over the past 24 hours or so has given us a glimmer of daylight on the potential thaw/rain Christmas Eve into Christmas Day though other data continues indicate a miserable set up. The system in question is already bringing rain and snow to the Pacific Northwest but will continue to hug the Canadian border as it progresses west to east across the continent eventually ending up in southwest Ontario Wednesday evening. The system is so far north that the thawing part of the weather system will advance deep into Minnesota and the UP of Michigan Tuesday into Wednesday. As bad as that seems, if the storm can manage to spend all its money over the Dakotas and Manitoba, it will provide the opportunity for subtropical energy to fuel a new low pressure center over Dixie; and ultimately, that new storm would move to the coast, thwarting the advance of the intense mild air and even allowing rain to change to snow Christmas Day. That scenario would still bring close temperatures to 40 degree temperatures and rain to the MRV but the thaw would be shortened to a day or less with snowfall returning as mentioned. Unfortunately there are other model simulations that are considerably worse with the intensity and longevity of the thaw. These same simulations also show a disastrous heavy rain even accompanied by very strong, perhaps even damaging south winds. Really not something we want to see for many reasons and it all happens because the subtropical energy in question would get pulled due northward into the primary low actually fueling it rather than competing with it. Were this to happen, our minimal amount of snow would be easily wiped out and most of the several feet of snow in southern Vermont would be gone as well. In spite of that glimmer of hope from the GFS, I am about ready to chalk this up as another big Christmas loss. I suppose the silver lining is that most locations in northern Vermont still have a minimal buildup of snow including less than 10 inches at the Mt Mansfield stake. It will likely get wiped away by early Christmas Day but we can't lose anymore than what we have and we don't have much.

At the very least, we got some modified arctic air and snow showers that should follow for the 26h and 27th of the month. We won't have the best wind direction for terrain enhanced snows in this period but 1-2 weak jet impulses are capable of providing an occasional burst of snow. Mostly it will be cold and blustery with temperatures generally in the teens or lower 20's during the ski day. 

In spite of our problems around Christmas, we continue to have a marginally supportive pattern anchored by the -AO/NAO tag team. The irritated Pacific jet stream will limit the southward advance of arctic air,  but will set the stage for continued storminess and it certainly appears that the next opportunity for such a storm would occur sometime between December 28th and 30th. Though still more than a week out, the setup does appear to be a colder one. It also likely won't be the last one in this holiday period with another lined up right around the time of New Years Day 2021. 



1 comment:

Unknown said...

We're trying to stay positive. We need natural snow 🤨