An area of low pressure continues to move into the Great Lakes region today and an associated frontal boundary will bring the possibility of heavy rain through Tuesday. Showers will begin Monday evening, rather light in nature, and will continue to overspread the D.C. area overnight.Surface map for Monday Evening
The Tuesday morning commute may be a wet one, but the heaviest rainfall is expected to fall Tuesday afternoon and evening. A few embedded thunderstorms will be possible, and some locations may see the potential of 1 to 2 inches of rain with isolated higher amounts.RPM Precipitation Forecast
Our in-house RPM model shows the potential for much of the D.C. area to be closer to the 0.5" to 1" range, with isolated spots mainly north and west of D.C. with the higher amounts. This is in line with other modeling as well as the excessive rainfall discussion, which is pegging the state of Pennsylvania with the potential for the heaviest rainfall.
While ponding on the roadways will be possible, flooding doesn't appear to be a big threat at the moment. However, if some of the heavier showers and storms begin training over the same locations, some localized flash flooding may be possible, especially by the afternoon and evening hours on Tuesday.
Rain should wrap up for the most part overnight Tuesday into Wednesday morning. Drier air will filter back into the area Wednesday afternoon and at this point, conditions look about perfect Thursday through Saturday with plenty of sunshine and comfortable temperatures in the lower 80s.