Could This Be the End of Winter ?

February 17 Snowfall in Germantown, Maryland  (Courtesy: Susan Granzow)

DC Area residents had a fleeting taste of winter yesterday with snow up to a few inches north and west of downtown.  However, temperatures are going to reach the 50° plateau today for much of the DC-Baltimore corridor and the snow will quickly fade from memory. 

February 2018 has featured beneficial rainfall in the Nation’s Capital.  Temperatures have also been significantly warmer than average.  This month has been 3.4° warmer than average, with 4.38” of rain through February 17.  That’s greater than the 2.62” of rain that DC averages during the entire month of February.  However, Washington, D.C. has had only 3.3” of snow since December 1, 2017, which ties for ninth lowest total on record.  The annual average is 15.4” of snow in the Nation’s Capital.

Despite the lack of snowfall the last two winters, there have been some extended periods of colder than average temperatures in Washington, D.C.  High temperatures remained in the 20s from January 7 – 9, 2017, and was the coldest stretch of last winter.  Meanwhile, temperatures remained at or below freezing at National Airport on 9 out of 11 days from December 27, 2017 to January 7, 2018.  That helped make December 2017 DC’s first colder than average December since 2010.  Unfortunately for snow lovers, the storm track was not favorable to coincide with the stretch of frigid weather in the Nation’s Capital.

Mid-Atlantic residents have had historic snow events over Presidents’ Day weekend on several occasions (1979, 1983, and 2003).  It snowed on Presidents’ Day in the Nation’s Capital as recently as 2015.  By comparison, February 2017 was DC’s warmest February on record and the rest of this month is poised to be significantly warmer than average.  Although snow is possible in March, it becomes increasingly difficult for accumulating snow to occur.  This can be attributed to the higher sun angle and warmer temperatures that coincide with the start of meteorological spring on March 1.

Given the scant amount of snowfall the last two winters, DC Area snow lovers should not give up as March approaches.  Snowfall records in the Nation’s Capital date back to January 1888.  During that time, March has been the snowiest month of the winter 23 times – with the most recent being just last year.  That said, temperatures could approach record levels with highs in the mid-70s this Tuesday and Wednesday.  No below freezing temperatures are expected in Washington, D.C. all week.

Record High / Record High Low Temperatures

February 20

DCA: 76° (1930) / 59° (1939)
IAD: 70° (1971) / 46° (1981)
BWI: 76° (1930) / 57° (1939)

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February 21

DCA: 75° (1953) / 51° (1954)
IAD: 70° (1997) / 45° (1981)
BWI: 74° (1930) / 49° (1981)

February’s Halfway Point

February is the third and final month of meteorological winter.  Now that February’s midway point has arrived, we have a more accurate idea of how the 2017-2018 winter will finish compared to average.

December and January were both exceptionally dry months in the DC Metro area, with significantly less rain and snow than average.  Only 1.44” of rain fell in Washington, D.C. from December 1, 2017 through January 31, 2018.  That’s 4.42” less rain than average and nearly 8” less snow than average for the two-month period.  In addition, the 1.44” of combined rain and liquid snow equivalent was DC’s driest December-January since December 1980 and January 1981 (1.03”).  

The exceptionally dry end of 2017 and start to 2018 contributed to moderate to severe drought conditions across the Mid-Atlantic Region.  Fortunately, February has gotten off to a wetter than average start, with a total of 3.9” of rain at National Airport as of February 14.  There have been three days with more than an inch of rain in the Nation’s Capital this month that have led to some improvement in the DC Area’s drought conditions.  The last time an inch or more of rain occurred three times in a calendar month in Washington, D.C. was in June 2015.

However, DC hasn’t had any measurable snow since January 17.  NOAA’s Climate Prediction Center indicates that generally warmer than average conditions are expected to continue for the rest of the month.  If February 2018 finishes without any measurable snowfall in the Nation’s Capital, then that would be the first time since 2004.  That would also make this winter’s seasonal snow total only 3.1”, or roughly 20% of DC’s annual average of 15.4”.  It would also be DC’s second consecutive winter with well below average snowfall. 

Aside from the dry weather, the dominant DC Area weather story this winter was the exceptional cold from December 27 through January 7.  High temperatures in Washington, D.C. remained at or below freezing on 9 of those 11 days.  DC’s high temperature of 23° on December 31, 2017 was the coldest December high temperature since 1989.

In contrast, temperatures over the first half of February have been almost as mild as they have been wet.  Through February 14, DC’s average temperature (combining daily high and low temperatures) was 1.5° warmer than average.  However, that pales in comparison to February 2017, which was DC’s warmest on record and finished more than 8° warmer than average.  Still, February 2018 is likely to become DC’s third consecutive warmer than average February.

Weather Quiz

What city has had the most snow since December 1, 2017 ?

A.  Atlanta, GA

 

B.  Norfolk, VA

 

C.  Washington, D.C.

 

D.  Birmingham, Alabama

 

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Answer to January 30 Weather Quiz question.

 

True.  January 2018 finished as DC’s fourth driest on record with only 0.94” of rain.

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.