I'm not an expert either but I've noticed it watching storms over the years as well, the Potomac seems to either inhibit or enhance the storms we get, I'm sure there's also the usual "sea breeze" attributes at play. I was too young during the La Plata 2002 event to understand it, but I've read that it intensified substantially over the water before hitting La Plata.
That storm packed a punch yesterday, I saw that most of it ended up around St. Leonard but there was some decent velocities on radar on the Southern end that ended up over Calvert, little to no precip, seemed like a dry microburst. Sky looked pretty wild too.