Ample low level moisture was in place across the region ahead of a slow moving frontal boundary.  Although skies were cloudy to start the day, breaks in the clouds towards the noon hour allowed for some instability to develop.  With the large amount of moisture in place and an unstable atmosphere, slow moving thunderstorms formed.  Some of these thunderstorms contained gusty winds, which caused damage to trees and power lines.
As thunderstorms with heavy rainfall moved over the same areas repeatedly, flash flooding occurred across portions of Columbia County.  Some areas received over four inches of rain, with the highest amount being 4.95 inches in Chatham.
Thunderstorm activity waned by evening due to the frontal boundary crossing the region.

Flash Flood in COLUMBIA, NEW YORK
From 11-AUG-12 15:55:00 to 11-AUG-12 18:45:00 (EST-5)
Location: BRICK TAVERN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Flash flooding was reported on State Route 9H, 1/4 mile south of State Route 66, due to heavy rainfall from repeated thunderstorms.

Thunderstorm Wind in COLUMBIA, NEW YORK
From 11-AUG-12 10:35:00 to 11-AUG-12 10:35:00 (EST-5)
Location: NIVERVILLE
Magnitude: 50.00 EG
Reported by: Department of Highways

Trees and wires were reported down on Route 9 between County Route 28 and County Route 32 in the town of Kinderhook due to thunderstorm winds.

Thunderstorm Wind in COLUMBIA, NEW YORK
From 11-AUG-12 11:56:00 to 11-AUG-12 11:56:00 (EST-5)
Location: GHENT
Magnitude: 50.00 EG
Reported by: Trained Spotter

Several trees were reported down to thunderstorm winds in Ghent.

Thunderstorm Wind in COLUMBIA, NEW YORK
From 11-AUG-12 11:25:00 to 11-AUG-12 11:25:00 (EST-5)
Location: GREEN RIVER
Magnitude: 50.00 EG
Reported by: Emergency Manager

Two trees were reported down on Mallory Road, near the intersection with Punsit Road, in the town of Austerlitz.

Thunderstorm Wind in FULTON, NEW YORK
From 11-AUG-12 12:45:00 to 11-AUG-12 12:45:00 (EST-5)
Location: CAROGA LAKE
Magnitude: 50.00 EG
Reported by: Law Enforcement

Two trees were reported down on County Road 11 and an additional two trees were reported down nearby on County Road 112 due to thunderstorm winds in Caroga Lake.

Thunderstorm Wind in COLUMBIA, NEW YORK
From 11-AUG-12 13:30:00 to 11-AUG-12 13:30:00 (EST-5)
Location: NEW CONCORD
Magnitude: 50.00 EG
Reported by: Law Enforcement

A tree was down and on a power line on State Route 295 near Hartigan Road in the town of Chatham.

Flash Flood in COLUMBIA, NEW YORK
From 11-AUG-12 15:20:00 to 11-AUG-12 17:20:00 (EST-5)
Location: WESTGHENT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash flooding was reported on Stockport Road off State Route 9H in the town of Ghent due to heavy rainfall from repeated thunderstorms.

Flash Flood in COLUMBIA, NEW YORK
From 11-AUG-12 13:11:00 to 11-AUG-12 15:11:00 (EST-5)
Location: STOTTVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash flooding was reported on State Route 9 near Hickory Lane in the town of Greenport due to heavy rain from repeated thunderstorms.

Thunderstorm Wind in COLUMBIA, NEW YORK
From 11-AUG-12 14:48:00 to 11-AUG-12 14:48:00 (EST-5)
Location: AUSTERLITZ
Magnitude: 50.00 EG
Reported by: Emergency Manager

Trees and wires were reported down due to thunderstorm winds in Austerlitz.

Thunderstorm Wind in WARREN, NEW YORK
From 11-AUG-12 19:10:00 to 11-AUG-12 19:10:00 (EST-5)
Location: LAKE GEORGE
Magnitude: 50.00 EG
Reported by: Utility Company

Trees limbs were reported down and on power lines in the Village of Lake George.