Severe Weather Expected in Eastern U.S., Forecasters Say

A “complicated and active” storm system was sweeping across the Eastern United States on Monday, bringing the potential for multiple rounds of widespread thunderstorms that are capable of producing damaging winds, flash flooding, hail and tornadoes, forecasters said.

Unsettled weather was expected to stretch from New York to Georgia, with the highest risk in the Mid-Atlantic.

Forecasters with the Storm Prediction Center use a five-level scale to indicate the probability that severe weather will occur in a given area. On Monday, they assigned the Washington-Baltimore area a four on that scale, a level not seen since widespread wind damage was reported across the Mid-Atlantic in June 2013.

“The atmosphere is forecast to be in a volatile state, and severe thunderstorms will likely affect much of the area,” Andrew Snyder, a National Weather Service meteorologist in Washington, said. “There is increased confidence for numerous damaging wind gusts along with the potential for locally destructive winds over 75 m.p.h.”

An area stretching from northeastern Tennessee to southern Pennsylvania could be affected by widespread severe storms, some long-lived and intense. Storms of this severity typically happen once a year, if that.

The risk expands beyond the Mid-Atlantic, with more than 40 million people living within an area that forecasters believe has a moderate probability of experiencing these severe storms. The area includes major cities like Philadelphia, Atlanta and Charlotte, N.C.

The risk was lower in New York City and other parts of the Northeast, but excessive rain that could lead to flash flooding was likely, forecasters said.