pretty much to the coast, was due to a single long lived severe thunderstorm cell embedded within the QLCS which generated numerous meso-vortices throughout its lifecycle. The extensive corridor of extreme wind damage which began in northern Oneida County and continued through central Herkimer, Fulton, central Saratoga, southern Washington, and north central Bennington counties locally, but also on through Windham County VT to Cheshire and Hillsborough Counties in N.H. The Storm Prediction Center at this time was putting together the tornado watch for the region, issued instead of the more common severe thunderstorm watch due to the high shear conditions that existed, especially in the vicinity of the warm front, which favored some rotating updrafts in storms and the potential for a couple of brief spin up type tornadoes. The image below illustrates the synoptic set-up at the surface by mid afternoon on the 15th.
Thunderstorms rapidly intensified in the highly sheared environment, quickly organizing into a line and then rapidly moving east at roughly 45 mph arriving in Herkimer County shortly after 430 pm.
Thunderstorm development occurred during the early to mid afternoon across western New York along a lake breeze/weak cold frontal boundary. This produced a favorable environment for widespread thunderstorm development with a line the most favored storm mode. And shear values increased during the late afternoon and early evening due to the approach of a mid level shortwave trough and surface low pressure system which tracked from Ontario and western New York from the mid to late afternoon then across the Adirondacks into Vermont through the evening. A tornado watch was issued in advance of the event at 3:30 pm for all counties except Ulster, Dutchess, and Litchfield which were later added at 5:48pm.Ĭompensating, however, for the relatively low CAPE values was impressive wind shear with strong mid level flow contributing to 40-50 knots of bulk shear along with some turning of the low level wind, especially in the vicinity of the stalled warm frontal boundary over the southern Adirondacks. Four tornado warnings were issued locally with severe thunderstorm warnings issued covering all or parts of every local county except for Rutland. Approximately 150 severe reports were relayed by the National Weather Service in the local area with a least one report of wind damage occurring in every county in the CBS6 coverage area except Hamilton, Warren, and Rutland.
The event resulted in 50,000 - 60,000 utility customers in the region losing power with hundreds of trees downed and damage to roofs and siding in some towns. The QLCS (quasi linear convective system, or squall line) produced widespread wind gusts of 50 mph with a zone from central Herkimer through Fulton, central Saratoga, central Washington, and northern Bennington counties hard hit with gusts ranging from 60-100 mph in pockets due to a particularly intense line segment, which also produced a brief spin up tornado in Wilton, Saratoga County, at 6 pm. One of the most widespread outbreaks of severe thunderstorms to hit the region in recent years blasted from west to east between 4:30 and 8 pm Friday May 15, 2020, rolling through the immediate Capital Region between 6 and 7 pm.
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