National Weather Service issues Winter Storm Watch for Tuesday

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

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)

(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)

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

Also on Capital Weather Gang

D.C. area forecast: Some melting today as ice/rain departs; more snow Tuesday?