Alert archive / Utah / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 65, NWS Salt Lake City, UT

August 4, 2011Salt Lake County, Utah County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 4, 2011, 4:07 PM MDT for Salt Lake County, Utah County, Utah. It was in force for 38 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 4, 2011, 4:07 PM MDT (22:07 UTC)
Expired: Aug 4, 2011, 4:45 PM MDT
In force: 38 min
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon

Counties Salt Lake County, UT, Utah County, UT

The radar

The Salt Lake City radar (KMTX), 105 km from the middle of the area, began a volume at 22:06 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

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, 10.1 hours before the alert went out and 35 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: 228 J/kg
Mixed-layer CIN: -245 J/kg
Mixed-layer LCL: 1745 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 23 m²/s²
0-3 km storm-relative helicity: 52 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

407 
WUUS55 KSLC 042207
SVRSLC
UTC035-049-042245-
/O.NEW.KSLC.SV.W.0065.110804T2207Z-110804T2245Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
407 PM MDT THU AUG 4 2011

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EAST CENTRAL SALT LAKE COUNTY IN UTAH
  NORTH CENTRAL UTAH COUNTY IN UTAH

* UNTIL 445 PM MDT

* AT 402 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  ALPINE...OR 11 MILES SOUTHEAST OF SANDY...MOVING NORTHEAST AT 25   
  MPH. A SIMILAR STORM PRODUCED PING PONG SIZE HAIL IN KEARNS AT 330 
  PM.

* LOCATIONS IN THE WARNING INCLUDE...
  ALPINE...SNOWBIRD... ALTA AND BRIGHTON

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.

&&

LAT...LON 4058 11159 4056 11158 4049 11158 4041 11175
      4045 11179 4066 11160 4062 11156 4059 11156
TIME...MOT...LOC 2206Z 225DEG 23KT 4047 11169

$$

ROGOWSKI

2 follow-up statements

365 
WWUS55 KSLC 042224
SVSSLC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
424 PM MDT THU AUG 4 2011

UTC035-049-042245-
/O.CON.KSLC.SV.W.0065.000000T0000Z-110804T2245Z/
UTAH UT-SALT LAKE UT-
424 PM MDT THU AUG 4 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM MDT
FOR EAST CENTRAL SALT LAKE AND NORTH CENTRAL UTAH COUNTIES...

AT 419 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
LOCATED NEAR SNOWBIRD...OR ABOUT 10 MILES EAST OF SANDY...MOVING
NORTHEAST AT 20 MPH.

* LOCATIONS IN THE WARNING INCLUDE...
  SNOWBIRD... ALTA AND BRIGHTON

LAT...LON 4058 11159 4056 11158 4049 11158 4046 11164
      4051 11173 4066 11160 4062 11156 4059 11156
TIME...MOT...LOC 2224Z 210DEG 19KT 4055 11164

$$

ROGOWSKI

084 
WWUS55 KSLC 042238 RRA
SVSSLC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
438 PM MDT THU AUG 4 2011

UTC035-049-042248-
/O.EXP.KSLC.SV.W.0065.000000T0000Z-110804T2245Z/
UTAH UT-SALT LAKE UT-
438 PM MDT THU AUG 4 2011

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL SALT LAKE AND
NORTH CENTRAL UTAH COUNTIES WILL EXPIRE AT 445 PM MDT...

THE STORM HAS WEAKENED AND IS NO LONGER SEVERE. THEREFORE THE WARNING
HAS BEEN ALLOWED TO EXPIRE.

LAT...LON 4058 11159 4056 11158 4049 11158 4046 11164
      4051 11173 4066 11160 4062 11156 4059 11156
TIME...MOT...LOC 2238Z 210DEG 19KT 4061 11159

$$

ROGOWSKI

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 4, 4:02 PM MDT, 5 minutes earlier.

Area forecast discussion, Aug 4, 4:02 PM MDT, 5 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
402 PM MDT THU AUG 4 2011

.SYNOPSIS...A DRYING TREND WILL BEGIN ACROSS THE AREA TODAY WITH
A MUCH DRIER AIRMASS SPREADING INTO THE REGION ON FRIDAY AND
LASTING INTO EARLY NEXT WEEK.

