Alert archive / Utah / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 91, NWS Salt Lake City, UT
NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 21, 2021, 6:40 PM MDT for 9 counties in Utah. It was in force for 50 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, 6:40 PM MDT (00:40 UTC)
- Expired
- Aug 21, 2021, 7:30 PM MDT
- In force
- 50 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, Summit County, UT, Tooele County, UT, Weber County, UT
The radar
The Salt Lake City radar (KMTX), 67 km from the middle of the area, began a volume at 00:41 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, 6:40 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 |
| Aug 21, 7:15 PM MDT | TSTM WND GST 67 | 3 Ese Bluffdale, UT | MEASURED AT THE FLIGHT PEAK SOUTH UUNET SITE |
| Aug 21, 7:20 PM MDT | NON-TSTM WND GST 65 | 3 Se Bluffdale, UT | MEASURED AT POINT OF THE MOUNTAIN UDOT STATION |
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, 0.7 hours before the alert went out and 16 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.
- 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
The text
As transmitted.
551
WUUS55 KSLC 220040
SVRSLC
UTC003-005-011-029-033-035-043-045-057-220130-
/O.NEW.KSLC.SV.W.0091.210822T0040Z-210822T0130Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Salt Lake City UT
640 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...
East central Box Elder County in northern Utah...
Southern Rich County in northern Utah...
Salt Lake County in northern Utah...
Davis County in northern Utah...
Morgan County in northern Utah...
Northwestern Summit County in northern Utah...
Northeastern Tooele County in northern Utah...
* Until 730 PM MDT
* At 639 PM MDT, severe thunderstorms were located along a line
extending from 12 miles east of Hyrum to Farmington to 7 miles
southeast of Skull Valley, moving east at 40 mph.
HAZARD...70 mph wind gusts and penny size hail.
SOURCE...Trained weather spotters reported wind gusts to 73 mph
with widespread 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, Sandy, Ogden, Layton, Murray,
Bountiful, Tooele, Farmington, Brigham City, Grantsville, Park
City, Morgan, Coalville, Randolph, Hill Air Force Base, West
Jordan, Taylorsville, South Jordan and Lehi.
This includes the following highways...
Interstate 15 between mile markers 285 and 362.
Interstate 84 between mile markers 82 and 119.
Interstate 80 in Utah between mile markers 76 and 196.
US Route 40 between mile markers 0 and 5.
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, Wasatch Back and the Cache
Valley. SEEK SHELTER NOW inside a sturdy structure and stay away
from windows!
&&
LAT...LON 4171 11105 4118 11105 4098 11114 4060 11153
4042 11195 4046 11204 4046 11221 4033 11220
4042 11303 4099 11239 4158 11200
TIME...MOT...LOC 0039Z 269DEG 33KT 4160 11160 4098 11188 4042 11262
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH
$$
CRK2 follow-up statements
822
WWUS55 KSLC 220110
SVSSLC
Severe Weather Statement
National Weather Service Salt Lake City UT
710 PM MDT Sat Aug 21 2021
UTC003-005-220119-
/O.CAN.KSLC.SV.W.0091.000000T0000Z-210822T0130Z/
Cache UT-Box Elder UT-
710 PM MDT Sat Aug 21 2021
...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN CACHE AND EAST
CENTRAL BOX ELDER COUNTIES IS CANCELLED...
The storms which prompted the warning have moved out of the warned
area. Therefore, the warning has been cancelled.
LAT...LON 4118 11105 4098 11114 4061 11152 4052 11178
4047 11186 4048 11188 4043 11193 4046 11204
4046 11221 4033 11220 4048 11247 4115 11215
4142 11155 4140 11154 4161 11105
TIME...MOT...LOC 0109Z 269DEG 33KT 4160 11127 4098 11155 4043 11230
$$
UTC011-029-033-035-043-045-057-220130-
/O.CON.KSLC.SV.W.0091.000000T0000Z-210822T0130Z/
Weber UT-Rich UT-Salt Lake UT-Davis UT-Morgan UT-Summit UT-Tooele UT-
710 PM MDT Sat Aug 21 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM MDT
FOR EASTERN WEBER...SOUTHERN RICH...SALT LAKE...DAVIS...MORGAN...
NORTHWESTERN SUMMIT AND EAST CENTRAL TOOELE COUNTIES...
At 709 PM MDT, severe thunderstorms were located along a line
extending from 6 miles southwest of Randolph to 6 miles north of East
Canyon State Park to near Ophir, moving east at 40 mph.
HAZARD...70 mph wind gusts and penny size hail.
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, Sandy, Ogden, Layton, Murray,
Bountiful, Tooele, Farmington, Park City, Morgan, Coalville, Hill Air
Force Base, West Jordan, Taylorsville, South Jordan, Draper,
Riverton, Roy and Cottonwood Heights.
This includes the following highways...
Interstate 15 between mile markers 286 and 342.
Interstate 84 between mile markers 82 and 119.
Interstate 80 in Utah between mile markers 92 and 196.
US Route 40 between mile markers 0 and 5.
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 northern Utah. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows.
&&
LAT...LON 4118 11105 4098 11114 4061 11152 4052 11178
4047 11186 4048 11188 4043 11193 4046 11204
4046 11221 4033 11220 4048 11247 4115 11215
4142 11155 4140 11154 4161 11105
TIME...MOT...LOC 0109Z 269DEG 33KT 4160 11127 4098 11155 4043 11230
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH
$$
CRK617
WWUS55 KSLC 220128
SVSSLC
Severe Weather Statement
National Weather Service Salt Lake City UT
728 PM MDT Sat Aug 21 2021
UTC011-029-033-035-043-045-057-220137-
/O.EXP.KSLC.SV.W.0091.000000T0000Z-210822T0130Z/
Weber UT-Rich UT-Salt Lake UT-Davis UT-Morgan UT-Summit UT-Tooele UT-
728 PM MDT Sat Aug 21 2021
...THE SEVERE THUNDERSTORM WARNING FOR EASTERN WEBER...SOUTHERN
RICH...SALT LAKE...DAVIS...MORGAN...NORTHWESTERN SUMMIT AND EAST
CENTRAL TOOELE COUNTIES WILL EXPIRE AT 730 PM MDT...
The storms which prompted the warning have moved out of the area.
Therefore, the warning will be allowed to expire. However gusty
winds and heavy rain are still possible with these thunderstorms.
LAT...LON 4118 11105 4098 11114 4061 11152 4052 11178
4047 11186 4048 11188 4043 11193 4046 11204
4046 11221 4033 11220 4048 11247 4115 11215
4142 11155 4140 11154 4161 11105
TIME...MOT...LOC 0127Z 269DEG 33KT 4160 11109 4098 11137 4043 11212
$$
CRKThe office that day
Everything else NWS Salt Lake City, UT issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 6:06 PM MDT | Severe Thunderstorm Warning | SLC | Box Elder, Cache, Davis, Morgan, Rich, Salt Lake and 3 more | 39 min |
| Aug 21, 6:29 PM MDT | Severe Thunderstorm Warning | SLC | Cache, Rich | 61 min |
| Aug 21, 6:59 PM MDT | Areal Flood Advisory | SLC | Davis, Weber | 2 hr |
| Aug 21, 7:08 PM MDT | Severe Thunderstorm Warning | 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 | SLC | Salt Lake | 91 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.