Think Snow, Tweet Snow !!!

Tuesday, December 21, 2010

Christmas Storm prospects looking up...

and after a 4-8 inch fluff-up Wednesday and Wednesday night, the focus will shift to the period following Christmas Day as the possibilities for a major, major storm in that time frame have increased over the last two days. Until then we can enjoy the pre-christmas snow mentioned above and the crisp, relatively dry and partly sunny days that follow between the Thursday and Saturday.

The storm's energy stems from the feet of snow that is falling over the Rocky Mountains from the Sierra Nevada Mountains to Colorado. By early Christmas Day it won't look like too much with some rain falling along the Gulf Coast and snow across northern Alabama and eventually the mountains of north Georga, perhaps enough in those areas for an unusual white Christmas. Fortunately, for us the jet stream will be split and polar jet energy will dive south out of Canada and give this system a major infusion of upper air support as it encounters the relative warmth of the Atlantic Ocean. The result will be a rapidly deepening system either on or just off the Carolina Coast by early Sunday. I think we have figured this much out regarding this very important and quite possibly very ferocious weather system but its exact position Sunday morning and eventual track from here will be the determining variable. The American GFS model has flirted with a big east coast snow event with a few runs taking the system off shore and a few runs showing a northeast hit. A succession of European model runs however have been far more bullish and the relative consistency of this data has gotten the SCWB very excited. So long as we can track this storm reasonable close to the Atlantic Coast, there is a good chance some of the moisture can get caught under the blocking we keep talking about post after post. Although we can still get a complete miss out of this storm, the upside has become huge with more snow than I even dare mention early next week.

Any snow Monday and Tuesday will be followed by a dry and relatively tranquil period in the days prior to new years. Temperatures in the wake of a storm, or no storm will be chilly diving below the zero degree mark on one or two mornings and rising only in the teens. The early week chill will be accompanied by strong winds but both the chill and the winds will subside by later in the week making the late week skiing pristine if our above storm comes to fruition. For now we can at least be optimistic.

4 comments:

Andy said...

AMEN.

Andy said...
This comment has been removed by the author.
Harvey44 said...

Josh ... can you explain the favorability index?

Joshua said...

The index is a cumulative measure of the NAO, PNA and AO over the next two weeks with the signs of the NAO and AO flipped. More importantly, a favorability rating of over "2" is excellent while anything under -2 is rather unfavorable. Hopefully this will keep me honest and perhaps keep me out of trouble !! Enjoy the early season turns.