Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 102, NWS Salt Lake City, UT

September 10, 2021Box Elder County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Sep 10, 2021, 5:04 PM MDT for Box Elder County, Utah. 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 10, 2021, 5:04 PM MDT (23:04 UTC)
Expired
Sep 10, 2021, 5:30 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

County Box Elder County, UT

The radar

The Salt Lake City radar (KMTX), 83 km from the middle of the area, began a volume at 23:04 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

Elko, NV (KLKN), launched 12:00Z, 11.1 hours before the alert went out and 128 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, Elko, NV at 12:00Z on 2021-09-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3 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, Elko, NV at 12:00Z on 2021-09-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -85 square meters per square second.19395878Sfc1 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
3 J/kg
Mixed-layer CIN
-243 J/kg
Mixed-layer LCL
2286 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
-85 m²/s²
0-3 km storm-relative helicity
48 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

235 
WUUS55 KSLC 102304
SVRSLC
UTC003-102330-
/O.NEW.KSLC.SV.W.0102.210910T2304Z-210910T2330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
504 PM MDT Fri Sep 10 2021

The National Weather Service in Salt Lake City has issued a

* Severe Thunderstorm Warning for...
  Northwestern Box Elder County in northern Utah...

* Until 530 PM MDT

* At 504 PM MDT, severe thunderstorms were located along a line
  extending from 9 miles northwest of Park Valley to 32 miles south
  of Almo, moving northeast at 35 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

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

* Locations impacted include...
  Park Valley, Curlew Junction, Rosette, Yost and Standrod. 

This includes Utah Route 30 between mile markers 30 and 81.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4160 11296 4156 11361 4199 11356 4199 11293
TIME...MOT...LOC 2304Z 224DEG 30KT 4190 11347 4163 11354 

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

$$

Webber
2 follow-up statements
757 
WWUS55 KSLC 102316
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
516 PM MDT Fri Sep 10 2021

UTC003-102330-
/O.CON.KSLC.SV.W.0102.000000T0000Z-210910T2330Z/
Box Elder UT-
516 PM MDT Fri Sep 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM MDT
FOR NORTH CENTRAL BOX ELDER COUNTY...

At 516 PM MDT, severe thunderstorms were located along a line
extending from 10 miles north of Park Valley to 29 miles south of
Almo, moving east at 35 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Park Valley, Curlew Junction, Rosette, Yost and Standrod. 

This includes Utah Route 30 between mile markers 44 and 81.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4162 11297 4168 11350 4199 11356 4199 11293
TIME...MOT...LOC 2316Z 270DEG 30KT 4196 11340 4169 11347 

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

$$

Webber
279 
WWUS55 KSLC 102329
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
529 PM MDT Fri Sep 10 2021

UTC003-102339-
/O.EXP.KSLC.SV.W.0102.000000T0000Z-210910T2330Z/
Box Elder UT-
529 PM MDT Fri Sep 10 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL BOX ELDER COUNTY
WILL EXPIRE AT 530 PM MDT...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

LAT...LON 4162 11297 4168 11350 4199 11356 4199 11293
TIME...MOT...LOC 2329Z 270DEG 30KT 4200 11334 4174 11341 

$$

Webber

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 10, 7:25 AM MDTSpecial Weather StatementSLCIron50 min
Sep 10, 1:38 PM MDTSpecial Weather StatementSLCSanpete52 min
Sep 10, 2:04 PM MDTSpecial Weather StatementSLCSalt Lake41 min
Sep 10, 2:07 PM MDTSpecial Weather StatementSLCSevier38 min
Sep 10, 2:23 PM MDTSevere Thunderstorm WarningSLCDavis, Morgan, Salt Lake, Weber37 min
Sep 10, 3:56 PM MDTSpecial Weather StatementSLCSummit49 min
Sep 10, 4:29 PM MDTSpecial Weather StatementSLCTooele61 min
Sep 10, 4:38 PM MDTSpecial Weather StatementSLCRich52 min
Sep 10, 4:41 PM MDTSpecial Weather StatementSLCBox Elder64 min
Sep 10, 5:51 PM MDTSpecial Weather StatementSLCDavis54 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.