Central Maryland is under a flash flood watch, with heavy rain and storms forecast late Thursday and Friday.
As much as 2-3 inches of rain could fall during showers and thunderstorms, with periods of heavy rain possible, according to the National Weather Service. Locally heavier rainfall totals are possible.
Flash flooding is of particular concern near small rivers and streams, according to the weather service.
So far this month, rainfall is running below normal, at about three-quarters of an inch at BWI Marshall Airport.
If the forecast holds up, though, it could be a fourth consecutive wetter-than-normal month at BWI. An average of about 4 inches of rain falls in May here.
In April, 8.6 inches of rain fell, the second-wettest on record in that month and a tenth of an inch shy of the record dating to 1889.