An upper level trough will continue to bring opportunities for drenching showers on Monday before some brief drying on Tuesday. Another front will move through Wednesday and behind that, a fall-like airmass will move into the northern tier of the country.
A relatively unstable environment is across the areas underneath upper trough which has plagued the mid-Atlantic for the last few days. The remnant upper low that was T.S. Lee will slowly work eastward into tomorrow, leading to more chances for showers and thunderstorms. Shortwave expected to fire convection in the high terrain to the west and push it over the D.C./Baltimore metro areas by this evening. A lot of the activity will diminish by midnight, but not before locally heavy downpours affect the area. Hence with the recent rains, that’s why a flash flood watch is in effect.
Upper trough will move through the area finally on Monday, but not before enough of a trigger for a spotty afternoon/evening t-storm. Beyond that, drier air moves into the region briefly for Tuesday. Southwest winds ahead of an approaching cold front will send warm and humid air across the area Tuesday into Wednesday. Dewpoints not all that impressive but with temperatures in the mid-upper 80s and dewpoints in the lower 60s, it’ll feet rather warm outside. Cold front moves through the region on Wednesday, but very limited moisture and upper support will cause any shower/t-storm activity to be rather spotty and confined to the afternoon hours on Wednesday.
Now comes the fall-like fun part of the forecast. An expansive area of high pressure at the surface builds in behind this cold front and sends a dramatically colder airmass into the area for the latter part of the week and the weekend. Dewpoints will fall into the 40s on Thursday and temperatures will struggle to reach the lower 70s despite a good deal of sunshine. Temperatures Friday and Saturday may not reach the 70 degree mark.