Alert archive / Utah / Flash Flood Warnings in 2012

Flash Flood Warning 35, NWS Salt Lake City, UT

July 31, 2012Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 31, 2012, 10:51 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
Jul 31, 2012, 10:51 PM MDT (04:51 UTC)
Expired
Aug 1, 2012, 2:45 AM 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), 39 km from the middle of the area, began a volume at 04:51 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, 4.9 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 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.

012 
WGUS55 KSLC 010451
FFWSLC
UTC053-010845-
/O.NEW.KSLC.FF.W.0035.120801T0451Z-120801T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1051 PM MDT TUE JUL 31 2012

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  LA VERKIN CREEK IN EAST CENTRAL WASHINGTON COUNTY IN UTAH

* UNTIL 245 AM MDT

* AT 1043 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED  
THUNDERSTORMS PRODUCING VERY HEAVY RAIN OVER THE HEADWATERS OF LA 
VERKIN CREEK IN THE KOLOB CANYONS SECTION OF ZION NATIONAL PARK. 
RADAR ESTIMATES ARE NEARING OVER 1 INCH OF RAIN IN THE PAST HOURS. 
THUNDERSTORMS CONTINUE TO DEVELOP IN THIS AREA.

* FLASH FLOODING IS EXPECTED ALONG THE LA VERKIN CREEK DRAINAGE AREA 
AND OTHER DRAINAGES WITHIN THE WARNED AREA. FLASH FLOODING FROM THIS 
AREA IS EXPECTED TO REACH THE TERMINATION OF LA VERKIN CREEK AT THE 
VIRGIN RIVER LATER TONIGHT. THIS WARNING INCLUDES AREAS IN THE TOWN 
LA VERKIN NEAR LA VERKIN 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.

FLOODING IS OCCURRING OR IS IMMINENT. IT IS IMPORTANT TO KNOW WHERE
YOU ARE RELATIVE TO STREAMS...RIVERS...OR CREEKS WHICH CAN BECOME
KILLERS IN HEAVY RAINS. CAMPERS AND HIKERS SHOULD AVOID STREAMS OR
CREEKS.

&&

LAT...LON 3748 11320 3745 11305 3732 11316 3720 11322
      3720 11330

$$

KRUSE
2 follow-up statements
650 
WGUS75 KSLC 010706
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
106 AM MDT WED AUG 1 2012

UTC053-010845-
/O.CON.KSLC.FF.W.0035.000000T0000Z-120801T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
106 AM MDT WED AUG 1 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 245 AM MDT FOR THE 
LA VERKIN CREEK DRAINAGE IN EAST CENTRAL WASHINGTON COUNTY...

HEAVY RAINFALL HAS LARGELY ENDED OVER THE LA VERKIN 
DRAINAGE...HOWEVER RUNOFF AND RESULTING FLASH FLOODING WILL CONTINUE 
DOWN THE DRAINAGE OVER THE NEXT SEVERAL HOURS. THIS WARNING REMAINS 
IN EFFECT THROUGH THE TERMINATION OF LA VERKIN CREEK AT THE VIRGIN 
RIVER INCLUDING SUSCEPTIBLE AREAS IN LA VERKIN NEAR THE 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 3748 11320 3745 11305 3732 11316 3720 11322
      3720 11330

$$

KRUSE
168 
WGUS75 KSLC 010836
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
236 AM MDT WED AUG 1 2012

UTC053-010846-
/O.EXP.KSLC.FF.W.0035.000000T0000Z-120801T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
236 AM MDT WED AUG 1 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 245 AM MDT FOR EAST CENTRAL
WASHINGTON COUNTY...

RUNOFF FROM EARLIER PRECIPITATION HAS DIMINISHED GREATLY AND RIVER 
AND STREAM LEVELS HAVE DECREASED. THEREFORE...THE FLASH FLOOD 
WARNING WILL BE ALLOWED TO EXPIRE. 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 3748 11320 3745 11305 3732 11316 3720 11322
      3720 11330

$$

MPS

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
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.