If it didn’t feel like the usual May to you, we promise you weren’t losing it. The month was not remarkable in terms of major storms, but it felt downright cold at times. Even as the days became considerably longer, nights were still regularly falling into the 30s at times. Indeed, even some snow managed to accumulate across interior Pennsylvania through New Hampshire in mid-May!
While the first few days started off on a slightly warmer note, repeated cold fronts suppressed temperatures up to 20 degrees below normal through basically the first half of the month. Roughly half of the precipitation fell during this period as well, some of it as snow! The first weekend in particular, saw a blast of cold Canadian air on the 8th and 9th along with an intense system. This caused high temperatures to barely make it past the 40s and nightly lows to dip near or below freezing. Up to an inch of snow fell in the hills of northwest NJ into the Berkshires, with higher amounts in the Catskills and northeast PA. Meanwhile, Southern New Hampshire received coatings. Amazingly, a trace of snow was observed on the 9th across all NYC airports and as far east as Islip, NY. In fact, all NYC area airports had the same exact snowfall as February! Islip was an exception, as it officially had more snow than February.
High pressure during the second week of May gradually stepped temperatures up to near normal by the 15th. This coincided with a disturbance that finally helped push warmer air back into the region. The trailing cold front caused a squall line to develop ahead of it, and resulted in numerous reports of wind damage across Massachusetts and central New York (the Hudson Valley and Connecticut was spared the worst).
On May 17th, Tropical Storm Arthur formed off of the Southeast U.S. coast, well before the official start of hurricane season (June 1st). Arthur grazed eastern North Carolina with heavy rain and with even some tropical storm force wind gusts on the Outer Banks. Fortunately, the center remained offshore and quickly pushed out to sea, sparring the Northeast. The third week of the month saw another shot of chilly air that sent nighttime lows into the 40s. A disorganized system on the 23rd off the New Jersey shoreline kicked off a few showers and storms, one of which dropped over an inch of rain on Philadelphia. Much quieter and finally, more seasonable weather then closed out the last few days of May and meteorological spring.
The central pressure of Tropical Storm #Arthur is down to 993 hPa. The only Atlantic named storms with lower pressure in May in the past 40 years are: Beryl (992 hPa in 2012) and Alberto (990 hPa in 2018). pic.twitter.com/pkcYDoraA4— Philip Klotzbach (@philklotzbach) May 18, 2020
The massive cool stretch to start the month caused May’s average temperature to fall 2 degrees below normal in some spots. It also ended on the dry side by 2 to 3 inches. While these were not record breakers, the early cold shot caused a few daily low records to fall: JFK airport set a new record of 41 degrees on the 13th, breaking the fairly old record of 42 set in 1962. Bridgeport, CT also set a new record low at 37 degrees, breaking the old 1967 mark by a degree.