Alert archive / Utah / Flash Flood Warnings in 2012

Flash Flood Warning 39, NWS Salt Lake City, UT

August 1, 2012Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Aug 1, 2012, 5:17 PM MDT for Washington 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
Aug 1, 2012, 5:17 PM MDT (23:17 UTC)
Expired
Aug 1, 2012, 9:15 PM MDT
In force
4 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Flood severity
None

County Washington County, UT

The radar

The Cedar City radar (KICX), 40 km from the middle of the area, began a volume at 23:17 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 12:00Z, 11.3 hours before the alert went out and 235 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 12:00Z on 2012-08-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 461 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 12:00Z on 2012-08-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 73 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
461 J/kg
Mixed-layer CIN
-123 J/kg
Mixed-layer LCL
1110 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
73 m²/s²
0-3 km storm-relative helicity
106 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.

006 
WGUS55 KSLC 012317
FFWSLC
UTC053-020315-
/O.NEW.KSLC.FF.W.0039.120801T2317Z-120802T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
517 PM MDT WED AUG 1 2012

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  LA VERKIN CREEK FROM THE HEADWATERS IN ZION NATIONAL PARK TO ITS   
  TERMINUS AT THE VIRGIN RIVER IN TOQUERVILLE

* UNTIL 915 PM MDT

* AT 508 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  HEAVY RAIN FROM A THUNDERSTORM OVER THE WARNED AREA. RAINFALL      
  ESTIMATES OF .50 TO 1.00 INCHES HAS FALLEN OVER THE LAST 30        
  MINUTES...AND AN ADDITIONAL .50 TO .75 INCHES OF RAIN IS EXPECTED  
  TO FALL OVER PORTIONS OF THE UPPER CREEK WITHIN THE NEXT 30        
  MINUTES. THIS RAINFALL IS EXPECTED TO CREATE A FLASH FLOOD DOWN    
  THE CREEK TO ITS TERMINUS AT THE VIRGIN RIVER IN TOQUERVILLE.

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.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

&&

LAT...LON 3728 11327 3730 11328 3743 11321 3749 11310
      3748 11308 3744 11307 3738 11311 3733 11321
      3719 11325 3719 11331

$$

MERRILL
2 follow-up statements
501 
WGUS75 KSLC 020123
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
723 PM MDT WED AUG 1 2012

UTC053-020315-
/O.CON.KSLC.FF.W.0039.000000T0000Z-120802T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
723 PM MDT WED AUG 1 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 PM MDT FOR LA 
VERKIN CREEK FROM THE HEADWATERS TO ITS TERMINUS IN THE VIRGIN RIVER 
IN TOQUERVILLE...

AT 712 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR ESTIMATES OF 
.50 TO 1.25 INCHES OF RAINFALL OCCURRED OVER THE UPPER REACHES OF LA 
VERKIN CREEK FROM EARLIER THUNDERSTORMS. THIS RAINFALL IS EXPECTED 
TO CREATE A FLASH FLOOD ALONG LA VERKIN CREEK FROM ZION NATIONAL 
PARK TO ITS TERMINUS AT THE VIRGIN RIVER IN TOQUERVILLE THROUGH 915 
PM MDT.

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 3728 11327 3730 11328 3743 11321 3749 11310
      3748 11308 3744 11307 3738 11311 3733 11321
      3719 11325 3719 11331

$$

MERRILL
405 
WGUS75 KSLC 020310
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
910 PM MDT WED AUG 1 2012

UTC053-020316-
/O.EXP.KSLC.FF.W.0039.000000T0000Z-120802T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
910 PM MDT WED AUG 1 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 915 PM MDT FOR EAST CENTRAL
WASHINGTON COUNTY...

PRECIPITATION HAS TAPERED OFF OVER LA VERKIN CREEK. THEREFORE... THE 
FLASH FLOOD WARNING HAS BEEN ALLOWED TO EXPIRE. ALTHOUGH WATER 
LEVELS MAY REMAIN HIGH ALONG PORTIONS OF LA VERKIN CREEK FROM ZION 
NATIONAL PARK TO ITS TERMINUS AT THE VIRGIN RIVER IN 
TOQUERVILLE...THEY WILL GRADUALLY RECEDE THROUGH THE REST OF THIS 
EVENING. MONITOR NOAA WEATHER RADIO OR LOCAL TELEVISION OR RADIO FOR 
THE LATEST WEATHER INFORMATION.

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 3728 11327 3730 11328 3743 11321 3749 11310
      3748 11308 3744 11307 3738 11311 3733 11321
      3719 11325 3719 11331

$$

LC

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 6:30 PM MDTFlash Flood WarningSLCIron4 hr
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, 5:23 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.