The February 5–6, 2010, North American blizzard, commonly referred to as Snowmageddon, was a blizzard that had major and widespread impact in the Northeastern United States. The storm's center tracked from Baja California Sur on February 2, 2010, to the east coast on February 6, 2010, before heading east out into the Atlantic. Effects were felt to the north and west of this track in northern Mexico, California, and the southwestern, midwestern, southeastern, and most notably Mid-Atlantic states. Severe weather, including extensive flooding and landslides in Mexico, and historic snowfall totals in every one of the Mid-Atlantic states, brought deaths to Mexico, New Mexico, Virginia, Pennsylvania, and Maryland.
Most crippling was the widespread 20 to 35 in (50 to 90 cm) of snow accumulated across southern Pennsylvania, the Eastern Panhandle of West Virginia, northern Virginia, Washington, D.C., Maryland, Delaware, and South Jersey, bringing air and interstate highway travel to a halt. Rail service south and west of Washington, D.C., was suspended, and rail travel between D.C. and Boston was available with limited service. Blizzard conditions were reported in a relatively small area of Maryland, but near-blizzard conditions occurred across much of the Mid-Atlantic region. The nor'easter reached a minimum central pressure of 976 mb while out at sea on February 7.
This event was the second of four nor'easters during the 2009–2010 winter that brought heavy snow to enough of the Northeast's population to be numerically recognized by NOAA's NESIS intensity rating. The first and third of these systems, the December 2009 Northeastern U.S. blizzard and the February 9–10, 2010 North American blizzard, respectively, combined with this event to bring the snowiest winter on record to much of the Mid-Atlantic. Additionally, this event was the second of three major Mid-Atlantic snowstorms that occurred over a 12-day period; each subsequent storm focused its heaviest snow slightly farther north: the January 30, 2010, storm (not recognized by NESIS) dropped more than a foot of snow across Virginia and the lower Chesapeake Bay region, while the February 9–10, 2010 North American blizzard bulls-eyed the Maryland-Pennsylvania border with as much as 38.3 inches.
Meteorological history
The main storm system originated in the Pacific Ocean, bringing heavy rain and mountain snow to California and Arizona on February 2. The storm center moved east through northern Mexico on February 3. The system produced over one foot of snowfall in the higher elevations and the eastern plains of New Mexico, shutting down major highways including Interstate 40 east of Albuquerque for several hours on February 3. The storm's center then advanced across Texas to the Louisiana Gulf Coast on February 4, while dropping rain and snow in Oklahoma and northern Texas, and severe thunderstorms further south. Meanwhile, a second, more-northern disturbance tracked from the central Rockies to the lower Missouri River Valley, bringing light snow showers to Montana, the Dakotas, parts of Minnesota, Wisconsin, Iowa, and Illinois.
On February 5, the two systems phased together, resulting in a band of heavy snow across Illinois, Indiana, Ohio, and Pennsylvania. That evening, the northern system's energy was absorbed into the main southern circulation, promoting fast intensification. Heavy snow subsequently developed over the Mid-Atlantic states as the storm's center tracked across North Carolina towards the Atlantic Coast.
An antecedent and nearly-stationary upper-level ridge over the Maritime Provinces of Canada served to block the storm system from following the traditional northeast track into New England. Instead, during the AM hours of February 6th, the storm center slowed its northeasterly movement as it continued to deepen east of Virginia Beach, before it eventually was forced eastward. The blocking pattern was reflected on the storm's snowfall map by a sharp northern gradient in northern New Jersey and by the axis of heaviest snow running WNW-ESE through Maryland and Delaware (opposed to the SW-NE pattern found from most nor'easters). Only moderate accumulations reached the southern suburbs of New York City, with no more than light snow falling in the city itself. Upstate New York and New England were spared from this system, receiving little more than isolated snow flurries in southern sections. Easterly winds and onshore flow contributed to light snow accumulations of less than one inch in Boston, Cape Cod, and parts of coastal Rhode Island.
According to the blog of Weather Channel senior meteorologist Stu Ostro, the storm formed from "Miller Type B" cyclogenesis: a storm centered over the Ohio river runs into a blocking ridge and redevelops along the Carolina coast. (This differed from the North American blizzard of 2009, of "Miller Type A" cyclogenesis where a storm center develops over the eastern Gulf of Mexico and strengthens while tracking north to a latitude of greater temperature contrast.) This storm was carrying an enormous amount of moisture drawn from both the Gulf of Mexico (as seen on February 3 satellite imagery over Mexico), and from the Atlantic (as seen in radar imagery from early on February 5). Ostro characterized the storm as having "strong dynamics" and expected the snowfall to be of long duration, typically leading to large accumulations.
Nicknames Media reports emphasized the magnitude of the storm, giving rise to many nicknames for it including Snowmageddon and Snowpocalypse.
The Capital Weather Gang blog on The Washington Post website ran an online poll on February 4, 2010, asking for reader feedback prior to the blizzard, and several blogs, including the paper's own blog, followed that up by using either "Snowmageddon" and/or "Snowpocalypse" during the following days, before, during, and after the storm hit.
The Washington Post also popularized other portmanteaus, including "snOMG" (from OMG) and "kaisersnoze" (from Keyser Soze), in response to the February snowstorms.
During the evening preceding the first blizzard hitting Washington, D.C., most of the United States federal government closed, and press coverage continued to characterize the storm using either "Snowmageddon", "Snowpocalypse", or both. The phrase was later popularized by the President of the United States, Barack Obama, on February 8, 2010, who used the term while speaking at the Democratic National Committee's meeting.
