Alert archive / Utah / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 71, NWS Salt Lake City, UT

August 22, 2026Box Elder County, Tooele County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 22, 2026, 5:14 PM MDT for Box Elder County, Tooele County, Utah. It was in force for 27 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 22, 2026, 5:14 PM MDT (23:14 UTC)
Expired
Aug 22, 2026, 5:41 PM MDT
In force
27 min
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Hail
1.0 in
Wind
70.0 mph

Counties Box Elder County, UT, Tooele County, UT

The radar

The Salt Lake City radar (KMTX), 96 km from the middle of the area, began a volume at 23:15 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.

What was reported inside it

TimeReportWhereRemark
Aug 22, 5:15 PM MDTTSTM WND GST 6210 W Knolls, UTUDOT Interstate 80.
Aug 22, 5:20 PM MDTTSTM WND GST 6410 W Knolls, UTUDOT Interstate 80.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 2 storm reports to this severe thunderstorm warning; the first came 1 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 11.2 hours before the alert went out and 127 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 12:00Z on 2026-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 18 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, Salt Lake City I, UT at 12:00Z on 2026-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 37 square meters per square second.193958Sfc1 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
18 J/kg
Mixed-layer CIN
-294 J/kg
Mixed-layer LCL
1899 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
37 m²/s²
0-3 km storm-relative helicity
97 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

986 
WUUS55 KSLC 222314
SVRSLC
UTC003-045-230000-
/O.NEW.KSLC.SV.W.0071.260822T2314Z-260823T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
514 PM MDT Sat Aug 22 2026

The National Weather Service in Salt Lake City has issued a

* Severe Thunderstorm Warning for...
  Southwestern Box Elder County in northern Utah...
  North central Tooele County in northern Utah...

* Until 600 PM MDT.

* At 512 PM MDT, a severe thunderstorm was located 10 miles west of
  Knolls, or 29 miles east of Wendover, moving northeast at 25 mph.

  HAZARD...70 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect considerable 
           tree damage. Wind damage is also likely to mobile homes, 
           roofs, and outbuildings.

* Locations impacted include...
  Utah Test and Training Range North.

This includes Interstate 80 in Utah between mile markers 26 and 36.
 
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 4067 11349 4077 11361 4106 11338 4084 11308
TIME...MOT...LOC 2312Z 225DEG 20KT 4076 11347 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

JCW
2 follow-up statements
968 
WWUS55 KSLC 222328
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
528 PM MDT Sat Aug 22 2026

UTC003-045-230000-
/O.CON.KSLC.SV.W.0071.000000T0000Z-260823T0000Z/
Box Elder UT-Tooele UT-
528 PM MDT Sat Aug 22 2026

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM MDT
FOR SOUTHWESTERN BOX ELDER AND NORTH CENTRAL TOOELE COUNTIES...

At 528 PM MDT, a severe thunderstorm was located 7 miles northwest of
Knolls, or 34 miles east of Wendover, moving east at 25 mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

Locations impacted include...
Utah Test and Training Range North.

This includes Interstate 80 in Utah between mile markers 31 and 32.
 
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 4072 11346 4081 11357 4106 11338 4084 11308
TIME...MOT...LOC 2328Z 270DEG 20KT 4080 11337 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

JCW
660 
WWUS55 KSLC 222341
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
541 PM MDT Sat Aug 22 2026

UTC003-045-222351-
/O.CAN.KSLC.SV.W.0071.000000T0000Z-260823T0000Z/
Box Elder UT-Tooele UT-
541 PM MDT Sat Aug 22 2026

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN BOX ELDER AND
NORTH CENTRAL TOOELE COUNTIES 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 gusty winds and
heavy rain are still possible with this thunderstorm.

LAT...LON 4072 11346 4081 11357 4106 11338 4084 11308
TIME...MOT...LOC 2339Z 225DEG 20KT 4085 11330 

$$

JCW

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Salt Lake City, UT wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 22, 1:35 PM MDT, 3 hours 39 minutes earlier. Its key messages:

  • There is a Marginal Risk (level 1/4) for excessive rainfall across most of the region through the weekend.
  • There is a Marginal Risk (level 1/5) for severe thunderstorms across portions of northwestern Utah today. There is a 5-10% chance of wind gusts in excess of 58 mph in this area through the evening.
  • A Slight Risk (level 2/5) for severe thunderstorms is outlooked for Sunday afternoon and evening across much of northern Utah. There is a 10% chance of wind gusts in excess of 70 mph with these thunderstorms Sunday afternoon and evening.
Area forecast discussion, Aug 22, 1:35 PM MDT, 3 hours 39 minutes before
Area Forecast Discussion
National Weather Service Salt Lake City UT
135 PM MDT Sat Aug 22 2026

.KEY MESSAGES...

