Needed Rainfall on the Way

Record Snowfall Occurs in the DC Metro in January 2016

Ironically, today is the second anniversary of DC’s fourth largest snowstorm on record.  That’s because the Nation’s Capital is mired in a growing drought resulting from a sustained stretch of drier than average weather.  Washington, D.C. has a rainfall deficit of more than 16”, dating back to August 2015.  In that time, 24 of the last 29 months have been drier than average according to NOAA.  Washington, D.C. hasn’t had more than 0.37” of rain since November 7 and that stretch of 76 days is the sixth longest on record.

Since September 1, 2017, DC’s rainfall deficit is approaching 9” at National Airport (“DCA” is DC’s official weather reporting site).  Since the start of meteorological winter on December 1, the rainfall deficit is nearly 4”.  That followed July and August which were both significantly wetter than average in the Mid-Atlantic Region with a rainfall surplus of 7.07” (at DCA).  Consequently, the DC Metro Region had no drought conditions on Labor Day weekend.  However, given how dry the fall and first half of winter have been, the latest Drought Monitor Index shows moderate drought conditions extend from parts of central Pennsylvania to South Carolina.  

Since only 0.67” of rain has occurred this month in Washington, D.C., meaning there is quite a bit of ground to reach the January average rainfall total of 2.81”.  In the Nation’s Capital, 14 of the last 20 January’s have been drier than average.  It’s somewhat ironic that January 2016 was drier than average in the Nation’s Capital despite it being DC’s eighth snowiest January on record with a monthly total of 18.8”.  That’s because outside of DC’s record January 22-23, 2016, snow event that brought 17.8” of snow, January 2016 was an otherwise dry month.  It will take several months of above average precipitation to alleviate the moderate drought conditions across the Mid-Atlantic and put a dent in DC’s growing rainfall deficit.

Fortunately, it’s not the growing season in the Mid-Atlantic Region and the arid conditions don’t have the same impact they otherwise would.  However, the combination of extreme cold and below average rainfall from late December through the first half of January has led to a lot of frozen ground in the DC Metro Area.  The current milder temperatures are allowing some of the ice to melt from area waterways and this thaw will help minimize any rainwater runoff.  

Some rain is actually expected tonight and tomorrow morning.  The storm track is such that much of the East Coast will be in the warm sector.  That means the precipitation will be rain and not snow, sleet or freezing rain.  Although snow-lovers are disappointed by this turn of events, they should take comfort that several of DC’s largest snowstorms have occurred in the month of February, including President’s Day 1979, 1983 and 2003.  NOAA’s Climate Prediction Center currently expects an equal chance for above or below average February precipitation in the DC Metro Area.  All it takes, though, is the right set of events to come together just once to create a significant DC snowstorm.