Snowfall +StateGreatest Measurement By StateCountyAmount (in)MD2 miles WSW of ElkridgeHoward38.3VA1 mile ENE of HowellsvilleWarren37WV2 miles WNW of LehewHampshire34PAUpper StrasburgFranklin31NJNational ParkGloucester28.5DCDalecarlia ReservoirNorthwest28.0DEWilmingtonNew Castle26.5
An unofficial storm total snowfall observation of 39.0" was made from Riverwood, MD (in Frederick County) on CoCoRaHS, and later referenced in the February 2010 Washington Baltimore Climate Review (not published electronically). However NOAA/NWS products list the 38.3" total at 2WSW Elkridge, MD as the "storm's greatest (so far)".
+StateOfficial Observation SitesCountyAmount (in)MDFrostburgAllegany36.0VAWashington Dulles International AirportLoudoun32.9PASomersetSomerset30MD2 miles W of RockvilleMontgomery29.2PAPhiladelphia International AirportPhiladelphia28.5VAViennaFairfax26DENew Castle AirportNew Castle25.8MDBaltimore/Washington International AirportAnne Arundel25NJCape MayCape May21.8PAPittsburgh International AirportAllegheny21.1NJHammontonAtlantic21NJAtlantic City International AirportAtlantic18.2PAHarrisburg International AirportDauphin18VARonald Reagan Washington National AirportArlington17.8PAState CollegeCentre14PALehigh Valley International AirportLehigh7.7NY[Throughout Staten Island]Richmond1–5NYCentral ParkNew YorkTrace
Pittsburgh with 21.1", was the first major city to experience the storm's heavier snowfall, separating sub-20" amounts over Indiana and Ohio from 20 to 35" readings found in the Laurel Highlands and east. This was Pittsburgh's 4th greatest snow event since records began in 1871. Areas south of Pittsburgh received up to 26" of snowfall. Although initially forecast to bring only 4–8" of snow to the area, the storm's track farther to the north lead to the explosive accumulations. The National Weather Service in Pittsburgh office recorded 7" of snow over 700P-1159P February 5 and 5.3" over 300A-600A on February 6.
The swath of heaviest snowfall then crossed the Appalachians and squeezed between Washington, D.C., and Baltimore. The District of Columbia's totals were generally near 20", ranging from 18 to 28". Baltimore City's totals were around 25", ranging from 21 to 28". Dulles
International Airport's 32.9" set all-time records (since 1962) for most 2-day and 3-day snowfall, shattering the old records from the Blizzard of 1996 of 23.2" and 24.6", respectively. Dulles received 17.5" on February 6, however, making the day's total only the 3rd greatest 24-hour snowfall amount. Baltimore Washington International Airport, despite being near numerous 30"+ reports, saw a relatively tame 25". This 2-day total was 2nd greatest (since 1892), behind 26.3" from the 1922 Knickerbocker Storm. Reagan National Airport's 17.8" was one of the metro region's lowest, but still ranked as Washington's 4th greatest (since 1871) in both 2-day and 3-day totals.
Additional local reports from Maryland include: Edgemere, 35.4"; Clarksville, 34.9"; Crofton, 34.0"; Columbia, 33.8"; Laurel, 32.9"; Pasadena, 31.0"; Dundalk, 30.5"; Ellicott City, 30.2"; Frederick, 29.0"; Olney, 28.0"; Germantown, 27.4"; and Catonsville, 22.9".
Philadelphia's 28.5" ranked the storm as the city's 2nd greatest on record (since 1872), falling not far behind the Blizzard of 1996's 30.7". This made for Philadelphia's first winter with multiple 20"+ storms, following the 23.2" from the North American blizzard of 2009. Wilmington, DE's 25.8" was their greatest storm total of all-time (since 1894), passing the 1996 storm's 22". In February 2021, the National Centers for Environmental Information announced that the official Delaware snow depth record was established near Greenwood on February 7, 2010, after the February 5–6, 2010 North American blizzard resulted in a measurement of 28 inches. The record was measured at the Greenwood 2.9 SE station of the Community Collaborative Rain, Hail and Snow Network.
+StateCounty/City Averaging > 24"RangeGreatest Report(in)VAClarke31–33"Berryville32MDAllegany26–36"Frostburg36MDHoward25–38"2 miles WSW of Elkridge38.3VAFrederick/Winchester25–32"3 miles WSW of Armel31.5VALoudoun22–35"Leesburg34MDFrederick24–34"Riverwood?37–39?MDMontgomery21–34"West Laurel33.5MDBaltimore County22–32"Randallstown32VAFauquier16–33"Marshall32MDAnne Arundel18–34"Crofton34MDCarroll22–29"Eldersburg29.1MDBaltimore City21–28"Pimlico28MDHarford23–29"Norrisville29MDWashington22–32"3 miles ENE of Hancock31.5VAPrince William/Manassas22–32"5 miles NNE of Antioch32 South Jersey saw as much as 29" of snow; Vineland reported 19.8". In South Central Pennsylvania, the areas of Harrisburg, Lancaster and York reported receiving over 18" of snow.
Many counties, including the rural areas across the Appalachian mountains and Delmarva averaged over two feet of snow.
The storm was well spotted by the winter storm reconnaissance (WSR) program at National Center of Environmental Predictions (NCEP). Two aircraft missions were deployed over the Pacific regions on February 1, 2010. Accurate measurement in the cloudy regions were taken, the data were assimilated by the global forecast models in different numerical forecast prediction centers.
The WSR program is led by Dr. Yucheng Song from the National Centers for Environmental Prediction (NCEP).
Source: CoCoRaHS
Source: NWS Washington/Baltimore Public Information Statement & Maps
Source: NWS Philadelphia/Mt. Holly Public Information Statement & Map