As we resume Standard Time this morning, Sunday November 7, 2010,the air is colder in Georgia (26 Peachtree) than in Massachusetts (32Worcester). This happens when the Steering Current high in the skybuckles into 'High Amplitude' flow.
High Amplitude flow features airmoving more south to north, and north to south (Zonal Flow is more eastto west). Usually we have a combination of the two. But today we have avery deep trough on the east coast, sending that early freeze to ThePeach Garden of the United States (quickly, buy some peach futures, theprice may jump tomorrow). On the east side of the deep trough we have acloud stretched from South America to Greenland. That's a Deeep Trough!
Does this remind you at all of late October 1991? Yes, this weatherpattern has similarities to the ('No Name') Halloween Hurricane of 1991(recently named 'Perfect Storm'). On October 27, 1991 a front stalledeast of the United States, while Hurricane Grace spun up south ofBermuda. This year the Hurricane name is Tomas. Grace was originally acold core storm that turned warm core and was about 50 miles south ofBermuda, Tomas is a long lived warm core storm that formed west ofBarbados, from an African wave, on October 29. Tomas is 400+ miles south of Bermuda, and has for the third time,strengthened from Tropical Storm to Hurricane.
The satellite image appears to have Tomas embedded in the same frontthat brought us the heavy rain and wind of last Thursday. Much likewhat happened in 1991, the old front is absorbing energy from Tomasinto a new storm developing east of New England Tonight. Unlike 1991,we have only old cold left from High Pressure over Quebec ( in 1991very cold air resulted in Blizzard Conditions in Minnesota). This oldcold is a limiting factor in how strong our new 2010 storm will gettonight and tomorrow.
We have just enough cold to get a period of snowand sleet late tonight, before a change to rain Monday. Cold is aningredient in storm development, as warm air rides over the cold, lowpressure deepens until the temperature gradient is wiped out, then thestorm occludes and spins out. This warmer air is arriving from thenorth and east, a 'Back Door' warm front!
This will all happen very fast tonight and tomorrow. In fact we mayhave a period of 'Bombogenesis' near Cape Cod tonight as the centralpressure of the new storm drops from 1011 millibars to 996 millibars in24 hours ending Monday Morning at 7 AM. After that the storm will tendto weaken for a day or two, but may be rejuvenated by slightly colderair from Nova Scotia , and the influx of the heart of Tomas into thestorm center on Wednesday.
The net result is heavy wintry mix from east to west tonight, with a4 hour period of Gale to Storm force wind for early Monday. Then we havebands of moderate to heavy rain spiraling counterclockwise through NewEngland into Tuesday. Rainfall amounts greater than 3" may causeflooding along the shore from Maine to Massachusetts, lighter rain isexpected in the west of New England. By Wednesday most of the stormwill be at Sea, but that make 6 days in a row of massive fetch wavesbattering New England during our new moon. Our Beaches are once againbeing rearranged by nature. Surf will be huge all week long. As for skiseason, Killington (8" new last Thurs/Fri) and Sunday River are open,an inch or two new will fall tonight and tomorrow, after that we aretoo warm to make snow until next weekend. But the Ski Show is coming toBoston, we have that to look forward to.