August 2021: Flooding Rainfall Impacts the Northeast

September 8, 2021 // Article by: Cody Hewitt

August was tumultuous to say the least. Stormy and hot weather marked the month all while hurricane season quickly ramped up, culminating in what would become Henri. And while that stole everyone’s attention, there were several severe outbreaks to contend with. Thanks to all of the above, no one was left emptyhanded in terms of rainfall.

Coming off of what was a relatively cooler than usual July, the pattern held through the first week following another cold front. This slowed down and became stationary offshore, which helped keep the region largely dry. Not long after, a four day stretch of severe weather then unfolded between the 10th and 13th due to multiple disturbances passing through. The most impacted area was Maryland where high winds knocked down trees and powerlines. Strong storms also swept across southeast PA as well as parts of NJ, NY, and MA. These rounds of storms, blew off part of the roof in downtown Richmond, VA, while county fair tents near Paterson, NJ were partially destroyed.

As a result of the increasingly active weather and despite returning high pressure, temperatures and the humidity also rebounded during the second week. Temperatures soared well into the 90s, setting off new daily records, including 98 degree records in Baltimore, MD on both the 11th and 12th. Right on the heels of that were the remnants of Tropical Storm Fred. Fred first made landfall across the panhandle of Florida before being swept up along a front across Appalachia and into the Northeast. Heavy rain fell from central Pennsylvania and through New England between the 18th and 19th, resulting in upwards of 2.00 – 5.00” across the region. Several tornadoes also touched down on the 18th, including an EF-1 in both Tilden, PA and Souderton, PA followed by an EF-0 near Rockaway, NJ.

Henri Radar loop as the storm made landfall in southern New England. Courtesy NWS.

Thereafter, Henri stole the spotlight as it got wrapped around an upper level disturbance and sped north towards the Northeast. It grew into a category 1 hurricane as it rode up the Gulf Stream and made landfall near Westerly, Rhode Island as a tropical storm on the 22nd. Areas of rain stretched all the way west into central-northern New Jersey, far eastern Pennsylvania, and New York City. Thanks to Fred leaving grounds saturated at this point, flooding was exacerbated as several inches fell, with close to 8” in Ringwood, NJ and near 7” in Harrison, NJ. Many homes and basements experienced flooding across central New Jersey, while winds on the eastern side of the storm in Massachusetts packed gusts up to 40 – 60 mph. Likewise, EF-0 tornadoes were recorded in Marlborough, Stow, and Bolton, MA as well as Windham, CT.

In contrast to July, it was a warm month, as much as 2 to 4 degrees above the norm thanks to two rounds of heat that pushed highs well into the 90s. More notably, precipitation well exceeded average in several cities, with New York City leading the way at just over 10.00” which ranked as the 4th wettest August on record. Even further south in Richmond, VA, precipitation totals were exceeded 7.00”. Washington, D.C. also witnessed its 4th wettest August on record at 9.07”. Unfortunately, nothing would prepare the region for the remnants of Ida at the beginning of September with everyone already well soaked from August rainfall.