Wind shear (winds that change direction with height) values will be increasing on Friday afternoon and evening. While strong thunderstorms with torrential rain and gusty winds will be the primary threats, enough low-level spin in the atmosphere will be present for some rotating super cells. According to the latest NAM model, the area with the highest risk may be from Fredericksburg Virginia across the Potomac into southern Maryland. With that said, everyone should pay close attention to the weather tomorrow as much of the region is under a slight risk for Severe Thunderstorms.
The image below, courtesy pivotal weather shows wind shear values increasing throughout the day on Friday
The 18Z NAM model shows that while much of the region could pick up between one and three inches of rain, locations picking up “training thunderstorms”, that is multiple storms that develop over the same areas could easily pick upwards of 5 or more inches of rainfall.
The image below, courtesy Tropical Tidbits shows the latest “high-resolution” radar simulation from 10 AM Friday through 5 AM Saturday
The 12Z NAM forecast Sounding valid at 8PM Friday evening over Fredericksburg, VA shows winds veering out of the east at the surface and then turning toward the south and eventually the west. This low-level wind shear aided by strong updrafts could spawn tornadoes in some of the strong thunderstorms on Friday afternoon and evening.