Discussion: The concern in the Mid-Atlantic region today regarding severe weather is the new squall line developing over central Pennsylvania to northeast West Virginia by mid-afternoon. A tornado watch is likely with this line of squalls.
Yesterday’s prolific severe thunderstorm activity which produced 32 tornado reports from Louisiana to Alabama has shifted east-southeast. A new tornado watch has been issued for Georgia and the most intense weather associated with remnants of yesterday’s storms should stay in the far southern states.
The northern portion of yesterday’s severe weather moves across the Carolinas and into eastern Virginia this afternoon. Locally heavy rains with isolated severe storms are likely in this zone. Expect a severe thunderstorm watch with this area of thunderstorms but tornado risk is low. Expect wind gusts to exceed 50 mph in this zone within strongest storms.
The squall line in Pennsylvania reaches peak intensity by 6PM-8PM. At that time heavy rain can produce flash flooding in northeast to south-central Pennsylvania shifting eastward toward Philadelphia and Baltimore. At this time a tornado risk is highest from east-central Pennsylvania to north-central Maryland to southeast Pennsylvania. Wind gusts associated with the strongest storms are in the 50-60 mph range.
By 9PM, the squall line remains intact but is starting loose intensity located in southeast New York to southeast Pennsylvania to just east of both Baltimore and Washington, DC. At this time, a tornado watch will still be in effect likely lasting to late evening
Fig. 1-2: HRRR short-range model projection of lightning strike frequency and radar depiction at 3PM.
Fig. 3-4: HRRR short-range model projection of lightning strike frequency and radar depiction at 6PM.
Fig. 5-6: HRRR short-range model projection of lightning strike frequency and radar depiction at 9PM.