During the day on May 29th, a warm front lifted northward across western Massachusetts. Although the day began cloudy, some breaks of sun started to occur by early afternoon. At the same time, a potent upper level disturbance over Ontario started to approach the region and a strong jet streak was located just to the north. With a moist southerly flow moving into the region at the surface, it became rather humid as well.
With all these ingredients coming together, thunderstorms developed across upstate New York by mid afternoon and began to spread eastward. The thunderstorms reached Berkshire County by the evening hours. Many of the thunderstorms organized into a strong squall line, producing wind damage. These thunderstorms produced a significant amount of lightning, as well, which in combination with the wind damage, led to some power outages across the area.
With the region already rather saturated from repeated thunderstorms over the past week, the additional heavy rainfall that occurred caused flash flooding in some areas. This caused roads to be closed due to being impassable by flowing water.  Portions of Williamstown were hit quite hard, as at least eight roads were damaged due to flooding.  Two homes were without road access as a result of the flooding.
Thunderstorms pushed east of the area by around midnight, ending the threat of severe weather.

Flash Flood in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 19:39:00 to 29-MAY-13 21:45:00 (EST-5)
Location: NORTH ADAMS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Flash flooding was reported in North Adams as a result of heavy rainfall from thunderstorms.  State Street was impassable due to flooding and was temporarily closed.

Flash Flood in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 19:45:00 to 29-MAY-13 21:45:00 (EST-5)
Location: WILLIAMSTOWN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash flooding was reported in Williamstown as a result of heavy rainfall from thunderstorms.  Route 43 was reported to be impassable due to flooding.

Flash Flood in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 20:15:00 to 29-MAY-13 21:45:00 (EST-5)
Location: WEST STOCKBRIDGE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Flash flooding was reported in West Stockbridge as a result of heavy rainfall from thunderstorms.  Several roads in the town was reported to be impacted by the flooding.

Flash Flood in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 19:42:00 to 29-MAY-13 21:45:00 (EST-5)
Location: GREYLOCK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash flooding was reported along Massachusetts Avenue in North Adams as a result of heavy rainfall from thunderstorms.

Thunderstorm Wind in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 18:51:00 to 29-MAY-13 18:51:00 (EST-5)
Location: LANESBOROUGH
Magnitude: 56.00 EG
Reported by: Trained Spotter

Widespread trees were reported down in Lanesborough as a result of thunderstorm winds.

Thunderstorm Wind in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 19:43:00 to 29-MAY-13 19:43:00 (EST-5)
Location: NEW MARLBOROUGH
Magnitude: 50.00 EG
Reported by: Trained Spotter

Multiple trees and wires were reported down in New Marlborough due to thunderstorm winds.

Flash Flood in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 19:31:00 to 29-MAY-13 21:45:00 (EST-5)
Location: NORTH ADAMS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Flash flooding was reported on Church Street north of Adams as a result of heavy rainfall from thunderstorms.  The force of flooding removed manhole covers off the road.

Flash Flood in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 19:30:00 to 29-MAY-13 21:45:00 (EST-5)
Location: WILLIAMSTOWN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Several culverts along Treadwell Hollow Road in Williamstown were reported to be damaged due to flash flooding.  Two homes were without road access as a result of the flooding.

Flash Flood in BERKSHIRE, MASSACHUSETTS
From 29-MAY-13 19:35:00 to 29-MAY-13 21:45:00 (EST-5)
Location: WILLIAMSTOWN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Flash flooding was reported along Northwest Hill Road near Williamstown.  A garage and its concrete slab was swept away from the force of the flooding.