Isolated Supercell T-Storm Event
Thursday Evening August 9, 2001

Excessive heat and humidity culminating in a record high temperature of 96 degrees at Albany and temperatures in the low 100's in the mid Hudson valley, created a potentially very unstable atmosphere over the region.  The atmosphere, however, was well capped by a layer of hot air aloft.  Capping inversions prevent updraft development and thus T'storms have difficulty forming.  In cases of extreme heat and humidity, and high potential instability, there always exists a small possibility that a very small air mass boundary or weak upper air disturbance (a slightly cooler pocket of air aloft) can trigger a T'storm allowing the updraft to break through the cap.  In cases where a T'storm does form and break through the cap, it then can feed off of the instability and become severe.

This was the case late in the afternoon and through the evening of August 9th.  A lake breeze boundary developed near Lake Ontario as the super heated air over the land (100 degrees at Syracuse) ascended, and the cooler air from the lake moved inland to replace it.  A very small upper air disturbance tracking across the bounding weakened the cap sufficiently for a T'storm to form on the front.  Once the storm broke through the cap it was off to the races as the hot unstable air near the ground raced aloft creating a monster cell.  The extreme instability and local wind shear created by the lake breeze boundary and terrain allowed the updraft to begin rotating creating a supercell T'storm.  Rotating updrafts are self sustaining systems and thus are able to survive for long periods of time.  Rotating updrafts sometimes produce tornadoes and almost always produce severe straight line winds.  This storm, remaining a single entity through it's life cycle, tracked through southern Herkimer and western Fulton counties through 6:45pm producing 60-80 mph straight line winds. (A tornado warning was in effect for the storm through 6:45pm but no tornado was confirmed after a National Weather Service damage survey.)  The storm continued it's eastward push through eastern Fulton, Saratoga, southern Washington, and northern Bennington counties through 9:30pm.  Almost continuous lightning, and bursts of damaging wind occurred along the storm's path.  WeatherNet 6 reports of up to 1.5" of rain occurred from the storm along it's path.  The outflow along the storm's southern periphery was quite impressive with winds of 45-50 mph in Schenectady and northern Rensselaer counties, with winds up to 40 mph as far south as Albany.  No rain fell at these southern periphery locations but some tree and power line damage did occur.

Several T'storms of lesser intensity trailed the super cell through 1:00am, following almost the same path, but no severe weather occurred.  The remainder of the region remained hot and sultry with no rain.

The table below lists the severe weather reports from this isolated supercell T'storm.

Town Name

County

Severe Report

Time of Weather
Russia Herkimer Wind damage, numerous trees down 5:50pm
Poland Herkimer Trees down 5:30pm
Herkimer, Ohio, Newport, Norway Herkimer Widespread wind damage 6:00pm
Dolgeville Herkimer Wind damage, trees and wires down 6:00pm
Fulton, County Wide Fulton Trees and wires down throughout the county 6:30pm
Lake Luzerne Warren Wind damage, lines down 7:30pm
Schenectady Schenectady Wind damage, trees down, siding off a building 7:35pm
Edinburg Saratoga Wind damage, trees down 7:35pm
Lake George Warren Wind damage, lines down 7:39pm
Stillwater Saratoga 75 mph wind gust 7:55pm
Malta, Clifton Park, Ballston Spa Saratoga Wind damage, trees and wires down 7:55pm
Melrose Rensselaer Wind damage, trees and wires down 8:10pm
Greenwich Washington Wind damage, trees down 8:20pm
Bennington, VT Bennington Wind damage, trees down 8:39pm
Arlington, VT Bennington Wind damage, multiple reports of trees down 8:45pm