Storm on the Potomac

Moderate instability and good deep-layer shear produced a line of storms near a surface trough in northern Virginia. ProbWind v3 was handling the severe threat better than v2, with a probability of 41% vs. 3%, seven minutes before reports of trees down. PWv3 increased by over 20% at 17:00 UTC, due to increases in the MRMS VIL and 0-3 km lapse rate, with the MRMS azimuthal shears and composite reflectivity also contributing. Forecasters at the HWT have noted this week that PWv3 seems to be better calibrated to the wind threat than its predecessor.