It seems geography, currents, and wind patterns help make the DC/Chesapeake Bay/Delmarva peninsula area a hurricane dead zone.
Possibly the large outgushing of hot air eminating from the general vicinity of Capitol Hill creates a high pressure barrier that deflects the oncoming hurricaines. That's my theory anyway.
Saw one of these at a science center on Lake Champlain in Burlington, VT. It was huge and once you were done terraforming you could make it rain and see rivers and lakes form.