Tuesday, December 4, 2007

Sunday-Monday wintry mix

Cold front slides through Saturday, triggering snow showers Friday, Fri N, and Saturday but minimal accumulation. High pressure moves south into southern Quebec.

Low pressure taking a similar path to this past storm up into the Great Lakes, combined with high pressure to our north, will create a tight temperature gradient over and just south of the region Sunday. The warm air advection to our south will create an overrunning senario, triggering precipitation along a warm front stretched to the east of the low. Warm air will flood in aloft, however high pressure to the north will keep a CAD situation in place over the region. GFS has 2M temperatures near 0C here, with 850mb temps near 3C. In summary, could see snow and sleet beginning Sunday with light accumulation followed by a period of freezing rain and/or sleet through Monday morning. How long it lasts will depend on the strength of the high to the north. At this point, it appears likely that a change to rain will occur in the late morning. Even still, a few icy hours may be enough for a school delay, and this is really our next shot at having one.

Past this, colder air flows in at the surface. Could have some light snow or sleet through Tuesday associated with a few weak surface features behind the cold front.

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