Saturday July 17, 2010 Severe Weather Event

Significant severe weather impacted the local region from the late afternoon through the evening on Saturday July 17, 2010 with major wind damage being reported in some communities along with large hail and frequent cloud to ground lightning. Essentially two supercell thunderstorms rampaging through the region produced much of the severe weather through 9:30pm. A few additional severe t-storms produced wind damage and large hail through 11:30pm in mainly the Catskills, Capital Region, and mid Hudson valley.

The first storm moved into Otsego County around 3pm slowly tracking to the east-southeast. At 4:03pm it developed a hook echo on radar near Laurens, maintaining that hook into Davenport in Delaware County through 4:08pm. The storm continued to strongly rotate as it moved through southern Schoharie and western Greene counties through 4:22pm. Wind damage and hail were observed along its path through 5pm from Maryland to Jefferson and Ashland. Between 5pm and 5:30pm some weakening occurred with the supercell in Greene County, weakening which would be short lived. As the storm moved into the Hudson valley, intersecting more of a backed wind flow and slightly higher dewpoint air, it re-intensified, becoming severe again at 5:45pm in southern Columbia County. The storm became outflow dominated for a time in southeast Columbia and southern Berkshire Counties, bowing out and causing considerable wind damage between 6:03 and 6:25pm. A hook echo reformed in Litchfield County, CT after 6:30pm with the storm out of the region by 7:30pm.

The second multicell/pseudo supercell storm fired up around 7pm in southern Herkimer County, quickly becoming severe as it tracked down the Mohawk valley, through the Capital Region into northern Rensselaer and southern Bennington counties. Significant outflow occurred with the storm. As the outflow boundary spread away from the storm it triggered additional t-storms to form after 8pm, especially in Schenectady County where severe wind gusts were reported. A supercell structure developed as the storm complex moved into Rensselaer County with extreme straight line wind damage reported at the Aquavista Park camp ground and a funnel cloud reported over Bennington, VT. Both storms, in addition to producing the high wind and hail, produced frequent, vivid, cloud to ground lightning, and locally torrential rain.

The trigger for the event was the approach of a cold front, located north of Lake Ontario, being forced into the region by an upper level low pressure trough. The upper trough brought cooling air into the mid and upper levels of the atmosphere which created significant instability. Local boundaries, especially a lake breeze boundary forced east off of Lake Ontario, also aided in surface convergence helping to develop the thunderstorms over eastern New York and western New England where dewpoint temperatures held in the lower 70s. CAPE values, (Convective Available Potential Energy) ranged from 1500 to 2500j/kg during the evening, indicating moderately strong instability which is favorable for deep convective development. Moderate wind shear was also present, coupled with the moderately high instability environment and low level terrain influences to create a favorable environment for rotating updrafts, creating the two long lived supercell storms which produced much of the severe wind and hail.

Storm Prediction Center Storm Reports Graphic for the Saturday July 17, 2010 Severe Event 

Severe Weather Reports For the Saturday July 17, 2010 Event

These reports were collected by the Albany and Binghamton NWS offices for the purpose of verifying the warnings that were issued for the event, and therefore, do not necessarily represent all of the wind damage and hail that may have occurred as a result of the thunderstorms.

