A large upper level low spinning slowly east from southern Idaho helped to trigger severe thunderstorms across the north half of Wyoming. Surface dew points in the 50s (degrees F), a favorable jet stream location, and a front sliding south from Montana all combined to set the stage for thunderstorms. The storms formed late in the afternoon and persisted through the evening and into the early morning hours.

Hail in JOHNSON, WYOMING
From 07-AUG-09 21:25:00 to 07-AUG-09 21:25:00 (MST-7)
Location: MAYOWORTH
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Nickel sized hail fell near Mayoworth.

Hail in JOHNSON, WYOMING
From 07-AUG-09 21:20:00 to 07-AUG-09 21:25:00 (MST-7)
Location: KAYCEE GOSNEY ARPT
Magnitude: 2.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Hail of 1.75 to 2.00 inches in diameter fell at a ranch northwest of Kaycee on State Highway 191. The hail broke a vehicle window.

Hail in BIG HORN, WYOMING
From 07-AUG-09 15:51:00 to 07-AUG-09 15:51:00 (MST-7)
Location: OTTO
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Half dollar sized hail struck a ranch near Otto.

Thunderstorm Wind in BIG HORN, WYOMING
From 07-AUG-09 16:24:00 to 07-AUG-09 16:24:00 (MST-7)
Location: GREYBULL ARPT
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Northwest wind gusted to 51 knots at the South Big Horn County Airport near Greybull.

Hail in JOHNSON, WYOMING
From 07-AUG-09 22:20:00 to 07-AUG-09 22:20:00 (MST-7)
Location: BUFFALO
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The Powder River Rest Area along Interstate 90 was bombarded with hail of nickel to golf ball size.

Hail in NATRONA, WYOMING
From 08-AUG-09 01:10:00 to 08-AUG-09 01:10:00 (MST-7)
Location: CASPER HARFORD ARPT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Nickel sized hail occurred near the Ormsby Road exit on Interstate 25 north of Casper.

Hail in BIG HORN, WYOMING
From 07-AUG-09 16:15:00 to 07-AUG-09 16:15:00 (MST-7)
Location: GREYBULL
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail of 2.00 to 2.50 inches was measured on the east side of the Greybull River above Greybull.

Hail in BIG HORN, WYOMING
From 07-AUG-09 15:44:00 to 07-AUG-09 15:44:00 (MST-7)
Location: BURLINGTON
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 25.00K
Reported by: Trained Spotter

Hail of quarter to half dollar size fell at a ranch southeast of Burlington.

Hail in BIG HORN, WYOMING
From 07-AUG-09 16:10:00 to 07-AUG-09 16:15:00 (MST-7)
Location: GREYBULL
Magnitude: 2.00 
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hailstones of golf ball size were numerous at a residence in Greybull. Some stones reached two inches in diameter.

Hail in BIG HORN, WYOMING
From 07-AUG-09 16:17:00 to 07-AUG-09 16:17:00 (MST-7)
Location: GREYBULL
Magnitude: 2.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail estimated at two inches in diameter dented the hood of a traveling vehicle. Most of the stones were the size of a half dollar coin.