Wednesday, August 30, 2006

Eagerly Eyeing Ernesto


Cloudy, cool. A Flash Flood Watch is in effect from Thursday afternoon through late Friday night for most of Maryland west of the Bay, DC, central and northern Virginia, and the eastern panhandle of West Virginia. Click on your county above for details. (And don't forget to check your gutters, since they've had plenty of time to collect debris over the last several weeks.)

Under cloudy skies and a northeasterly breeze, this afternoon's official Washington temperatures have failed to reach the 82° observed at 1am last night. In the southern portion of the metro region, however, low 80s and even a few mid 80s have been seen at Fredericksburg, Stafford, Culpeper, Manassas, and Winchester.

Radar shows some light to moderate showers and some heavier thunderstorms from eastern West Virginia southeastward to north of Richmond on I-95 and toward the Northern Neck of Virginia. These are moving generally northeastward toward the metro area.

Tonight and Tomorrow

Cool, some showers likely. Tonight will be cloudy and cool with a 50% chance of showers, especially in the southern and western suburbs this evening, and lows in the low to mid 60s. Tomorrow will be cloudy with a 40% of showers and highs in the low 70s.

Scroll down to Dan's post below for the outlook through the holiday weekend, and look for Larson's Long-Range later.

Tropical Topics

Ernesto continued to weaken over southern Florida last night and was declared tropically depressed this morning; peak winds were only 35 mph at 2pm and again at 5pm. Some strengthening is possible as it re-emerges over the Atlantic, so tropical storm warnings have been extended along the northern Florida, Georgia, and Carolina coasts as far as Cape Lookout, NC.

The main threat from this storm is clearly heavy rain rather than wind, although winds will increase as it moves northward and a stronger pressure gradient develops with a "blocking" high pressure area to the north. Although the exact path of the center of such a weak circulation is not that significant, recent forecasts have tended to push the track westward over the mountains as it approaches our latitude. Models are notoriously unreliable in forecasting amounts of this kind of convective precipitation, but some areas are definitely going to be very wet. The most likely locations for the heaviest rain are from central North Carolina through central Virginia and westward to the eastern slopes of the Blue Ridge.

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Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.