Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 113, NWS Salt Lake City, UT

September 12, 2021Box Elder County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Sep 12, 2021, 5:54 PM MDT for Box Elder County, Utah. It was in force for 51 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 12, 2021, 5:54 PM MDT (23:54 UTC)
Expired
Sep 12, 2021, 6:45 PM MDT
In force
51 min
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Box Elder County, UT

The radar

The Salt Lake City radar (KMTX), 101 km from the middle of the area, began a volume at 23:58 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, 11.9 hours before the alert went out and 112 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 2021-09-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 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 2021-09-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 10 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1594 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
10 m²/s²
0-3 km storm-relative helicity
135 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

177 
WUUS55 KSLC 122354
SVRSLC
UTC003-130045-
/O.NEW.KSLC.SV.W.0113.210912T2354Z-210913T0045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
554 PM MDT Sun Sep 12 2021

The National Weather Service in Salt Lake City has issued a

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

* Until 645 PM MDT

* At 554 PM MDT, a severe thunderstorm was located 16 miles west of
  Park Valley, or 33 miles southeast of Oakley Reservoir, moving east
  at 30 mph.

  HAZARD...60 mph wind gusts and quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees. 

* Locations impacted include...
  Park Valley and Rosette. 

This includes Utah Route 30 between mile markers 37 and 65.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4167 11375 4183 11375 4185 11310 4162 11310
TIME...MOT...LOC 2354Z 269DEG 25KT 4174 11363 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

CRK
4 follow-up statements
213 
WWUS55 KSLC 122359
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
559 PM MDT Sun Sep 12 2021

UTC003-130045-
/O.CON.KSLC.SV.W.0113.000000T0000Z-210913T0045Z/
Box Elder UT-
559 PM MDT Sun Sep 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM MDT
FOR NORTHWESTERN BOX ELDER COUNTY...

At 559 PM MDT, a severe thunderstorm was located 13 miles southwest
of Park Valley, or 34 miles southeast of Oakley Reservoir, moving
east at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees. 

Locations impacted include...
Park Valley and Rosette. 

This includes Utah Route 30 between mile markers 36 and 65.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4166 11367 4183 11360 4185 11310 4162 11310
TIME...MOT...LOC 2359Z 269DEG 25KT 4174 11358 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

CRK
068 
WWUS55 KSLC 130010
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
610 PM MDT Sun Sep 12 2021

UTC003-130045-
/O.CON.KSLC.SV.W.0113.000000T0000Z-210913T0045Z/
Box Elder UT-
610 PM MDT Sun Sep 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM MDT
FOR NORTH CENTRAL BOX ELDER COUNTY...

At 610 PM MDT, a severe thunderstorm was located near Park Valley, or
37 miles south of Malta, moving east at 35 mph.

HAZARD...60 mph wind gusts and penny size hail. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Park Valley and Rosette. 

This includes Utah Route 30 between mile markers 41 and 65.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4172 11355 4182 11352 4185 11310 4169 11310
TIME...MOT...LOC 0010Z 261DEG 29KT 4177 11344 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

CRK
346 
WWUS55 KSLC 130021
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
621 PM MDT Sun Sep 12 2021

UTC003-130045-
/O.CON.KSLC.SV.W.0113.000000T0000Z-210913T0045Z/
Box Elder UT-
621 PM MDT Sun Sep 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM MDT
FOR NORTH CENTRAL BOX ELDER COUNTY...

At 621 PM MDT, a severe thunderstorm was located over Park Valley, or
33 miles west of Snowville, moving east at 35 mph.

HAZARD...60 mph wind gusts and penny size hail. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Park Valley and Rosette. 

This includes Utah Route 30 between mile markers 50 and 65.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4176 11343 4183 11344 4185 11310 4174 11310
TIME...MOT...LOC 0021Z 257DEG 31KT 4180 11332 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

CRK
686 
WWUS55 KSLC 130035
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
635 PM MDT Sun Sep 12 2021

UTC003-130045-
/O.EXP.KSLC.SV.W.0113.000000T0000Z-210913T0045Z/
Box Elder UT-
635 PM MDT Sun Sep 12 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL BOX ELDER COUNTY
WILL EXPIRE AT 645 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.

LAT...LON 4176 11343 4183 11344 4185 11310 4174 11310
TIME...MOT...LOC 0035Z 269DEG 25KT 4180 11321 

$$

CRK

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 11, 6:19 PM MDTFlash Flood Warning Considerable damage threatSLCEmery, Garfield, Wayne3 hr
Sep 11, 6:30 PM MDTSpecial Weather StatementSLCJuab45 min
Sep 11, 7:16 PM MDTSpecial Weather StatementSLCJuab44 min
Sep 11, 7:24 PM MDTSpecial Weather StatementSLC51 min
Sep 11, 8:15 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Wayne3 hr
Sep 11, 8:22 PM MDTSpecial Weather StatementSLCSanpete38 min
Sep 11, 9:06 PM MDTSpecial Weather StatementSLCSanpete39 min
Sep 12, 3:29 PM MDTSpecial Weather StatementSLCBox Elder46 min
Sep 12, 3:37 PM MDTSevere Thunderstorm WarningSLCBox Elder23 min
Sep 12, 3:54 PM MDTSevere Thunderstorm WarningSLCBox Elder51 min
Sep 12, 4:13 PM MDTSpecial Weather StatementSLCBox Elder47 min
Sep 12, 4:31 PM MDTSevere Thunderstorm WarningSLCBox Elder44 min
Sep 12, 4:42 PM MDTSevere Thunderstorm WarningSLCBox Elder24 min
Sep 12, 5:08 PM MDTSevere Thunderstorm WarningSLCBox Elder20 min
Sep 12, 5:14 PM MDTSpecial Weather StatementSLC46 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.