Sunday July 19, 2015
Severe T'Storm Event - SE Albany, SW Rensselaer, No. Columbia County Supercell

An outbreak of severe thunderstorms occurred in a cluster largely in and around the Capital Region during the late afternoon and early evening on Sunday July 19 in a hot, oppressively humid and unstable environment resulting in 37 reports of damaging wind and large hail. Seventeen of those severe weather reports came from wind damage and hail generated from one highly photogenic supercell storm (a storm with a rotating updraft and associated mesocyclone) which impacted parts of Albany, Rensselaer, Columbia, and Berkshire counties between 4pm and 6pm.

Supercell thunderstorm coming into Ghent, NY around 5:30pm on Sunday July 19 - The photograph shows a well defined storm structure with some striations in the clouds indicating a rotating updraft. Photograph by former WeatherNet 6 spotter and research meteorologist Tim Melino.

Supercell Thunderstorm Ghent, NY Columbia County July 19, 2015

Another view of the supercell from Niverville, Columbia County where considerable tree damage occurred due to 85-90 mph straight line winds. Photograph contributed via facebook by Michael Masten

Wall cloud area of the supercell over Niverville, Columbia County, July 19, 2015 

The wall cloud from the storm as it appeared in Chatham Center. Photograph contributed by Kelli Coates Baccaro via facebook.

Dramatic wall cloud structure with the supercell over Chatham Center, July 19, 2015 

Set Up:
A hot and oppressively humid air mass, characterized by strong heating through the afternoon with air temperatures soaring into the low 90s in the Capital Region and mid 90s in the mid Hudson valley with dewpoints ranging through the lower 70s, was in place after a warm frontal passage on Saturday July 18. A weak upper level disturbance and slowly advancing cold front acted as the main trigger mechanisms for scattered thunderstorm developed which began after 3pm across the region. Very high CAPE (convective available potential energy) values ranging from 2000 to 3000 j/kg provided considerable energy for robust thunderstorm development providing a focus for thunderstorms to form, which existed in the advancing weak upper level disturbance and small scale boundaries across the region as well as elevated heat sources (higher elevation locations.) Once a few thunderstorms developed, the potential would exist in such a potentially unstable environment for explosive development and severe weather, which is what occurred throughout the Capital Region on this day.

The first cluster of thunderstorms began developing after 3pm in Schoharie and Albany counties, slowly moving to the ESE, ultimately intensifying and consolidating into a supercell storm (a storm with a rotating updraft) which moved across southeast Albany, southwest Rensselaer, and northern Columbia counties between 4pm and 5:30pm and then weakening over south central Berkshire county through 6pm. The rotating updraft and reports of funnel clouds prompted a tornado warning on the storm at 5pm through 5:45pm for SW Rensselaer and northeast Columbia counties. It was determined by a National Weather storm damage assessment on Monday July 20 that the storm did not produce a tornado but rather violent straight line winds ranging from 85-90 mph from south Schodack in Rensselaer County through Niverville, Kinderhook into Chatham along an eight mile path. Other significant wind damage and 2" diameter hail occurred with the storm in Selkirk as it moved out of Albany County on a slow southeastward track at 20-25 mph.

Additional thunderstorms intensified throughout the Capital Region, tracking into Vermont and northern Berkshire County through the remainder of the late afternoon and early evening, generally exiting the region between 7pm and 8pm. During this period a second briefly rotating thunderstorm prompted a tornado warning for east central Montgomery, northeast Schenectady, southwest Saratoga, and southeast Fulton counties from 6:00pm to 6:20pm with the rotation quickly weakening after being detected on radar. Pockets of wind damage and up to 1" diameter hail fell in Niskayuna from this cell as it moved east across the Capital Region producing torrential rain along its path.

The low hanging cloud base in the image below was from the tornado warned storm as it moved over West Glenville after 6pm. Although difficult to determine from a still image because rotation is not discernable, the feature appears was either a brief wall or funnel cloud formation. This photograph contributed by Erica Larrabee.

Storm with possible brief funnel cloud over West Glenville, Schenectaday County, July 19, 2015

Shelf cloud going over Crossgates Mall in Guilderland around 5:45pm. This cloud formation is formed by the cool thunderstorm outflow air forcing the warm humid air in front of the storm to lift allowing the water vapor to condense into the laminar formed cloud. Strong wind gusts can sometimes follow the passage of a shelf cloud, which was the case in many instances on this day. This photograph was contributed by Thomas Pudvar via Facebook.

Shelf cloud passing over Crossgates Mall in Guilderland, July 19, 2015

NWS Storm Reports for Sunday July 19, 2015. Note, these reports are used to verify the NWS warnings which were issued for this event and therefore do not necessarily represent an accounting for all of the wind damage or large hail which may have occurred during the event.

