A boundary zone across the center part of the Pennsylvania became the focusing mechanism today for an organized line of severe thunderstorms to rally around, and this line is now slowly advancing to the south and east. Strong thunderstorms have already reached the region between Allentown, Reading and Harrisburg in Pennsylvania and, like last night, the line of storms will tend to weaken as it approaches the big cities in the I-95 corridor. However, there still exists the threat for storms to reach the DC metro region between about 9 PM and midnight with the greatest threat in the N and W suburbs. Any storm that does make it to this region can produce heavy rainfall as they are quite slow-moving, and there would likely be some vivid lightning and strong winds. Looking ahead, a shower or thunderstorm cannot be ruled out for Memorial Day, but the chances are probably a bit better for Tuesday. Meanwhile, Tropical Storm Beryl is spinning off the Southeast US coast and it will make a turn to the west over the next day or two and affect northern Florida and southern Georgia with some very heavy rain (6” or more) and strong winds.