Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 99, NWS Salt Lake City, UT

September 2, 2021Rich County, Summit County, Utah; Uinta County, Wyoming

NWS Salt Lake City, UT issued this severe thunderstorm warning at Sep 2, 2021, 7:49 PM MDT for Rich County, Summit County, Utah; Uinta County, Wyoming. It was in force for 26 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 2, 2021, 7:49 PM MDT (01:49 UTC)
Expired
Sep 2, 2021, 8:15 PM MDT
In force
26 min
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Rich County, UT, Summit County, UT, Uinta County, WY

The radar

The Salt Lake City radar (KMTX), 127 km from the middle of the area, began a volume at 01:48 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 00:00Z, 1.8 hours before the alert went out and 95 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-pSkew-T log-p diagram, Salt Lake City I, UT at 00:00Z on 2021-09-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 942 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Salt Lake City I, UT at 00:00Z on 2021-09-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
942 J/kg
Mixed-layer CIN
-15 J/kg
Mixed-layer LCL
2400 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.6

Open this sounding in Storm Lab

The text

As transmitted.

128 
WUUS55 KSLC 030149
SVRSLC
UTC033-043-WYC041-030215-
/O.NEW.KSLC.SV.W.0099.210903T0149Z-210903T0215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
749 PM MDT Thu Sep 2 2021

The National Weather Service in Salt Lake City has issued a

* Severe Thunderstorm Warning for...
  Southeastern Rich County in northern Utah...
  North central Summit County in northern Utah...
  Western Uinta County in southwestern Wyoming...

* Until 815 PM MDT

* At 749 PM MDT, a severe thunderstorm was located near Evanston, 
  moving east at 35 mph. A wind gust to 60 mph was reported 
  along Interstate 80 near the Utah/Wyoming border with this storm.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

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

* Locations impacted include...
  Evanston, Ragen, Wahsatch, Almy, Altamont, Piedmont and Leroy. 

This includes the following highways...
 Interstate 80 in Wyoming between mile markers 1 and 27.
 Interstate 80 in Utah between mile markers 186 and 196.

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.

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

&&

LAT...LON 4103 11114 4142 11124 4153 11064 4109 11049
TIME...MOT...LOC 0149Z 259DEG 32KT 4123 11104 

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

$$

MT
2 follow-up statements
767 
WWUS55 KSLC 030202
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
802 PM MDT Thu Sep 2 2021

UTC033-043-WYC041-030215-
/O.CON.KSLC.SV.W.0099.000000T0000Z-210903T0215Z/
Rich UT-Summit UT-Uinta WY-
802 PM MDT Thu Sep 2 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM MDT
FOR SOUTHEASTERN RICH...NORTH CENTRAL SUMMIT AND WESTERN UINTA
COUNTIES...

At 801 PM MDT, a severe thunderstorm was located near Evanston, 
moving east at 35 mph. A wind gust to 71 mph was reported at 
Evanston airport with this storm. 

HAZARD...70 mph wind gusts. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Evanston, Ragen, Wahsatch, Almy, Altamont, Piedmont and Leroy. 

This includes the following highways...
 Interstate 80 in Wyoming between mile markers 1 and 27.
 Interstate 80 in Utah between mile markers 186 and 196.

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.

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

&&

LAT...LON 4103 11114 4142 11124 4153 11064 4109 11049
TIME...MOT...LOC 0201Z 259DEG 32KT 4125 11090 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

MT
674 
WWUS55 KSLC 030214
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
814 PM MDT Thu Sep 2 2021

UTC033-043-WYC041-030223-
/O.EXP.KSLC.SV.W.0099.000000T0000Z-210903T0215Z/
Rich UT-Summit UT-Uinta WY-
814 PM MDT Thu Sep 2 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN RICH...NORTH
CENTRAL SUMMIT AND WESTERN UINTA COUNTIES WILL EXPIRE AT 815 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, so it will be 
replaced by a Special Weather Statement through 845 pm.

LAT...LON 4103 11114 4142 11124 4153 11064 4109 11049
TIME...MOT...LOC 0213Z 259DEG 32KT 4127 11077 

$$

MT

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 2, 6:13 PM MDTSpecial Weather StatementSLCSalt Lake32 min
Sep 2, 6:29 PM MDTSevere Thunderstorm WarningSLCDavis, Morgan, Salt Lake31 min
Sep 2, 6:59 PM MDTSpecial Weather StatementSLCMorgan31 min
Sep 2, 7:31 PM MDTSpecial Weather StatementSLCSummit29 min
Sep 2, 8:15 PM MDTSpecial Weather StatementSLCUinta30 min

Nearby

Severe Thunderstorm Warnings in Utah, 2021Severe 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.