The last thing people in the Mid-Atlantic want to hear is more rain and storms, but that’s exactly what’s in the forecast today. Cities from Pittsburgh to Philly and D.C. to New York will see the risk for strong thunderstorms this afternoon, some of which could produce damaging winds and even a few tornadoes.
According to the Storm Prediction Center, an enhanced risk for severe weather—a three on a scale from zero to five—exists across much of southeastern Pennsylvania and northern Maryland in anticipation for widespread severe weather this afternoon and evening. A wider slight risk (two out of five) radiates out from there, encompassing the entire D.C. metro area and locations west through West Virginia, east into the Newark area, and north up through Scranton.
We can’t ignore the risk anywhere, but if you live in or around places like Philadelphia, Allentown, Baltimore, Wilmington (DE), or Trenton, I’d keep a really close eye on the radar and listen up for watches and warnings this evening.
The severe weather is a result of an approaching cool front making its way across the Appalachians—when you combine the lift from the front, powerful wind shear in the atmosphere, and instability resulting from the warm, muggy air along and east of the mountains, the setup is ripe for an atmospheric temper tantrum.
This afternoon’s storms will come in two modes: lines and supercells. We’re already seeing this come to fruition—a peek at the radar from 2:35 PM EDT shows discrete storms/supercells beginning to take shape across west-central Pennsylvania, while a more linear storm mode is taking shape across the Appalachians.
Discrete supercells will carry the greatest risk for tornadoes, as they can tap into the atmospheric dynamics required to support their formation. As the evening wears on, however, the threat will transition more toward damaging winds, with gusts up to (or even exceeding) 70 MPH possible in the most organized storms that develop. Tornadoes are always concerning, but 60+ MPH winds can produce just as much damage as a tornado but over a much wider area.
As usual, the threat for severe weather will start to approach the major cities during rush hour, which could create a commuter mess for thousands of people trying to get home before the skies open up. However, current models suggest that the worst storms won’t arrive in the Interstate 95 corridor until the tail-end of rush hour, but it’s a good idea to keep an eye out regardless.
Destructive thunderstorms have already created one commuter hell so far this year—storms tore through the I-95 corridor on the evening of June 23, knocking out power to nearly a million people and stranding travelers on trains, planes, and automobiles while officials rushed to clean up the damage and restore electricity.
You can follow the latest severe weather watches from the Storm Prediction Center and the latest warnings from the National Weather Service. As a reminder, a watch means that conditions are favorable for the development of severe weather over the next couple of hours, and a warning means that damaging winds, large hail, or a tornado is imminent and you need to take immediate action.