Summer Storms Along Cold Front

The Weather Prediction Center Surface Analysis from August 13, 2013: 
http://www.hpc.ncep.noaa.gov/html/sfc2.shtml

D.C is squeezed between two strong cold fronts in the above surface analysis from the Weather Prediction Center as of 21Z August 13, 2013. Severe storms rumbled through the D.C. area around 0Z this evening a couple hours after the surface analysis snapshot. The most intense activity lasted less than an hour around D.C., but delivered brief heavy downpours. The meteorology of cold fronts is notorious for localized short duration intense precipitation. The rapid advancement of cold dense air along the front buoyantly forces warm air upward over the denser cold air mass to produce clouds along the thermal boundary. Precipitation falls ahead of the advancing cold front until the colder and drier air mass behind the front stabilizes atmospheric conditions.

Diagram source from the University of Illinois:
http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/af/frnts/home.rxml