Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 92, NWS Salt Lake City, UT

August 21, 2021Uinta County, Wyoming; Summit County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 21, 2021, 7:08 PM MDT for Uinta County, Wyoming; Summit County, Utah. It was in force for 37 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 21, 2021, 7:08 PM MDT (01:08 UTC)
Expired: Aug 21, 2021, 7:45 PM MDT
In force: 37 min
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties Summit County, UT, Uinta County, WY

The radar

The Salt Lake City radar (KMTX), 134 km from the middle of the area, began a volume at 01:07 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.

What was reported inside it

Time	Report	Where	Remark
Aug 21, 7:40 PM MDT	TSTM WND GST 78	5 N Altamont, WY	MEASURED AT THE WYDOT SITE ALONG INTERSTATE 80 AT FRIST DIVIDE
Aug 21, 7:54 PM MDT	TSTM WND GST 58	4 Ese Leroy, WY	MEASURED AT THE WYDOT SITE ALONG INTERSTATE 80 AT FRENCH

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 00:00Z, 1.1 hours before the alert went out and 101 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: 422 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 2862 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 171 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.1

Open this sounding in Storm Lab

The text

As transmitted.

583 
WUUS55 KSLC 220108
SVRSLC
UTC043-WYC041-220145-
/O.NEW.KSLC.SV.W.0092.210822T0108Z-210822T0145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
708 PM MDT Sat Aug 21 2021

The National Weather Service in Salt Lake City has issued a

* Severe Thunderstorm Warning for...
  Central Summit County in northern Utah...
  Uinta County in southwestern Wyoming...

* Until 745 PM MDT

* At 706 PM MDT, a severe thunderstorm was located 11 miles south of
  Woodruff, or 14 miles northwest of Evanston, moving northeast at 55
  mph.  Additional strong storms are located south toward Coalville.

  HAZARD...70 mph wind gusts and penny size hail. 

  SOURCE...Trained weather spotters reported widespread damage with 
           this line of storms.  

  IMPACT...Expect considerable tree damage. Damage is likely to 
           mobile homes, roofs, and outbuildings. 

* Locations impacted include...
  Evanston, Oakley, Robertson, Ragen, Peoa, Millburne, Almy,
  Altamont, Piedmont, Carter, Leroy and Rockport State Park.

This includes the following highways...
 Interstate 80 in Wyoming between mile markers 1 and 35.
 US Route 40 near mile marker 5.
 Mirror Lake Highway between mile markers 41 and 54.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This is a DANGEROUS SITUATION. This storm is producing widespread 
wind damage across northern Utah. SEEK SHELTER NOW inside a sturdy 
structure and stay away from windows!

&&

LAT...LON 4158 11041 4092 11040 4066 11147 4098 11114
      4119 11104 4158 11104
TIME...MOT...LOC 0106Z 245DEG 47KT 4136 11122 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

crk

2 follow-up statements

053 
WWUS55 KSLC 220137
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
737 PM MDT Sat Aug 21 2021

UTC043-WYC041-220145-
/O.CON.KSLC.SV.W.0092.000000T0000Z-210822T0145Z/
Summit UT-Uinta WY-
737 PM MDT Sat Aug 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM MDT
FOR CENTRAL SUMMIT AND UINTA COUNTIES...

At 737 PM MDT, a severe thunderstorm was located 14 miles southwest
of Elkol, or 19 miles southwest of Kemmerer, moving northeast at 55
mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to roofs, siding, and trees. 

Locations impacted include...
Evanston, Oakley, Robertson, Ragen, Peoa, Millburne, Almy, Altamont,
Piedmont, Carter, Leroy and Rockport State Park.

This includes the following highways...
 Interstate 80 in Wyoming between mile markers 1 and 35.
 US Route 40 near mile marker 5.
 Mirror Lake Highway between mile markers 41 and 54.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4158 11041 4092 11040 4066 11147 4098 11114
      4119 11104 4158 11104
TIME...MOT...LOC 0137Z 245DEG 47KT 4153 11073 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH

$$

CRK

285 
WWUS55 KSLC 220141
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
741 PM MDT Sat Aug 21 2021

UTC043-WYC041-220151-
/O.EXP.KSLC.SV.W.0092.000000T0000Z-210822T0145Z/
Summit UT-Uinta WY-
741 PM MDT Sat Aug 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL SUMMIT AND UINTA
COUNTIES WILL EXPIRE AT 745 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 gusty
winds are still possible with this thunderstorm.

LAT...LON 4158 11041 4092 11040 4066 11147 4098 11114
      4119 11104 4158 11104
TIME...MOT...LOC 0141Z 245DEG 47KT 4152 11075 

$$

CRK

The office that day

Everything else NWS Salt Lake City, UT issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 21, 7:41 PM MDT	Special Weather Statement	SLC	Uinta	49 min
Aug 21, 7:45 PM MDT	Severe Thunderstorm Warning Destructive damage threat	SLC	Uinta	30 min
Aug 21, 8:07 PM MDT	Special Weather Statement	SLC	Uinta	38 min
Aug 21, 9:16 PM MDT	Special Weather Statement	SLC	Uinta	44 min
Aug 21, 6:06 PM MDT	Severe Thunderstorm Warning Considerable damage threat	SLC	Box Elder, Cache, Davis, Morgan, Rich, Salt Lake and 3 more	39 min
Aug 21, 6:29 PM MDT	Severe Thunderstorm Warning	SLC	Cache, Rich	61 min
Aug 21, 6:40 PM MDT	Severe Thunderstorm Warning Considerable damage threat	SLC	Box Elder, Cache, Davis, Morgan, Rich, Salt Lake and 3 more	50 min
Aug 21, 6:59 PM MDT	Areal Flood Advisory	SLC	Davis, Weber	2 hr
Aug 21, 7:23 PM MDT	Special Weather Statement	SLC	Salt Lake	37 min
Aug 21, 7:33 PM MDT	Areal Flood Advisory	SLC	Davis, Morgan, Salt Lake, Summit	117 min
Aug 21, 7:49 PM MDT	Special Weather Statement	SLC	Duchesne	41 min
Aug 21, 8:09 PM MDT	Special Weather Statement	SLC	Summit	51 min
Aug 21, 8:14 PM MDT	Special Weather Statement	SLC		31 min
Aug 21, 8:19 PM MDT	Severe Thunderstorm Warning	SLC	Duchesne, Summit	26 min
Aug 21, 8:32 PM MDT	High Wind Warning	SLC	Utah	3 hr
Aug 21, 9:59 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Salt Lake	91 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2021 Severe Thunderstorm Warnings in Utah, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.