Alert archive / Wyoming / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 67, NWS Riverton, WY

July 17, 2018Johnson County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Jul 17, 2018, 2:54 PM MDT for Johnson County, Wyoming. It was in force for 36 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: Jul 17, 2018, 2:54 PM MDT (20:54 UTC)
Expired: Jul 17, 2018, 3:30 PM MDT
In force: 36 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

County Johnson County, WY

The radar

The Riverton/Lander radar (KRIW), 187 km from the middle of the area, began a volume at 20:55 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, 8.9 hours before the alert went out and 182 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: 90 J/kg
Mixed-layer CIN: -338 J/kg
Mixed-layer LCL: 1461 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 116 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 Jul 17, 11:59 AM MDT, 2 hours 55 minutes earlier.

Area forecast discussion, Jul 17, 11:59 AM MDT, 2 hours 55 minutes before

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Hazardous weather outlook, Jul 17, 1:34 AM MDT, 13 hours 20 minutes before

Hazardous Weather Outlook
National Weather Service Riverton WY
134 AM MDT Tue Jul 17 2018

WYZ001>020-022>030-181200-
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-
134 AM MDT Tue Jul 17 2018

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight

Isolated to widely scattered thunderstorms; most numerous in
northern and eastern areas. Hail and heavy rain are the main
threats.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Saturday and Sunday...Isolated thunderstorms, mainly in the
afternoon and evening hours.

Monday...Isolated late day thunderstorms, mainly along and east of
the divide.

.SPOTTER INFORMATION STATEMENT...

Spotters are urged to report hail, wind gusts over 45 mph and
heavy rainfall. Thank you.

In the hours before

Local storm report, Jul 17, 12:36 PM MDT, 2 hours 18 minutes before

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Local storm report, Jul 17, 12:38 PM MDT, 2 hours 16 minutes before

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Special weather statement, Jul 17, 1:37 PM MDT, 1 hour 17 minutes before

Special Weather Statement
National Weather Service Riverton WY
137 PM MDT TUE JUL 17 2018

WYZ003-004-172015-
North Big Horn Basin-Cody Foothills-
137 PM MDT TUE JUL 17 2018

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL PARK COUNTY UNTIL
215 PM MDT...

At 137 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles southwest of Ralston, or 9 miles northeast of Cody, moving east
at 15 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

This strong thunderstorm will be near...
  Ralston around 155 PM MDT.

Other locations impacted by this storm include Park County
Fairgrounds and Northwest College.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4456 10911 4472 10912 4479 10867 4449 10870
TIME...MOT...LOC 1937Z 273DEG 14KT 4464 10896

Baker

Special weather statement, Jul 17, 2:17 PM MDT, 37 minutes before

Special Weather Statement
National Weather Service Riverton WY
217 PM MDT TUE JUL 17 2018

WYZ012-013-172100-
Jackson Hole-Teton and Gros Ventre Mountains-
217 PM MDT TUE JUL 17 2018

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL TETON COUNTY UNTIL 300 PM
MDT...

At 216 PM MDT, Doppler radar was tracking a strong thunderstorm over
Mount Moran, or 13 miles northeast of Alta, moving east at 30 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

This strong thunderstorm will be near...
  Moran Bay and Leigh Lake around 225 PM MDT.
  Colter Bay Village around 235 PM MDT.
  Moran Junction around 245 PM MDT.
  Buffalo Valley Ranch around 255 PM MDT.

Other locations impacted by this storm include Grand Targhee Resort,
Lutons Log Cabins And Lodge, Signal Mountain Lodge, Leek's Marina,
Jackson Lake Lodge, Lost Creek Ranch And Spa and Jenny Lake Lodge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4374 11097 4390 11099 4404 11042 4368 11037
TIME...MOT...LOC 2016Z 265DEG 28KT 4384 11080

Baker

Special weather statement, Jul 17, 2:32 PM MDT, 22 minutes before

Special Weather Statement
National Weather Service Riverton WY
232 PM MDT TUE JUL 17 2018

WYZ002-003-172115-
Cody Foothills-Absaroka Mountains-
232 PM MDT TUE JUL 17 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN PARK COUNTY UNTIL
315 PM MDT...

