Tuesday, March 8, 2011

More Heavy Rain Likely Wed-Thur

More heavy rain is likely Wednesday and Thursday from a storm system developing Tuesday morning in the Southern Plains. A Flood Watch is already in effect in advance of this storm system for the Virginia counties highlighted in green on the map below:

The center of the storm system (the L for low) will track to our north, pulling in moisture and warmer temperatures from the south.

Rain should be nearly constant for western parts of the state Wednesday and Thursday, which is why they will be able to accumulate the highest rainfall amounts.

But Thursday the rest of central Virginia will have a shot at some heavy downpours and thunderstorms as a result of the instability generated ahead of the approaching surface cold front and the ample moisture and warmer temperatures in the 60s surging northward into the Commonwealth.

Instability, as shown below by the CAPE value (Convective Available Potential Energy), should be sufficient to support strong to severe thunderstorms in central Virginia Thursday afternoon and evening. Damaging straight-line winds (of the likes we saw Sunday in parts of the state) will be our primary threat again on Thursday. However, the Tidewater region of Southeast Virginia may also have the threat for a few tornadoes.

By the time the rain ends from west to east late Thursday night, one to three inches of accumulation looks likely for much of central and western Virginia.

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