On July 16th, a strong upper atmospheric area of low pressure was located north of the Great Lakes in south central Canada. In addition, a significant mid-level shortwave and associated surface low moved across the eastern Great Lakes, while a warm front and subsequent cold front swept across northern New York and Vermont during the afternoon and evening.
Numerous thunderstorms developed and moved across Vermont, in a moderate to strong unstable atmosphere during the afternoon and evening. In addition there were a few super-cell thunderstorms that produced very large hail, up to 3.3 inches in diameter in Westford (Chittenden county) with numerous reports of damage to vehicles, homes, crop and livestock and a brief EF-0 tornado along the Williamstown-Chelsea town line (Orange county).
The measured 3.3 inch diameter hail in Westford, also had a circumference of 6.8 inches and has been determined by the State Climate Extremes Committee as the largest recorded hail stone in Vermont.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 16-JUL-09 15:45:00 to 16-JUL-09 15:45:00 (EST-5)
Location: (BTV)BURLINGTON ARPT
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: NWS Employee

Several trees and large limbs down across South Burlington, including Hinesburg Road between Williston and Kennedy roads.

Thunderstorm Wind in ADDISON, VERMONT
From 16-JUL-09 17:00:00 to 16-JUL-09 17:00:00 (EST-5)
Location: ORWELL
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several trees and branches downed by thunderstorm winds in southern Orwell. Power outages reported as well.

Hail in CHITTENDEN, VERMONT
From 16-JUL-09 16:06:00 to 16-JUL-09 16:10:00 (EST-5)
Location: WESTFORD
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Golf Ball size hail lasted for about 5 minutes with windows broken in house, car vehicles and house siding dented, broken plastic lawn furniture and family garden smashed.

Hail in CHITTENDEN, VERMONT
From 16-JUL-09 16:08:00 to 16-JUL-09 16:13:00 (EST-5)
Location: WESTFORD
Magnitude: 3.30 
Property damage: 50.00K
Crop damage: 50.00K
Reported by: NWS Employee

Several golf ball and larger hail, including a hail stone that measured 3.25 inches in diameter measured by NWS employee. Large hail with reported damage to vehicles, lawn furniture, siding, windows, gardens and crops throughout the Westford vicinity, including local farms, landscaping businesses and apple orchard.

Hail in CHITTENDEN, VERMONT
From 16-JUL-09 15:57:00 to 16-JUL-09 15:57:00 (EST-5)
Location: MILTON
Magnitude: 1.50 
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Estimated Ping-pong to golf ball size hail reported that dented vehicles, damaged lawn furniture, house siding and local gardens.

Hail in CHITTENDEN, VERMONT
From 16-JUL-09 16:05:00 to 16-JUL-09 16:07:00 (EST-5)
Location: WESTFORD
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Half dollar sized hail reported.

Hail in RUTLAND, VERMONT
From 16-JUL-09 18:30:00 to 16-JUL-09 18:30:00 (EST-5)
Location: KILLINGTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail reported near Killington Ski Resort.

Hail in LAMOILLE, VERMONT
From 16-JUL-09 19:10:00 to 16-JUL-09 19:10:00 (EST-5)
Location: WATERVILLE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail reported.

Hail in FRANKLIN, VERMONT
From 16-JUL-09 16:13:00 to 16-JUL-09 16:15:00 (EST-5)
Location: FAIRFAX FALLS
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 20.00K
Reported by: Public

Golf ball to ping-pong size hail reported at Riverberry Farm in Fairfax. Hail caused significant damage to berry and other crops.

Hail in FRANKLIN, VERMONT
From 16-JUL-09 16:15:00 to 16-JUL-09 16:15:00 (EST-5)
Location: FAIRFAX FALLS
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Nickel size hail reported.

Hail in ORANGE, VERMONT
From 16-JUL-09 18:00:00 to 16-JUL-09 18:00:00 (EST-5)
Location: BROOKFIELD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Quarter size hail reported in Brookfield.

Hail in FRANKLIN, VERMONT
From 16-JUL-09 16:25:00 to 16-JUL-09 16:25:00 (EST-5)
Location: EAST FLETCHER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Quarter size hail reported on Metcalf Pond Road.

Hail in RUTLAND, VERMONT
From 16-JUL-09 18:00:00 to 16-JUL-09 18:00:00 (EST-5)
Location: CHITTENDEN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Nickel size hail reported.

Tornado in ORANGE, VERMONT
From 16-JUL-09 18:05:00 to 16-JUL-09 18:09:00 (EST-5)
Location: WILLIAMSTOWN
Tornado F-scale: EF0
Property damage: 50.00K
Crop damage: 25.00K
Reported by: NWS Storm Survey

A tornado produced a broken path of damage. The most significant damage occurred to a blown barn roof near the beginning of the track along South Hill Road near  Lighthouse Road In Williamstown. The tornado moved southeast and lifted near the
intersection of Stellar and Williamstown Roads in Chelsea.
The majority of the damage was downed softwood trees along the Chelsea/Williamstown Road. The north side of the path had over a hundred trees blown down in a east to west direction. Meanwhile on the south side of the path, dozens of trees were blown in a west to east direction.

Hail in CHITTENDEN, VERMONT
From 16-JUL-09 16:08:00 to 16-JUL-09 16:12:00 (EST-5)
Location: WESTFORD
Magnitude: 2.50 
Property damage: 10.00K
Crop damage: 20.00K
Reported by: Newspaper

Numerous large hail of golf ball to tennis ball size and possibly larger lasting for 3 to 5 minutes. Damage to house windows, vehicles and crops at Down To Earth Landscaping. In addition, at least 40 farm animals (combined chicken and geese) as well as a pig were killed due to fallen hail stones.

Lightning in CHITTENDEN, VERMONT
From 16-JUL-09 15:50:00 to 16-JUL-09 15:50:00 (EST-5)
Location: (BTV)BURLINGTON ARPT
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Airplane Pilot

Lightning struck a Jet Blue aircraft at the gate, while embarking passengers. The lightning bolt apparently entered the tail section and traveled along the length of the airplane to the gate ramp. No injuries but visible entrance and exit points on aircraft.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 16-JUL-09 15:47:00 to 16-JUL-09 15:47:00 (EST-5)
Location: (BTV)BURLINGTON ARPT
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tree downed by thunderstorm winds on Marshall Ave.