Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 64, NWS Salt Lake City, UT

August 13, 2021Washington County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 13, 2021, 5:14 PM MDT for Washington County, Utah. It was in force for 16 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, 5:14 PM MDT (23:14 UTC)
Expired
Aug 13, 2021, 5:30 PM MDT
In force
16 min
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Hail
1.0 in
Wind
50.0 mph

County Washington County, UT

The radar

The Cedar City radar (KICX), 73 km from the middle of the area, began a volume at 23:16 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, 11.2 hours before the alert went out and 201 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°0°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.

846 
WUUS55 KSLC 132314
SVRSLC
UTC053-132345-
/O.NEW.KSLC.SV.W.0064.210813T2314Z-210813T2345Z/

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

The National Weather Service in Salt Lake City has issued a

* Severe Thunderstorm Warning for...
  Central Washington County in southwestern Utah...

* Until 545 PM MDT

* At 513 PM MDT, a severe thunderstorm was located near Washington,
  or 26 miles northeast of Virgin River Gorge, moving south at 20
  mph.

  HAZARD...Quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Damage to vehicles is expected. 

* Locations impacted include...
  Washington and Snow Canyon State Park. 

This includes the following highways...
 Interstate 15 near mile marker 14.
 Utah Route 18 between mile markers 9 and 10.

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 3720 11365 3733 11356 3727 11343 3715 11348
TIME...MOT...LOC 2313Z 022DEG 17KT 3723 11353 

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

$$

AD
1 follow-up statement
679 
WWUS55 KSLC 132330
SVSSLC

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

UTC053-132340-
/O.CAN.KSLC.SV.W.0064.000000T0000Z-210813T2345Z/
Washington UT-
530 PM MDT Fri Aug 13 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL WASHINGTON COUNTY IS
CANCELLED...
                
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 has been cancelled.  However heavy rain is
still possible with this thunderstorm.

LAT...LON 3720 11365 3733 11356 3727 11343 3715 11348
TIME...MOT...LOC 2327Z 022DEG 17KT 3715 11357 

$$

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, 4:20 PM MDTSevere Thunderstorm WarningSLCIron, Washington25 min
Aug 13, 4:40 PM MDTSevere Thunderstorm WarningSLCWashington35 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.