MD Weather: Severe Thunderstorm, Flood Watches Issued For 17 Counties

Updated at 3:15 p.m.

MARYLAND — A severe thunderstorm has been added to the weather hazards making for a soggy start to the July 4 holiday weekend. A tropical storm has formed off the Outer Banks and 3 inches of rain is possible Saturday in parts of Maryland.

The severe thunderstorm watch is in effect until 9 p.m. for Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil, Charles, Dorchester, Frederick, Harford, Howard, Kent, Montgomery, Prince George's, Queen Anne, St. Marys and Talbot counties, plus the city of Baltimore.

For Marylanders traveling to beaches in the Carolinas, Tropical Storm Colin formed near Myrtle Beach, South Carolina, Saturday morning. Tropical storm warnings are in effect for the Outer Banks south of Duck, North Carolina.

"We're not expecting impacts from Colin locally, but if you're in the Outer Banks for the holiday weekend, expect heavy rain and gusty winds," the National Weather Service office in Wakefield, Virginia said.

A flood watch is in effect from 2 to 10 p.m. for communities from Baltimore to Washington, D.C.
Isolated instances of flooding are possible through this evening, the National Weather Service said.

Areas in the flood watch include: Baltimore, Prince George's, Anne Arundel, Montgomery and Howard counties, plus the cities of Silver Spring, Bowie, Annapolis, Odenton, Bethesda, Severn, College Park, Columbia, Severna Park, Greenbelt, Rockville, Arnold, Suitland-Silver Hill, Laurel, Ellicott City, Baltimore, Glen Burnie and Gaithersburg.

The National Weather Service said, "Showers and thunderstorms are expected this afternoon and evening, with the most widespread activity late this afternoon into early this evening. Thunderstorms will produce heavy rainfall with localized rainfall amounts around 1 to 3 inches within an hour or two. Heavy amounts of rain in a short period of time may lead to rapid rises of creeks and streams, as well as the potential for flash flooding in urban areas."

Tropical Storm Colin is expected to turn toward the east-northeast late Sunday and Sunday night. The National Hurricane Center said the center of Colin is expected to move northeastward along or just inland of the South Carolina and North Carolina coasts through Sunday, and then emerge over the western Atlantic Ocean late Sunday.

Here's the forecast for Ocean City:

Saturday: A slight chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 80. South wind 15 to 17 mph. Chance of precipitation is 20%.

Saturday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 71. Southwest wind 8 to 13 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Sunday: A chance of showers and thunderstorms. Cloudy, then gradually becoming mostly sunny, with a high near 78. West wind around 6 mph becoming east in the afternoon. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Sunday Night: Partly cloudy, with a low around 68. East wind 5 to 7 mph becoming calm in the evening.

Independence Day: Sunny, with a high near 78. Northeast wind 6 to 8 mph becoming southeast in the afternoon.

Monday Night: Mostly clear, with a low around 70.

Here's the latest forecast for the Baltimore-DC region:

Saturday: A slight chance of showers before noon, then a slight chance of showers and thunderstorms between noon and 2pm, then showers and possibly a thunderstorm after 2pm. Some of the storms could produce small hail, gusty winds, and heavy rain. High near 90. Southwest wind around 6 mph. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.

Saturday Night: Showers and thunderstorms before 2am, then a slight chance of showers. Low around 70. Light and variable wind. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.

Sunday: Mostly cloudy, then gradually becoming sunny, with a high near 87. North wind 3 to 6 mph.

Sunday Night: Mostly clear, with a low around 68. Light north wind.

Independence Day: Sunny, with a high near 88. Light and variable wind becoming south around 6 mph in the morning.

Monday Night: A slight chance of showers and thunderstorms after 2am. Partly cloudy, with a low around 71. Chance of precipitation is 20%.