Alert archive / Utah / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 7, NWS Salt Lake City, UT

April 21, 20116 counties in Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Apr 21, 2011, 12:52 PM MDT for 6 counties in Utah. It was in force for 23 min. 3 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
Apr 21, 2011, 12:52 PM MDT (18:52 UTC)
Expired
Apr 21, 2011, 1:15 PM MDT
In force
23 min
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon

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

The radar

The Salt Lake City radar (KMTX), 35 km from the middle of the area, began a volume at 18:54 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
Apr 21, 1:10 PM MDTTSTM WND DMGTremonton, UTTREES DOWN IN TREMONTON. WINDOWS BLOWN OUT IN VEHICLES.
Apr 21, 1:20 PM MDTTSTM WND DMGOgden, UTMULTIPLE TREES DOWN IN THE OGDEN AREA.
Apr 21, 1:20 PM MDTTSTM WND DMGPleasant View, UTMULTIPLE TREES DOWN. POWERLINES REPORTED DOWN ACROSS THE COUNTY.

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, 6.9 hours before the alert went out and 40 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 2011-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 411 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 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 2011-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 87 square meters per square second.1939587897Sfc1 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
411 J/kg
Mixed-layer CIN
-62 J/kg
Mixed-layer LCL
1122 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
87 m²/s²
0-3 km storm-relative helicity
138 m²/s²
Significant tornado parameter
0.0
Supercell composite
-1.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

263 
WUUS55 KSLC 211852
SVRSLC
UTC003-005-011-029-045-057-211915-
/O.NEW.KSLC.SV.W.0007.110421T1852Z-110421T1915Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1252 PM MDT THU APR 21 2011

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN BOX ELDER COUNTY IN UTAH
  SOUTHWESTERN CACHE COUNTY IN UTAH
  DAVIS COUNTY IN UTAH
  WEST CENTRAL MORGAN COUNTY IN UTAH
  NORTHEASTERN TOOELE COUNTY IN UTAH
  WEBER COUNTY IN UTAH

* UNTIL 115 PM MDT

* AT 1250 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
  HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
  LOCATED ALONG A LINE EXTENDING FROM 8 MILES NORTH OF PROMONTORY TO
  6 MILES WEST OF HOOPER TO 11 MILES SOUTHWEST OF ANTELOPE ISLAND
  STATE PARK...MOVING EAST AT 50 MPH.

* LOCATIONS IN THE WARNING INCLUDE...
  ANTELOPE ISLAND STATE PARK... WEST WARREN... HOOPER... WARREN...
  WEST POINT... HOWELL... WEST WEBER... CLINTON... PLAIN CITY... WEST
  HAVEN... SYRACUSE... AND  WILSON... ROY... PENROSE AND SLATERVILLE

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

WIND GUSTS IN EXCESS OF 70 MPH HAVE BEEN REPORTED AS THIS LINE OF 
THUNDERSTORMS CROSSED THE GREAT SALT LAKE.

&&

LAT...LON 4132 11161 4090 11173 4083 11194 4086 11197
      4092 11195 4093 11200 4084 11217 4074 11226
      4068 11244 4115 11233 4200 11290 4201 11210
TIME...MOT...LOC 1852Z 252DEG 44KT 4173 11260 4118 11221
          4090 11229

$$

CRK
1 follow-up statement
831 
WWUS55 KSLC 211901
SVSSLC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
101 PM MDT THU APR 21 2011

UTC003-005-011-029-045-057-211915-
/O.CON.KSLC.SV.W.0007.000000T0000Z-110421T1915Z/
TOOELE UT-BOX ELDER UT-WEBER UT-DAVIS UT-CACHE UT-MORGAN UT-
101 PM MDT THU APR 21 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 115 PM MDT
FOR WEST CENTRAL MORGAN...SOUTHWESTERN CACHE...DAVIS...CENTRAL
WEBER...NORTHEASTERN BOX ELDER AND NORTHEASTERN TOOELE COUNTIES...

AT 1259 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER
SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS
WERE LOCATED ALONG A LINE EXTENDING FROM HOWELL TO HOOPER TO 8 MILES
SOUTH OF ANTELOPE ISLAND STATE PARK...MOVING EAST AT 50 MPH.

* LOCATIONS IN THE WARNING INCLUDE...
  HOWELL... WEST WEBER... CLINTON... PLAIN CITY... WEST HAVEN...
  SYRACUSE... WILSON... ROY... PENROSE... SLATERVILLE... SUNSET...
  CLEARFIELD... FARR WEST... THATCHER AND RIVERDALE

LAT...LON 4132 11161 4090 11173 4083 11194 4086 11197
      4092 11195 4093 11200 4084 11217 4074 11226
      4068 11244 4119 11228 4200 11276 4201 11210
TIME...MOT...LOC 1901Z 252DEG 44KT 4176 11245 4121 11207
          4093 11215

$$

CRK

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 21, 10:41 AM MDTWind AdvisorySLC10 hr
Apr 21, 11:03 AM MDTSpecial Weather StatementSLCTooele57 min
Apr 21, 11:12 AM MDTSevere Thunderstorm WarningSLCBox Elder, Tooele48 min
Apr 21, 11:39 AM MDTSpecial Weather StatementSLCRich51 min
Apr 21, 11:55 AM MDTSpecial Weather StatementSLCTooele50 min
Apr 21, 12:12 PM MDTSevere Thunderstorm WarningSLCBox Elder, Tooele48 min
Apr 21, 12:25 PM MDTHigh Wind WarningSLC6 hr
Apr 21, 12:29 PM MDTSevere Thunderstorm WarningSLCBox Elder46 min
Apr 21, 12:33 PM MDTSpecial Weather StatementSLCRich27 min
Apr 21, 12:37 PM MDTSevere Thunderstorm WarningSLCJuab, Tooele23 min
Apr 21, 12:43 PM MDTSevere Thunderstorm WarningSLCDavis, Weber17 min
Apr 21, 12:55 PM MDTSevere Thunderstorm WarningSLCJuab, Morgan, Salt Lake, Tooele, Utah35 min
Apr 21, 1:12 PM MDTSevere Thunderstorm WarningSLCBox Elder, Cache, Davis, Morgan, Salt Lake, Tooele and 1 more48 min
Apr 21, 1:24 PM MDTSevere Thunderstorm WarningSLCJuab, Salt Lake, Tooele, Utah36 min
Apr 21, 1:45 PM MDTSevere Thunderstorm WarningSLCBox Elder, Cache, Davis, Morgan, Rich, Salt Lake and 3 more30 min
Apr 21, 1:55 PM MDTSpecial Weather StatementSLCUtah, Wasatch50 min
Apr 21, 2:10 PM MDTSpecial Weather StatementSLCCarbon50 min
Apr 21, 2:14 PM MDTSevere Thunderstorm WarningSLCCache, Morgan, Rich, Summit46 min
Apr 21, 2:16 PM MDTSevere Thunderstorm WarningSLCCarbon29 min
Apr 21, 2:41 PM MDTSevere Thunderstorm WarningSLCRich35 min
Apr 21, 2:44 PM MDTSevere Thunderstorm WarningSLCCarbon16 min

Nearby

Severe Thunderstorm Warnings in Utah, 2011Every severe thunderstorm warning in 2011

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.