&&

.DISCUSSION...SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
ACROSS THE FORECAST AREA THIS AFTERNOON...AS A PACIFIC TROUGH
MOVES THROUGH THE GREAT BASIN. AS EXPECTED...THE BEST COVERAGE OF
THUNDERSTORMS HAS BEEN IN THE EASTERN HALF OF THE CWA...WITH MANY
HEAVY RAINERS IN CENTRAL AND EASTERN UTAH. HOWEVER...THERE HAVE
ALSO BEEN ISOLATED STORMS IN NORTHWEST UTAH...WITH THE STRONGEST
OF THESE STORMS PRODUCING 1.5 INCH DIAMETER HAIL IN THE SALT LAKE
VALLEY. THESE SHOWERS ARE EXPECTED TO CONTINUE INTO THE EVENING
HOURS...BUT WILL GENERALLY BE PUSHED EASTWARD AS SIGNIFICANTLY
DRIER AIR MOVES IN FROM THE WEST.

THE DRYING BEGINNING THIS AFTERNOON WILL BE DRAMATIC...WITH THE
NAM FORECASTING PRECIPITABLE WATER VALUES AS LOW AS 0.25 INCHES
MOVING INTO FAR WESTERN UTAH BY 00Z FRIDAY. THIS DRIER AIRMASS IS
EXPECTED TO SPREAD INTO PRETTY MUCH THE ENTIRE CWA BY 12Z
FRIDAY...GREATLY RESTRICTING ANY CONVECTIVE DEVELOPMENT FRIDAY
THROUGH AT LEAST THE BEGINNING OF NEXT WEEK.

BOTH THE GFS AND ECMWF KEEP A DRY AND STABLE ZONAL FLOW OVER THE
REGION THROUGH THE NEXT WORK WEEK. THIS WILL KEEP THE DRY AIRMASS
IN PLACE...WITH TEMPERATURES THROUGH THE WEEK GENERALLY AROUND
CLIMATOLOGICAL NORMALS. BOTH THE 12Z GFS AND ECMWF HINT THAT
MONSOONAL MOISTURE MAY RETURN FOR THE WEEKEND OF AUGUST 13TH.

&&

.AVIATION...THERE IS A 30 PERCENT CHANCE THAT THE SLC TERMINAL
WILL BE IMPACTED BY SHOWERS AND THUNDERSTORMS BETWEEN 22Z AND 03Z.
THE MOST LIKELY IMPACT WILL BE CLOUD TO GROUND LIGHTNING AND BRIEF
HEAVY RAIN...WITH GUSTY ERRATIC WINDS ALSO POSSIBLE. MVFR
VISIBILITIES ARE POSSIBLE IN THE HEAVIEST SHOWERS. AWAY FROM
SHOWERS...SURFACE WINDS ARE EXPECTED TO REMAIN SOUTHERLY THROUGH
THE EVENING HOURS.

&&

.FIRE WEATHER...DRIER AIR HAS BEGUN TO MOVE INTO THE DISTRICT THIS
AFTERNOON...BUT DEEP MOISTURE REMAINS OVER THE EASTERN TWO-THIRDS OF
THE AREA...ALLOWING SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP
ONCE AGAIN. THE DRY AIRMASS WILL MOVE RAPIDLY INTO THE DISTRICT
TONIGHT AND TOMORROW...ALLOWING FOR ONLY VERY ISOLATED COVERAGE OF
THUNDERSTORMS TOMORROW. GUSTY WINDS TODAY WILL DECREASE TONIGHT
BEHIND AN EXITING STORM SYSTEM. DRY CONDITIONS WITH RELATIVELY LIGHT
WINDS WILL CONTINUE THROUGH THE WEEKEND.

&&

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

SCHOENING/TRAPHAGAN

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)

Hazardous weather outlook, Aug 4, 5:45 AM MDT, 10 hours 22 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
545 AM MDT THU AUG 4 2011

UTZ001>016-019>021-517-518-WYZ021-051200-
CACHE VALLEY/UTAH PORTION-NORTHERN WASATCH FRONT-
SALT LAKE AND TOOELE VALLEYS-SOUTHERN WASATCH FRONT-
GREAT SALT LAKE DESERT AND MOUNTAINS-WASATCH MOUNTAIN VALLEYS-
WASATCH MOUNTAINS I-80 NORTH-WASATCH MOUNTAINS SOUTH OF I-80-
WESTERN UINTA MOUNTAINS-WASATCH PLATEAU/BOOK CLIFFS-
WESTERN UINTA BASIN-CASTLE COUNTRY-SAN RAFAEL SWELL-
SANPETE/SEVIER VALLEYS-WEST CENTRAL UTAH-SOUTHWEST UTAH-
UTAHS DIXIE AND ZION NATIONAL PARK-SOUTH CENTRAL UTAH-
GLEN CANYON RECREATION AREA/LAKE POWELL-CENTRAL MOUNTAINS-
SOUTHERN MOUNTAINS-SOUTHWEST WYOMING-
545 AM MDT THU AUG 4 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN TWO THIRDS OF
UTAH AND FAR SOUTHWEST WYOMING.

