March 4th-5th Severe Thunderstorms and Flooding
A closed upper low moved northeast into the Ohio Valley and the associated surface low tracked across eastern Kentucky into southwest Pennsylvania during the afternoon and evening of March 4th. The trailing cold front moved through the central Appalachians that evening. A strong upper level jet rotating around the upper low provided additional energy to the storm system by the evening as well. The day started overcast with southeast flow resulting in upslope showers in the vicinity of the Blue Ridge, with heavier rain becoming focused in the North Carolina mountains. During the afternoon, breaks in the clouds over the Piedmont created slightly more unstable conditions. These factors ultimately resulted in two main lines of precipitation which affected our area. The first line was composed of scattered showers and isolated thunderstorms which moved northeast mainly across the piedmont of north-central North Carolina and Southside Virginia. One of the storms produced an EF-0 tornado over southern Caswell County, North Carolina.
A second, solid line of showers and thunderstorms developed just ahead of the cold front in northern Georgia and eastern Tennessee. This second line moved across our region during the evening. As the second line approached the Blue Ridge and foothills, smaller lines of storms developed ahead of the main line and these storms moved rapidly northeast. This line produced wind damage all along it, even from weaker showers.
Moderate to heavy rain earlier in the day across the mountains, combined with some snow melt from the highest elevations, produced some minor flooding as well. As the second line of storms moved through the mountains in the evening, the additional 0.5 to 1.0 inches of rain was all it took to cause some flash flooding in a few locations. The graphic below shows total rainfall which was collected from automated rain gages and volunteer observers. Some of the data is estimated and based on radar information. Thanks to those who provided rainfall data, and severe weather data. We will add more images and information to this summary as time allows.
