Dropping 17.8 inches of snow in Washington, the original “Snowmageddon” of Feb. 5-6, 2010, tied for the fourth largest snowstorm in the city’s modern record, and it was one of three top-25 winter storms of the historic season.
Snowmageddon was a spectacle in its own right and came amid an onslaught of snowstorms that was hard to believe.
Washington’s snowiest 12 days on record
On Jan. 25, 2010, it was 68 degrees.
With over a month since the last major snowstorm, Snowpocalypse, the record-breaking December storm, people were wondering whether it was a one-and-done kind of winter. Then a powdery snow arrived Jan. 30, from a storm that was initially supposed to miss to the south, and 6.4 inches accumulated. Three more snowstorms would follow through Feb. 10, utterly transforming our region.
Just three days before “Snowmageddon,” on Feb. 2-3, a smaller storm dropped 3.3 inches of wet, clingy snow on the District. Then Snowmageddon dumped its 17.8 inches on Feb. 5-6.
But, we weren’t done. On Feb. 9-10, the blizzard dubbed “Snoverkill” unloaded another 10.8 inches, while unleashing howling winds.
In the 12 days ending Feb. 10, Washington picked up 38.3 inches of snow, surpassing the 34.2 inches over 12 days in 1899, the most previously observed over such a stretch. Many locations around the region received even more.
Washington Dulles International Airport, to the west, registered 50.2 inches. Baltimore posted 54.5 inches.
A few locations picked up over five feet of snow in this span.
The 12-day snowfall totals in Washington even exceeded historical amounts observed in cities to the north. New York’s Central Park has only seen a maximum of 29.7 inches over 12 days, and Providence only 30.2 inches. Before 2015′s snow bonanza, Boston’s peak 12-day total was pretty similar at 40.3 inches.
Snow stuck around for weeks
In February 2010, there were 21 days with measurable snow cover in Washington, the third most days on record in February.
The 30 days with snow cover across the whole winter ranked ninth most of all time.
The peak of 21 inches on the ground in the District on Feb. 11 was the eighth highest daily value on record for the city, only falling behind days in 1899, 1922 and 1979.
To the west at Dulles, where records began in 1963, the peak snow depth of 26 inches on Feb. 10 was the top mark at the time there, before later being surpassed by 28 inches in Snowzilla (2016).
The maximum snow depth of 34 inches at BWI set a record that still stands for Baltimore. Some spots north and west of the cities had more than four feet of snow on the ground by Feb. 11.
The onslaught of snow began in December
What made the stretch of snow around Snowmageddon so remarkable was that a historic storm had already hit the area earlier in the season.
The 15 inches that fell on Dec. 19 during Snowpocalypse ranked as the third most on record in a single day. The 16.4 inches that fell over the storm’s duration ranked as the most on record in December.
And even before Snowpocalypse, a coating of snow had fallen on Dec. 5.
An exceptional pattern for heavy snow
The winter of 2009-2010 offered a textbook pattern for Mid-Atlantic snowstorms. It featured a persistent high pressure zone over Greenland, sometimes referred to as the Greenland Block. This feature helped establish a jet stream pattern that dipped over the eastern United States, facilitating a supply of cold air while also slowing down the flow in the atmosphere, allowing storms to linger and dump prolific snowfall.
An index of the strength of the Greenland Block, known as the negative phase of the North Atlantic Oscillation, was record-setting in December, ranked 10th strongest in January and second strongest in February.
At the same time, the winter featured a moderate El Niño event that helped feed Pacific moisture across the southern United States and was ingested into storms coming up the East Coast.
Together, the strong Greenland Block and moderate El Niño were a snow-making machine in the Mid-Atlantic.
With a seasonal total more common of New England or the Upper Midwest, the 56.1 inches that fell across the winter ended up the most on record in Washington. It surpassed 54.4 inches in 1898-1899.
The mark was broken during the Snoverkill blizzard, which was another anomaly that winter. Sparked by a strong disturbance in the northern branch of the jet stream, such events often miss Washington and slam New England. But this one dug just far enough south to plaster Washington.
“We are living through some of the most extreme winter weather we’ll ever experience in the metro region this morning,” wrote CWG’s Jason Samenow as it happened. The region looked more like an alpine wonderland than the D.C. area.
While Washington’s 56.1 inches of snow that winter was impressive, totals in other parts of the region were truly jaw dropping. Baltimore received 77 inches, while Dulles posted 73.2 inches. A few of the big totals in the broader region included Gaithersburg at 80.7 inches, Herndon at 83 inches, and Leesburg at 88.6 inches.
Some spots in northern Maryland even topped 100 inches. The totals were a good 300 to 450 percent above normal regionwide. Ten years later, it still feels safe to say the winter of 2009-2010 was the snowmaker of a lifetime.
Jason Samenow contributed to this article.