Setting the Stage for a White Christmas

We had snow for Halloween and Thanksgiving, why not Christmas too? No Reason. Today, Sunday December 11, 2011, the high temperature in Boston was 38 degrees. That is 5 below the climatological average, and the coldest day since March. Same on Mt.Washington, the first sub zero (-1F) reading since March 28th. Have you noticed we are seeing Cold High Pressure systems in New England every Sunday since the Halloween Snowstorm? Then we see warming trends every Monday, with rain, or mostly rain, storms each mid week. This week does not look much different. Last Sunday I made the poor forecast of Cold Air arriving before our midweek storm, that's why I called for ice & snow. Guess what, once again the guidance is calling for cold to arrive before a midweek storm. Do I jump on the potential for ice again? Not bloody likely. (So that means we probably get ice).. seriously though, last weeks storm ended up much more powerful and close to the coast than any forecast made until with 36 hours of being hit. We can not trust any 5 day forecast right now, just too much going on. For example, check out this forecast map, for Friday December 16. Thursday 'should be' mild and wet, though some ice may happen in Maine behind a cold back door high that gets us Wednesday (with a touch of flaky drizzle). Friday will see a powerful front, with gusts past 60 mph early. Then this set up.

This is my favorite set up.. Trough under Ridge West, Trough over Ridge East. This delivers Pacific Warmth and Humidity AND Canadian Cold, to the eastern United States. This is a classic rain, ice, & snow pattern for New England. This is our pattern late week, and into the week preceding Christmas.
Out of time for tonight, hope to add more Monday Dec 12th..

Monday Update.
Where does the time go? I want to buy my Dad a tree today, so this has to be quick..
My intention was to list all the weather possibilities in the pattern shown above.. such as the delivery of arctic chill to eastern Canada. And the Hawaii connection.. supplying tropical pacific energy to the southeastern USA.. and how a major (really hard to predict) battle zone sets up over New England. Especially with these powerful cold Highs we have been seeing. Yes, your barometer hit 30.6" a couple times lately.
But instead of elaborating on the myriad of possible events from now to Christmas.. I will paste a message from Glen Field of Taunton NWS.

Did anyone notice the Tropopause Fold last Thursday Morning?
Southern Rhode Island residents did.
Here's what happened (note the similarity to Dec 9 2005 Wintercane.)
The point is, like 12/9/05, we are in a highly volatile and unpredictable pattern. Anything can happen.

Hi TV meteorologists,

 You may have been wondering about the validity of the 79 mph wind report we listed from Point Judith, RI from 4 AM this morning in our PNS. Upon reviewing this further, we have concluded that it is, in fact, likely to be a real occurrence. (There were also reports of tree and wire damage at Westerly and Scituate and a 63 mph wind gust at Burrillville.) At first thought, you might think it was thunderstorm-related, but the thunderstorms were past there by then. Radar imagery showed a pronounced back edge to the rapidly deepening cyclone. There was a tremendous pressure rise-fall couplet associated with back side of the storm. Forecast model data showed that the 1.5 PV (potential vorticity) surface, which is the best PV surface to approximate the tropopause, was lowering to approximately 550 mb at that time...quite low. If you recall the December 9th event from several years ago, where there were 100+ mph winds gusts with thunderstorms and snow squalls along the south coast/Cape Cod/Islands...the tropopause surface had 'folded' down to as low as 700 mb in that event. In recent years, this feature has gained some notoriety and has been dubbed a 'sting jet' in the professional literature. There was an article in the November, 2010 edition of the Monthly Weather Review journal entitled "Sting Jets in Simulations of a Real Cyclone by Two Mesoscale Models." The original article is from 2004 by K.A. Browning, published in the Quarterly Journal of the Royal Meteorological Society

 ("The Sting at the End of the Tail...").

[Thanks to Frank Nocera and Joseph Dellicarpini at BOX for providing the info and references on the sting jet.]

Happy holidays to all.

-- Glenn

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