Tuesday, December 19, 2023

5 days of mostly dry weather through Christmas, a possible storm next week and an encouraging outlook start 2024

To those impacted by Monday's flooding, my sincerest sympathies. I've been on the receiving end of a few floods and the cleanup is not a fun existence, especially when one has to deal with it multiple times in a year.  Rainfall amounts were impressive in many areas totalling 2-3 inches, but it was the intensity of the melt-off, much of it fueled by the combination of high winds and high dewpoints that was the catalyst for this event. Without the deep early season snow across the northern VT high country, I think the flooding would be fairly minimal. 

River levels are dropping quite rapidly as of Tuesday and an extended period of dry weather will help them drop further. Starting Wednesday, we are looking at 5 days with minimal precipitation chances. This takes us through Christmas with many of those day, including the winter solstice, featuring sunshine. We actually have some arctic air working its way into eastern Canada late this week and some of this will work its way into Vermont Thursday and Friday. This will be a big assist to snowamaking operations which can expect an extended duration of sub-freezing temperatures beginning Wednesday night and persisting through early Saturday. Temperatures are expected to moderate during the day Saturday, and the sunshine which will be a big part of the Thursday/Friday weather picture is likely to fade behind some high cloudiness. Saturday, would be the one day we could see some warm advection induced light snow, but chances of this are low and chances of an accumulation are lower. Christmas Eve and Christmas Day will feature milder days with sub-freezing nights which is weather more typical of March. Both appear comfortable for getting outside though it would certainly be a lot better with more snow on the ground. 

Our next shot at that aforementioned snow comes in the days after Christmas. Models are converging on the significant east coast storm idea and its again being fueled by El Nino and it will again arrive with only minimal amounts of available cold air. Fortunately "minimal" is not zero, at the risk of sounding like Jim Carrey, and significant snowfall is certainly a possible outcome. By Tuesday, December 26h, mild air will be encompassing a large portion of the eastern seaboard and will include most, if not all of interior New England. As the conglomeration of storminess makes its approach either Tuesday, Tuesday night or Wednesday, colder air or at least that minimal amount of it, will have the capability of becoming a significant part of this winter storm and providing us with "a chance". Elevation is likely to play a role in snowfall amounts and consistency and a more rainy outcome is also still on the table. 

Our chances for snow with the system next week appear better as teleconnection indices gradually become more favorable. The biggest ally next week will be the PNA as the expanded ridge in the jet stream responsible for the large swath of North American warmth is pushed west. Looking toward New Year's weekend and beyond we get some additional support from the EPO and AO, both of which become favorable. It's the specific structure of the indicated jet stream which is most encouraging and includes a ridge isolated to western North America with  the pineapple express tunneling underneath and colder arctic air pushing south towards the eastern part of North America. It will take some for the cold to get anchored on our continent, its been sitting in Mongolia and eastern Russia for much of this month and this is why the snow/rain situation remains tenuous next week. Beyond that storm though, we should have better cold air support yielding an outlook for the early part of 2024 that is pretty encouraging.


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