A powerful cold front will push through the Washington Area on Sunday evening. A Squall Line (strong line of thunderstorms with very heavy rain and gusty winds) will likely be accompanied with the passage of the cold front.
A backdoor cold front will slide through the Washington area on Sunday morning. A backdoor cold front is given the term “backdoor” because the cooler air mass moves from northeast to southwest, off of the cold, waters of the Atlantic Ocean. Typically cooler air masses arrive from the north and west and push south and eastward.
Check out the animation below of surface temperatures plummeting during the morning hours on Sunday. The Fredericksburg Area and lower-southern Maryland may be the only locations that can hold onto the warmth before the cold front slides through our area from the west on Sunday evening.
Heavy Snow is finally breaking out across the metropolitan Washington Area. My favorite forecast model (the European) lowered its accumulation output during the overnight run. Regardless, Winter Storm Warning criteria (5″ or more) is likely across the Metropolitan area today with snow… heavy at times, continuing through the afternoon before tapering off and ending later this evening.
The images below show the short-range high-resolution rapid refresh (HRRR) American models for how today may play out. Heaviest snow is indicated by the darkest shades of blue (time stamp is located on top-right hand corner of image):