Trouble for the Potomac?

The Isaac storm track will probably turn abruptly to the Northeast when it hits Alabama; and that means it could travel straight up the South Branch, North Branch, Cacapon and Shenandoah watersheds.  That could provide anywhere from 3 to 6 inches of rain (or more if it slows or stalls) in each, as all three travel in that same direction.

Check for updates at
http://www.nhc.noaa.gov/refresh/graphics_at4+shtml/205536.shtml?gm_track?large#contents