Not Mutually Exclusive?

Could someone please tell me how it is that where I live (and where I work) can be under a Winter Storm Watch and a Flood Watch at the same time? How are those 2 warnings not mutually exclusive? But sure enough, the NWS (National Weather Service) says the county where I live and work (among many other counties and principalities north and west of DC) are under both for the same timeframe. I can understand if the Flood Watch started after the winter stuff turned to rain, but it's for the time period when they are expecting us to be getting sleet and freezing rain. It seems to me we wouldn't have to worry about flooding until it warmed up and turned to rain...

ETA: It appears the Winter Storm Watch has been lifted, but I'm still under a Flood watch. Normal wet rain (as opposed to freezing rain) I can deal with.