Friday, March 12, 2010

Flood Watch Expanded


The Flood Watch has been expanded to cover all of Virginia from this evening through Saturday morning, when 1"-3" of rain is expected to fall. A developing low pressure center off the Southeast Coast will track northward tonight over Central Virginia into Saturday, providing the lift needed for precipitation. In addition, ample moisture will be in place as easterly surface flow ushers in moisture from the Atlantic, which will allow heavy rainfall to occur. Here is a snapshot of the surface observations from shortly after 11 a.m. Friday:

Rain from this developing low currently off the coast of South Carolina will expand into Central VA later this afternoon, and rain will be heavy at times this evening and overnight while the low tracks northward. This system will be east of the Chesapeake Bay mid-day Saturday, with heavy rain over much of Central Virginia, especially along I-64. Rain will gradually diminish Saturday night, but scattered showers will linger into Sunday. Flooding will be an issue in urban areas with poor drainage, especially when the rain is heavy. You can also expect ponding on the roads, flooding in the usual low-lying spots, and also in gullies, creeks, streams, and drainage ditches. Remember never to drive on roads covered with water. You cannot tell if the road underneath has washed out!

Heavy Rain Expected Through Saturday


Rain showers will continue off and on through the day Friday, but a round of heavy rain is expected tonight through Saturday morning in Central Virginia. Several inches of rainfall is possible, with isolated totals up to 5" in the Watch area. Heavy rain will result from moisture streaming in from the Atlantic and Gulf, combined with a potent upper-level low pressure system slowly tracking eastward out of the Midwest. In addition, a surface low will develop and track over eastern Virginia, further aiding the likelihood of heavy rain.