Alert archive / Utah / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 89, NWS Salt Lake City, UT

August 21, 20219 counties in Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 21, 2021, 6:06 PM MDT for 9 counties in Utah. It was in force for 39 min. 20 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, 6:06 PM MDT (00:06 UTC)
Expired: Aug 21, 2021, 6:45 PM MDT
In force: 39 min
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties Box Elder County, UT, Cache County, UT, Davis County, UT, Morgan County, UT, Rich County, UT, Salt Lake County, UT, Tooele County, UT, Utah County, UT, Weber County, UT

The radar

The Salt Lake City radar (KMTX), 54 km from the middle of the area, began a volume at 00:09 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, 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
Aug 21, 6:19 PM MDT	TSTM WND GST 65	Woods Cross, UT	TREE BRANCHES DOWN.
Aug 21, 6:20 PM MDT	TSTM WND GST 59	4 Nw Magna, UT
Aug 21, 6:20 PM MDT	TSTM WND GST 73	4 Nne Stansbury Park, UT
Aug 21, 6:21 PM MDT	TSTM WND GST 63	1 Wsw Farmington, UT	MEASURED AT A PERSONAL WEATHER STATION IN FARMINGTON
Aug 21, 6:25 PM MDT	TSTM WND DMG	2 Wsw Bountiful, UT	POWER POLE SNAPPED AND FELL ACROSS ROAD AT 2400 S AND 500 W IN BOUTIFUL.
Aug 21, 6:30 PM MDT	TSTM WND DMG	5 Ene Ogden, UT	TWO TREES DOWN IN GRAYCLIFF PARKING LOT IN OGDEN CANYON WITH LIMBS ON TWO VEHICLES. PHONE LINES ALSO WENT DOWN.
Aug 21, 6:30 PM MDT	TSTM WND DMG	Farmington, UT	PUBLIC REPORTS OF TREE BRANCHES DOWN AT LAGOON
Aug 21, 6:30 PM MDT	TSTM WND GST 58	15 W West Warren, UT	PROMONTORY POINT
Aug 21, 6:30 PM MDT	TSTM WND GST 59	3 Wnw Bountiful, UT	MEASURED AT THE LEGACY PARKWAY UDOT SITE
Aug 21, 6:30 PM MDT	TSTM WND GST 63	5 Nnw Bountiful, UT	MEASURED AT THE CENTERVILLE UDOT SITE
Aug 21, 6:30 PM MDT	TSTM WND GST 67	5 Ese Ogden, UT	MEASURED AT SNOWBASIN OGDEN PEAK. ELEVATION 9570.
Aug 21, 6:32 PM MDT	TSTM WND GST 63	5 W Salt Lake City, UT	MEASURED AT THE MIDFIELD FAA SENSOR AT SALT LAKE CITY INTERANTIONAL AIRPORT
Aug 21, 6:35 PM MDT	TSTM WND DMG	4 Wnw Salt Lake City, UT	TREE DOWN ON NORTH STAR IN ROSE PARK, BARELY MISSED PARKED TRUCK.
Aug 21, 6:37 PM MDT	TSTM WND DMG	Clinton, UT	REPORTS OF TREES DOWN
Aug 21, 6:38 PM MDT	TSTM WND DMG	Nnw Salt Lake City, UT	TREE DOWN IN ROAD NEAR H STREET AND 11TH AVE IN THE AVENUES.
Aug 21, 6:40 PM MDT	TSTM WND GST 62	2 Se Salt Lake City, UT	MEASURED AT THE UNIVERSITY OF UTAH
Aug 21, 6:40 PM MDT	TSTM WND GST 63	1 Se Snowbasin, UT	MEASURED AT TRAPPERS LOOP ROAD UDOT WEATHER STATION.
Aug 21, 6:45 PM MDT	TSTM WND DMG	Taylorsville, UT	TREE DOWN

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 00:00Z, 0.1 hours before the alert went out and 17 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: 422 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 2862 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 171 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.1

Open this sounding in Storm Lab

The text

As transmitted.

779 
WUUS55 KSLC 220006
SVRSLC
UTC003-005-011-029-033-035-045-049-057-220045-
/O.NEW.KSLC.SV.W.0089.210822T0006Z-210822T0045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
606 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...
  Southern Cache County in northern Utah...
  Southeastern Box Elder County in northern Utah...
  West central Rich County in northern Utah...
  Northwestern Salt Lake County in northern Utah...
  Davis County in northern Utah...
  Morgan County in northern Utah...
  Northwestern Utah County in northern Utah...
  Eastern Tooele County in northern Utah...

* Until 645 PM MDT

* At 605 PM MDT, severe thunderstorms were located along a line
  extending from near Wellsville to 7 miles east of Great Salt Lake
  South of the Causeway to 13 miles west of Skull Valley, moving east
  at 40 mph.

  HAZARD...70 mph wind gusts. 

