National Weather Service concludes Wednesday's severe weather event was a derecho | WNYT.com

National Weather Service concludes Wednesday's severe weather event was a derecho

Reid Kisselback
Updated: October 13, 2020 03:12 PM
Created: October 13, 2020 01:08 PM

Wednesday's Derecho | Wednesday's Derecho |
 

A 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. During this time, New York State Mesonet weather stations recorded widespread wind gusts between 50 and 60mph down the Mohawk Valley into the Greater Capital District. Albany International Airport recorded a 67mph wind gust measurement, giving us the highest gust for the month of October with records dating back to 1987. Three 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. 

The National Weather Service investigated this incident and classified this as a serial derecho based on the 320-mile-long damage swath and distribution of significant wind gusts of 75 mph and above. The fact that trees across the region were fully leafed intensified the resulting wind damage and produced widespread power outages.

Downed power line on 155 between Washington Avenue Extension and Western Avenue. | Andy Smith Downed power line on 155 between Washington Avenue Extension and Western Avenue. | Andy Smith
  

Wednesday’s weather event was created by an intensifying low pressure system that progressed eastward from Ontario, Canada into northern New England. After the system’s surface warm front moved northward through the region in the morning, the atmosphere became slightly unstable. 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, a strong line of rapidly moving thunderstorms developed. These storms accelerated east at about 50 – 70mph and allowed the impressive winds aloft to mix down to the surface.

Plymouth Street, Schenectady | Plymouth Street, Schenectady |
 For those of you who do not know, a derecho is a widespread, long-lived wind storm. Derechos are associated with bands of rapidly moving showers or thunderstorms variously known as bow echoes, squall lines, or quasi-linear convective systems. Even though a derecho can produce destruction similar to that of a tornado, the damage typically occurs in one direction along a relatively straight path. As a result, the term "straight-line wind damage" is sometimes used to describe derecho damage. By definition, if the swath of wind damage extends for more than 250 miles, includes wind gusts of at least 58 mph along most of its length, and includes several, well-separated 75 mph or greater gusts, then the event can be classified as a derecho.

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.


Copyright 2020 - WNYT-TV, LLC A Hubbard Broadcasting Company

Comment on Facebook