Posted by: pyeager | April 21, 2012

Major and Potentially Damaging Winter Storm Coming–in Late April!

By Paul Yeager, author of Weather Whys: Facts, Myths, and Oddities

After a winter that was much less snowy than might have been expected, a major and potentially damaging winter storm will affect parts of the mid-Atlantic region and Northeast late in the weekend into early next week. Some areas from the mountains of West Virginia, western Pennsylvania, and western New York will receive more than six inches of heavy, wet snow from later Sunday through Monday. A foot of snow is possible in the higher elevations.

Predicting the amount of snowfall is very difficult in a situation like this (insert your favorite joke about the weatherman here). The ground is very warm and temperatures will be above freezing while the snow is falling, so the amount of official snowfall will be higher than any amount of snow that accumulates on the ground. For instance, in a given location, four inches of snow might fall, but there might never be more than two on the ground at any given time.

What is easier to predict–and more important–is the impact of the storm. Travel will be slowed at night when snow will accumulate on the ground, but the main danger is the potential for power outages caused by tree limbs (and possibly entire trees) being brought down by the accumulation of snow on the leaves, which are well ahead of schedule given the amount of warmth this spring.

Downed tree limbs, of course, also pose a danger to house roofs, cars, and pedestrians.

Only three or four inches of heavy, wet snow will cause major tree damage in a situation like this, and some locations will receive double that.

The areas in blue on the map below are in a winter storm watch (as of Saturday evening). The dark green areas along the East Coast are flood watches, where rain amounts will locally exceed four inches.

It’s going to be an April storm that’s remembered for a very long time.

national weather service watches and warnings on April 21, 2012


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