How Impressive have January’s Storms been in DC ?

The two major ingredients required for a significant snow event are a sufficient amount of cold air combined with the ideal track of a moisture-laden storm.  This weekend’s storm produced a lot of rain in the DC Metro Region since one of the two major ingredients were in place.  However, the storm track was such that Washingtonians were on the warm side of the storm.  This morning’s high temperature climbed to a March-like 56° before the cold air began to envelop the DC area.

The ideal storm track would take the center of low pressure along the Carolina coast far north as roughly the Norfolk, Virginia area.  That would allow the requisite area of cold Canadian high pressure to hold enough cold air in place as the moisture began to fall in the form of snow in the DC area.  If the area of low pressure tracks too far north or west, then the column of cold air erodes leading to a wintry mix or just rain.

Nearly three years have passed since DC residents experienced one of the largest winter storms on record.  The Blizzard of 2016 occurred on January 22-23, 2016 and had the ideal storm track to produce record snowfall in the Nation’s Capital.  This weekend’s storm couldn’t have been more different.  The way this storm tracked put the DC Metro Area in the warm sector of the storm, keeping the precipitation predominantly rain (in some areas well north and west of DC such as Frederick and Washington Counties in Maryland the rain began as some snow).

The rain began late yesterday afternoon and continued until early this morning in Washington, D.C.  The Nation’s Capital had 0.8” by the time it tapered off before dawn today.  That was DC’s largest January two-day rainfall total since January 2-3, 2017 (1.21”).  By comparison, there was plenty of cold air in place last weekend when DC had 10.2” of snow, or the liquid equivalent of 0.84”.  If there was adequate cold air in place for this weekend’s storm, then Washingtonians could have potentially had two 10” snowfalls within a week.

Only two months in the last 20 years have had 20”/+ snow (February 2003 and February 2010).  The last time DC residents experienced 20”/+ snow during the month of January was in 1996.  DC Area snow-lovers shouldn’t be discouraged that this weekend’s storm was predominantly rain.  Washington, D.C. has already had 12.7” of snow since November 1, 2018, which is more than 80% of DC’s seasonal snowfall average of 15.4”. 

NOAA expects below average temperatures to continue for the rest of January.  That’s in conjunction with a 33% probability for above average precipitation for the DC Metro Area.  The ideal circumstances for a significant snow event (5”/+) in the Nation’s Capital don’t come together often.  However, if they come together just once, then the entire winter season could finish snowier than average.