Alert archive / Utah / Flash Flood Warnings in 2012

Flash Flood Warning 34, NWS Salt Lake City, UT

July 31, 2012Iron County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 31, 2012, 6:30 PM MDT for Iron County, Utah. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 31, 2012, 6:30 PM MDT (00:30 UTC)
Expired
Jul 31, 2012, 10:30 PM MDT
In force
4 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Flood severity
None

County Iron County, UT

The radar

The Cedar City radar (KICX), 16 km from the middle of the area, began a volume at 00:31 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.

The nearest sounding before it

Las Vegas, NV (KVEF), launched 00:00Z, 0.5 hours before the alert went out and 267 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, Las Vegas, NV at 00:00Z on 2012-08-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 646 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Las Vegas, NV at 00:00Z on 2012-08-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -12 square meters per square second.1939Sfc1 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
646 J/kg
Mixed-layer CIN
-52 J/kg
Mixed-layer LCL
1370 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
-12 m²/s²
0-3 km storm-relative helicity
16 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.

191 
WGUS55 KSLC 010030
FFWSLC
UTC021-010430-
/O.NEW.KSLC.FF.W.0034.120801T0030Z-120801T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
630 PM MDT TUE JUL 31 2012

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTH CENTRAL IRON COUNTY IN UTAH

* UNTIL 1030 PM MDT

* AT 624 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
HEAVY RAIN FROM A THUNDERSTORM OVER THE COAL CREEK DRAINAGE JUST 
EAST OF CEDAR CITY.  THIS WATERSHED ALSO HAS HAD PRIOR ISSUES WITH 
LANDSLIDES ALONG SR14 AND THE INTENSE RAINFALL MAY INCREASE ROCKFALL 
IN THE AREA.

RAINFALL AMOUNTS OF OVER AN INCH IN A SHORT PERIOD OF TIME HAS 
FALLEN OVER THIS DRAINAGE...AND FLASH FLOODING IS ANTICIPATED AS 
COAL CREEK FLOWS THROUGH CEDAR CITY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 3771 11310 3768 11280 3758 11287 3767 11318

$$

MCINERNEY
2 follow-up statements
317 
WGUS75 KSLC 010241
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
841 PM MDT TUE JUL 31 2012

UTC021-010430-
/O.CON.KSLC.FF.W.0034.000000T0000Z-120801T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
IRON UT-
841 PM MDT TUE JUL 31 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 PM MDT FOR
SOUTH CENTRAL IRON COUNTY...

AT 830 PM MDT...SR 143 NEAR THE BRIANHEAD SKI AREA HAS BEEN CLOSED 
DUE TO FLASH FLOODING.  THIS ROAD IS LOCATED IN THE HEADWATERS OF 
COAL CREEK DRAINAGE EAST OF CEDAR CITY.

ADDITIONAL THUNDERSTORM ACTIVITY THROUGHOUT THE DRAINAGE IS EXPECTED 
THROUGH 1030PM. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 3771 11310 3768 11280 3758 11287 3767 11318

$$

MCINERNEY
603 
WGUS75 KSLC 010425
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1025 PM MDT TUE JUL 31 2012

UTC021-010432-
/O.EXP.KSLC.FF.W.0034.000000T0000Z-120801T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
IRON UT-
1025 PM MDT TUE JUL 31 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 1030 PM MDT FOR SOUTH
CENTRAL IRON COUNTY...

HEAVY RAIN HAS ENDED ACROSS THE AREA. WHILE FLASH FLOODING IS NO 
LONGER EXPECTED ACROSS THE COAL CREEK DRAINAGE BASIN...RUNOFF MAY 
CONTINUE FOR SEVERAL MORE HOURS. IN ADDITION...WHILE TRAVELING 
ALONG STATE ROUTE 14 THIS EVENING AND INTO THE OVERNIGHT HOURS...BE 
ON THE LOOKOUT FOR ROCKFALLS FROM EARLIER HEAVY RAIN AS PREVIOUS 
FLASH FLOODS HAVE CAUSED ROCKFALLS TO THE ROAD.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

LAT...LON 3771 11310 3768 11280 3758 11287 3767 11318

$$

KRUSE

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 6:30 PM MDTSpecial Weather StatementSLCKane30 min
Jul 31, 10:51 PM MDTFlash Flood WarningSLCWashington4 hr
Aug 1, 2:30 AM MDTFlash Flood WatchSLC20 hr
Aug 1, 2:51 PM MDTFlash Flood WarningSLCGarfield4 hr
Aug 1, 3:09 PM MDTFlash Flood WarningSLCGarfield, Kane6 hr
Aug 1, 4:05 PM MDTFlash Flood WarningSLCKane4 hr
Aug 1, 5:17 PM MDTFlash Flood WarningSLCWashington4 hr
Aug 1, 5:23 PM MDTFlash Flood WarningSLCKane, Washington4 hr
Aug 1, 5:27 PM MDTFlash Flood WarningSLCCarbon, Emery4 hr

Nearby

Flash Flood Warnings in Utah, 2012Every flash flood warning in 2012

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.