Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 18, NWS Riverton, WY

September 3, 2021Sweetwater County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Sep 3, 2021, 3:23 PM MDT for Sweetwater County, Wyoming. It was in force for 37 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: Sep 3, 2021, 3:23 PM MDT (21:23 UTC)
Expired: Sep 3, 2021, 4:00 PM MDT
In force: 37 min
Issued by: NWS Riverton, WY
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Sweetwater County, WY

The radar

The Riverton/Lander radar (KRIW), 219 km from the middle of the area, began a volume at 21:25 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

Salt Lake City I, UT (KSLC), launched 12:00Z, 9.4 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.

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: 252 J/kg
Mixed-layer CIN: -183 J/kg
Mixed-layer LCL: 2006 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 135 m²/s²
0-3 km storm-relative helicity: 90 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

634 
WUUS55 KRIW 032123
SVRRIW
WYC037-032200-
/O.NEW.KRIW.SV.W.0018.210903T2123Z-210903T2200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Riverton WY
323 PM MDT Fri Sep 3 2021

The National Weather Service in Riverton has issued a

* Severe Thunderstorm Warning for...
  Southwestern Sweetwater County in south central Wyoming...

* Until 400 PM MDT.

* At 320 PM MDT, a severe thunderstorm was located near the McKinnon 
  Junction where Highway 1 intersects with Highway 530, or about 18 
  miles southwest of Green River, moving northeast at 15 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 move parallel to Highway 530 
  southeast of Green River. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds are likely 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.

&&

LAT...LON 4116 10968 4126 10984 4152 10961 4138 10939
TIME...MOT...LOC 2120Z 219DEG 12KT 4130 10967 

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

$$

21

1 follow-up statement

746 
WWUS55 KRIW 032151
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
351 PM MDT Fri Sep 3 2021

WYC037-032201-
/O.EXP.KRIW.SV.W.0018.000000T0000Z-210903T2200Z/
Sweetwater-
351 PM MDT Fri Sep 3 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN SWEETWATER COUNTY
WILL EXPIRE AT 400 PM MDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However small hail
and gusty winds are still possible with this thunderstorm.

LAT...LON 4116 10968 4126 10984 4152 10961 4138 10939
TIME...MOT...LOC 2151Z 216DEG 16KT 4143 10955 

$$

21

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 2, 8:23 PM MDT	Special Weather Statement	RIW	Uinta	37 min
Sep 2, 8:32 PM MDT	Special Weather Statement	RIW		28 min
Sep 2, 8:47 PM MDT	Special Weather Statement	RIW		43 min
Sep 2, 9:26 PM MDT	Special Weather Statement	RIW		34 min
Sep 2, 9:45 PM MDT	Special Weather Statement	RIW	Sublette	30 min
Sep 2, 10:56 PM MDT	Special Weather Statement	RIW	Johnson	19 min
Sep 3, 3:50 PM MDT	Special Weather Statement	RIW	Sweetwater	25 min
Sep 3, 4:11 PM MDT	Special Weather Statement	RIW	Sweetwater	34 min
Sep 3, 4:36 PM MDT	Special Weather Statement	RIW	Sweetwater	24 min

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.