Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 10, NWS Riverton, WY

August 4, 2021Natrona County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Aug 4, 2021, 8:25 PM MDT for Natrona County, Wyoming. It was in force for 50 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: Aug 4, 2021, 8:25 PM MDT (02:25 UTC)
Expired: Aug 4, 2021, 9:15 PM MDT
In force: 50 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Natrona County, WY

The radar

The Riverton/Lander radar (KRIW), 182 km from the middle of the area, began a volume at 02:26 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 00:00Z, 2.4 hours before the alert went out and 176 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: 26 J/kg
Mixed-layer CIN: -78 J/kg
Mixed-layer LCL: 3254 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 96 m²/s²
0-3 km storm-relative helicity: 223 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

As transmitted.

317 
WUUS55 KRIW 050225
SVRRIW
WYC025-050315-
/O.NEW.KRIW.SV.W.0010.210805T0225Z-210805T0315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Riverton WY
825 PM MDT Wed Aug 4 2021

The National Weather Service in Riverton has issued a

* Severe Thunderstorm Warning for...
  Southeastern Natrona County in central Wyoming...

* Until 915 PM MDT.

* At 824 PM MDT, a severe thunderstorm was located over eastern
  Casper, moving south at 35 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Public. At 820 PM, Quarter size hail was reported 
           in Evansville.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* This severe thunderstorm will be near...
  Beartrap Meadows County Park around 835 PM MDT.

This includes Interstate 25 between mile markers 176 and 188.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Heavy rainfall is occurring with this storm, and may lead to flash 
flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4243 10660 4295 10627 4293 10607 4243 10607
TIME...MOT...LOC 0224Z 358DEG 30KT 4283 10625 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Fisher

3 follow-up statements

838 
WWUS55 KRIW 050240
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
840 PM MDT Wed Aug 4 2021

WYC025-050315-
/O.CON.KRIW.SV.W.0010.000000T0000Z-210805T0315Z/
Natrona-
840 PM MDT Wed Aug 4 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 915 PM MDT
FOR SOUTHEASTERN NATRONA COUNTY...

At 839 PM MDT, a severe thunderstorm was located 8 miles east of
Beartrap Meadows County Park, or 11 miles southeast of Casper, moving
southeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

This severe thunderstorm will remain over mainly rural areas of
southeastern Natrona County, including the following locations...
Casper Mountain.

This includes Interstate 25 between mile markers 176 and 178.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4276 10630 4287 10607 4243 10607 4243 10625
TIME...MOT...LOC 0239Z 329DEG 29KT 4274 10615 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Fisher

195 
WWUS55 KRIW 050256
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
856 PM MDT Wed Aug 4 2021

WYC025-050315-
/O.CON.KRIW.SV.W.0010.000000T0000Z-210805T0315Z/
Natrona-
856 PM MDT Wed Aug 4 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 915 PM MDT
FOR SOUTHEASTERN NATRONA COUNTY...

At 855 PM MDT, a severe thunderstorm was located 12 miles west of
Boxelder, or 19 miles southeast of Casper, moving south at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

This severe thunderstorm will remain over mainly rural areas of
southeastern Natrona County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4263 10619 4270 10608 4243 10607 4243 10619
TIME...MOT...LOC 0255Z 347DEG 43KT 4260 10611 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Fisher

688 
WWUS55 KRIW 050306
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
906 PM MDT Wed Aug 4 2021

WYC025-050316-
/O.EXP.KRIW.SV.W.0010.000000T0000Z-210805T0315Z/
Natrona-
906 PM MDT Wed Aug 4 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN NATRONA COUNTY
WILL EXPIRE AT 915 PM MDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.

LAT...LON 4263 10619 4270 10608 4243 10607 4243 10619
TIME...MOT...LOC 0306Z 358DEG 30KT 4252 10611 

$$

Fisher

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 4, 8:05 PM MDT	Special Weather Statement	RIW	Natrona	25 min
Aug 5, 2:03 PM MDT	Red Flag Warning	RIW	Fremont, Lincoln, Natrona, Sweetwater, Uinta	30 hr

Nearby

Severe Thunderstorm Warnings in Wyoming, 2021 Every 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.