Storms to unleash isolated tornado risk in mid-Atlantic

 By Alex Sosnowski, AccuWeather senior meteorologist

Published Sep. 3, 2020 10:55 AM

Thunderstorms may again pack a punch in the mid-Atlantic region of the United States during Thursday afternoon and evening, ahead of a slow-moving push of cooler air.

On Wednesday late afternoon and evening, thunderstorms erupted in portions of Maryland and Virginia and produced winds strong enough to knock down trees and lead to sporadic power outages.

As sunshine warms the atmosphere from Virginia and Maryland to Delaware, southern Pennsylvania and southern New Jersey on Thursday, thunderstorms that erupt from parts of the Ohio Valley and Appalachians are likely to peak toward evening east of the mountains.

The greatest threats from the storms will be strong wind gusts with an AccuWeather Local StormMax™ of 70 mph and flash flooding.

However, a couple of the strongest storms could produce a brief tornado. The zone of showers and thunderstorms spreading over the region has had a history of producing a few isolated tornadoes over the South Central states this week.

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Cities that could be affected by severe weather into Thursday evening include Washington, D.C.; Baltimore and Hagerstown, Maryland; Philadelphia and Lancaster, Pennsylvania; Dover and Wilmington, Delaware; Millville and Atlantic City, New Jersey; Martinsburg, West Virginia; and Charlottesville, Virginia.

Forecasters say that conditions could change rapidly and that people on the road or spending time outdoors should stay alert and move inside and away from windows at the first rumble of thunder.

"Since the atmosphere is ripe with moisture and the ground is nearly saturated, any downpour that lingers for more than several minutes will have the potential to set rapid urban and small stream flooding into motion," AccuWeather Meteorologist Nicole LoBiondo said.

As portions of New England and the central Appalachians are recovering from abnormally dry to drought conditions over the summer, "most cities from New York City to Richmond, Virginia, in the Interstate-95 corridor have been abnormally wet, with up to three times the average rainfall for August," LoBiondo said.

Just enough cooler and less humid air will filter into the region during Friday and Friday night to change the atmosphere conditions to a less volatile setup in this portion of the mid-Atlantic region.

There can still be a pop-up shower or thunderstorm, but any heavy thunderstorms are likely to occur farther south toward North Carolina and perhaps southeastern Virginia, where the air will still be quite warm and humid.

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The weather over much of the Northeast for the Labor Day weekend is expected to be pleasant with cool nights and comfortably warm afternoons. Dry conditions with sunshine are anticipated at most beaches for the last unofficial weekend of summer.

During next week, a gradual uptick in temperature and humidity levels are likely, as well as an eventual increase in the risk of showers and thunderstorms once again.

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