Overview Significant rainfall is headed to the Mid-Atlantic region and it looks like it will come as two separate events affecting each of the next three days with more than two inches possible by the time the weekend winds down.
Event 1 and the cold frontal passage The first rain event will be “light-to-moderate” occurring later tomorrow into early tomorrow night and it will be associated with a cold frontal passage. Showers will break out later tomorrow morning or early tomorrow afternoon and will continue into the early evening hours with perhaps a quarter to half an inch of rainfall by the time the front exits the region late tomorrow night. The break in the rainfall that occurs from late Friday night into early Saturday will be short-lived.
Event 2 and the strengthening low pressure system The cold front will stall out early Saturday over the Delmarva Peninsula setting the stage for a “heavy” rain event in the Mid-Atlantic region from later Saturday into Sunday. Low pressure will form over the Ohio Valley on Saturday – aided by an amplifying upper-level trough - and it will ride along the stalled out frontal boundary zone right into our area bringing with it substantial rainfall. The low pressure system will be slow to depart on Sunday given the continuing intensification of an upper-level trough. The strengthening low pressure system will generate a tightening pressure gradient and the result will be increasing winds later Sunday into Sunday night. Finally, just in time for back-to-work, there will be much improvement on Monday with the return of sunshine and milder conditions.