Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 86, NWS Salt Lake City, UT

August 21, 20215 counties in Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 21, 2021, 5:27 PM MDT for 5 counties in Utah. It was in force for 48 min. 5 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 21, 2021, 5:27 PM MDT (23:27 UTC)
Expired: Aug 21, 2021, 6:15 PM MDT
In force: 48 min
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Box Elder County, UT, Cache County, UT, Davis County, UT, Morgan County, UT, Weber County, UT

The radar

The Salt Lake City radar (KMTX), 19 km from the middle of the area, began a volume at 23:28 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

Time	Report	Where	Remark
Aug 21, 5:30 PM MDT	TSTM WND GST 60	15 W West Warren, UT	MEASURED AT THE PROMONTORY POINT SNOWNET SITE.
Aug 21, 5:45 PM MDT	TSTM WND GST 64	15 W West Warren, UT	PROMONTORY POINT
Aug 21, 6:00 PM MDT	TSTM WND GST 61	15 W West Warren, UT	PROMONTORY POINT
Aug 21, 6:15 PM MDT	TSTM WND DMG	Layton, UT	TREE LIMB BROKE THROUGH KITCHEN WINDOW
Aug 21, 6:15 PM MDT	TSTM WND GST 62	15 W West Warren, UT	PROMONTORY POINT

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

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 11.5 hours before the alert went out and 61 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 77 J/kg
Mixed-layer CIN: -271 J/kg
Mixed-layer LCL: 2167 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 239 m²/s²
0-3 km storm-relative helicity: 260 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

320 
WUUS55 KSLC 212327
SVRSLC
UTC003-005-011-029-057-220015-
/O.NEW.KSLC.SV.W.0086.210821T2327Z-210822T0015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
527 PM MDT Sat Aug 21 2021

The National Weather Service in Salt Lake City has issued a

* Severe Thunderstorm Warning for...
  Weber County in northern Utah...
  Southwestern Cache County in northern Utah...
  Southeastern Box Elder County in northern Utah...
  Northern Davis County in northern Utah...
  West central Morgan County in northern Utah...

* Until 615 PM MDT

* At 526 PM MDT, severe thunderstorms were located along a line
  extending from 7 miles west of Corinne to 10 miles north of Great
  Salt Lake South of the Causeway, moving east at 45 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

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

* Locations impacted include...
  Ogden, Layton, Brigham City, Hill Air Force Base, Roy, Clearfield,
  Syracuse, Clinton, North Ogden, South Ogden, Washington Terrace,
  Riverdale, Hyrum, Hooper, South Weber, Perry, Wellsville, Willard,
  Marriott-Slaterville and Uintah.

This includes the following highways...
 Interstate 15 between mile markers 331 and 370.
 Interstate 84 between mile markers 82 and 94.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4167 11161 4106 11182 4105 11247 4108 11250
      4105 11258 4105 11268 4156 11249
TIME...MOT...LOC 2326Z 262DEG 38KT 4153 11225 4115 11239 

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

$$

Webber

1 follow-up statement

948 
WWUS55 KSLC 212358
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
558 PM MDT Sat Aug 21 2021

UTC003-005-011-029-057-220015-
/O.CON.KSLC.SV.W.0086.000000T0000Z-210822T0015Z/
Weber UT-Cache UT-Box Elder UT-Davis UT-Morgan UT-
558 PM MDT Sat Aug 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM MDT
FOR WEBER...SOUTHWESTERN CACHE...SOUTHEASTERN BOX ELDER...NORTHERN
DAVIS AND WEST CENTRAL MORGAN COUNTIES...

At 557 PM MDT, severe thunderstorms were located along a line
extending from near Hyrum to South Ogden, moving east at 45 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Weather station reported. 

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

Locations impacted include...
Ogden, Layton, Brigham City, Hill Air Force Base, Roy, Clearfield,
Syracuse, Clinton, North Ogden, South Ogden, Washington Terrace,
Riverdale, Hyrum, Hooper, South Weber, Perry, Wellsville, Willard,
Marriott-Slaterville and Uintah.

This includes the following highways...
 Interstate 15 between mile markers 331 and 370.
 Interstate 84 between mile markers 82 and 94.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4167 11161 4106 11182 4105 11247 4108 11250
      4105 11258 4105 11268 4156 11249
TIME...MOT...LOC 2357Z 262DEG 38KT 4157 11183 4119 11197 

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

$$

Webber

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 1:25 PM MDT	Special Weather Statement	SLC	Rich	50 min
Aug 21, 3:14 PM MDT	Special Weather Statement	SLC	Box Elder	61 min
Aug 21, 4:31 PM MDT	Special Weather Statement	SLC	Tooele	59 min
Aug 21, 4:34 PM MDT	Special Weather Statement	SLC	Cache	56 min
Aug 21, 5:10 PM MDT	Special Weather Statement	SLC	Davis	20 min
Aug 21, 5:19 PM MDT	Special Weather Statement	SLC	Davis	26 min
Aug 21, 5:42 PM MDT	Severe Thunderstorm Warning	SLC	Davis, Salt Lake, Tooele	33 min
Aug 21, 5:52 PM MDT	Severe Thunderstorm Warning	SLC	Box Elder, Cache	38 min

Nearby

Severe Thunderstorm Warnings in Utah, 2021 Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.