Tim’s 2013 – 2014 DC Winter Forecast

Please Click HERE for Tim’s 2014 – 2015 DC, Baltimore, Philadelphia, New York City & Boston Winter Forecast

 

We are rapidly approaching winter and many want to know how much snow will fall across the D.C. Area.  I have seen predictions ranging from a “brutally cold winter” (Old Farmer’s Almanac) to a mild winter with very little snow. 

• Last year in the D.C. Region, snowfall varied greatly across short distances. Fredericksburg, Warrenton, Manassas and Leesburg received between 10 and 20 inches of snow with the Urban Heat Island of DC receiving less than 4″.  March was incredibly snowy across the southwestern suburbs/exurbs with nearly 11″ that month alone.  I remember friends calling me in D.C. with wet snow falling (but not sticking) and yet I was shoveling 8″ of snow off my driveway.  Let’s briefly take a look at conditions across the Equatorial Pacific to see the factors that can shed light on this year’s winter forecast.

 

• The Oceans play a huge role in our climate.  Two factors have not changed since last winter.  First, current Sea Surface Temperature (SSTs) anomalies depict neutral conditions (“La Nada”) continuing during the upcoming winter.  Second, the PDO (Pacific Decadal Oscillation) remains negative (in its cold phase).
  

 

• Bottom Line: Just like last winter, I don’t expect an active southern branch of the jet stream to be a major player.  I expect either a split jet stream or a strong northern branch to be dominant during the upcoming winter season. (The strong southern branch during the El Nino winter of 2009 – 2010 produced the moisture needed for very heavy snows across the D.C. Area.

Let’s look at specifics:

Latest forecast models show a high probability of neutral conditions (“La Nada”) continuing through March of 2014.

Winter 2013 – 2014 Analogs

In choosing my analog package for this upcoming winter forecast (December through February) I looked for the following:

• Neutral ENSO (La Nada) winters

• Followed by a wet spring and summer

• Occurring after back-to-back La Nina Winters
  

The analog packages of 1961, 1962, and 2008 matched up fairly well. It is impossible to get a winter forecast 100% right every single year, so it really comes down to probabilities.   A winter forecast is only as accurate as the analogs (historical years) that you choose. Last year, my winter forecast was accurate for most locations in the Virginia piedmont (Warrenton, Leesburg, Fredericksburg, Manassas, etc.) and northwestern Maryland (Frederick) while D.C. was a bust (thanks to the low level easterly flow off the warm Chesapeake that destroyed the temperature profile during the mid-march snow storm).

 Temperatures and Precipitation:

 

Winter 2013-2014 Highlights:

• New York, Philly, Baltimore and Washington (pink zone) will be situated in the battle zone between snow and ice this winter as the southeastern ridge and strong northern branch of the jet stream may play a role in keeping the average storm track off to our north and west this winter.  If this track verifies, mixed precipitation events as well as several snow events can be expected with near normal to below normal snowfall.
  

 

• I expect average snowfall across southern New England (Boston, Hartford, Providence) with above average snowfall in northern New England and the Midwest.

Based on the analog years I chose, how much snow could fall across the Washington D.C. Metropolitan Area during the upcoming winter season?

 

Average Snowfall in the Washington Region: