Alert archive / Utah / Flash Flood Warnings in 2012

Flash Flood Warning 42, NWS Salt Lake City, UT

August 3, 2012Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Aug 3, 2012, 5:58 PM MDT for Washington County, Utah. It was in force for 3 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 3, 2012, 5:58 PM MDT (23:58 UTC)
Expired
Aug 3, 2012, 9:00 PM MDT
In force
3 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 00:02 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, 12.0 hours before the alert went out and 236 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 2012-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 507 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Las Vegas, NV at 12:00Z on 2012-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -31 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
507 J/kg
Mixed-layer CIN
-231 J/kg
Mixed-layer LCL
2780 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
-31 m²/s²
0-3 km storm-relative helicity
39 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

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

035 
WGUS55 KSLC 032358
FFWSLC
UTC053-040300-
/O.NEW.KSLC.FF.W.0042.120803T2358Z-120804T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
558 PM MDT FRI AUG 3 2012

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EAST CENTRAL WASHINGTON COUNTY IN UTAH...SPECIFICALLY LA VERKIN    
  CREEK FROM ZION NATIONAL PARK TO ITS TERMINUS AT THE VIRGIN RIVER  
  IN TOQUERVILLE AND NORTH CREEK.

* UNTIL 900 PM MDT

* AT 549 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  HEAVY RAIN FROM A THUNDERSTORM OVER THE WARNED AREA. DOPPLER RADAR 
  ESTIMATES OF 1 TO 1.5 INCHES OF RAINFALL HAS FALLEN OVER UPPER LA  
  VERKIN CREEK...AND .50 TO .75 INCHES OF RAIN OVER MUCH OF NORTH    
  CREEK. THESE RAINFALL AMOUNTS ARE EXPECTED TO CAUSE FLASH FLOODING 
  IN THESE AREAS.

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 3745 11319 3742 11313 3739 11311 3733 11313
      3734 11305 3732 11302 3719 11317 3724 11324
      3719 11329 3719 11330

$$

MERRILL
2 follow-up statements
249 
WGUS75 KSLC 040129
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
729 PM MDT FRI AUG 3 2012

UTC053-040300-
/O.CON.KSLC.FF.W.0042.000000T0000Z-120804T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
729 PM MDT FRI AUG 3 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 900 PM MDT FOR EAST
CENTRAL WASHINGTON COUNTY...

RUNOFF FROM EARLIER HEAVY RAIN IS EXPECTED TO CONTINUE TO CAUSE 
FLASH FLOODING ALONG LA VERKIN CREEK FROM ZION NATIONAL PARK TO ITS 
TERMINUS AT THE VIRGIN RIVER IN TOQUERVILLE...AS WELL AS ALONG NORTH 
CREEK INSIDE AND SOUTHWEST OF ZION NATIONAL PARK.

RADAR ESTIMATES OF 1 TO 1.5 INCHES OF RAIN HAS FALLEN OVER LA VERKIN 
CREEK...AND 0.5 TO 0.75 INCHES OVER MUCH OF NORTH CREEK.

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 3745 11319 3742 11313 3739 11311 3733 11313
      3734 11305 3732 11302 3719 11317 3724 11324
      3719 11329 3719 11330

$$

LC
900 
WGUS75 KSLC 040254
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
854 PM MDT FRI AUG 3 2012

UTC053-040300-
/O.EXP.KSLC.FF.W.0042.000000T0000Z-120804T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
854 PM MDT FRI AUG 3 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 900 PM MDT FOR EAST CENTRAL
WASHINGTON COUNTY...

RUNOFF FROM EARLIER PRECIPITATION HAS DIMINISHED. THEREFORE...THE 
FLASH FLOOD WARNING HAS BEEN ALLOWED TO EXPIRE FOR LA VERKIN CREEK 
AND NORTH CREEK. ALTHOUGH STREAM LEVELS MAY REMAIN ELEVATED...THEY 
WILL GRADUALLY DECREASE THROUGH THE REMAINDER OF THE 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 3745 11319 3742 11313 3739 11311 3733 11313
      3734 11305 3732 11302 3719 11317 3724 11324
      3719 11329 3719 11330

$$

LC

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.