DC’s Winter Without Snow

North America is approaching the midway point of the third and final month of meteorological winter.  Washingtonians have had 3.1” of snow since December 1, or only 20% of the seasonal average.  This follows the 2016-2017 winter season when only 3.4” of snow occurred in the Nation’s Capital.  

With a total of only 6.5” of snow since December 1, 2016, area snow lovers haven’t had much to get excited about.  NOAA expects above average temperatures in the Mid-Atlantic Region to continue over the next two weeks.  If this happens, then last winter and this winter would be the least snowiest in the Nation’s Capital since 2011-2012 (2.0”) and 2012-2013 (3.1”).  The difference, however, between then and now is that the DC Metro Area was not experiencing drought conditions.

For the three-year period from January 1, 2011 through December 31, 2013, Washington, D.C. had a rainfall surplus of 4.36”.  By comparison, DC has a rainfall deficit of 17.03” for the period from August 1, 2015 through January 31, 2018.  The rainfall so far this month has been especially beneficial following the exceptionally dry five month period from September 2017 through January 2018 (when DC had a rainfall deficit of more than 9”).

February is historically the snowiest month of the year in Washington, D.C.  Nearly half of DC’s largest snowstorms on record occurred in February.  However, 14 of the last 20 February’s have been drier than average with less snow.

Because colder air has a smaller capacity to hold water vapor, snow that falls with a temperature of say 15° contains less liquid water than snow that occurs at 30°.  This had a practical effect in Washington, D.C. as February’s in 2006, 2007 and 2015 were each colder and snowier than average.  However, these three months also finished with below average liquid precipitation (rain and melted snow) at National Airport.  

Last season’s and this season’s lack of snow stands out because it has been part of a larger overall dry pattern in the Mid-Atlantic Region.  The years of 2016 and 2017 finished with a total of only 67.3” of rain in Washington, D.C. making that the driest consecutive two-year stretch since 2001-2002 (64.28”).  According to the National Weather Service, Washington, D.C. averages 79.48” of rain in a two-year stretch.  Given the dry conditions, DC Area residents should put aside any disappointment over the lack of snow and be pleased with the beneficial rainfall that’s occurred this month.