During the morning of April 30, low pressure was strengthening over South Carolina. Meanwhile, a potent, negatively tilted southern stream shortwave trough was lifting northeast over Georgia.
Showers and a few thunderstorms were ongoing across the forecast area, with a quasi-stationary frontal boundary positioned from east-central NC to eastern VA. The morning convection was elevated and thus did not pose a severe threat. The atmosphere did not have time to recover from the morning storms and there was still not much in the way of instability across the area.
This second round of convection did not produce severe weather. With 2 to 3 hours of clearing and the fact that the low track was just to the northwest of Hampton Roads , the environment changed rapidly between 2 and 5 pm. Deep-layer shear was sufficient for supercells throughout the day.
However, instability especially in the km layer increased significantly during the late afternoon before the arrival of the final round of thunderstorms which were coincident with the upper shortwave itself. Note that the instability was much less over the eastern shore and cool Atlantic waters, creating a tight CAPE gradient near the coast in the past, we have seen tornadoes form along instability gradients. In addition, low-level directional shear increased significantly by that time.
Finally, the low deepened to mb and was centered over the Peninsula at around 5 PM see regional surface observations for more details. The final round of convection produced wind gusts in excess of 50 knots as it moved through eastern NC and far SE VA although most of the severe wind reports were south of our area.
