Area covered by Winter Storm Watch shaded in blue (National Weather Service)

The National Weather Service sees the potential for five or more inches of snow Tuesday and has issued a Winter Storm Watch for much of the D.C. region – southern Maryland is excluded. We think this watch may be a bit aggressive and that 5 or more inches of snow is a low probability (not out of the question). But we’ll have our complete analysis up – with our projected snowfall amounts – by around 2 p.m.

(Update- 11:20 a.m.: To clarify my comment above – I think the 5″+ assessment is aggressive, not because it’s impossible, but because it’s a “boom” (high-end) scenario – rather than the most likely scenario. Having said that, I don’t want to be overly critical of NWS as the storm will be coming in around rush hour and could have a high impact. It’s a borderline Winter Storm Watch situation, overall.)

In the mean time, here’s the National Weather Service’s watch statement, in full:

1009 AM EST MON DEC 9 2013

...WINTER STORM WATCH IN EFFECT FROM LATE TONIGHT THROUGH TUESDAY
AFTERNOON...

THE NATIONAL WEATHER SERVICE IN BALTIMORE MD/WASHINGTON HAS
ISSUED A WINTER STORM WATCH...WHICH IS IN EFFECT FROM LATE
TONIGHT THROUGH TUESDAY AFTERNOON.

* PRECIPITATION TYPE...POTENTIAL FOR HEAVY SNOW. THE PRECIPITATION
  MAY START AS A PERIOD OF SLEET...ESPECIALLY SOUTH OF INTERSTATE
  66 IN VIRGINIA...THE DISTRICT OF COLUMBIA...AND U.S. ROUTE 50 IN
  MARYLAND.

* ACCUMULATIONS...POTENTIAL FOR FIVE INCHES OR MORE OF SNOW.

* TIMING...NEAR DAWN TUESDAY THROUGH EARLY TUESDAY AFTERNOON...INCLUDING
  THE TUESDAY MORNING RUSH HOUR.

* TEMPERATURES...UPPER 20S AND LOWER 30S.

* WINDS...NORTH 5 TO 10 MPH.

* IMPACTS...HAZARDOUS TRAVEL CONDITIONS ARE PROBABLE DUE TO
  ACCUMULATING SNOW...WHICH WILL CAUSE ADVERSE TRAVELING
  CONDITIONS. THE SNOW WILL LIKELY IMPACT THE MORNING RUSH TUESDAY
  WITH THE POTENTIAL FOR ACCUMULATION RATES OF 1-2 INCHES PER HOUR
  FOR A TWO-TO-FOUR HOUR PERIOD FROM DAYBREAK TO MID-TO-LATE
  MORNING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.
CONTINUE TO MONITOR THE LATEST FORECASTS.

Here’s the National Weather Service’s snowfall map – from its office in Sterling, Va.:

(National Weather Service)

Interestingly, the NWS office in College Park suggests amounts over 4″ are a fairly low probability – just a 20-40 percent chance:

Probability of more than 4″ of snow Tuesday (National Weather Service)