Flood Warning in Effect Until 3:45 a.m.

UPDATE 1:25 a.m.: The flood warning has been extended until 3:45 a.m. and now covers central Howard County, said the National Weather Service, which reported that streams were continuing to rise and would gradually recede over the course of the evening. 

"DPW's Bureau of Highways continues to tackle debris cleanup this evening," said Howard County Government on Facebook. "As a result of the severe storms and flooding, some roadways may have standing water and debris that will be difficult to see during nighttime hours. Please drive w/ caution and be safe!"

UPDATE 12:55 a.m.: A flood warning remains in effect until 3:15 a.m. for northwestern Howard County, according to the National Weather Service. The weather service said a number of roads had been closed due to flooding and people should move to high ground if they observe water levels rising.

UPDATE 11:05 p.m.: The National Weather Service has canceled the tornado watch in Howard County. A flash flood warning is in effect for eastern Howard until 11:30 p.m., particularly Elkridge, Ellicott City, Columbia and Arbutus, according to the National Weather Service.

"If you must drive, be cautious of standing water and fallen debris," wrote Howard County Government on Facebook, noting that traffic lights were out at Route 108 and Old Montgomery and Route 108 at Bendix Road.

UPDATE 10:50 p.m.: A tornado watch is in effect for Howard County until 2 a.m. and a flash flood watch is effective until midnight, according to the National Weather Service. In a tornado watch, strong thunderstorms create conditions that increase the likelihood of a tornado. In a flash flood watch, there is the potential for flooding.

UPDATE 7:40 p.m.: The National Weather Service expired its previous tornado warning in Howard County at 7:30 p.m., although it remains in effect in some areas, including BWI Airport. 

The tornado watch remains in effect until 9 p.m.

UPDATE 7 p.m.: The National Weather Service at 6:55 p.m. issued another tornado warning for southeastern Howard County as well parts of Prince George's and Anne Arundel Counties.

The warning is in effect until 7:30 p.m.

Dopler Radar is showing thunderstorms that could produce tornadoes along a line from Laurel to 5 miles southeast of Laurel, moving east at 20 mph.

A flash flood warning remains in effect in Howard County until 9:15 p.m.

UPDATE 6:20 p.m.: The National Weather Service has canceled the tornado warning for Howard, Anne Arundel and Baltimore Counties.

The thunderstorm that prompted the warning has weakened below severe limits, according to the NWS.

UPDATE 6:15 p.m.:  A flash flood warning is in effect for Howard County until 9:15 p.m.

A severe weather statement was issued at 6:09 p.m. warning of a severe thunderstorm capable of producing a tornado near Severn moving north at 25 mph. Locations impacted include Elkridge, Linthicum, Arbutus, Halethorpe, Catonsville, Ilchester, Lansdown and Oella.

UPDATE 5:32 p.m.: The National Weather Service extended the tornado warning until 6 p.m. and imposed a tornado watch until 9 p.m.

A tornado warning is issued when a tornado has been spotted by a person or by radar. A watch indicates favorable conditions exist for a tornado.

The watch also includes Carroll, Montgomery, Prince George's and Anne Arundel Counties.

UPDATE 4:48 p.m.: The National Weather Service has issued a second tornado warning for Howard County, this time in the southeast, particularly the Elkridge area.

The warning, in effect until 5 p.m., also included Southern Baltimore County and Northwest Anne Arundel County.

According to NWS, the thunderstorm is "capable of producing a tornado near Elkridge."

The storm was reported centered around the Elkridge/Waterloo area. Trees were reported down on Route 29.

The storm was moving northeast at 20 mph and could also affect Baltimore-Washington International Airport, Catonsville, Arbutus, Ferndale, Pumphrey and Brooklyn Park.

NWS recommends moving to an interior room on the lowest floor of a sturdy building and to avoid windows. If outdoors, move to the closest substantial shelter and seek protection from flying debris.

UPDATE 4:30 p.m.: Several schools delayed dismissal due to the weather, and HCPSS says parents can expect some delays in the students' return home.

All evening activities at Howard County Public Schools have been canceled due to hazardous weather, according to a statement from HCPSS.

Cancellations include aftercare sponsored by the Columbia Association and the Department of Recreation and Parks.

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UPDATE 4:10 p.m.: The National Weather Service upgraded the tornado threat from a watch to a tornado warning, through 3:30 p.m. NWS said a storm in Damascus, MD, was "capable of producing a tornado." A tornado produced in the area could head toward northwest Howard County, according to NWS.

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Bryan Jackson is from Nebraska, and he’s never seen a tornado.

But now that he’s in Sterling, VA, they may be closer than ever.

Jackson works at the National Weather Service and fielded some questions about Friday night’s ominous weather reports.

There’s a tornado watch in effect in Howard County until 9 p.m., he said Friday at about 2:20 p.m. as thunderstorms formed between Interstate 95 and the Blue Ridge.

Later tonight, between 7 and 10 p.m., the line of thunderstorms should roll in, with the potential “to produce widespread, damaging winds and tornadoes across Central Maryland,” Jackson said.

Tornadoes aren’t too common in the area, though Jackson said there had been a few in Frederick and Carroll Counties in the past two years. But, according to the Storm Prediction Center, tonight there’s a 15 percent chance of a tornado in Howard County.

That means there’s is a 15 percent chance, at any point in Howard County, that there will be a tornado within a 25 mile radius. 

“That may not sound very high,” Jackson said, “but it’s about as high as it gets here.”

And, report from Elkridge Patch Reporter Elizabeth Janney at 2:45 p.m.: "It's hailing on Interstate 695."