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Northeast Overview - May 2013

Monthly Summary

PLEASE NOTE: Data is preliminary and subject to change.

With an average temperature of 57.7 degrees F (14.3 degrees C), the Northeast was 1.3 degrees F (0.7 degrees C) above normal for May. New Jersey was the lone cool state at -0.1 degrees F (-0.1 degrees C). Departures for the rest of the states ranged from +0.1 degrees F (+0.1 degrees C) in Maryland to +2.4 degrees F (+1.3 degrees C) in Vermont. As for spring, the Northeast was slightly above normal. The average temperature of 45.8 degrees F (7.7 degrees C) was 0.1 degrees F (0.1 degrees C) above average. Seven states ended the season cooler than normal. Departures for those states ranged from -1.3 degrees F (-0.7 degrees C) in West Virginia and Maryland to -0.1 degrees F (-0.1 degrees C) in New York. For the five warm states, departures ranged from +0.1 degrees F (+0.1 degrees C) in Rhode Island to +1.6 degrees F (+0.9 degrees C) in Maine.

After four dry months in a row, the Northeast was slightly wetter than normal in May. The region received 4.09 inches (103.89 mm) of precipitation, 102 percent of normal. The states were split with six wetter than normal and six drier. Both Maine (149 percent of normal) and Vermont (140 percent of normal) ranked this May as their 12th wettest since 1895. New Hampshire, with 123 percent of normal, ranked the month as their 17th wettest May while Massachusetts, with 119 percent of normal, ranked it as their 20th wettest. New York's departure was 108 percent of normal and Connecticut's was 102 percent of normal. For the dry states departures ranged from 64 percent of normal in Delaware to 94 percent of normal in Rhode Island and New Jersey. Receiving 9.24 inches (234.70 mm), 83 percent of normal, the Northeast was below normal for spring precipitation. Despite a wet May in some states, all states ended spring drier than normal. Rhode Island was the driest state at 59 percent of normal, making it their 17th driest spring in 119 years. Connecticut, with 62 percent of normal precipitation, had their 20th driest spring on record. Departures for the rest of the states ranged from 74 percent of normal in Pennsylvania to 99 percent of normal in Vermont.

At the beginning of May a continuing lack of precipitation caused most of New England to be under abnormally dry (D0) or moderate drought (D1) conditions according to the U.S. Drought Monitor. Rains during the second half of the month helped ease dryness, but areas of D0 and D1 remained. Though D1 conditions eased, abnormal dryness lingered in parts of New York. At the start of the month around two-thirds of Pennsylvania was abnormally dry, but improving conditions lowered that to one-fourth by month's end. Despite improvement in other parts of Pennsylvania, conditions deteriorated to D1 in the southwest corner. Much of West Virginia was under abnormally dry or moderate drought conditions at the start of the month and although conditions improved slightly, areas of D0 and D1 remained. In New Jersey and western Maryland, dry conditions were eased.

Severe storms throughout May produced eight tornadoes in the Northeast: an EF-0 in Massachusetts on the 9th; three EF-1s and an EF-0 in Pennsylvania on the 28th; and two EF-1s and a mile-wide (1.6 km) EF-2 in New York on the 29th. The Pennsylvania tornadoes downed hundreds of trees while the EF-2 tornado in New York tore roofs off buildings and toppled high-tension power line towers. Several funnel clouds were also spotted throughout the month. Additionally, severe storms produced damaging straight-line winds, hail up to 2.5 inches (6.4 cm) in diameter, and flash flooding. One of the hardest hit areas for flash flooding was Chittenden County, Vermont, which received up to 7 inches (177.8 mm) of rain during the week of the 19th through the 24th. Flash flooding washed out roads and culverts, damaged bridges, and caused road closures. Located on the border of the county, Mount Mansfield set a record (and tied the New England record) for most consecutive days with an inch (2.5 cm) of precipitation with five such days from the 22nd through the 26th. Also located in Chittenden County, Burlington set a new precipitation record for May with 8.74 inches (222 mm). The old record was 8.67 inches (220.22 mm) set in 2011. Cold air behind the flood-inducing system allowed some higher elevations of New York, Vermont, and New Hampshire to see snow the weekend before Memorial Day. Mount Mansfield accrued 13.2 inches (33.5 cm) from the 25th to the 26th, making it the latest in the season that the peak has received a foot (30.5 cm) of snow, while Whiteface Mountain in upstate New York accumulated 36 inches (91.4 cm) at its peak.