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Sunday, January 7, 2007

Some Sunday adjustments and an MLK update

Some adjustments need to be made to the short term prognosis and it never hurts to update the prospects for MLK weekend.

1. Update on new snow through Wednesday morning
Friday's post included a prediction of 1-2 feet of snow for the mountain in the period beginning Sunday Night and ending Wednesday morning. I had envisioned that 3-6 inches would fall from the system which will approach the region Sunday Night and exit Monday. Indications are that this system is both stronger and is also tracking farther inland which has ramifications on temperatures in critical lowest layers of the atmosphere. I looked at this situation closely this morning and it appears as if precipitation arrives early Monday morning with precipitation type, at least initially, highly sensitive to elevation. Valley locations in Vermont may see very little snow out of this, maybe just a few wet flakes. Areas above 2,000 and especially 2,500 feet may fair significantly better with a few inches of wet snow falling before precipitation changes to rain or tapers off later Monday. With virtually no base at MRG's base, the debate over a few inches of wet snow at 2,500 feet is irrelevant; furthermore, the colder weather Monday evening combined with the instability will be enough to bring new snow to the entire mountain Monday Night, Tuesday and Tuesday night. This brings us to the second part of the adjustment which involves the impulse rotating into the newly formed trough trough Tuesday. Indications are that the best dynamics with this moisture-starved system will be south of the region, over Pennsylvania and Maryland, as opposed to Vermont. We will still see some much needed new snow here just not as much. My guess now is 6-14 inches in the period between Monday and Wednesday morning with the big range accounting for the elevation sensitive snow.

2. MLK Weekend Update
We are starting to get a better resolution on the period beginning Friday the 12th to Monday the 15th. There remain plenty of question marks and a big range of possibilities. I had mentioned that the American Model was indicating a meridional and almost perfectly "symmetrical" solution placing all the cold air and snow in the West while allowing for a push of very mild weather in the eastern quarter of the United States. Not surprisingly, the model has trended away from that scenario, showing a very important trough split in the West and thus allowing cold weather to stay much closer and possibly stay mostly entrenched across northern New England. This above-mentioned idea seems to in fact represent a loose model consensus although plenty of slight but very consequential adjustments are sure to occur. This "loose consensus" would be to allow for a push of milder weather Friday and Saturday, enough to get northern Vermont back into the 40's during the day time. Colder weather would subsequently make a push back into New England Sunday as the "broken" piece of the trough knocks down part of the newly established eastern ridge. The more potent part of the trough trough would then push east Sunday and Monday in the El Nino-fueled southern branch of the jet stream. This system as it approaches would bring the threat of snow or ice to the region possibly as early as Sunday but most likely Monday. I am actually fairly confident in the basic premise here but the very important details are entirely up for grabs. The first "broken" piece of the trough must beat back the eastern ridge significantly. If it does so successfully, more successfully then currently progged, then significant amounts of new snow become possible in the late part of the holiday weekend. If the above does not occur we will be in big trouble again.

Still encouraged about what I see following the holiday weekend and I can touch on that more with Tuesday's update.

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