Alert archive / Wyoming / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 10, NWS Riverton, WY

June 6, 2020Sweetwater County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Jun 6, 2020, 12:52 PM MDT for Sweetwater County, Wyoming. It was in force for 53 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 6, 2020, 12:52 PM MDT (18:52 UTC)
Expired
Jun 6, 2020, 1:45 PM MDT
In force
53 min
Issued by
NWS Riverton, WY
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Sweetwater County, WY

The radar

The Riverton/Lander radar (KRIW), 160 km from the middle of the area, began a volume at 18:54 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

Riverton, WY (KRIW), launched 12:00Z, 6.9 hours before the alert went out and 162 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-pSkew-T log-p diagram, Riverton, WY at 12:00Z on 2020-06-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Riverton, WY at 12:00Z on 2020-06-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -7 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
2034 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
-7 m²/s²
0-3 km storm-relative helicity
27 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 Jun 6, 11:53 AM MDT, 59 minutes earlier.

Area forecast discussion, Jun 6, 11:53 AM MDT, 59 minutes before
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Hazardous weather outlook, Jun 6, 3:59 AM MDT, 8 hours 53 minutes before
Hazardous Weather Outlook
National Weather Service Riverton WY
359 AM MDT Sat Jun 6 2020

WYZ001>020-022>030-071200-
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-
359 AM MDT Sat Jun 6 2020

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight.

Widespread afternoon and evening thunderstorms. Some of the
thunderstorms could be strong to severe. The main hazard will be
strong winds.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Sunday and Monday...Isolated to scattered showers and
thunderstorms. Higher elevation snow possible over far western
mountains.

Sunday night and, or Monday night...A widespread freeze is
possible over the west and south as well as the Dubois area.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions.

In the hours before

Special weather statement, Jun 6, 9:59 AM MDT, 2 hours 53 minutes before
Special Weather Statement
National Weather Service Riverton WY
959 AM MDT Sat Jun 6 2020

WYZ026>030-070000-
Upper Green River Basin-South Lincoln County-
Rock Springs and Green River-Flaming Gorge-East Sweetwater County-
Including the cities of La Barge, Big Piney, Farson, Kemmerer,
Cokeville, Rock Springs, Green River, and Wamsutter
959 AM MDT Sat Jun 6 2020

...Strong Wind Gusts Possible With Any Showers or Storms Today...

Scattered showers and thunderstorms will be capable of producing
gusty outflow wind today.

* WHAT...Outflow wind gusts of 40 to 55 mph with the potential for
  isolated gusts around 60 mph on exposed ridges and plateaus.

* WHERE...Southwest Wyoming, including much of Sweetwater and
  Sublette counties, and south Lincoln County.

* WHEN...Until Saturday 6 PM MDT.

* ADDITIONAL DETAILS...Any shower or storm, even one that is
  weakening, will be capable of producing these winds. Be prepared
  for strong winds along I-80, and US highways 189 and 191.
Special weather statement, Jun 6, 10:04 AM MDT, 2 hours 48 minutes before
Special Weather Statement
National Weather Service Riverton WY
1004 AM MDT Sat Jun 6 2020

WYZ013-023-061800-
Jackson Hole-Star Valley-
Including the cities of Jackson, Afton, Alpine,
Star Valley Ranch, and Thayne
1004 AM MDT Sat Jun 6 2020

...Strong Wind Gusts Possible With Any Showers or Thunderstorms
Through at Least Saturday Morning...

Scattered showers and thunderstorms will be capable of producing
gusty outflow wind until at least midday Saturday.

* WHAT...Outflow wind gusts of 40 to 50 mph.

* WHERE...Far West Wyoming, including Star Valley and Jackson Hole.

* WHEN...Until Saturday 12 PM MDT.

* ADDITIONAL DETAILS...Any shower or thunderstorm, even one that
  is weakening, will be capable of producing these winds.
Special weather statement, Jun 6, 10:14 AM MDT, 2 hours 38 minutes before
Special Weather Statement
National Weather Service Riverton WY
1014 AM MDT Sat Jun 6 2020

WYZ002-003-005-007-015>019-030-061715-
Owl Creek and Bridger Mountains-Wind River Basin-East Sweetwater
County-Upper Wind River Basin-Wind River Mountains East-Cody
Foothills-Green Mountains and Rattlesnake Range-Southwest Big Horn
Basin-Absaroka Mountains-Lander Foothills-
1014 AM MDT Sat Jun 6 2020

...SIGNIFICANT WEATHER ADVISORY FOR WESTERN HOT SPRINGS...
SOUTHWESTERN NATRONA...FREMONT...SOUTHEASTERN PARK AND NORTHEASTERN
SWEETWATER COUNTIES UNTIL 1115 AM MDT...

At 1010 AM MDT, Doppler radar was showers and thunderstorms along a
line extending from 11 miles east of Pinnacle Buttes to 16 miles
north of Creston Junction. Movement was east at 45 mph.

Wind gusts of 50 to 60 mph will be possible with these storms.
lander Hunt Field has already reported a gust of 45 mph.

Other locations impacted by these storms include Arapahoe, Midvale,
St Stephens, Bonneville, Riverton, Fremont County Fairgrounds,
Riverton Regional Airport and Lander Hunt Field.

This includes Interstate 80 between mile markers 189 and 198.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Occasional cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4392 11006 4402 11005 4401 10874 4244 10719
      4243 10752 4169 10751 4169 10766
TIME...MOT...LOC 1610Z 268DEG 40KT 4379 10972 4196 10780

Lipson

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 5, 6:33 PM MDTSpecial Weather StatementRIWLincoln42 min
Jun 5, 7:10 PM MDTSpecial Weather StatementRIW50 min
Jun 5, 7:13 PM MDTSpecial Weather StatementRIWFremont47 min
Jun 5, 7:50 PM MDTSpecial Weather StatementRIWSublette40 min
Jun 5, 7:53 PM MDTSpecial Weather StatementRIWHot Springs37 min
Jun 5, 8:32 PM MDTSpecial Weather StatementRIWSublette28 min
Jun 5, 9:00 PM MDTSpecial Weather StatementRIW45 min
Jun 6, 12:56 AM MDTSevere Thunderstorm WarningRIWFremont61 min
Jun 6, 1:46 AM MDTSevere Thunderstorm WarningRIWHot Springs, Johnson, Natrona, Washakie74 min
Jun 6, 10:14 AM MDTSpecial Weather StatementRIWFremont61 min
Jun 6, 1:26 PM MDTSevere Thunderstorm WarningRIWSweetwater64 min
Jun 6, 2:10 PM MDTSevere Thunderstorm WarningRIWSweetwater50 min
Jun 6, 2:32 PM MDTSevere Thunderstorm WarningRIWFremont, Natrona58 min
Jun 6, 2:58 PM MDTSpecial Weather StatementRIWFremont32 min
Jun 6, 3:14 PM MDTSevere Thunderstorm WarningRIWFremont61 min
Jun 6, 3:34 PM MDTSevere Thunderstorm WarningRIWFremont, Natrona56 min
Jun 6, 3:53 PM MDTSevere Thunderstorm WarningRIWJohnson, Natrona37 min
Jun 6, 3:59 PM MDTSevere Thunderstorm WarningRIWHot Springs, Washakie46 min
Jun 6, 4:35 PM MDTSevere Thunderstorm WarningRIWJohnson25 min
Jun 6, 4:51 PM MDTSpecial Weather StatementRIW54 min
Jun 6, 5:02 PM MDTSevere Thunderstorm WarningRIWBig Horn, Johnson30 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2020Every 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.