State College, Pa. — AccuWeather.com — A large swath of snow will stretch across the northern third of the nation later Thursday through this weekend from a fast-moving “clipper” storm. This storm is found in southern areas of British Columbia and Alberta today and will dive southeast bringing a large area of 3 to 6 inches of snow with isolated 8-inch amounts from the Canadian Prairies through the mid-Atlantic and Northeast, including the cities of New York, Pittsburgh, Cleveland, Detroit, Chicago, and Boston. This will potentially be the largest snowfall so far this winter in New York City and Philadelphia.
This storm system will first be dynamically driven, generating all of its own moisture. However, by Friday night, this storm system begins to draw moisture from the Gulf of Mexico due to southerly winds on the southeast side of the low pressure system. More moisture means more snow, but it also means more warmth working into the system. The main forecasting problem with this type of system is the exact track of the low pressure system.
If the track of the system is along the Mason-Dixon Line, cities like Pittsburgh, Philadelphia, and New York will receive moderate snowfall amounts. A track farther north will mean more warmth so less snow will fall in these cities, while cities farther north like Chicago, Detroit, Cleveland, and Boston will get the most snowfall. Baltimore and Washington, D.C., may also get some accumulating snow, but being farther south, the snow will mix with and change to rain during the event.
Current thinking has the storm beginning to affect Chicago Friday around noon, Detroit Friday afternoon, Cleveland before midnight Friday night, Pittsburgh around midnight Friday, Philadelphia, Baltimore, and Washington, D.C., early Saturday morning, New York City late Saturday morning and Boston Saturday afternoon.
Starting next week, extreme cold will blast into the Midwest and Northeast, marking what could be the coldest days of the season for the big cities.
