Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 1, NWS Riverton, WY
NWS Riverton, WY issued this severe thunderstorm warning at May 20, 2021, 3:16 PM MDT for Johnson County, Wyoming. It was in force for 30 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- May 20, 2021, 3:16 PM MDT (21:16 UTC)
- Expired
- May 20, 2021, 3:46 PM MDT
- In force
- 30 min
- Issued by
- NWS Riverton, WY
- Area
- Storm-based polygon
- Hail
- 1.0 in
- Wind
- 50.0 mph
County Johnson County, WY
The radar
The Riverton/Lander radar (KRIW), 204 km from the middle of the area, began a volume at 21:19 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, 9.3 hours before the alert went out and 198 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1758 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 167 m²/s²
- 0-3 km storm-relative helicity
- 232 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
907
WUUS55 KRIW 202116
SVRRIW
WYC019-202200-
/O.NEW.KRIW.SV.W.0001.210520T2116Z-210520T2200Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Riverton WY
316 PM MDT Thu May 20 2021
The National Weather Service in Riverton has issued a
* Severe Thunderstorm Warning for...
Southeastern Johnson County in north central Wyoming...
* Until 400 PM MDT.
* At 316 PM MDT, a severe thunderstorm was located near Fort Reno
Historical Site and Sussex, or 18 miles east of Kaycee, moving
north at 25 mph.
HAZARD...Quarter size hail.
SOURCE...Radar indicated.
IMPACT...Damage to vehicles is expected.
* This severe thunderstorm will be near...
Fort Reno Historical Site around 330 PM MDT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.
Very heavy rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4362 10616 4364 10637 4411 10645 4407 10601
4402 10601
TIME...MOT...LOC 2116Z 189DEG 21KT 4373 10628
HAIL...1.00IN
WIND...<50MPH
$$
McDonald2 follow-up statements
953
WWUS55 KRIW 202133
SVSRIW
Severe Weather Statement
National Weather Service Riverton WY
333 PM MDT Thu May 20 2021
WYC019-202200-
/O.CON.KRIW.SV.W.0001.000000T0000Z-210520T2200Z/
Johnson-
333 PM MDT Thu May 20 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM MDT
FOR SOUTHEASTERN JOHNSON COUNTY...
At 332 PM MDT, a severe thunderstorm was located near Fort Reno
Historical Site, or 25 miles northeast of Kaycee, moving north at 30
mph.
HAZARD...Quarter size hail.
SOURCE...Radar indicated.
IMPACT...Damage to vehicles is expected.
This severe thunderstorm will remain over mainly rural areas of
southeastern Johnson County, including the following locations...
Sussex.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.
Very heavy rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4367 10614 4370 10638 4411 10645 4407 10601
4402 10601
TIME...MOT...LOC 2132Z 184DEG 27KT 4391 10621
HAIL...1.00IN
WIND...<50MPH
$$
McDonald274
WWUS55 KRIW 202146
SVSRIW
Severe Weather Statement
National Weather Service Riverton WY
346 PM MDT Thu May 20 2021
WYC019-202156-
/O.CAN.KRIW.SV.W.0001.000000T0000Z-210520T2200Z/
Johnson-
346 PM MDT Thu May 20 2021
...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN JOHNSON COUNTY IS
CANCELLED...
The storms which prompted the warning have weakened below severe
limits, and have exited the warned area. Therefore, the warning has
been cancelled. However small hail, gusty winds and heavy rain are
still possible with these thunderstorms.
LAT...LON 4367 10614 4370 10638 4411 10645 4407 10601
4402 10601
TIME...MOT...LOC 2143Z 189DEG 21KT 4399 10619
$$
McDonaldThe office that day
Everything else NWS Riverton, WY issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 19, 6:15 PM MDT | Special Weather Statement | RIW | 30 min | |
| May 19, 6:17 PM MDT | Special Weather Statement | RIW | 28 min | |
| May 19, 6:20 PM MDT | Special Weather Statement | RIW | Big Horn | 25 min |
| May 19, 6:44 PM MDT | Special Weather Statement | RIW | 31 min | |
| May 19, 7:17 PM MDT | Special Weather Statement | RIW | 28 min | |
| May 19, 7:47 PM MDT | Special Weather Statement | RIW | 28 min | |
| May 19, 9:43 PM MDT | Special Weather Statement | RIW | Johnson | 32 min |
| May 19, 9:58 PM MDT | Special Weather Statement | RIW | Johnson | 32 min |
| May 19, 10:34 PM MDT | Special Weather Statement | RIW | Johnson | 26 min |
| May 19, 11:07 PM MDT | Special Weather Statement | RIW | Johnson | 23 min |
| May 20, 2:23 PM MDT | Special Weather Statement | RIW | Johnson | 22 min |
| May 20, 2:46 PM MDT | Special Weather Statement | RIW | Washakie | 29 min |
| May 20, 2:58 PM MDT | Special Weather Statement | RIW | Johnson | 32 min |
| May 20, 3:49 PM MDT | Severe Thunderstorm Warning | RIW | Johnson | 29 min |
| May 20, 5:22 PM MDT | Special Weather Statement | RIW | Johnson | 23 min |
Nearby
Severe Thunderstorm Warnings in Wyoming, 2021Every severe thunderstorm warning in 2021
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.