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Monday, December 9, 2013

Much improved expectations for the middle of December

The first potential decent winter storm deposited much of its snow on southern Pennsylvania and managed largely fizzle as its depleted moisture overspread Vermont. Still, the limited snow provides the setting for a wintry scene which will prevail through much of this week and even into early next week. There is little doubt in my mind that the ferocity and expansiveness of the arctic chill so far this winter has been impressive, specifically how the arctic cold has managed to defy some of the less than optimal upper air configurations. It is vital to note that this is a very empirical observation yet an important one that must invariably be incorporated into our medium and long term expectations. In spite of the fact that the pattern has yet to favor cold or snow of any real magnitude over New England, it has favored cold and snow across the central and western United States and the result has been widespread areas of 20-25 degree below normal temperatures. We actually haven't seen much of this the last few years; in fact, we probably have to go back to 2003-2004 or maybe even prior to that since we have seen cold weather of that magnitude in the United States. Needless to say, when the pattern does align itself for cold across the northeast, the cold weather is likely to be considerably more intense than anything we have seen in the recent decade or so.

In the near term and specifically over the next week, we are actually set up for some very chilly December temperatures. A wave of low pressure will bring some mixed precipitation to coastal areas of New England Tuesday but will mostly miss interior areas like the Green and White Mountains of Vermont and New Hampshire.  On Wednesday, the Polar Vortex will take aim at New England and upper level impulse marking the leading edge of this surge of arctic chill should spread snow showers and a few snow squalls to the high country Wednesday and Wednesday night. It then turns bitterly cold by Thursday morning and this chill persists through Friday before modifying slightly before the weekend.

The "slightly" part of the last sentence is noteworthy since we had expressed some concern about a big warm-up for the middle of the month or maybe even a ugly pre-holiday thaw. Ensembles over the last two days have suggested that is much less likely which marks a big shift in the medium range guidance and certainly changes some of my expectations in the important week leading up to Christmas.  A reenforcing shot of arctic air is expected in the latter part of next weekend and this may or may not be accompanied by some snow. The European model is actually hinting at a significant snow producer for the Mid Atlantic while the American and Canadian model packages of hinted at a light to moderate snow event for the likes of us. I no longer expect a big move toward above normal temperatures after the 15th of the month and instead expect normal and even a few days of below normal temperatures with 1 or 2 chances for snow. This is a big improvement and some very good news in spite of the disappointing results from our Sunday Night-Monday event.

1 comment:

david Blinken said...

Fascinating considering we were looking at some warm weather affecting USA week ago.
I just love the unpredictability of weather.
Keep us snowy Josh❄ :)