- There is a Marginal Risk (level 1/4) for excessive rainfall
  across most of the region through the weekend.

- There is a Marginal Risk (level 1/5) for severe thunderstorms
  across portions of northwestern Utah today. There is a 5-10%
  chance of wind gusts in excess of 58 mph in this area through
  the evening.

- A Slight Risk (level 2/5) for severe thunderstorms is outlooked
  for Sunday afternoon and evening across much of northern Utah.
  There is a 10% chance of wind gusts in excess of 70 mph with
  these thunderstorms Sunday afternoon and evening.

&&

.DISCUSSION...Increased moisture across the region will support
thunderstorms capable of heavy rainfall rates. With relatively
slow storm motions today, already seeing convection anchored on
terrain training in locations and producing localized flooding of
small streams and dry washes. Will need to continue to monitor
central and southern Utah through the evening as rainfall rates in
excess of 0.50-0.75 inches per hour have been observed. The most
prone locations will be slot canyons, normally dry washes, slick
rock areas, areas with poor drainage and of course the numerous
recent burn scars across the region.

Across northwestern Utah, CAMS suggest the threat of strong to
severe microburst winds. One inhibiting factor will be the mid-
morning to early afternoon convection that moved across
northwestern Utah. This likely stabilized the atmosphere a
bit...and additional convective potential may be suppressed for
several hours. While earlier runs of the HRRR showed significant
wind gusts impacting northwestern Utah and perhaps the Wasatch
Front in the 21Z-02Z timeframe, later runs have largely shifted
away from this solution. Mesoanalysis correlates a fair amount of
inhibition...and guidance suggests this CIN may not be overcome by
the end of peak heating.

Sunday looks to be a potentially interesting day convection-wise.
A weak area of convergence associated with a Pacific trough will
shift into northwestern Utah. Mean HREF SBCAPE values will near
1000 J/kg across much of northern Utah by noon to 1 PM. This
combined with deep layer shear around 25-30 kts and general
synoptic scale lift will support convective development across
much of Utah after noon. The most intense convection will likely
be across northern Utah. HREF suggests a neighborhood probability
of wind gusts in excess of 55 mph around 15-25%, especially near
and west of the Great Salt Lake, and 10% or so in excess of 60
mph. The Storm Prediction Center has outlooked this area with a
slight risk (level 2/5) for Sunday afternoon and evening including
the Wasatch Front.

Across central and southern Utah, another day of thunderstorms
with the threat of heavy rainfall is expected. Peak rainfall rates
in guidance are notably lower than Saturday, correlating well with
a net drying trend. That said, the threat of at least isolated
flash flooding in the most prone locations will continue Sunday
afternoon and evening, especially across central and southern
Utah.

The Pacific trough will finally shift into the northern High
Plains, shifting any large scale forcing for convection to the
east. Given there wasn't a front to sweep out the low-level
moisture in the low desert areas, expect the threat of isolated
flash flooding to persist in any areas that develop convection
through at least Monday...if not longer.

&&

.AVIATION...

KSLC...There is low confidence in wind direction this afternoon and
evening, particularly near any storms. High-based showers and
thunderstorms will begin to develop over the Oquirrh Mountains after
20z, with storms potentially moving over the terminal after 21z or
so, resulting in gusty and erratic outflow winds reaching 40kts for
a brief period (10% chance). BLDU may result in brief VIS
reductions. The threat of showers will linger well into the
evening/overnight hours (until 09-10z), with a continued threat of
outflow winds.

REST OF UTAH AND SOUTHWEST WYOMING...High-based showers and
thunderstorms will continue to develop across much of the area (all
but KCDC-KSGU) this afternoon, first over higher terrain. These
storms will be capable of producing gusty and erratic outflow winds
up to 40kts (up to 50kts across NW-UT). Storms will likely subside
across southern UT between 02-04z, though showers are likely to
linger through the overnight hours across the rest of the
area...gradually weakening through the night. Outflow winds will
result in low confidence in wind direction through much of the valid
TAF period.

&&

.FIRE WEATHER...Afternoon and evening showers and thunderstorms
will become more isolated through early Monday, and largely tied
to terrain. Any showers and thunderstorms this weekend will have
the threat of strong, gusty microburst winds.

Over the work-week, valley humidities will fall slowly each day,
reaching near critical to critical levels as early as Monday.
There is little sign of an additional monsoon surge after this
weekend until after the next weekend.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

Kruse/Cunningham

For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecity

In the hours before

Special weather statement, Aug 22, 4:13 PM MDT, 1 hour 1 minute before
Special Weather Statement
National Weather Service Salt Lake City UT
413 PM MDT Sat Aug 22 2026

UTZ101-222300-
Great Salt Lake Desert and Mountains UT-
413 PM MDT Sat Aug 22 2026

...A strong thunderstorm will impact portions of west central Tooele
County through 500 PM MDT
...