At 231 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles southeast of Dead Indian Pass, or 14 miles northwest of Cody,
moving east at 30 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

This storm will remain over mainly rural areas of northeastern Park
County, including the following locations... Dead Indian Campground.

LAT...LON 4472 10892 4468 10890 4467 10887 4456 10885
      4457 10954 4472 10961 4483 10893
TIME...MOT...LOC 2031Z 266DEG 26KT 4466 10928

Baker

Special weather statement, Jul 17, 2:34 PM MDT, 20 minutes before

Special Weather Statement
National Weather Service Riverton WY
234 PM MDT TUE JUL 17 2018

WYZ003-004-172115-
North Big Horn Basin-Cody Foothills-
234 PM MDT TUE JUL 17 2018

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL BIG HORN AND EAST
CENTRAL PARK COUNTIES UNTIL 315 PM MDT...

At 234 PM MDT, Doppler radar was tracking a strong thunderstorm 12
miles east of Cody, moving east at 25 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

This storm will remain over mainly rural areas of west central Big
Horn and east central Park Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4440 10895 4451 10896 4458 10851 4433 10851
TIME...MOT...LOC 2034Z 265DEG 20KT 4446 10882

Baker

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 16, 6:19 PM MDT	Special Weather Statement	RIW	Hot Springs	26 min
Jul 16, 6:39 PM MDT	Special Weather Statement	RIW	Lincoln	36 min
Jul 16, 6:43 PM MDT	Special Weather Statement	RIW	Teton	47 min
Jul 16, 6:48 PM MDT	Special Weather Statement	RIW	Hot Springs	27 min
Jul 16, 7:14 PM MDT	Special Weather Statement	RIW	Lincoln	46 min
Jul 16, 7:15 PM MDT	Special Weather Statement	RIW	Hot Springs	30 min
Jul 16, 7:26 PM MDT	Special Weather Statement	RIW		49 min
Jul 16, 8:12 PM MDT	Special Weather Statement	RIW	Fremont	48 min
Jul 16, 8:52 PM MDT	Special Weather Statement	RIW	Fremont	38 min
Jul 16, 9:11 PM MDT	Special Weather Statement	RIW	Fremont	49 min
Jul 16, 9:43 PM MDT	Special Weather Statement	RIW	Fremont	32 min
Jul 16, 9:47 PM MDT	Special Weather Statement	RIW	Fremont	43 min
Jul 17, 1:37 PM MDT	Special Weather Statement	RIW		38 min
Jul 17, 2:17 PM MDT	Special Weather Statement	RIW	Teton	43 min
Jul 17, 2:20 PM MDT	Severe Thunderstorm Warning	RIW	Johnson	40 min
Jul 17, 2:32 PM MDT	Special Weather Statement	RIW	Park	43 min
Jul 17, 2:34 PM MDT	Special Weather Statement	RIW		41 min
Jul 17, 3:24 PM MDT	Special Weather Statement	RIW	Big Horn	21 min
Jul 17, 3:25 PM MDT	Severe Thunderstorm Warning	RIW	Johnson	35 min
Jul 17, 3:28 PM MDT	Special Weather Statement	RIW	Johnson	47 min
Jul 17, 3:41 PM MDT	Severe Thunderstorm Warning	RIW	Johnson	12 min
Jul 17, 4:02 PM MDT	Special Weather Statement	RIW	Hot Springs	28 min
Jul 17, 4:08 PM MDT	Special Weather Statement	RIW	Teton	37 min
Jul 17, 4:20 PM MDT	Special Weather Statement	RIW	Johnson	40 min
Jul 17, 4:23 PM MDT	Severe Thunderstorm Warning	RIW	Big Horn, Hot Springs, Washakie	37 min
Jul 17, 4:29 PM MDT	Special Weather Statement	RIW	Johnson	31 min
Jul 17, 4:32 PM MDT	Severe Thunderstorm Warning	RIW	Johnson	28 min
Jul 17, 4:44 PM MDT	Special Weather Statement	RIW	Hot Springs	31 min
Jul 17, 5:35 PM MDT	Special Weather Statement	RIW	Washakie	25 min
Jul 17, 5:52 PM MDT	Special Weather Statement	RIW	Fremont	23 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.