Alert archive / Wyoming / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 22, NWS Riverton, WY

June 7, 2020Natrona County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Jun 7, 2020, 6:16 PM MDT for Natrona County, Wyoming. It was in force for 14 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: Jun 7, 2020, 6:16 PM MDT (00:16 UTC)
Expired: Jun 7, 2020, 6:30 PM MDT
In force: 14 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Natrona County, WY

The radar

The Riverton/Lander radar (KRIW), 137 km from the middle of the area, began a volume at 00:16 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 nearest sounding before it

Rapid City, SD (KUNR), launched 00:00Z, 0.3 hours before the alert went out and 339 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: 50 J/kg
Mixed-layer CIN: -68 J/kg
Mixed-layer LCL: 2941 m above ground
0-6 km bulk shear: 65 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 228 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.3

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 Jun 7, 5:54 PM MDT, 22 minutes earlier.

Area forecast discussion, Jun 7, 5:54 PM MDT, 22 minutes before

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Hazardous weather outlook, Jun 7, 11:15 AM MDT, 7 hours 1 minute before

Hazardous Weather Outlook
National Weather Service Riverton WY
1115 AM MDT Sun Jun 7 2020

WYZ001>020-022>030-081300-
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-
1115 AM MDT Sun Jun 7 2020

...A Slight Risk of Severe Thunderstorms Today for Portions of
Southern and Central Wyoming...

...Winter Weather Advisory for Teton and Gros Ventre Mountains and
Yellowstone Tonight and Monday Morning...

...Freeze Warning Tonight for the lower elevations of Western
Wyoming...

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Rest of Today and Tonight

Showers and thunderstorms will become widespread this afternoon
and evening. Some of the thunderstorms could be severe east of a
line from around Kemmerer to Riverton to Greybull. The main hazard
will be damaging winds.

Attention then turns to northwest Wyoming where accumulating snow
will fall in the western mountains mainly tonight into Monday
morning. The most significant impacts will be across the Teton
and Gros Ventre Mountains as well as Yellowstone National Park.

Low temperatures will drop below freezing in the lower elevations
of western Wyoming tonight.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Monday...Isolated to scattered showers and thunderstorms. Higher
elevation snow gradually ends in most locations by Monday night.

Friday and Saturday...Above normal temperatures, gusty southwest
wind, and low relative humidity could lead to elevated fire
weather conditions across southwest and central Wyoming.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions, especially wind gusts and wind damage.

In the hours before

Special weather statement, Jun 7, 5:06 PM MDT, 1 hour 10 minutes before

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Special weather statement, Jun 7, 5:23 PM MDT, 53 minutes before

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Special weather statement, Jun 7, 5:32 PM MDT, 44 minutes before

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Special weather statement, Jun 7, 5:55 PM MDT, 21 minutes before

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Special weather statement, Jun 7, 5:59 PM MDT, 17 minutes before

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Special weather statement, Jun 7, 5:59 PM MDT, 17 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
Jun 7, 6:33 PM MDT	Special Weather Statement	RIW	Johnson	27 min
Jun 8, 10:16 AM MDT	Special Weather Statement	RIW	Big Horn	44 min
Jun 8, 11:38 AM MDT	Freeze Warning	RIW	Fremont, Lincoln, Sublette, Sweetwater, Teton	21 hr
Jun 8, 1:51 PM MDT	Areal Flood Advisory	RIW	Lincoln, Sublette	48 hr

Nearby

Severe Thunderstorm Warnings in Wyoming, 2020 Every severe thunderstorm warning in 2020

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.