Thursday, December 25, 2008

Rumblings of an Early January Major Storm...

Merry Christmas to all those who celebrate it out there today. Happy Hanukkuah as well. Well, I am moving away from the short range this afternoon and gearing more towards the long range as the next 5-7 days look rather quiet, but warm on Sunday with a few showers and temperatures near 60 degrees. Now, in regards to this storm threat, it looks like all the teleconnections out there are aligning towards a potentially major widespread event along the eastern seaboard sometime in the beginning of the New Year. Later next week, the NAO will be tanking as well as the AO. These are two ingredients that we must attain in achieving a major east coast winter storm. Now, I have the upper air map from the GFS for around hour 200. This would put us roughly to the January 3rd timeframe. In red, I outlined the intense blocking over Greenland. This is vital to keep a storm from leaving the coast and jetting past Newfoundland. This allows storms to 'stall' along the coast as we see with our larger winter storms like in February 2003 and February 2006. Starred in red is the 50/50 low, but is not in the most ideal location as well. To be in the most ideal location, you would want to see it off the coast of Newfoundland as marked with the black 'x.' The only caveat to a major east coast winter storm is highlighted in the Pacific. If you look at that arrow in blue I drew, it shows how fast the flow is into the Pac NW. This pounding jetstream into the Pac NW will like to speed storms across the country and it makes it harder for a storm to develop along the coast and ride the coast delivering snows from DC to Boston. We need more of a ridge in the western third of the country to make this setup just right. There are indications on a few of the ensembles that a +PNA will develop. Right now I would say that the chances of a big east coast storm are above average for the Jan 2-Jan 7 timeframe and we may just do it. Many of our LR computer models (GFS, EURO..) are in good agreement about a storm and the most important thing is the blocking. If we get the blocking, there will most certainly have to be something that jumps off the coast and can only move up the coast because of the flow. Storms that are forced to sit off the coast will explode and this is how we get our big winter storms. This is a pattern that we have not seen since Feb '06. We may wipe the slate clean regarding snowcover in SNE later this weekend with temperatures in the 50s/60s, but we may replenish it sooner rather than later.

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