The Clear Sky Clock graphic above uses models from Environment Canada. Here are direct links to the maps these are based on:
Cloud models for the next twelve hours from UCAR.
(Times are in Universal time [essentially GMT] so to get our local time, subtract 5 hours during standard time, 4 hours during daylight savings time.)
National Weather Service forecast:
Animated Doppler radar.
Satellite IR loop for BWI (or this non-java version).
Satellite visible loop for BWI (or non-java version).
Latest visible image.
Latest infrared image.
Radar from Mt. Holly, NJ.
Phillywx.com, comprehensive local weather commentary (especially good for focused forecasts of winter storms with more local nuance).