An energetic storm system moved from the Great Lakes across the St. Lawrence Valley into Ontario/Quebec during the afternoon and evening hours of May 4th. Instability was marginal for thunderstorm development during the evening hours with thunderstorms ahead of a cold front. However, winds were unseasonably strong in the atmosphere, accounting for some thunderstorms to produce damaging winds and there was some localized damage in non-thunderstorm winds accompanying the arrival of colder air.
Very brief heavy rainfall of up to 2 inches in less than an hour accounted for localized flash flooding and a mudslide. Strong winds and a lake level at/above flood stage caused for 4 to 6 foot waves to batter a causeway between Colchester and Grand Isle on Lake Champlain, resulting in numerous washouts and a closure of the causeway.

Flash Flood in CHITTENDEN, VERMONT
From 04-MAY-18 19:18:00 to 04-MAY-18 21:15:00 (EST-5)
Location: NASHVILLE
Flood cause: Heavy Rain
Property damage: 400.00K
Crop damage: 0.00K
Reported by: NWS Employee

Brief training thunderstorms dumped nearly an inch of rain within 10 minutes and up to 2 inches of rain in less than an hour. Several roads were flooded, including the corner of Bentley Lane and Nashville road in Nashville with partial road washouts in Richmond and greater washouts in Bolton.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 04-MAY-18 18:25:00 to 04-MAY-18 18:28:00 (EST-5)
Location: SHELBURNE
Magnitude: 60.00 EG
Property damage: 125.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Another round of thunderstorms produced additional damage in the form of trees, utility lines down and some structural damage from fallen trees, including roof damage.

Hail in CHITTENDEN, VERMONT
From 04-MAY-18 18:10:00 to 04-MAY-18 18:10:00 (EST-5)
Location: SHELBURNE
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Estimated dollar size hail or larger reported.

Hail in CHITTENDEN, VERMONT
From 04-MAY-18 18:20:00 to 04-MAY-18 18:20:00 (EST-5)
Location: WILLISTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter size hail reported.

Thunderstorm Wind in GRAND ISLE, VERMONT
From 04-MAY-18 17:18:00 to 04-MAY-18 17:20:00 (EST-5)
Location: ALBURG
Magnitude: 55.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Utility Company

Several trees down and power outages due to thunderstorms winds.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 04-MAY-18 17:58:00 to 04-MAY-18 18:00:00 (EST-5)
Location: COLCHESTER
Magnitude: 60.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Numerous trees and utility lines down due to thunderstorm winds across portions of Colchester.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 04-MAY-18 18:05:00 to 04-MAY-18 18:07:00 (EST-5)
Location: SHELBURNE
Magnitude: 65.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several reports of large trees and utility lines down across Shelburne.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 04-MAY-18 18:06:00 to 04-MAY-18 18:06:00 (EST-5)
Location: WESTFORD
Magnitude: 55.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Utility Company

Trees and utility lines down.

Thunderstorm Wind in ORLEANS, VERMONT
From 04-MAY-18 18:06:00 to 04-MAY-18 18:06:00 (EST-5)
Location: JAY
Magnitude: 55.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Trees and utility lines down.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 04-MAY-18 18:22:00 to 04-MAY-18 18:24:00 (EST-5)
Location: JERICHO
Magnitude: 55.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Public

Several trees and utility lines down on roads.

Thunderstorm Wind in CHITTENDEN, VERMONT
From 04-MAY-18 18:30:00 to 04-MAY-18 18:35:00 (EST-5)
Location: BOLTON
Magnitude: 55.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Trees down along Interstate 89 and adjacent Route 2.

Thunderstorm Wind in CALEDONIA, VERMONT
From 04-MAY-18 19:10:00 to 04-MAY-18 19:12:00 (EST-5)
Location: SHEFFIELD
Magnitude: 50.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Public

Several trees and utility lines down.

