SOUTHERN MARYLAND — A wetter and potentially more disruptive weather pattern is expected across Southern Maryland on Saturday, Aug. 22, with periods of showers and thunderstorms capable of producing heavy rainfall and isolated flash flooding.
The National Weather Service Baltimore-Washington office said thunderstorms Saturday will bring heavy rainfall that could result in isolated instances of flash flooding. The outlook specifically includes Charles, Calvert and St. Mary’s counties. As of Friday, no widespread watch or warning had been issued for Southern Maryland for Saturday, but the hazardous weather outlook marks heavy rain as the primary concern.
Residents should expect a mostly cloudy and humid day, with showers possible during the morning and thunderstorms becoming an increasing concern as the day progresses. Current forecast guidance places rain chances generally around 60% to 70% across the broader region, although individual communities could see substantially different conditions depending on where thunderstorms develop.
Temperatures are expected to remain cooler than a typical late-August afternoon. Forecast guidance generally places daytime highs in the upper 70s to lower 80s across the region. Current forecast data for Leonardtown calls for a cooler high near the mid-70s, while some National Weather Service guidance has temperatures closer to the upper 70s and lower 80s elsewhere in the region.
The main concern Saturday will not necessarily be severe thunderstorms with damaging wind or hail, but rather the amount of rain that could fall over a short period of time.
Thunderstorms are capable of producing intense rainfall rates, and repeated storms moving across the same location could create localized flooding problems. The National Weather Service said isolated flash flooding will be possible, particularly where thunderstorms produce heavy downpours.
That means residents should pay particular attention to low-lying roads, areas with poor drainage and locations that typically collect water during heavy rain. Drivers should never attempt to cross a roadway covered by floodwater because the depth and condition of the road underneath may not be visible.
Saturday does not appear likely to be a steady all-day rain for every Southern Maryland community. Instead, conditions may vary significantly throughout the day.
Some locations could experience extended dry periods between showers, while nearby communities receive heavy rain and thunderstorms. Residents planning outdoor activities should therefore continue checking radar and updated forecasts rather than relying only on a daily precipitation percentage.
The forecast for the Leonardtown area calls for mostly cloudy and humid conditions with showers and the possibility of a heavy thunderstorm. That forecast also specifically highlights the possibility of flash flooding from heavier storms.
Earlier National Weather Service guidance for the Leonardtown area indicated showers and thunderstorms would be likely Saturday, with precipitation chances around 60%.
Winds outside thunderstorms should generally remain light. Stronger gusts may occur in or near thunderstorms, but the latest National Weather Service hazardous weather outlook does not currently identify widespread damaging winds as the primary threat for Southern Maryland Saturday.
Humidity will remain high, making the day feel damp even with temperatures held down by cloud cover and precipitation.
The unsettled conditions are expected to continue into at least Saturday evening, with additional showers or thunderstorms possible before precipitation begins becoming more scattered overnight.
Conditions should gradually improve Sunday. Current guidance indicates lower rain chances and more opportunities for sunshine, although an isolated afternoon shower or thunderstorm cannot be completely ruled out in parts of the region.
Sunrise Saturday in Leonardtown is about 6:26 a.m., with sunset around 7:52 p.m.
Residents should monitor updated National Weather Service forecasts through Saturday because localized flash flood warnings could be issued quickly if thunderstorms begin producing excessive rainfall.
Anyone receiving a flash flood warning should move away from flood-prone areas and avoid flooded roadways.
The Southern Maryland Chronicle will continue monitoring forecast changes, watches and warnings affecting Charles, Calvert and St. Mary’s counties throughout the weekend.
