Hopes (or fears) of a major winter storm later this week seem to be fading today. Forecasters out at Sterling say our temperatures will be cold enough for snow, with a high Thursday of only 30 degrees. But their models have begun to lean toward a storm track that would carry the low out to sea rather than up the East Coast. Here's a snippet of this morning's forecast discussion from Sterling:
"While the current expectation is for little or no snow impacts for the [forecast area] ...low chances [for snow] were maintained, particularly for southern and eastern portions of the forecast area due to a history of model uncertaintly regarding mid-Atlantic cyclogenesis in the medium [time] range."
There is still time for that to change. But for now the NWS has cut the snow chances for BWI-Marshall back to just 30 percent (from 50 percent) for Wednesday night and Thursday.
More immediately, there is a pair of low-pressure systems crossing the country today that could have an indirect effect on the region tonight. One disturbance tracking along the southern jet stream will pass to our south, bringing rain to the Deep South. The other, following the northern jet, will pass to our north, dropping more snow across Pennsylvania, New York and New England.
As long as the lows don't merge, or "phase," we're in line for rain as the cold front associated with the northern storm crosses the region. It shouldn't amount to much - less than a tenth of an inch is forecast. Cold air rushing in behind the front may bring light snow to Western Maryland.
The real news this week may be the cold and windy conditions expected after the cold front passes by. As the northern storm intensifies or the northeast, it will combine its counterclockwise circulation with the clockwise circulation of the high behind it to draw cold air down from Canada.
Winds of 17 to 24 mph, gusting to 37 will drop wind chills into the single digits to low teens in the Baltimore and Washington region late Tuesday and Tuesday night. Tuesday night's low is forecast to fall to 17 degrees. The average low for this time of year at BWI is 25 degrees.