The evening may not be as tumultuous weatherwise as previously anticipated. The track of the storm has trended a bit to the east, so it's the counties along the Bay (Anne Arundel, Calvert, St. St. Mary's County) and on the Delmarva peninsula that will catch the brunt of the storm.
Around town and the immediate suburbs (PG, Fairfax and Montgomery), the steady rain will end from west (9pm) to east (11pm). The winds may pick up for a time in DC and point east between about 7 and 10pm. But power outages and severe weather do not appear likely in the immediate DC area.
Tomorrow should be a very nice day, with partly cloudy skies and a high temperature in the low 80s.