Town County Storm Report Time
Bethlehem Center Albany One tree reported blown down and 0.88" diameter hail 4:36pm
Castleton-On-Hudson Rensselaer Multiple trees and wires down on Campbell Ave, Knickerbocker Road and Muitzeskill Road 4:47pm
Selkirk Albany Wind damage, trees and wires blown down, 1.75" to 2" hail reported 4:50pm
Castleton-On-Hudson Rensselaer FLASH FLOOD: Car reported stuck in flood waters 4:59pm
Ghent Chatham Funnel cloud 5:06pm
Coeymans Albany Wind damage: Downed trees along River Road 5:10pm
South Schodack, Nassau, Valatie, Kinderhook, Niverville, Chatham Center SW Rensselaer to Columbia 8 Mile path of significant tree damage and damage to cars and buildings from falling trees, determined by NWS to be from 85-90 mph straight line winds. Greatest damage to trees was concentrated along Kinderhook Lake in Niverville with tree damage on County Route 13 in Chatham, County Route 28B and Round Lake Rd. in Chatham, Kinderhook St. in Valatie 5:15pm-5:30pm
Williamsville, MA Berkshire Measured 1" diameter hail 5:23pm
Boght Corners Albany Large tree limbs blown down 5:23pm
Niskayuna Schenectady Measured 1" diameter hail 5:30pm
Cobleskill Schoharie Wind damage: Multiple trees and branches blown down 5:30pm
Middleburgh Schoharie Wind damage: Multiple trees and branches blown down 5:30pm
Schoharie Schoharie Wind damage: Multiple trees and branches blown down 5:30pm
Latham Albany Penny sized hail at Exit 7 of the Northway 5:32pm
Cranesville Montgomery Wind damage: tree blown down 5:36pm
Charleston Montgomery Wind damage: One tree blown down 5:42pm
1 Mile WNW of Watervliet Albany Lightning strike on an apartment complex causing a fire 5:55pm
Amsterdam Montgomery FLASH FLOOD: Route 30 partially flooded between Amsterdam and Perth 6:00pm
Schodack Center Rensselaer Wind damage: Multiple trees blown down 6:00pm
Greenfield Saratoga Wind damage, trees and wires blown down 6:06pm
Latham Albany Measured 1" diameter hail 6:10pm
Wilton Saratoga Wind damage, trees and wires blown down 6:18pm
Troy Rensselaer FLASH FLOOD: Second avenue closed due to flooding, 1.5 feet of water across the road 6:20pm
1 Mile E. of Brookview Rensselaer Wind damage, trees blown down 6:27pm
1 Mile NW of Travers Corners Saratoga Large tree down on wires along northern Pines Road 6:38pm
Hoosick Falls Rensselaer Wind damage, 1 injured by a falling tree on a moving vehicle 6:41pm
Hoosick Rensselaer Wind damage, trees blown down 6:41pm
1 Mile ENE of Hartford Washington Wind damage, trees blown down 7:00pm
Marbletown Ulster Wind damage, numerous trees blown down 7:06pm
Stone Ridge Ulster Wind damage, numerous large branches blown down 7:07pm

Storm Prediction Center Storm Damage Reports for July 19, 2015

Storm Prediction Center storm reports for Sunday July 19, 2015 

WeatherNet 6 Rainfall Reports for Sunday July 19, 2015 

Town County Rainfall Report Town County Rainfall Report
Clarksburg, MA Berkshire 0.20"      
Colonie Albany 0.40" Westmere Albany 0.24"
Boght Corners Albany 1.71" (NWS) Cohoes Albany 3.24" (CWOP)
North Chatham Columbia 1.49" Austerlitz Columbia 1.00"
Wells Hamilton 0.29"      
Arkville Delaware 0.20"      
Amsterdam Montgomery 0.62" to 0.82" Fonda Montgomery 0.13"
Florida Montgomery 0.09"      
Perth Fulton 1.06"      
Oneonta Otsego 0.64"      
Speigletown Rensselaer 2.30" Center Brunswick Rensselaer 1.58"
Milton Saratoga 0.30" Corinth Saratoga 0.18"
Richmondville Schoharie 0.20"      
Hartford Washington 0.30"      
Landgrove, VT Bennington 0.65"      

Additional Storm Photographs

Supercell thunderstorm viewed from Spencertown, Columbia County on Sunday July 19, 2015. Photograph contributed by Alyssa Brigs
Supercell thunderstorm seen from Spencertown, Columbia County July 19, 2015
Supercell thunderstorm wall cloud with possible funnel cloud over Selkirk, Albany County on Sunday July 19, 2015. Photograph contributed by Amanda Kindlon. The storm produced up to 2" diameter hail and wind damage as it moved over the Selkirk area.
Supercell thunderstorm over Selkirk, Albany County, Sunday July 19, 2015