DELMARVA -Â Clouds increase this afternoon with temperatures in the upper 70s and lower 80s, then changes this evening as a developing low-pressure system approaches Delmarva. A warm front will lift through the peninsula today, followed closely by a cold front Saturday night into Sunday. High temperatures this afternoon with be in the low to mid 80s.
Widespread showers and thunderstorms are expected to develop, particularly later this evening into Sunday as the cold front approaches. The greatest concern will be heavy rainfall and localized flash flooding. The Weather Prediction Center has the entire area in a "Marginal" risk for excessive rainfall.
Atmospheric moisture levels are expected to become unusually high for mid-September, increasing the potential for torrential downpours. The greatest flooding concerns will be in urban and poor-drainage locations along with smaller creeks and streams. River flooding appears less likely because recent dry weather has kept larger waterways relatively low.
The severe thunderstorm threat remains limited because atmospheric instability is expected to be relatively weak. Damaging winds, large hail and tornadoes are not expected to be the primary hazards with this system.
Drier air should begin moving across Delmarva behind the cold front Sunday. A secondary front could produce an isolated shower Sunday night, but most locations should remain dry.
Canadian high pressure will then build across the region early next week, delivering beautiful September weather Monday and Tuesday. Expect plenty of sunshine, low humidity and highs near the lower 80s. Sunshine should continue into the middle of the week as temperatures climb into the mid 80s before another cold front approaches late in the week.