Thunderstorm Wind in ORANGE, VERMONT
From 04-MAY-18 19:39:00 to 04-MAY-18 19:40:00 (EST-5)
Location: BROOKFIELD
Magnitude: 60.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Utility Company

Multiple trees and utility lines down along Route 14.

Thunderstorm Wind in RUTLAND, VERMONT
From 04-MAY-18 19:39:00 to 04-MAY-18 19:40:00 (EST-5)
Location: PITTSFORD
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Several trees downed by thunderstorm winds.

Thunderstorm Wind in RUTLAND, VERMONT
From 04-MAY-18 19:45:00 to 04-MAY-18 19:47:00 (EST-5)
Location: DANBY
Magnitude: 55.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Utility Company

Numerous trees and utility lines down.

Thunderstorm Wind in WINDSOR, VERMONT
From 04-MAY-18 20:15:00 to 04-MAY-18 20:17:00 (EST-5)
Location: ASCUTNEY
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Public

Trees downed by thunderstorm winds.

Thunderstorm Wind in ESSEX, VERMONT
From 04-MAY-18 19:55:00 to 04-MAY-18 19:56:00 (EST-5)
Location: CONCORD
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Utility Company

Several trees and utility lines down.

Thunderstorm Wind in ORANGE, VERMONT
From 04-MAY-18 20:10:00 to 04-MAY-18 20:12:00 (EST-5)
Location: FAIRLEE
Magnitude: 55.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Utility Company

Trees and utility lines down along Rte 244.

Thunderstorm Wind in RUTLAND, VERMONT
From 04-MAY-18 19:44:00 to 04-MAY-18 19:44:00 (EST-5)
Location: DANBY FOUR CORNERS
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in ORANGE, VERMONT
From 04-MAY-18 20:13:00 to 04-MAY-18 20:15:00 (EST-5)
Location: THETFORD
Magnitude: 55.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Utility Company

Multiple trees and utility lines down.

Thunderstorm Wind in ESSEX, VERMONT
From 04-MAY-18 19:43:00 to 04-MAY-18 19:45:00 (EST-5)
Location: BRUNSWICK SPGS
Magnitude: 55.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Several trees downed by thunderstorm winds.

Lakeshore Flood in WESTERN CHITTENDEN, VERMONT
From 04-MAY-18 16:00:00 to 05-MAY-18 00:00:00 (EST-5)
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The lake level of Lake Champlain was at Flood Stage of 100 feet, which generally does little damage. However, a line of thunderstorms brought west winds of 40 to 60 mph for a few hours, then gradient winds of 35 to 50 mph for several more hours. The Colchester causeway is an old railroad line connecting Colchester with South Hero. Several hours of 1-2 foot surge and 4 to 6 foot waves battered the causeway and caused considerable erosion, closing the causeway for possibly the entire summer.

Hail in FRANKLIN, VERMONT
From 04-MAY-18 18:00:00 to 04-MAY-18 18:00:00 (EST-5)
Location: RICHFORD
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Dollar to possibly golf ball size hail reported.

Thunderstorm Wind in ORLEANS, VERMONT
From 04-MAY-18 19:00:00 to 04-MAY-18 19:02:00 (EST-5)
Location: GLOVER
Magnitude: 55.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: COOP Observer

Trees and utility lines down.

Hail in ORLEANS, VERMONT
From 04-MAY-18 19:02:00 to 04-MAY-18 19:02:00 (EST-5)
Location: GLOVER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Quarter size hail as well as trees and utility lines down.

Flash Flood in ORLEANS, VERMONT
From 04-MAY-18 20:14:00 to 04-MAY-18 22:00:00 (EST-5)
Location: WESTMORE
Flood cause: Heavy Rain
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Brief training of thunderstorms with rainfall amounts over an inch in less than an hour as well as saturated soils due to snow melt lead to a landslide at the south end of lake Willoughby, blocking parts of Route 5A.