Central Maryland is in for a gusher of rain throughout the day Thursday as a potent storm system moves out of the Gulf states with a heavy load of Gulf and Atlantic moisture.
On top of rainfall that could total 3 inches before the storm ends Friday morning, forecasters said persistent winds from the east and southeast will pile up high tides on the bay Thursday evening, 2 to 3 feet above normal.
The National Weather Service Wednesday posted flood watches for interior counties in anticipation of the heavy rains, and coastal flood advisories for the Western Shore of the Chesapeake Bay.
"The heaviest rain is going to occur toward the afternoon and into the evening," said Steve Zubrick, science and operations officer at the National Weather Service's regional forecast office in Sterling, Va.
"That's going to fall on ground already saturated from last weekend's rainstorm. Streams and creeks are going to rise pretty rapidly. Hopefully, people will heed their senses and heed any signs put out by local authorities, and not drive around any barricades," he said. "I think [Thursday] afternoon will be quite a challenge for commuters, in places."
Baltimore public works officials appealed to residents to clear trash from storm drains before the heavy rains start, and to report those they can't clear to 311. "Keeping them clear of trash and debris is crucial in preventing localized flooding," officials said in a statement.
The new rain could amount to nearly a month's worth in just 30 hours. It caps a long period of relatively dry weather for Central Maryland. Baltimore has seen below-average precipitation every month since October. The winter has produced only 14 inches of snow at BWI-Marshall Airport. That's 4 inches below the long-term average there.
With this storm, Zubrick said, "we have a connection to the Gulf of Mexico, so that moisture is being pulled up into our area, and focused in our area, especially in the afternoon and evening. … And with the low-pressure system expected to go west of the Baltimore area, a prolonged period of east and southeast winds are going to pile up water in the bay … so we're looking at coastal flood issues."
The forecasts look great for Friday and the weekend, with sunshine and highs in the 50s to nearly 60 degrees on Saturday.
http://twitter.com/froylanceMaryland weather blog: Frank Roylance on meteorology
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