Tuesday, September 29, 2009

Tuesday Morning Mountain Waves

West to Northwest winds being lifted over the mountains in West Virginia and western Virginia have helped create a cloud formation known as "Mountain Waves" or "Lee Waves," because these are clouds that form in the lee of the mountains. When the air is orographically lifted on the "windward" side of the mountain, the air condenses and forms a cloud. On the other side of the mountain, the air begins to descend, and the sky is clear there. But an oscillation has begun in the atmosphere, so the air rises again, condenses, and forms another row of clouds on the leeward side of the mountain.
This oscillation can continue for miles, and we are seeing that early this morning in the Commonwealth! Watch the visible satellite loop here.

Monday Rainfall & Severe Reports

The strong cold front that moved through the Commonwealth Monday afternoon and evening did kick off some strong to severe thunderstorms in the region with locally heavy rainfall. Here is a snapshot of the storm-total precipitation:
(Radar image from Wakefield at NWS)
The highest rain totals were in northern Sussex County, with up to 4"-5" in isolated spots. More widespread totals were in the 2"-3" range in the swath of yellow.
Here are the severe weather reports from Monday:
Severe weather reports included Quarter to Golf-ball Size Hail in Boydton in Mecklenburg County, and also tree damage in South Boston, Ringgold, and Nathalie in south-central Virginia.