Alert archive / Utah / Flash Flood Warnings in 2012

Flash Flood Warning 30, NWS Salt Lake City, UT

July 30, 2012Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 30, 2012, 4:32 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
Jul 30, 2012, 4:32 PM MDT (22:32 UTC)
Expired
Jul 30, 2012, 7:30 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), 55 km from the middle of the area, began a volume at 22:33 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, 10.5 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 2012-07-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2012-07-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2888 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
63 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.

281 
WGUS55 KSLC 302232
FFWSLC
UTC053-310130-
/O.NEW.KSLC.FF.W.0030.120730T2232Z-120731T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
432 PM MDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHEASTERN WASHINGTON COUNTY IN UTAH

* UNTIL 730 PM MDT

* AT 430 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
HEAVY RAIN FROM A THUNDERSTORM OVER SMALL DRAINAGES SOUTH OF THE 
TOWN OF ROCKVILLE...SOUTH OF ZION NATIONAL PARK.  RAINFALL AMOUNTS 
OF OVER 1.86 INCHES HAS FALLEN IN AN HOUR.

* THIS STORM IS VERY LOCALIZED AND IS EXPECTED TO PRODUCE FLASH 
FLOODING IN THE SMALL DRAINAGES LEADING INTO ROCKVILLE AND THEN 
TERMINATING INTO THE VIRGIN RIVER.

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.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 3717 11310 3716 11303 3709 11300 3707 11303
      3709 11307

$$

MCINERNEY
1 follow-up statement
179 
WGUS75 KSLC 310127
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
727 PM MDT MON JUL 30 2012

UTC053-310134-
/O.EXP.KSLC.FF.W.0030.000000T0000Z-120731T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
727 PM MDT MON JUL 30 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 730 PM MDT FOR SOUTHEASTERN
WASHINGTON COUNTY...

THUNDERSTORM ACTIVITY IN THE AREA SOUTH OF ROCKVILLE HAS DIMINISHED 
AND FLASH FLOODING IN THE AREA IS EXPECTED TO HAVE PASSED THROUGH 
THE HYDROLOGIC SYSTEM.

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 3717 11310 3716 11303 3709 11300 3707 11303
      3709 11307

$$

MCINERNEY

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 30, 3:51 AM MDTFlash Flood WatchSLC18 hr
Jul 30, 1:33 PM MDTFlash Flood WarningSLCCarbon, Emery4 hr
Jul 30, 2:01 PM MDTFlash Flood WarningSLCJuab, Sanpete, Utah4 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.