The NWS released a public information statement. They are in the process of compiling and analyzing rain gauge reports in the Washington-Baltimore region from Hurricane Irene and Ex-Tropical Storm Lee. There are a few stations (including Largo, MD and Forestville, MD) that recorded a total of ***24 INCHES*** of rainfall from these two storms. To put this in perspective, our region averages about 35"-40" of rain in any given year. Imagine receiving 2/3 of this in the space of a single week!
Additionally, stations in Northern Virginia accumulated rainfall at such an extreme rate that these locations have effectively just experienced a 500- to 1000- year storm event.
The hydrologic (land surface) response to these events was quite varied across the Mid Atlantic. These aspects are being studied by Professor Andrew Miller and colleagues in UMBC's Geography Department.