A series of storms is raising the risk of flash flooding Thursday in already flooded areas of the Northeast and mid-Atlantic.
Flash flooding has repeatedly occurred in these areas throughout the summer, and as recently as Thursday, a storm with torrential rain flooded roads in New York City and New Jersey, disrupting air traffic on the busy corridor.
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Multiple similar occurrences are possible into early Friday morning, some of which could be severe with damaging wind gusts and possibly tornadoes.
The first showers and thunderstorms affected parts of northern New Jersey and southern New York Thursday morning, and other smaller storms began to develop farther west into the Appalachians.
A new, more organized storm system will develop Thursday afternoon as a cold front moves northeast out of the Ohio Valley. This round is most likely to be severe, especially from mid-afternoon to early evening.
A severe storm threat level 5/5 has been set from south of the New York/Vermont border to northern Virginia. Parts of Washington, DC, Philadelphia, and New York City are included in this risk area.
The most powerful storms will lose strength by midnight, reducing the risk of damage such as gusty winds, isolated hail and tornadoes. Still, the rain may not completely stop until Friday morning.
Rainfall could exceed 1 inch per hour on Thursday, potentially causing flash flooding, especially in urban areas.
A Level 2/4 flood risk is in effect Thursday from Washington, D.C., to parts of southern New York, including New York City, and the state of Connecticut.
Most areas will see rainfall totals of about 1 to 2 inches, but some locations hit by the most severe storms could receive as much as 3 to 5 inches.
New showers and thunderstorms could develop further east on Friday, extending from southern New England into parts of Delaware and Maryland. At this time, these storms are not expected to pose a significant flooding threat, but that could change if the storms hit flooded areas on Thursday.
