Drought Conditions Continue In the Mid-Atlantic

Although Washingtonians had their snowiest December (1.7”) since 2010, DC’s rainfall deficit continues to grow.  The first half of December was especially dry with only 0.29” of rain (including liquid equivalent of the snowfall) at National Airport through December 18.  Eight of the first 11 months of 2017 have been drier than average.

Now DC residents have an accrued rainfall deficit of 14.19” dating back to August 2015.  So far this year the rainfall deficit is only 3.61” largely because May, July and August were a combined 8.63” wetter than average.  On the other hand, September, October and November were a combined 6.42” drier than average.  These dry conditions have lingered into December.  According to a tweet from the Capital Climate blog: “Washington #DCA last 30 days are 3rd driest on record for Nov 19-Dec 18.”  

The December 14 update to the Drought Monitor Index shows moderate drought conditions have enveloped much of the DC-Baltimore corridor with abnormally dry conditions covering a larger portion of the Mid-Atlantic Region.  This contributes to an increased risk of brushfires, so it’s important to be careful when doing any outdoor burning of brush or yard debris.

Since this rainfall deficit has increased gradually to a double-digit amount, it’s important to make it up slowly.  If an area with a significant rainfall deficit gets too much precipitation quickly, the ground cannot absorb it.  There are several rain chances for the Mid-Atlantic Region this weekend into early next week.  However, NOAA’s longer term outlook for December, January and February is for near average precipitation.  Ordinarily, near average precipitation would be a good thing, but not when faced with an ongoing rainfall deficit and moderate drought conditions in places.

With 31.70” of rain during all of 2016, it was DC’s 11^th driest year on record dating back to 1871.  There has been only 33.37” of rain so far this year in the Nation’s Capital through December 18.  While not as dry as last year, 2017 will more than likely finish well below the annual average of 39.74” of rain.  Winter weather enthusiasts are pleased, though, since this December has had measurable snow for the first time since 2013.