A stationary front, coupled with an approaching upper level trough caused severe thunderstorms, including isolated supercells, across Southern Connecticut.  One supercell was responsible for a microburst in Middlesex County.

Thunderstorm Wind in NEW HAVEN, CONNECTICUT
From 21-JUL-10 15:30:00 to 21-JUL-10 15:30:00 (EST-5)
Location: CHESHIRE
Magnitude: 70.00 EG
Property damage: 8.00K
Reported by: Public

Large trees were reported  down in Cheshire.

Thunderstorm Wind in FAIRFIELD, CONNECTICUT
From 21-JUL-10 16:35:00 to 21-JUL-10 16:35:00 (EST-5)
Location: WESTPORT
Magnitude: 70.00 EG
Property damage: 25.00K
Reported by: Trained Spotter

Widespread tree damage was reported, with some trees snapped a few feet above the ground. One tree fell onto a car on Compo Road North, near State Route 136.

Thunderstorm Wind in FAIRFIELD, CONNECTICUT
From 21-JUL-10 17:40:00 to 21-JUL-10 17:40:00 (EST-5)
Location: RIVERSVILLE
Magnitude: 65.00 EG
Property damage: 15.00K
Reported by: Trained Spotter

Multiple trees were reported down in the town of Greenwich, CT, including an oak tree torn up through its roots.

Thunderstorm Wind in FAIRFIELD, CONNECTICUT
From 21-JUL-10 19:30:00 to 21-JUL-10 19:30:00 (EST-5)
Location: RIVERSVILLE
Magnitude: 52.00 EG
Property damage: 4.00K
Reported by: Broadcast Media

Trees were reported down in the town of Greenwich.

Thunderstorm Wind in FAIRFIELD, CONNECTICUT
From 21-JUL-10 17:30:00 to 21-JUL-10 17:30:00 (EST-5)
Location: RIVERSVILLE
Magnitude: 70.00 EG
Property damage: 15.00K
Reported by: Newspaper

Dozens of trees were reported down in the town of Greenwich, with the most signficant impact in the northeast corner of the town.

Thunderstorm Wind in NEW LONDON, CONNECTICUT
From 21-JUL-10 16:15:00 to 21-JUL-10 16:15:00 (EST-5)
Location: COLCHESTER
Magnitude: 61.00 EG
Property damage: 10.00K
Reported by: Law Enforcement

Multiple trees were reported down along State Route 16 in Colchester.

Hail in MIDDLESEX, CONNECTICUT
From 21-JUL-10 15:50:00 to 21-JUL-10 15:50:00 (EST-5)
Location: MIDDLETOWN
Magnitude: 1.00 
Reported by: Amateur Radio

Quarter size hail was reported in Middletown.

Hail in FAIRFIELD, CONNECTICUT
From 21-JUL-10 16:20:00 to 21-JUL-10 16:20:00 (EST-5)
Location: WILTON
Magnitude: 0.88 
Reported by: Trained Spotter

Nickel size hail was reported in Wilton.

Hail in FAIRFIELD, CONNECTICUT
From 21-JUL-10 17:40:00 to 21-JUL-10 17:40:00 (EST-5)
Location: STAMFORD
Magnitude: 1.75 
Reported by: Public

Golf ball size hail was reported.

Lightning in NEW HAVEN, CONNECTICUT
From 21-JUL-10 16:23:00 to 21-JUL-10 16:23:00 (EST-5)
Location: GUILFORD
Reported by: Trained Spotter

A woman was indirectly struck by lightning resulting in minor burns on her leg.

Thunderstorm Wind in NEW LONDON, CONNECTICUT
From 21-JUL-10 16:15:00 to 21-JUL-10 16:15:00 (EST-5)
Location: GILMAN
Magnitude: 61.00 EG
Property damage: 5.00K
Reported by: Law Enforcement

Multiple trees were reported down in the Town of Bozrah.

Thunderstorm Wind in FAIRFIELD, CONNECTICUT
From 21-JUL-10 16:30:00 to 21-JUL-10 16:30:00 (EST-5)
Location: NEW CANAAN
Magnitude: 61.00 EG
Property damage: 15.00K
Reported by: Newspaper

Multiple trees were reported down throughout New Canaan, including two onto cars.

Thunderstorm Wind in NEW LONDON, CONNECTICUT
From 21-JUL-10 16:15:00 to 21-JUL-10 16:15:00 (EST-5)
Location: CHESTNUT HILL
Magnitude: 61.00 EG
Property damage: 5.00K
Reported by: Law Enforcement

Multiple trees were reported down in Hebron.

Thunderstorm Wind in MIDDLESEX, CONNECTICUT
From 21-JUL-10 15:40:00 to 21-JUL-10 15:55:00 (EST-5)
Location: RIVERDALE
Magnitude: 96.00 EG
Property damage: 75.00K
Reported by: NWS Storm Survey

A National Weather Service Storm Survey team, along with officials from Portland Emergency Management, found damage consistent with microburst winds up to 110 mph along a swath approximately 2 miles long. The damage swath began near the intersection of State Route 66 and Middle Haddam Road in Portland and ended about 2 miles to the east at Keighly Pond Road in the town of East Hampton. The damage path was approximately 0.5 miles wide at its eastern edge and 1.5 miles wide at its western edge, indicative of divergent winds.
Significant damage to many large, mainly hardwood, trees was observed throughout the damage path, with trees averaging 80 feet in height and up to 2 feet in diameter snapped, in almost all cases, 20 to 30 feet above the ground. This is indicative of wind speeds of 90 to 110 mph.
Most of the damage was observed generally along Middle Haddam Road, with trees mostly oriented directly east or east-southeast. To the north, along Breezy Corners Road and Jobs Pond Road, tree damage was oriented east or east-northeast. To the south, along Lyman Lane and Wellwyn Road, trees were oriented to the southeast. This pattern also indicated diverging winds.
Damage to structures was confined to those in open areas away from trees. One such building, a Farm Center on Middle Haddam Road had a large section of roof ripped off that was carried by the wind for about 100 yards. Other buildings in open areas received minor damage to windows and screens.

Lightning in MIDDLESEX, CONNECTICUT
From 21-JUL-10 15:55:00 to 21-JUL-10 15:55:00 (EST-5)
Location: EAST HAMPTON
Property damage: 30.00K
Reported by: Law Enforcement

Two house fires were caused by lightning strikes.

Hail in FAIRFIELD, CONNECTICUT
From 21-JUL-10 18:50:00 to 21-JUL-10 18:50:00 (EST-5)
Location: MONROE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail was reported.

Lightning in MIDDLESEX, CONNECTICUT
From 21-JUL-10 15:44:00 to 21-JUL-10 15:44:00 (EST-5)
Location: GOODRICH HGTS
Property damage: 7.50K
Reported by: Newspaper

Lightning struck a tree at 161 Shunpike Road, and from there went into the house, causing a fire.