Direct from The National Weather Service:

GUSTY NORTHEAST WINDS 20 TO 30 MPH WITH VISIBILITIES FREQUENTLY. FALLING BELOW ONE-QUARTER MILE DUE TO HEAVY SNOW WILL DEVELOP TONIGHT TO PRODUCE NEAR-BLIZZARD AND EXTREMELY HAZARDOUS WINTER WEATHER CONDITIONS TONIGHT THROUGH SATURDAY MORNING.

TRAVEL IS HIGHLY DISCOURAGED TONIGHT AND WILL BE VERY DANGEROUS. LOOKING BACK AT THE BIGGEST STORM OF RECORD FOR WASHINGTON DC... THE JANUARY 1922 KNICKERBOCKER STORM...28.0 INCHES OF SNOW WAS PRODUCED FROM 3.02 INCHES OF LIQUID WATER.

CURRENT FORECASTS FOR THIS EVENT HAVE TOTAL LIQUID FALLING FROM THIS STORM APPROACHING 3 INCHES...WHICH ACCORDINGLY WOULD CREATE A SNOWFALL THAT WILL RIVAL THE KNICKERBOCKER STORM TOTAL. GENERALLY ACROSS THE REGION...20 TO 30 INCHES OF SNOW WILL FALL BY SATURDAY EVENING.