Persistent rain is likely to continue through the 143rd Preakness Stakes on Saturday, though meteorologists expected soaking precipitation to have ended by then.
A flood watch was put in effect Saturday morning until 8 p.m. for most of the state. Heavier rain is expected in Southern Maryland and on parts of the Eastern Shore.
Flash floods are possible, and the National Weather Service warned that small streams and low-lying areas are especially at risk for floods. Ground already saturated with rainwater could also increase risk of flooding, the weather service warns.
By the time revelers gather at Pimlico Race Course, rain was expected to be scattered and lighter, said Cody Ledbetter, a meteorologist at the weather service’s Baltimore-Washington forecast office.
“I wouldn’t expect long periods of heavy rain or anything like that,” he said.
There is a chance of some storms, especially in the afternoon, though, Ledbetter said. Humid conditions and highs in the lower 70s are in the forecast.
The unsettled weather comes as a front is parked over the region, and weather systems over the Southeast U.S. and off the Atlantic coast pump tropical moisture into the region.
Forecasters warn it won’t take much rain to cause flooding over the next few days.
“These amounts of rain would definitely be sufficient (given already saturated soil and elevated streams) to cause flooding/flash flooding almost any day through the forecast period, with some potential for significant river flooding late in the week through the weekend,” weather service forecasters wrote.
“With a deep and near-persistent moisture feed from the Gulf and Atlantic pumping moisture in through at least Saturday, and that boundary remaining somewhere nearby, this will act as a recipe for heavy rain potential … which is starting to look like more a matter of when and how much, rather than if,” the forecasters wrote.
From Sunday through Thursday, more than 4 inches of rain had already fallen at Baltimore-Washington International Thurgood Marshall Airport.
Though temperatures are expected to stay seasonably cool this week, in the 60s and lower 70s, the persistent rain is also keeping humidity levels high. Relative humidity is forecast to hover close to 100 percent through Saturday, meaning dew points will stay in the mid to upper 60s, an uncomfortable level of moisture in the air.
Drier conditions are not expected until Sunday, and they are forecast to be short-lived, with another front coming through Monday and Tuesday.