Major Supercell Severe Weather Outbreak
The second major outbreak of severe thunderstorms within a week developed immediately over the Capital Region during the evening of Wednesday, June 5 and affected the area from approximately 7:30pm to 11:30pm. The storms produced a significant damage path from Amsterdam in Montgomery county through Charlton, Round Lake, Milton, and Stillwater in Saratoga county, Easton and Cambridge in Washington county, Schaghticoke in Rensselaer county, and across southern Bennington county Vermont, where and F1 ranked tornado touched down near Woodford Hollow. A tornado watch was issued by the Storm Prediction Center from 5pm through 10pm to cover this event.
The set up in the atmosphere for this outbreak was somewhat unique and particularly interesting in that the development of thunderstorms did not occur until early in the evening, after peak heating had occurred. A warm front passed through the area during the late morning and early afternoon accompanied by clouds and scattered showers. Dewpoint temperatures behind the warm front surged to around 70 degrees in the Hudson Valley illustrating strong moisture convergence over eastern New York, a favorable parameter for thunderstorm development. Sunshine also developed behind the warm front allowing temperatures to climb into the low and mid 80's. The interesting aspect to the set up was a mid level capping temperature inversion that developed over the area during the afternoon as the warm front moved east into New England. (A midlevel capping inversion is created when very warm air flows into a region aloft. Warm air aloft creates stability in the atmosphere and therefore precludes the development of clouds, let alone thunderstorms. Often the atmosphere above a capping inversion is explosively unstable and therefore supportive of very dangerous thunderstorms, if thunderstorms are able to break through the cap to form.) The evidence of a mid level cap was apparent when skies cleared completely for a couple of hours with no cumulus development during the afternoon. For a time during the late afternoon and early evening it appeared to many in the local meteorological community that the capping inversion could be strong enough to suppress convective development, and thus prevent the anticipated thunderstorm outbreak. It should be noted that the potential instability above the inversion was very high suggesting significant development, should thunderstorms form. To say the least, the area was sitting under an atmospheric time bomb with area meteorologists on pins and needles waiting to see if the atmosphere would let go.
Analysis of local weather data suggested that the air temperature needed to reach the low 80's with dewpoint temperatures at the surface around 70 to produce sufficient buoyancy to break the capping inversion. Those thermodynamic parameters were reached early in the evening and aided in the development of widely scattered thunderstorms over the Adirondacks and across central New York. These thunderstorms, as they expanded, drew energy from the extreme potential instability in the atmosphere and eventually became severe as they developed into the Capital Region during the evening. The south to south east surface wind that was evident over eastern New York and western New England enhanced the local wind shear sufficiently to start some of the thunderstorm updrafts rotating as they intersected the low level flow and moisture axis centered on the Hudson Valley. It should also be noted that local surface convergence due to the Mohawk/Hudson confluence aided in the rapid and rotating development of some of the T'storms. Rotating thunderstorms, called supercells, usually always produce severe weather in the form of large hail and damaging straight line winds and sometimes go on to produce tornadoes.
Thunderstorms began rapidly intensifying as they moved into Otsego and Montgomery counties, becoming severe by 7:45pm. Rotation became very apparent in two storms and somewhat apparent in one other by 8:00pm when tornado warnings were issued for southern Saratoga and southern Washington counties. The two strong supercells formed almost on top of each other in eastern Montgomery county and tracked east through southern Saratoga, southern Washington, and northern Rensselaer counties through 8:45pm. The Instant Doppler 6 radar image below shows the two supercell storms at 7:58pm. The lead storm is in southern Washington county with the trailing storm in southern Saratoga county. (Notice the hook shape to each of the cells on the right most side of the line. The radar signature illustrated here is called a hook echo and is a radar reflectivity indication of rotation within a thunderstorm.)
The Washington county storm did not produce a tornado until it moved into Bennington county Vermont. At 9pm an F1 ranked tornado (Winds of 80 to 100 mph) touched down one mile north of Woodford Hollow. The damage path was 150 yards wide and 1/2 mile long. There was considerable damage to trees as well as several homes and cars due to falling trees. This storm went on to produce a second stronger tornado at 9:45pm in Windham county Vermont. The Windham county, VT tornado was ranked an F2 (Winds of 125-150 mph) and touched down four miles northeast of Wilmington. The damage path with this tornado was 50 yards wide and 1/2 mile long and included a partially destroyed home.
The saratoga county supercell produced a long lived straight line wind damage path that began in Amsterdam and continued through Charlton, Round Lake, Milton, Stillwater, and Schaghticoke.
The two supercell storms early in the outbreak were the most significant storms and produced the majority of the damage in a relatively concentrated area of the region. Thunderstorms did overspread the entire WRGB coverage area through 11:30pm, producing almost continuous lightning, torrential rain and wind gusts to 40 mph. The Albany National Weather Service issued a total of 21 severe weather warnings for this event, half the number issued for the event preceding this one on May 31, 2002.
There were scattered reports of hail and downburst wind damage with these storms as they passed through and south of the Capital Region into Berkshire county, MA through 11:00pm. Rainfall amounts with the storms were quite impressive with some areas receiving up to three inches. No significant flooding developed as a result of this severe thunderstorm outbreak. The table immediately below is a listing of WeatherNet 6 rainfall reports for this event. Scroll down further to view the damage reports received from this severe thunderstorm outbreak as reported by both WeatherNet 6 spotters and trained National Weather Service Skywarn spotters.
Reported Rainfall: June 5, 2002 Outbreak
Reported severe weather and damage for the June 5, 2002 Outbreak