At 413 PM MDT, Doppler radar was tracking a strong thunderstorm 15
miles west of Utah Test and Training Range South, or 18 miles
southeast of Wendover, moving northeast at 15 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Utah Test and Training Range South and Bonneville Salt Flats.

This includes Interstate 80 in Utah between mile markers 10 and 17.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4041 11385 4054 11401 4080 11381 4057 11346
TIME...MOT...LOC 2213Z 220DEG 15KT 4049 11386

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

JCW
Special weather statement, Aug 22, 4:37 PM MDT, 37 minutes before
Special Weather Statement
National Weather Service Salt Lake City UT
437 PM MDT Sat Aug 22 2026

UTZ101-222315-
Great Salt Lake Desert and Mountains UT-
437 PM MDT Sat Aug 22 2026

...A strong thunderstorm will impact portions of northwestern Tooele
County through 515 PM MDT
...

At 437 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles northwest of Utah Test and Training Range South, or 20 miles
east of Wendover, moving northeast at 25 mph.

HAZARD...Wind gusts of 50 to 55 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Knolls and Utah Test and Training Range South.

This includes Interstate 80 in Utah between mile markers 13 and 45.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4054 11361 4071 11383 4102 11350 4072 11317
TIME...MOT...LOC 2237Z 238DEG 21KT 4064 11366

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...55 MPH

JCW
Local storm report, Aug 22, 4:48 PM MDT, 26 minutes before
Preliminary Local Storm Report
National Weather Service Salt Lake City UT
448 PM MDT Sat Aug 22 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0440 PM     Tstm Wnd Gst     4 SW Scipio             39.20N 112.14W
08/22/2026  M59 MPH          Millard            UT   Mesonet

            Mesonet station PC291 Scipio Summit.

&&

CRK
Local storm report, Aug 22, 5:03 PM MDT, 11 minutes before
Preliminary Local Storm Report
National Weather Service Salt Lake City UT
503 PM MDT Sat Aug 22 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0450 PM     Tstm Wnd Gst     12 W Knolls             40.73N 113.50W
08/22/2026  M67 MPH          Tooele             UT   Mesonet

            Mesonet station UT33 I-80 at MP 29.

&&

CRK
Local storm report, Aug 22, 5:11 PM MDT, 3 minutes before
Preliminary Local Storm Report
National Weather Service Salt Lake City UT
511 PM MDT Sat Aug 22 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0500 PM     Tstm Wnd Gst     12 W Knolls             40.73N 113.50W
08/22/2026  M73 MPH          Tooele             UT   Mesonet

            UDOT I-80 @ MP 29.

&&

JCW
Local storm report, Aug 22, 5:12 PM MDT, 2 minutes before
Preliminary Local Storm Report
National Weather Service Salt Lake City UT
512 PM MDT Sat Aug 22 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0505 PM     Tstm Wnd Gst     10 W Knolls             40.73N 113.47W
08/22/2026  M75 MPH          Tooele             UT   Mesonet

            UDOT Interstate 80.

&&

JCW

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 21, 9:48 PM MDTSpecial Weather StatementSLCTooele42 min
Aug 22, 12:09 PM MDTAreal Flood AdvisorySLCSevier96 min
Aug 22, 1:38 PM MDTSpecial Weather StatementSLCDuchesne52 min
Aug 22, 1:48 PM MDTFlash Flood Warning Considerable damage threatSLCWayne3 hr
Aug 22, 2:04 PM MDTSevere Thunderstorm WarningSLCDuchesne41 min
Aug 22, 2:44 PM MDTSpecial Weather StatementSLCDuchesne31 min
Aug 22, 3:00 PM MDTSpecial Weather StatementSLCSalt Lake45 min
Aug 22, 3:31 PM MDTSpecial Weather StatementSLCDuchesne44 min
Aug 22, 3:51 PM MDTSpecial Weather StatementSLC39 min
Aug 22, 3:58 PM MDTSpecial Weather StatementSLCSalt Lake47 min
Aug 22, 4:13 PM MDTSpecial Weather StatementSLCTooele47 min
Aug 22, 4:37 PM MDTSpecial Weather StatementSLCTooele38 min
Aug 22, 4:50 PM MDTSevere Thunderstorm WarningSLCTooele25 min
Aug 22, 5:15 PM MDTAreal Flood AdvisorySLCTooele3 hr
Aug 22, 5:27 PM MDTSpecial Weather StatementSLCTooele48 min
Aug 22, 5:45 PM MDTSevere Thunderstorm WarningSLCBox Elder, Tooele45 min

Nearby

Severe Thunderstorm Warnings in Utah, 2026Every severe thunderstorm warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.