Town County Severe Report Time of Severe
Laurens Otsego Numerous trees blown down, 1 person injured as a tree fell on a golf cart 3:48pm
Hartwick Otsego Wind damage, numerous trees down through the town 4:00pm
Maryland Otsego Wind damage, large branches broken 4:06pm
Davenport Delaware Funnel Cloud and straight line wind damage, winds blew a hay wagon over 4:15pm to 4:20pm
Jefferson Schoharie Trees and wires blown down 4:30pm
Ashland Greene 1.00" diameter Hail, (Quarter Sized)
5:00pm
Copake Columbia Wind damage, trees and wires blown down on Route 7A, Farm and Mountainview roads 6:09pm
Taghkanic Columbia Wind damage, tree down, lawn furniture and tents blown over, pea sized hail 6:15pm
Ancram Columbia Trees blown down on Wiltsie Bridge Rd and Near Route 3 6:16pm
Lakeville, CT Litchfield Roof blown off a house on Washnee Road 6:25pm
Sheffield, MA Berkshire Trees and wires blown down 6:28pm
Salisbury, CT Litchfield Trees and wires blown down along Routes 41 and 44 6:38pm
Salisbury Center Herkimer Wind damage, tree down blocking a portion of Route 29 7:02pm
Fairfield Herkimer Wind damage, tree down on Castle Road 7:02pm
Dolgeville Herkimer Multiple trees blown down, power lines blown down onto homes 7:15pm
Gloversville Fulton Trees and power lines blown down 8:00pm
Oppenheim Fulton Trees and wires blown down on Keyser and Olsen Roads 8:00pm
Niskayuna Schenectady 1/2" to 3/4" hail (sub-severe) WRGB 8:35pm
Schaghticoke Rensselaer Wind damage, trees blown down 8:40pm
Pittstown Rensselaer Wind damage, tress blown down 8:45pm
Grafton Rensselaer 1.50" diameter sized hail 9:05pm
Petersburg Rensselaer MAJOR WIND DAMAGE: 60-70 trees uprooted at the Aquavista Campground, trailers hit, one injured, determined to be 80-90 mph straight line winds by NWS survey 9:05pm
Grafton Rensselaer Trees and large limbs down, wind gusts estimated to be 65 mph 9:05pm
Bennington, VT Bennington Funnel cloud sighted on Route 279 near the center of Bennington 9:15pm
Bennington, VT Bennington 1.00" diameter hail 9:24pm
North Adams, MA Berkshire 3/4" diameter hail (sub-severe) 9:42pm
Glenville Schenectady Wind damage, tree blown down onto a home 10:00pm
Oppenheim Fulton FLASH FLOOD: A beaver dam burst flooding portions of State Route 29 10:06pm
Alplaus Schenectady Wind damage, trees and wires blown down 10:08pm
Latham Albany 1.00" diameter hail 10:36pm
Thacher Park Albany 2.00" diameter hail, (Hen Egg sized) 10:45pm
East Greenbush Rensselaer 1.00" diameter sized hail, completely covering the ground along State Route 4 10:49pm
Jewett Greene Wind damage, trees and wires blown down 11:14pm
Lexington Greene Trees and wires blown down 11:30pm

Assorted Storm Related Photographs From CBS6 Viewers

Photographer: CBS6 Viewer Deb Shang
The cloud scene over Amsterdam at 8:06pm on Saturday July 17, 2010
Photographer: CBS6 Viewer Deb Shang
The cloud scene over Amsterdam at 8:06pm on Saturday July 17, 2010
T-Storm related cloud formations over the city of Amsterdam, Saturday July 17, 2010 at 8:06pm  -Storm related cloud formations over the city of Amsterdam, Saturday July 17, 2010 at 8:06pm   
   
Photographer: CBS6 Viewer Rodney Brooker
Lightning over Lawyersville, Schoharie County, looking towards Cobleskill at approximately 10:30pm Saturday, July 17, 2010
Photographer: CBS6 Viewer Rodney Brooker
Lightning over Lawyersville, Schoharie County, looking towards Cobleskill at approximately 10:30pm Saturday, July 17, 2010
Lightning over Lawyersville in Schoharie County around 10:30pm on Saturday, July 17, 2010  Lightning over Lawyersville in Schoharie County around 10:30pm on Saturday, July 17, 2010    
Photographer: CBS6 Viewer Rodney Brooker
Lightning over Lawyersville, Schoharie County, looking towards Cobleskill at approximately 10:30pm Saturday, July 17, 2010
Photographer: Shannon Greeen
Lightning over the city of Albany
Lightning over Lawyersville in Schoharie County around 10:30pm on Saturday, July 17, 2010 Lightning over the city of Albany, Saturday July 17, 2010
   
Photographer: Unknown
Lightning over Malta, Saratoga County, Saturday July 17, 2010
Photographer: Unknown
Lightning over Malta, Saratoga County, Saturday July 17, 2010
Lightning over Malta, NY Saturday July 17, 2010  Lightning over Malta, NY Saturday July 17, 2010 
Photographer: Don Edwards
A spectacular mamatus cloud display over the Sacandaga Lake in Northville, Fulton County Saturday evening July 17, 2010
Photographer: Don Edwards
A spectacular mamatus cloud display over the Sacandaga Lake in Northville, Fulton County Saturday evening July 17, 2010
Mamatus Clouds over the Sacandaga Lake in Northville, Fulton County, Saturday July 17, 2010  Mamatus Clouds over the Sacandaga Lake in Northville, Fulton County, Saturday July 17, 2010