Squall Line/High Wind Washington, DC to Possibly New York City Later Today

Squall line brings enhanced risk of damaging wind to Washington, DC to Philadelphia.

Fig. 1-2: NOAA/WPC has upgraded the risk of damaging wind gusts for an afternoon squall line in the DCA/BWI/PHL area. The position of the squall line is indicated by the HRRR model at 6PM.

Discussion: NOAA/SPC has raised the probability of damaging wind gusts in the Washington to Philadelphia stretch possibly reaching the NYC area (Fig. 1) for an incoming squall line forecast over this region by late this afternoon (Fig. 2). CAPE values are near 2000 j/kg and a jet-maxima is aloft over this zone. Implications are the CAPE-inspired instability can generate sufficiently strong convection to pull down 60 mph wind at 500 MB to the surface. At 250 MB, wind speeds are near 80 mph. Wind gust potential in the enhanced area described is 70+ mph in the 5-8PM timeframe for northern Virginia, central Maryland, and southeast Pennsylvania. Expect a severe thunderstorm watch by 2PM. Helicity values indicate minimal tornado risk. HRRR model indicates strongest lightning risk is in the D.C. area by 7PM.