A combination of an abnormally strong upper level low, strong jet dynamics and an approaching cold front produced one of the biggest severe weather outbreaks across western and central Wyoming in many years. A total of 4 tornadoes were confirmed, including an EF2 tornado which was the strongest tornado that occurred in the NWS Riverton county warning area since 2001 which completely destroyed a trailer and threw it's base over 200 yards. There were also multiple reports of large hail, especially in Johnson County where hail up to tennis ball size was reported. In the dry slot across central and southern Wyoming, strong mid level winds mixed to the surface. The strongest winds were in the Lander foothills where wind gusts up to 76 mph occurred. Many trees were uprooted with some damage to outbuildings. Wind gusts 58 mph or over were also reported in Sweetwater County.

High Wind in GREEN MOUNTAINS & RATTLESNAKE RANGE, WYOMING
From 12-JUN-17 13:50:00 to 12-JUN-17 20:50:00 (MST-7)
Magnitude: 75.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

High winds occurred across much of the Green and Rattlesnake Ranges. The highest winds occurred at Camp Creek where several gusts of hurricane force occurred with a maximum gusts of 86 mph. Some other notable gusts included 82 mph at Fales Rock and 66 mph at Beaver Rim.

High Wind in EAST SWEETWATER COUNTY, WYOMING
From 12-JUN-17 14:00:00 to 12-JUN-17 14:45:00 (MST-7)
Magnitude: 55.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Strong winds occurred in portions of Eastern Sweetwater County. The strongest gust was 63 mph at Bitter Creek.

High Wind in ROCK SPRINGS & GREEN RIVER, WYOMING
From 12-JUN-17 14:00:00 to 12-JUN-17 16:00:00 (MST-7)
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

High winds occurred in portions of the Rock Springs and Green River areas. The highest gust reported was 62 mph at the site on the west side of Rock Springs.

High Wind in UPPER GREEN RIVER BASIN, WYOMING
From 12-JUN-17 13:11:00 to 12-JUN-17 14:50:00 (MST-7)
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

High winds occurred in portions of the Upper Green River Basin. The highest wind gust recorded was 67 mph at Farson. A 58 mph gust was recorded at the Big Piney airport.

High Wind in LANDER FOOTHILLS, WYOMING
From 12-JUN-17 16:42:00 to 12-JUN-17 17:57:00 (MST-7)
Magnitude: 66.00 MG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: ASOS

Very strong winds occurred across the Lander Foothills. Some of the strongest winds included 76 mph at the Lander Airport and 75 mph at the North Fork of the Popo Agie River. The wind downed many trees in and around Lander and ripped the roof off of a garage.

High Wind in WIND RIVER BASIN, WYOMING
From 12-JUN-17 18:46:00 to 12-JUN-17 18:46:00 (MST-7)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

The RAWS site at Sharpnose near Hudson reported a wind gust of 58 mph.

High Wind in SOUTHWEST BIG HORN BASIN, WYOMING
From 12-JUN-17 18:50:00 to 12-JUN-17 18:56:00 (MST-7)
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A pair of weather stations in Thermopolis reported wind gusts of 62 mph.

Hail in BIG HORN, WYOMING
From 12-JUN-17 15:00:00 to 12-JUN-17 15:05:00 (MST-7)
Location: MANDERSON
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The Big Horn County sheriff reported hail from the size of nickels up to the size of Ping Pong balls.

Tornado in NATRONA, WYOMING
From 12-JUN-17 17:36:00 to 12-JUN-17 17:37:00 (MST-7)
Location: BAR NUNN
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The Natrona County emergency manager reported a brief tornado touchdown to the west of Bar Nunn. The tornado remained over open country and did little damage.

Tornado in BIG HORN, WYOMING
From 12-JUN-17 17:14:00 to 12-JUN-17 17:23:00 (MST-7)
Location: WINCHESTER
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A supercell thunderstorm dropped a weak rope tornado that moved slowly northward in southern Big Horn County and skipped along around a 3 mile path. The tornado remained over open country and caused no damage.

Hail in NATRONA, WYOMING
From 12-JUN-17 17:05:00 to 17-JUN-17 17:20:00 (MST-7)
Location: EVANSVILLE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported hail up to the size of half dollars around Evansville.

Funnel Cloud in JOHNSON, WYOMING
From 12-JUN-17 17:42:00 to 12-JUN-17 17:42:00 (MST-7)
Location: BUFFALO
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

An off-duty NWS meteorologist reported a funnel cloud near the Trabing Road interchange of Interstate 25.

Hail in WASHAKIE, WYOMING
From 12-JUN-17 18:20:00 to 12-JUN-17 18:25:00 (MST-7)
Location: TEN SLEEP
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported quarter size hail to the east of Ten Sleep.

Hail in NATRONA, WYOMING
From 12-JUN-17 18:40:00 to 12-JUN-17 18:45:00 (MST-7)
Location: MIDWEST
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported hail up to the size of nickels in Midwest and Edgerton.

Flash Flood in JOHNSON, WYOMING
From 12-JUN-17 18:30:00 to 12-JUN-17 22:30:00 (MST-7)
Location: BUFFALO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A CocoRaHS reporter reported flash flooding along Crazy Woman Creek near the south end of Espinoza Road south of Interstate 90.

Hail in PARK, WYOMING
From 12-JUN-17 15:25:00 to 12-JUN-17 15:30:00 (MST-7)
Location: CODY FLYING L ARPT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported nickel size hail 10 miles west of Wapati.

Tornado in JOHNSON, WYOMING
From 12-JUN-17 16:30:00 to 12-JUN-17 16:36:00 (MST-7)
Location: KAYCEE GOSNEY ARPT
Tornado F-scale: EF2
Property damage: 10.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A storm survey was conducted near Kaycee and confirmed a tornado. The tornado touched down on a hill just west of Interstate 25 and just north of the Middle Fork of the Powder River. The tornado downed many trees moving down the hill. The tornado then strengthened as it crossed a field. An abandoned trailer was destroyed with the base thrown over 200 yards. Trees in the field were snapped off above the bases with some ground scouring noted. The tornado then crossed Barnum Road and moved northward toward Pine Ridge. The tornado narrowly missed a house and a barn as it moved up the ridge. Numerous trees were downed along both sides of the ridgeline before the funnel lifted. Winds were estimated at 110 to 120 mph, a minimal EF2 tornado.

Hail in JOHNSON, WYOMING
From 12-JUN-17 16:13:00 to 12-JUN-17 16:34:00 (MST-7)
Location: BARNUM
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A thunderstorm developed along the east side of the Bighorn Range and slowly strengthened. The storm became a supercell and dropped very large hail from Barnum to Kaycee. There were widespread reports of quarter size or bigger hail along the path. The largest report of hail was tennis ball size 5 miles southwest of Kaycee, not far from where a tornado developed. Hail up to the size of ping pong balls was reported in Barnum.

Tornado in PARK, WYOMING
From 12-JUN-17 16:50:00 to 12-JUN-17 16:52:00 (MST-7)
Location: (COD)YELLOWSTONE APT
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported a tornado that briefly touched down several times in the Oregon Basin southeast of Cody. The tornado remained over open country and caused no damage.