Think Snow, Tweet Snow !!!

Wednesday, January 9, 2008

Winter returns January 13th...

but first we have to take out the last of the garbage. That being another non-snow event on Friday. I have gotten some emails concerning this event and I am well aware that forecasts from the National Weather Service and some other sources are talking about accumulating snow. First of all let me say that any snow would have to fall prior to 5 am. Precipitation is indicated to arrive in Central and Northern Vermont just prior to that time but an hour or two of wet snow early Friday morning will be a foggy memory by daybreak when warmer temperatures aloft change precipitation to a mix of sleet and freezing rain. Ultimately, precipitation goes to plain rain later in the morning. During this event, temperatures will rise to just above the freezing mark and thus we will avoid another base wrecking rain event. Still it will mark the second "non-snow" event in 3 days making the week one to quickly forget at MRG.

Shutting down the La Nina wrecking ball

La Nina has most certainly challenged us in the last few weeks. We had a beautiful reprieve in the days surrounding New Years but the strong Jet in the Pacific has been the biggest most dominant feature in the pattern overall and is certainly one byproduct of La Nina which when measured in terms of sea surface temperatures anomalies as strengthened to -1.6 C. Over the next week or so some key changes in that very critical region will allow winter to make a return to Vermont. The upper ridge which has been positioned northeast of Hawaii for over three weeks will strengthen and push northeastward. Eventually it will establish itself just off the west coast which forces the PNA index upward into positive territory and allows the mean trough position to shift into the Mississippi Valley. With out blocking at the high latitudes (I use the AO to measure this), it will be hard for cold weather to attack Vermont with any ferocity. This new pattern should be favorable enough for some new snow which we would gladly accept after a week like this.

Next chance for powder comes early next week
The first such chance for snow comes Monday/Tuesday and the various computer model simulations have made a mess of themselves sorting through the details. The European model brings a lot of juice are way. It was the warmer of the two simulations but also shows a sizable storm moving up the Atlantic Coast and dumping sizable amounts of snow (with temperatures not far from freezing) on the mountains of Vermont. The American model suggests that the juicy moisture remains offshore and that snow on Monday or Tuesday is lighter and more sensitive to elevation. Loyal readers now the regard I have for the European model and giving it some credence in this instance is both a prudent and fun thing to do. Either way we should get some much needed assistance early next week.

3 or 4 powder days from Jan 14 - Jan 20th ?? - Its possible !!!

More help should follow later in the week. I can only speak more generally out this far but ensembles do indicate a significant jet amplification toward the weekend of the 19th and 20th. Snow would probably fall from a clipper-like system but jet amplifications are typically kind to the mountains of Vermont when it comes to new snowfall. In addition, this ridge west/trough east scenario is in the indication for a 10-14 day period beginning January 13th. Without the blocking at the critical high latitudes it will be difficult to sustain below normal cold; in fact, temperatures in that time frame could average above normal. If we can avoid the rain and continue to accumulate the snow then I am a buyer. And 3 or even 4 powder days are becoming a real possibility in the period beginning Monday and ending January 20th.

1 comment:

matt said...

Thanks for the update as usual, i'm looking forward to the return of good news.