Severe weather expected to affect 64 million Americans today

Postado Junho 20, 2017

Timing: 2 to 8 p.m. Northwest has an "enhanced" chance for severe weather while the rest of the state has a "slight" chance for storms. Flash flooding due to torrential downpours and strong/damaging wind gusts are likely in any storms that develop. During that time, residents may experience heavy wind gusts blowing up to 70 miles per hour and may see hail up to 1 1/2 inches wide.

Urban street flooding, washed out culverts or dirt roads, and fast, high streams and smaller waterways are all possible impacts we'll be watching for this afternoon. Any stronger storms that move over any given area will have the potential to put down a lot of rain in a hurry. However, very humid air and changes in wind direction/speed with height (known as shear) are key ingredients to making a tornado.

Today's severe thunderstorm watch comes on top of an earlier flash flood warning for most of upstate NY. With the increasing sunshine, our atmosphere is becoming increasingly more unstable.

How much rain will we see?

The approaching cold front will provide the means to lift this humid air mass, releasing the instability. Another round of strong to severe storms will strike the Piedmont this afternoon and evening. The freshening winds will cause wind shear (the difference in wind speed between the ground and regions aloft) to increase, to about 30 to 40 knots. A convective line has been ongoing across West Virginia and western Maryland this morning.