National Weather Service United States Department of Commerce

Overview

A high-end severe weather event unfolded across the Northeast on Wednesday October 7, 2020 resulting in over 120 damaging wind reports across eastern New York and western New England. New York State Mesonet weather stations recorded widespread wind gusts between 50 and 60mph down the Mohawk Valley into the Greater Capital District with a 67mph wind gust measurement at the Albany International Airport. This ranks as the highest gust for the month of October with records dating back to 1987.  Microbursts were confirmed by storm surveys in Root, Pittstown, and Johnsonville, NY, with estimated wind speeds of 80, 90, and 100 mph, respectively.  In addition, a brief EF0 tornado occurred in Canajoharie, NY.  This event was classified as a serial derecho based on the 320 mile long damage swath and distribution of significant wind gusts (75 mph and above). The fact that trees across the region were fully leafed exacerbated the resulting wind damage and produced widespread power outages.
 

The culprit for this weather event was an intensifying low pressure system that progressed eastward from Ontario, Canada into northern New England. Its initially positively tilted parent trough became negatively tilted as it swung through the region. It directed an anomalously strong mid-level jet streak characterized by 500mb winds ranging between 70 and 100kts into southern New England. After the system’s surface warm front moved northward through the region in the morning, the atmosphere became slightly unstable with mixed-layer cape values rising to around 250 – 500 J/kg. Given the very strong winds aloft, this produced a classic high shear low cape environment. As the main cold front and associated upper level cold pool moved into the area during the afternoon, mid-level lapses quickly steepened to 6.0 – 7.0C/km resulting in a strong line of rapidly moving thunderstorms. These storms accelerated towards New England at about 50 – 70mph and allowed the impressive winds aloft of mix down to the surface.

This ranks as one of the strongest severe weather events for 2020 with only the May 15, 2020 severe weather event leading to similar widespread wind damage. The National Weather Service in Albany would like to thank all our emergency managers and broadcast media partners as well our network of trained weather spotter and social media followers for assisting our data collection and survey storm efforts.

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