.DAY ONE...TODAY AND TONIGHT

DRIER AIR WILL BEGIN TO SPREAD INTO THE OUTLOOK AREA TODAY BUT
SHOWERS AND THUNDERSTORMS ARE AGAIN POSSIBLE...WITH THE GREATEST
COVERAGE ACROSS THE NORTH AND EAST. THERE IS STILL A THREAT OF
LOCAL HEAVY RAIN AND ISOLATED FLASH FLOODING OVER EASTERN UTAH
THIS AFTERNOON INTO THIS EVENING.

ISOLATED HAZARDOUS FIRE WEATHER CONDITIONS WILL BE POSSIBLE ACROSS
THE SOUTHWEST THIS AFTERNOON.

THE SHOWERS AND THUNDERSTORMS WILL END FROM THE SOUTHWEST THIS
EVENING WITH ONLY A FEW STORMS LINGERING OVER THE FAR NORTH AND
EAST OVERNIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE DRYING TREND WILL CONTINUE FRIDAY AND ONLY ISOLATED STORMS
ARE EXPECTED OVER THE EASTERN MOUNTAINS FRIDAY AFTERNOON.

A GENERALLY DRY PATTERN WITH NEAR SEASONAL TEMPERATURES IS
FORECAST FOR THE WEEKEND THROUGH THE MIDDLE OF NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

In the hours before

Local storm report, Aug 4, 3:37 PM MDT, 30 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
337 PM MDT THU AUG 04 2011

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

0330 PM     HAIL             KEARNS                  40.65N 112.01W
08/04/2011  M1.50 INCH       SALT LAKE          UT   COUNTY OFFICIAL

0330 PM     HAIL             CIRCLEVILLE             38.16N 112.26W
08/04/2011  M0.75 INCH       PIUTE              UT   PUBLIC

            VERY HEAVY RAIN ALSO REPORTED.

&&

CRK

Local storm report, Aug 4, 3:48 PM MDT, 19 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
348 PM MDT THU AUG 04 2011

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

0310 PM     HAIL             PAYSON                  40.03N 111.73W
08/04/2011  M0.75 INCH       UTAH               UT   CO-OP OBSERVER

&&

CRK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 3, 6:26 PM MDT	Special Weather Statement	SLC	Piute	34 min
Aug 3, 8:54 PM MDT	Special Weather Statement	SLC	Piute	21 min
Aug 3, 10:26 PM MDT	Flash Flood Warning	SLC	Piute, Sevier	3 hr
Aug 4, 2:31 PM MDT	Severe Thunderstorm Warning	SLC	Juab, Utah	29 min
Aug 4, 3:14 PM MDT	Flash Flood Warning	SLC	Piute	3 hr
Aug 4, 3:27 PM MDT	Severe Thunderstorm Warning	SLC	Salt Lake	32 min
Aug 4, 3:28 PM MDT	Flash Flood Warning	SLC	Wayne	4 hr
Aug 4, 3:31 PM MDT	Severe Thunderstorm Warning	SLC	Duchesne	59 min
Aug 4, 3:41 PM MDT	Severe Thunderstorm Warning	SLC	Utah	64 min
Aug 4, 3:44 PM MDT	Flash Flood Warning	SLC	Garfield, Piute	117 min
Aug 4, 3:58 PM MDT	Flash Flood Warning	SLC	Wayne	2 hr
Aug 4, 4:11 PM MDT	Severe Thunderstorm Warning	SLC	Duchesne, Wasatch	36 min
Aug 4, 4:43 PM MDT	Severe Thunderstorm Warning	SLC	Juab	62 min
Aug 4, 4:56 PM MDT	Severe Thunderstorm Warning	SLC	Emery	34 min
Aug 4, 5:27 PM MDT	Severe Thunderstorm Warning	SLC	Utah	63 min

Nearby

Severe Thunderstorm Warnings in Utah, 2011 Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.