Alert archive / Utah / Flash Flood Warnings in 2012

Flash Flood Warning 21, NWS Salt Lake City, UT

July 24, 2012Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 24, 2012, 8:58 AM MDT for Washington County, Utah. It was in force for 6 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 24, 2012, 8:58 AM MDT (14:58 UTC)
Expired
Jul 24, 2012, 2:45 PM MDT
In force
6 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), 82 km from the middle of the area, began a volume at 15:01 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, 3.0 hours before the alert went out and 199 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 2012-07-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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 2012-07-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 9 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2422 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
9 m²/s²
0-3 km storm-relative helicity
13 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.

397 
WGUS55 KSLC 241458
FFWSLC
UTC053-242045-
/O.NEW.KSLC.FF.W.0021.120724T1458Z-120724T2045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
858 AM MDT TUE JUL 24 2012

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTH CENTRAL WASHINGTON COUNTY IN UTAH...SPECIFICALLY FOR THE     
  FORT PEARCE WASH FROM THE ARIZONA BORDER NORTHWEST TO THE          
  CONFLUENCE OF THE VIRGIN RIVER IN ST GEORGE.

* UNTIL 245 PM MDT

* AT 847 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  HEAVY RAIN FROM A THUNDERSTORM OVER THE HEADWATERS OF THE FORT     
  PEARCE AND COTTONWOOD WASHES. RADAR ESTIMATES OF 1 TO 2 INCHES OF  
  RAINFALL HAVE OCCURRED OVER THE LAST HOUR...AND ADDITIONAL         
  RAINFALL OF UP TO .50 INCHES ARE POSSIBLE.

* THE STORM PRODUCING FLASH FLOODING WILL OTHERWISE REMAIN OVER
  MAINLY RURAL AREAS OF THE INDICATED COUNTY.

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 3708 11359 3708 11354 3703 11349 3701 11328
      3700 11328 3699 11328 3699 11352 3699 11353

$$

MERRILL
1 follow-up statement
660 
WGUS75 KSLC 241739
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1139 AM MDT TUE JUL 24 2012

UTC053-242045-
/O.CON.KSLC.FF.W.0021.000000T0000Z-120724T2045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
1139 AM MDT TUE JUL 24 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 245 PM MDT FOR THE 
FORT PEARCE WASH IN SOUTH CENTRAL WASHINGTON COUNTY...

HEAVY RAINFALL HAS BEEN OCCURRING OVER THE FORT PEARCE DRAINAGE 
THROUGHOUT THE MORNING. THE GAGE ON THE FORT PEARCE WASH SOUTH OF ST 
GEORGE HAS SHOWN AN INCREASED IN FLOW TO 717 CFS OR CUBIC FEET PER 
SECOND THIS MORNING AND THE FLOW MAY INCREASE FURTHER OVER THE NEXT 
FEW HOURS.

INTERESTS NEAR THE FORT PEARCE WASH SHOULD EXPECT TO CONTINUE TO 
EXPERIENCE FLASH FLOODING THROUGH 245 PM MDT THIS AFTERNOON.

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 3708 11359 3708 11354 3703 11349 3701 11328
      3700 11328 3699 11328 3699 11352 3699 11353

$$

KRUSE

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 24, 12:56 PM MDTFlash Flood WarningSLCGarfield3 hr
Jul 24, 1:28 PM MDTFlash Flood WarningSLCWayne4 hr
Jul 24, 1:34 PM MDTSpecial Weather StatementSLCWashington41 min
Jul 24, 1:45 PM MDTSevere Thunderstorm WarningSLCWashington18 min
Jul 24, 2:44 PM MDTFlash Flood WarningSLCWashington6 hr
Jul 24, 3:18 PM MDTSpecial Weather StatementSLCIron42 min

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.