Several mid-atmospheric impulses traveled along a stationary boundary across northern Vermont during the early afternoon and evening hours of July 18th. This stationary boundary separated warm, humid air across much of Vermont from cooler, drier air across the international border with Canada.
Several rounds of thunderstorms moved across northern Vermont during the afternoon of July 18th. A developing squall line across the Champlain Valley of New York moved into northwest Vermont by mid-afternoon and continued across the state. Widespread tree and structural damage occurred with this system in Grand Isle, Franklin, Lamoille and Orleans counties.
This squall line interacted with an individual thunderstorm near Fletcher, that eventually produced an extensive damage path around 7 miles in length between North Cambridge and Waterville (Lamoille county), caused by straight-line winds of 60 to 80 mph. However, within this greater damage field was a tornadic storm with two very brief touchdown with EF0 and EF1 damage.
Another area of thunderstorms moved across central Vermont with pockets of significant damage across Addison, Washington and Orange counties.

Hail in CHITTENDEN, VERMONT
From 18-JUL-08 15:30:00 to 18-JUL-08 15:30:00 (EST-5)
Location: WEST BOLTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail reported at West Bolton golf course.

Hail in WINDSOR, VERMONT
From 18-JUL-08 15:30:00 to 18-JUL-08 15:30:00 (EST-5)
Location: SOUTH POMFRET
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Nickel size hail reported.

Thunderstorm Wind in ADDISON, VERMONT
From 18-JUL-08 14:20:00 to 18-JUL-08 14:20:00 (EST-5)
Location: NEW HAVEN JCT
Magnitude: 55.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Trees down and flag pole bent in Waltham.

Thunderstorm Wind in FRANKLIN, VERMONT
From 18-JUL-08 14:15:00 to 18-JUL-08 14:15:00 (EST-5)
Location: GEORGIA CENTER
Magnitude: 60.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Dozens of large trees down along Route 7 near Georgia Center. Additional tree, power line and some structural damage throughout Georgia.

Thunderstorm Wind in ADDISON, VERMONT
From 18-JUL-08 14:25:00 to 18-JUL-08 14:25:00 (EST-5)
Location: NEW HAVEN
Magnitude: 55.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous trees down between Waltham and New Haven, including a tree on a vehicle in New Haven.

Thunderstorm Wind in ADDISON, VERMONT
From 18-JUL-08 14:25:00 to 18-JUL-08 14:25:00 (EST-5)
Location: NEW HAVEN
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous trees down between New Haven and Waltham and East Middlebury. Several trees and power lines down in New Haven, including on a vehicle.

Thunderstorm Wind in ADDISON, VERMONT
From 18-JUL-08 14:55:00 to 18-JUL-08 14:55:00 (EST-5)
Location: GRANVILLE
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Post Office

Several trees down along Route 100 in Granville.

Thunderstorm Wind in ORANGE, VERMONT
From 18-JUL-08 15:40:00 to 18-JUL-08 15:40:00 (EST-5)
Location: THETFORD CENTER
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Post Office

Trees and power lines down in Thetford.

Thunderstorm Wind in WASHINGTON, VERMONT
From 18-JUL-08 14:55:00 to 18-JUL-08 14:55:00 (EST-5)
Location: NORTHFIELD
Magnitude: 55.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous trees and power lines downed by thunderstorm winds that have blocked several roads in Northfield.

Thunderstorm Wind in ORLEANS, VERMONT
From 18-JUL-08 15:00:00 to 18-JUL-08 15:00:00 (EST-5)
Location: LOWELL
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Post Office

Several trees down and power lines down in Lowell.

Thunderstorm Wind in ADDISON, VERMONT
From 18-JUL-08 14:30:00 to 18-JUL-08 14:30:00 (EST-5)
Location: NEW HAVEN MILLS
Magnitude: 55.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Widespread tree and power line damage between Middelbury, East Middlebury and New Haven on Route 116 and Quarry road. Trees fallen on roads and vehicles.

Hail in WASHINGTON, VERMONT
From 18-JUL-08 13:35:00 to 18-JUL-08 13:35:00 (EST-5)
Location: CABOT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail reported.

Hail in WASHINGTON, VERMONT
From 18-JUL-08 14:10:00 to 18-JUL-08 14:10:00 (EST-5)
Location: IRASVILLE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Post Office

Quarter size hail reported.

Thunderstorm Wind in ADDISON, VERMONT
From 18-JUL-08 14:18:00 to 18-JUL-08 14:18:00 (EST-5)
Location: FERRISBURG
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several trees down along Route 7 between Ferrisburg and Vergennes.

Thunderstorm Wind in FRANKLIN, VERMONT
From 18-JUL-08 14:20:00 to 18-JUL-08 14:20:00 (EST-5)
Location: BAKERSFIELD
Magnitude: 55.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees down and some structural damage across Bakersfield.

Thunderstorm Wind in FRANKLIN, VERMONT
From 18-JUL-08 14:13:00 to 18-JUL-08 14:13:00 (EST-5)
Location: ST ALBANS
Magnitude: 55.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Newspaper

Numerous trees down and some structural damage to homes, porches and decks across St. Albans.

Thunderstorm Wind in LAMOILLE, VERMONT
From 18-JUL-08 14:25:00 to 18-JUL-08 14:35:00 (EST-5)
Location: NORTH CAMBRIDGE
Magnitude: 65.00 EG
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Widespread and extensive damage between North Cambridge and Waterville, mainly from straight line winds estimated between 60 and 80 mph. Thousands of trees downed, uprooted or snapped and structural damage to several farms.

Tornado in LAMOILLE, VERMONT
From 18-JUL-08 14:27:00 to 18-JUL-08 14:27:00 (EST-5)
Location: NORTH CAMBRIDGE
Tornado F-scale: EF0
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Employee

A brief tornado touchdown along North Cambridge road with winds estimated at 80 mph with dozens of trees downed, snapped or uprooted along with some minor structural damage.

Thunderstorm Wind in GRAND ISLE, VERMONT
From 18-JUL-08 14:05:00 to 18-JUL-08 14:05:00 (EST-5)
Location: ISLE LA MOTTE
Magnitude: 60.00 EG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hundreds of trees downed by thunderstorms winds with several fallen on houses in Isle La Motte.

Thunderstorm Wind in GRAND ISLE, VERMONT
From 18-JUL-08 14:10:00 to 18-JUL-08 14:10:00 (EST-5)
Location: NORTH HERO
Magnitude: 60.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous trees and power lines down across North Hero and Route 2 between North Hero and Isle La Motte. Route 2 closed and several structures damaged as well.

Tornado in LAMOILLE, VERMONT
From 18-JUL-08 14:28:00 to 18-JUL-08 14:29:00 (EST-5)
Location: NORTH CAMBRIDGE
Tornado F-scale: EF1
Property damage: 100.00K
Crop damage: 0.00K
Reported by: NWS Employee

Another brief tornado touchdown occurred at a farmstead along Route 108 in North Cambridge. Winds were estimated between 80 and 100 mph. Hundreds of trees damaged or destroyed along with significant structural damage to house and barn.