Although most of June 2020 was rather dry and uneventful, there were two notable exceptions at the beginning and end of the month. One was a derecho (a long-lived windstorm) and the other was a pesky upper level low that brought localized flooding and hail to parts of New England.
June began with a nasty derecho that formed on the morning of the 3rd near Erie, PA, and raced into southern Pennsylvania and much of southern New Jersey. Over half a million residents lost power across both states, and sadly took the lives of four people. As is typically the hazard of derechos, powerful winds left a path of damage in its wake. The line peaked as it neared the Philadelphia metro area close to midday, and as it passed over the New Jersey coastline, Beach Haven recorded a 93 mph gust! PHL and PNE measured 61 mph and 67 mph gusts, respectively.
Yet another severe outbreak occurred in Massachusetts as a cold front approached on the 6th, interacting with a leftover boundary along the New England coastline. This produced a number of wind damage reports across the state, mostly thanks to downed trees and power lines. High pressure then kept the second week quiet as Tropical Storm Christobal’s remnants were carried into the Upper Midwest and eventually Canada. This morphed into a larger low system that eventually gave us a series of showers and thunderstorms on the 11th. The front was initially stubborn to clear the coast, but was ultimately pushed out by a reinforcing front on the 13th. This triggered a cooler and drier than normal period across the Northeast with low humidity and highs not really warming past the 80s anywhere. For northern spots like New England, this provided refreshingly cool nights in the 50s.
An upper level low that sat over the Southeast was temporarily squashed with this pattern, but it finally won the battle between the 17th and 19th. While this gradually pushed temperatures back above average, scattered storms (though most not severe) followed, which only gave a handful of folks rain. An exception was in eastern MA where thunderstorms were triggered by a stubborn upper level low on the 28th and 29th. These storms produced locally excessive rainfall, causing flash flooding, particularly in Norwood, MA. With cold air aloft from the upper low, some large hail was also reported, up to golf ball size! A more typical summertime pattern then took hold to close out of the remainder of the month. Temperatures ran a bit above the norm as they regularly warmed into the 80s and even 90s.
Pictures of flooding in downtown Norwood. Nahatan St RR underpass, Central St near Cottage St, East Hoyle St near Norwood Hospital, & Washington St near Dean St (where there was also a lot of debris). Avoid these areas! @NWSBoston pic.twitter.com/F5qsESkdhX— Joe DelliCarpini (@JoeDawg42) June 28, 2020
As alluded, temperatures ranged between 1.5 and 2.5 degrees above normal across much of the region. Precipitation was more of a hodge-podge as some cities missed out on heavier showers and storms. Washington, D.C. exceeded their average by around 2.50 inches while Baltimore, MD landed near their usual amount. Parts of New England suffered the worst, sometimes up to 3” deficits. As of June 23rd, the US Drought Monitor extended their “abnormally dry” conditions into part of northern Rhode Island through the southern Hudson Valley and even across all of Long Island. Northern Litchfield County in CT through New Hampshire and much of Maine are now classified in a moderate drought.
Northeast US Drought Monitor from June 23rd. Courtesy https://droughtmonitor.unl.edu/