Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 62, NWS Salt Lake City, UT

August 13, 2021Iron County, Washington County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 13, 2021, 4:20 PM MDT for Iron County, Washington County, Utah. It was in force for 25 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 13, 2021, 4:20 PM MDT (22:20 UTC)
Expired
Aug 13, 2021, 4:45 PM MDT
In force
25 min
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Hail
1.0 in
Wind
50.0 mph

Counties Iron County, UT, Washington County, UT

The radar

The Cedar City radar (KICX), 43 km from the middle of the area, began a volume at 22:22 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

Las Vegas, NV (KVEF), launched 12:00Z, 10.3 hours before the alert went out and 233 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, Las Vegas, NV at 12:00Z on 2021-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 487 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, Las Vegas, NV at 12:00Z on 2021-08-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -8 square meters per square second.1939Sfc1 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
487 J/kg
Mixed-layer CIN
-323 J/kg
Mixed-layer LCL
2453 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
-8 m²/s²
0-3 km storm-relative helicity
80 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

059 
WUUS55 KSLC 132220
SVRSLC
UTC021-053-132245-
/O.NEW.KSLC.SV.W.0062.210813T2220Z-210813T2245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
420 PM MDT Fri Aug 13 2021

The National Weather Service in Salt Lake City has issued a

* Severe Thunderstorm Warning for...
  North central Washington County in southwestern Utah...
  South central Iron County in southern Utah...

* Until 445 PM MDT

* At 419 PM MDT, a severe thunderstorm was located near New Harmony,
  or 16 miles southwest of Cedar City, and is nearly stationary.

  HAZARD...Quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Damage to vehicles is expected. 

* Locations impacted include...
  New Harmony, Kanarraville and Kolob Canyon. 

This includes the following highways...
 Interstate 15 between mile markers 40 and 48.
 Utah Route 56 between mile markers 43 and 46.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3756 11347 3764 11333 3752 11311 3738 11335
TIME...MOT...LOC 2219Z 322DEG 4KT 3754 11332 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

AD
2 follow-up statements
065 
WWUS55 KSLC 132235
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
435 PM MDT Fri Aug 13 2021

UTC021-053-132245-
/O.CON.KSLC.SV.W.0062.000000T0000Z-210813T2245Z/
Washington UT-Iron UT-
435 PM MDT Fri Aug 13 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM MDT
FOR NORTH CENTRAL WASHINGTON AND SOUTH CENTRAL IRON COUNTIES...

At 434 PM MDT, a severe thunderstorm was located near New Harmony, or
16 miles southwest of Cedar City, and is nearly stationary.

HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
New Harmony, Kanarraville and Kolob Canyon. 

This includes the following highways...
 Interstate 15 between mile markers 40 and 48.
 Utah Route 56 between mile markers 43 and 46.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3756 11347 3764 11333 3752 11311 3738 11335
TIME...MOT...LOC 2234Z 322DEG 4KT 3753 11331 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

AD
688 
WWUS55 KSLC 132242
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
442 PM MDT Fri Aug 13 2021

UTC021-053-132251-
/O.EXP.KSLC.SV.W.0062.000000T0000Z-210813T2245Z/
Washington UT-Iron UT-
442 PM MDT Fri Aug 13 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL WASHINGTON AND
SOUTH CENTRAL IRON COUNTIES WILL EXPIRE AT 445 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 heavy rain
is still possible with this thunderstorm.

LAT...LON 3756 11347 3764 11333 3752 11311 3738 11335
TIME...MOT...LOC 2241Z 322DEG 4KT 3752 11330 

$$

AD

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 12, 6:26 PM MDTFlash Flood Warning Considerable damage threatSLCWashington114 min
Aug 13, 4:40 PM MDTSevere Thunderstorm WarningSLCWashington35 min
Aug 13, 5:14 PM MDTSevere Thunderstorm WarningSLCWashington16 min

Nearby

Severe Thunderstorm Warnings in Utah, 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.