Alert archive / Wyoming / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 23, NWS Riverton, WY

May 31, 2018Teton County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at May 31, 2018, 2:21 PM MDT for Teton County, Wyoming. It was in force for 39 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 31, 2018, 2:21 PM MDT (20:21 UTC)
Expired: May 31, 2018, 3:00 PM MDT
In force: 39 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 50.0 mph

County Teton County, WY

The radar

The Pocatello radar (KSFX), 193 km from the middle of the area, began a volume at 20:22 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 31, 1:10 PM MDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Riverton, WY (KRIW), launched 12:00Z, 8.4 hours before the alert went out and 201 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1930 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 67 m²/s²
0-3 km storm-relative helicity: 172 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Riverton, WY wrote its last area forecast discussion before this severe thunderstorm warning went out at May 31, 1:23 PM MDT, 58 minutes earlier.

Area forecast discussion, May 31, 1:23 PM MDT, 58 minutes before

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Hazardous weather outlook, May 31, 1:29 PM MDT, 52 minutes before

Hazardous Weather Outlook
National Weather Service Riverton WY
129 PM MDT Thu May 31 2018

WYZ001>020-022>030-011930-
Yellowstone National Park-Absaroka Mountains-Cody Foothills-
North Big Horn Basin-Southwest Big Horn Basin-
Southeast Big Horn Basin-Owl Creek and Bridger Mountains-
Bighorn Mountains West-Bighorn Mountains Southeast-
Northeast Johnson County-Southeast Johnson County-
Teton and Gros Ventre Mountains-Jackson Hole-
Wind River Mountains West-Wind River Mountains East-
Upper Wind River Basin-Wind River Basin-Lander Foothills-
Green Mountains and Rattlesnake Range-
Natrona County Lower Elevations-Casper Mountain-Star Valley-
Salt River and Wyoming Ranges-Upper Green River Basin Foothills-
Upper Green River Basin-South Lincoln County-
Rock Springs and Green River-Flaming Gorge-East Sweetwater County-
129 PM MDT Thu May 31 2018

...A severe thunderstorm watch is in effect for Teton and Park
counties until 8 pm mdt this evening...

This Hazardous Weather Outlook is for Western and Central
Wyoming.

.DAY ONE...This Afternoon and Tonight.

A severe thunderstorm watch is in effect for Park County through
8 PM MDT this evening for large hail and wind gusts of 60 mph or
greater.

Scattered showers and thunderstorms, mainly in the north and
west.  Isolated thunderstorms across the south.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...Isolated to scattered showers and thunderstorms, mainly
across the north.

Monday...Isolated thunderstorms in the northern mountains.

Tuesday...Isolated thunderstorms across the north.

.SPOTTER INFORMATION STATEMENT...

Spotters are urged to report hail of any size, wind gusts of 45
mph or more, and any flooding. Thank you.

In the hours before

Special weather statement, May 31, 1:22 PM MDT, 59 minutes before

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Special weather statement, May 31, 1:23 PM MDT, 58 minutes before

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Special weather statement, May 31, 1:26 PM MDT, 55 minutes before

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Special weather statement, May 31, 1:39 PM MDT, 42 minutes before

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Special weather statement, May 31, 2:06 PM MDT, 15 minutes before

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Special weather statement, May 31, 2:06 PM MDT, 15 minutes before

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The office that day

Everything else NWS Riverton, WY issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 30, 7:11 PM MDT	Special Weather Statement	RIW		34 min
May 30, 10:19 PM MDT	Special Weather Statement	RIW	Fremont	26 min
May 30, 11:14 PM MDT	Special Weather Statement	RIW	Fremont	31 min
May 30, 11:31 PM MDT	Special Weather Statement	RIW	Fremont	29 min
May 31, 1:04 PM MDT	Special Weather Statement	RIW		41 min
May 31, 1:22 PM MDT	Special Weather Statement	RIW	Park	23 min
May 31, 1:23 PM MDT	Special Weather Statement	RIW	Lincoln	37 min
May 31, 1:26 PM MDT	Special Weather Statement	RIW	Hot Springs	34 min
May 31, 1:39 PM MDT	Special Weather Statement	RIW	Teton	51 min
May 31, 2:06 PM MDT	Special Weather Statement	RIW	Teton	39 min
May 31, 2:28 PM MDT	Special Weather Statement	RIW	Park	32 min
May 31, 2:30 PM MDT	Special Weather Statement	RIW	Teton	45 min
May 31, 2:33 PM MDT	Special Weather Statement	RIW		42 min
May 31, 2:58 PM MDT	Special Weather Statement	RIW	Teton	47 min
May 31, 3:04 PM MDT	Special Weather Statement	RIW		26 min
May 31, 3:14 PM MDT	Special Weather Statement	RIW	Johnson	31 min
May 31, 3:17 PM MDT	Special Weather Statement	RIW	Big Horn	43 min
May 31, 3:21 PM MDT	Special Weather Statement	RIW	Park	39 min
May 31, 3:56 PM MDT	Special Weather Statement	RIW	Teton	34 min
May 31, 4:00 PM MDT	Special Weather Statement	RIW	Big Horn	45 min
May 31, 4:12 PM MDT	Severe Thunderstorm Warning	RIW	Big Horn	48 min
May 31, 4:27 PM MDT	Special Weather Statement	RIW	Johnson	33 min
May 31, 5:00 PM MDT	Special Weather Statement	RIW	Johnson	30 min
May 31, 5:03 PM MDT	Special Weather Statement	RIW	Big Horn	42 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2018 Every severe thunderstorm warning in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.