Above: Snow accumulates on grass and trees in Syracuse, New York, on Saturday, May 9, 2020. At one point early Saturday afternoon, Syracuse reported heavy snow with a temperature of 32°F. The day’s official snowfall of 0.3” fell short of the record for the date of 1.0” set in 1977, but the low of 30°F and the high of 39°F were both the coldest ever recorded on May 9. The high was the city’s second latest high in the 30s in Syracuse records going back to 1902. (Timothy Ferris via AP)
It’s not every mid-May afternoon when temperatures above 65°F are virtually nonexistent from the central and northern Rockies all the way to the U.S. East Coast. That was the case on Monday, as a freight train of chilly air continued chugging from central Canada into the Plains, Midwest, and Northeast. A reinforcing shot arrived on Monday, ensuring that it would be later in the week before truly springlike air could make its way back north.
The cold blast that intensified Friday into Saturday led to a broad swath (by May standards) of light snowfall from the lake-effect belts of the Great Lakes and the highest southern Appalachians across much of Pennsylvania, New York and New England. Most of the accumulations were limited to grassy areas, but a few pockets of heavier snow (on the order of 3 to 6 inches) developed from the Catskills and Adirondacks of New York across northern New England, with as much as 14 inches falling in eastern Maine.
Pittsburgh reported a trace of snow both Friday and Saturday, the first consecutive May days of snow there in 97 years. And, as noted by National Weather Service-Charleston, West Virginia, meteorologist Nick Webb, Snowshoe, West Virginia, set its record 24-hour May snowfall in 45 years of records. Elkins, West Virginia, also set a new 24-hour May snow record, picking up 1.5 inches of snow Friday.
Even New York City got in on the snowy act. In the predawn hours Saturday, rain briefly changed to wet snow at all six of the metropolitan area’s official reporting stations, making it a tie as the city's record-latest spring snow. A trace of snow and a new record-low temperature for the date (34°F) will go into the Central Park record books, which extend back to 1869. (Other traces of frozen precipitation later in the spring and summer were associated with hail rather than snow.) The latest measurable snowfall at Central Park is 0.5 inches on April 29, 1874; the latest in modern times is 0.8” on April 19, 1983.
On Saturday afternoon, as the surface atmosphere struggled to warm beneath frigid air aloft, widespread showers of graupel (soft ice pellets) formed across the Northeast, including the Interstate 95 corridor. Another round of graupel—in some cases apparently mixed with hail—swept across the Northeast on Monday, with some thunder and lightning in the mix.
It was not only the coldest Mother’s Day weekend of the century for millions, but in some places it was the coldest temperature ever recorded so late in the spring. Even more impressive, several sites with long periods of record (PORs), including two state capitols, had their coldest reading for any day in May. All-time record lows for the month (all set on Saturday unless otherwise noted) include:
Binghamton, NY: 24°F (old record 25°F on multiple days; POR 1951–)
Fort Wayne, IN: 23°F (old record 27°F on multiple days; POR 1897–)
Harrisburg, PA: 30°F on Sunday (old record 31°F on May 11, 1966; POR 1888–)
Indianapolis, IN: 27°F (old record 28°F from May 10, 1966; POR 1871–)
Jackson, KY: 30°F (old record 32°F on multiple days; POR 1981–)
Kokomo, IN: 26°F, repeated on Sunday (old record 27°F from May 7, 1974; POR 1901–)
London, KY: 28°F (tied May 2, 1963; POR 1954–)
New York/LaGuardia Airport, NY: 36°F (old record 37°F from May 8, 1947; POR 1939–)
New York/JFK Airport, NY: 34°F (tied May 10, 1966; POR 1948–)
State College, PA: 27°F (tied May 10, 1966; POR 1893–)
Broadcast meteorologist Ben Gelber (WCMH/Columbus), author of The Pennsylvania Weather Book, said in an email: "Unheard-of May wind chill readings plunged to 8°F degrees at Mt. Pocono and 21°F in Stroudsburg at sunrise on Saturday. Snow flurries were seen Friday night and again Saturday afternoon between breaks of sun, in the mountains and the lower elevations, whipped by a winter-like northwesterly wind." Gelber added that the Saturday high of 37°F at Mt. Pocono tied May 5, 1917, for the lowest daily maximum in May.
The cold air was driven southward by a lobe of upper-level energy a few miles above the surface. Conditions at ground level in northern Canada testified to the strength of the pattern at the source region of the cold air. A number of stations in the Northwest Territories broke their all-time surface high pressure records, and in some cases the new values are 10 mb or more higher than the old records, as mapped by David Roth (NOAA/NWS Weather Prediction Center).
A few more record lows and record-low highs could fall by the wayside from late Monday into Tuesday, but a stout warming trend will get under way by midweek. By Friday, well above average temperatures are forecast from southern New England to the mid-Atlantic. Highs should range from the mid-70s Fahrenheit in Boston to around 80 in New York City, the lower 80s in Philadelphia and the mid-80s in Washington, D.C.
If Philly reaches 80°F on Friday, it will be its first 80-degree day of the year, just five days shy of the latest first occurrence of 80: May 20, 1984. In an average year, Philadelphia records a high of 80°F by April 16, but it has yet to be warmer than 79°F this year.
Brian Donegan contributed to this post.
