Major Severe Thunderstorm Outbreak
A major severe thunderstorm outbreak developed during the early afternoon across western New York state and quickly propagated and developed into eastern New York and western New England through the late afternoon and early evening hours. The event was comprised of initially multicell and isolated supercell thunderstorms which merged, eventually forming an organized squall line over western New England which moved east through much of central and southern New England producing widespread wind damage. Several of the imbedded supercell thunderstorms in eastern New York and western New England may have produced brief tornado touchdowns during the event. Widespread wind damage and hail occurred throughout eastern New York and western New England between 3pm and 6pm with the passage of the storms. Frequent, intense lightning, and torrential rain also accompanied the thunderstorms. Severe thunderstorm warnings were issued, in some cases several times, for every county in the Channel 6 coverage area except Hamilton, Warren, and Rutland county Vermont. Severe weather was verified to have occurred in all the warned counties, classifying this as a major, widespread severe weather event.
Rainfall amounts were tremendous in some localized areas leading to flash flooding in Rensselaer, eastern Greene, Columbia, northern Dutchess and Berkshire counties. 2.54" of rain fell in East Greenbush in about an hour according to our WeatherNet 6 weather watchers.
The storm set-up was fairly classic for Northeast severe weather outbreaks. An intensifying area of low pressure over northern Michigan early Friday morning moved east up the St. Lawrence valley and across northern New England during the afternoon and evening. The storm pulled a warm front north through New York and New England by early afternoon. The warm front supported a cluster of thunderstorms between 7:00am and 10:00am in and north of the Mohawk valley east into southern Vermont. Those thunderstorms left an outflow boundary which acted later in the day as a convergence zone for the main round of severe thunderstorms that developed.
Behind the warm front and out ahead of a strong cold front in western New York, strong moisture convergence occurred over New York and New England with dewpoint temperatures at Albany rising from an early morning reading of 50 degrees to the mid and upper 60's by mid to late afternoon. Strong westerly winds at the jet stream level down to about 5000 feet provided much of the wind energy and shear for the thunderstorms to feed on as their updrafts developed. Southerly surface winds in eastern New York, as result of channeling in the Hudson valley, increased the low level wind shear which helped support several rotating (supercell) thunderstorms in Albany, Rensselaer, Columbia, Berkshire, Dutchess, and Litchfield counties. The rotating updrafts allowed the supercells to produce large hail and high wind as well as several suspected brief tornado touchdowns in Columbia, Berkshire, and Litchfield counties. High heat, for early June, and a mid atmospheric level incursion of dry air, also strongly contributed to the rapid destabilization of the atmosphere allowing for rapid updraft development and thus the rapid development to the thunderstorms. Temperatures reached the mid 80's in the Capital Region and into the low 90's in the mid Hudson valley immediately prior to the storms' arrival.
Thunderstorms, caught in the fast steering, flow moved quickly from west to east through the area at speeds between 35 and 50 mph, making any one storm's visit to a particular community rather short. However, several severe thunderstorms hit the same communities on several occasions during the outbreak.
Severe weather ended by 6:30pm as the last severe thunderstorms in Dutchess and Litchfield counties moved south and east. The cold front passed through the Capital Region accompanied by a few light showers between 8:00 and 9:00pm with a wind shift into the northwest and a drop in the humidity.
The following table lists the severe weather reports in the Channel 6 coverage area for this event.