CAMs appear to have the activity swing down through Loudoun County / WV Panhandle between now and 20z. Wouldn't surprise me to see the watch expanded further south a county or two.
CAMs putting all their money into a 3 - 6 hours period of rain after beginning around midnight - 2:00 am Tuesday. Been watering my lawn all day so maybe I'll tick off the rain gods.
EDIT: 18z NAM is ugly. Less than 0.3" rain south and east of I-81. If this were winter people would be screaming.
Yes 18z GFS is good. Let's hope this holds. Would really like to see 1.5" - 3" regionwide over 36 hours. Even the reservoirs in Baltimore, Howard, and Montgomery counties are getting low.