  SOURCE...Trained weather spotters. 

  IMPACT...Expect considerable tree damage. Damage is likely to 
           mobile homes, roofs, and outbuildings. 

* Locations impacted include...
  Salt Lake City, West Valley City, Ogden, Layton, Murray, Bountiful,
  Tooele, Farmington, Brigham City, Grantsville, Morgan, Randolph,
  Hill Air Force Base, Dugway English Village, West Jordan,
  Taylorsville, South Jordan, Roy, Clearfield and Midvale.

This includes the following highways...
 Interstate 15 between mile markers 299 and 371.
 Interstate 84 between mile markers 82 and 113.
 Interstate 80 in Utah between mile markers 48 and 127.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This is a DANGEROUS SITUATION. These storms are producing widespread 
wind damage across the Wasatch Front and Tooele Valley. SEEK SHELTER 
NOW inside a sturdy structure and stay away from windows! 
&&

LAT...LON 4172 11115 4108 11144 4099 11160 4096 11153
      4092 11153 4046 11213 4046 11222 4041 11219
      4000 11244 4026 11355 4099 11291 4156 11264
TIME...MOT...LOC 0005Z 273DEG 33KT 4161 11198 4099 11225 4042 11299 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

CRK

1 follow-up statement

919 
WWUS55 KSLC 220023
SVSSLC

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

UTC003-005-011-029-033-035-045-049-057-220045-
/O.CON.KSLC.SV.W.0089.000000T0000Z-210822T0045Z/
Weber UT-Cache UT-Box Elder UT-Rich UT-Salt Lake UT-Davis UT-
Morgan UT-Utah UT-Tooele UT-
623 PM MDT Sat Aug 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM MDT
FOR WEBER...SOUTHERN CACHE...SOUTHEASTERN BOX ELDER...WEST CENTRAL
RICH...NORTHWESTERN SALT LAKE...DAVIS...MORGAN...NORTHWESTERN UTAH
AND EASTERN TOOELE COUNTIES...

At 622 PM MDT, severe thunderstorms were located along a line
extending from near Hyrum to 7 miles south of Syracuse to near Skull
Valley, moving east at 40 mph.

HAZARD...70 mph wind gusts. 

SOURCE...Trained weather spotters have reported wind gusts to 65 mph 
         and large branches down causing property damage.  

IMPACT...Expect considerable tree damage. Damage is likely to mobile 
         homes, roofs, and outbuildings. 

Locations impacted include...
Salt Lake City, West Valley City, Ogden, Layton, Murray, Bountiful,
Tooele, Farmington, Brigham City, Grantsville, Morgan, Randolph, Hill
Air Force Base, Dugway English Village, West Jordan, Taylorsville,
South Jordan, Roy, Clearfield and Midvale.

This includes the following highways...
 Interstate 15 between mile markers 299 and 371.
 Interstate 84 between mile markers 82 and 113.
 Interstate 80 in Utah between mile markers 48 and 127.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This is a DANGEROUS SITUATION. These storms are producing widespread 
wind damage across the Wasatch Front! SEEK SHELTER NOW inside a 
sturdy structure and stay away from windows.
 
&&

LAT...LON 4172 11115 4108 11144 4099 11160 4096 11153
      4092 11153 4046 11213 4046 11222 4041 11219
      4000 11244 4026 11355 4099 11291 4156 11264
TIME...MOT...LOC 0022Z 270DEG 33KT 4160 11182 4098 11209 4041 11283 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

CRK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 6:29 PM MDT	Severe Thunderstorm Warning	SLC	Cache, Rich	61 min
Aug 21, 6:40 PM MDT	Severe Thunderstorm Warning Considerable damage threat	SLC	Box Elder, Cache, Davis, Morgan, Rich, Salt Lake and 3 more	50 min
Aug 21, 6:59 PM MDT	Areal Flood Advisory	SLC	Davis, Weber	2 hr
Aug 21, 7:08 PM MDT	Severe Thunderstorm Warning Considerable damage threat	SLC	Summit	37 min
Aug 21, 7:23 PM MDT	Special Weather Statement	SLC	Salt Lake	37 min
Aug 21, 7:33 PM MDT	Areal Flood Advisory	SLC	Davis, Morgan, Salt Lake, Summit	117 min
Aug 21, 7:41 PM MDT	Special Weather Statement	SLC	Summit	49 min
Aug 21, 7:49 PM MDT	Special Weather Statement	SLC	Duchesne	41 min
Aug 21, 8:09 PM MDT	Special Weather Statement	SLC	Summit	51 min
Aug 21, 8:14 PM MDT	Special Weather Statement	SLC		31 min
Aug 21, 8:19 PM MDT	Severe Thunderstorm Warning	SLC	Duchesne, Summit	26 min
Aug 21, 8:32 PM MDT	High Wind Warning	SLC	Utah	3 hr
Aug 21, 9:59 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Salt Lake	91 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.