Alert archive / Utah / Flash Flood Warnings in 2011

Flash Flood Warning 8, NWS Salt Lake City, UT

July 11, 2011Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 11, 2011, 9:10 PM MDT for Washington County, Utah. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 11, 2011, 9:10 PM MDT (03:10 UTC)
Expired
Jul 11, 2011, 11:46 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), 39 km from the middle of the area, began a volume at 03:11 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.

What was reported inside it

TimeReportWhereRemark
Jul 11, 9:37 PM MDTFLASH FLOODZion Np, UTFLASH FLOOD REPORTED ALONG THE NORTH FORK OF THE VIRGIN. AREAS AFFECTED WERE THE TEMPLE OF SINAWAVA, AND REFIGERATOR CANYON, WHICH IS WHERE THE HIKE TO ANGELS LANDING BEGINS. ADDITIONALLY, THE RIVER GAGE ALONG THE NORTH FORK AT SPRINGDALE-NFVU1-JUMPED FROM 103

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Las Vegas, NV (KVEF), launched 00:00Z, 3.2 hours before the alert went out and 248 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 2011-07-12Temperature 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°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Las Vegas, NV at 00:00Z on 2011-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -9 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
4915 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
-9 m²/s²
0-3 km storm-relative helicity
17 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.

153 
WGUS55 KSLC 120310
FFWSLC
UTC053-120600-
/O.NEW.KSLC.FF.W.0008.110712T0310Z-110712T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
910 PM MDT MON JUL 11 2011

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  THE NORTH FORK OF THE VIRGIN RIVER IN EAST CENTRAL WASHINGTON 
  COUNTY IN UTAH...
  THIS INCLUDES ZION NATIONAL PARK...

* UNTIL MIDNIGHT MDT

* AT 856 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  HEAVY RAIN FROM A THUNDERSTORM OVER THE WARNED AREA.

* RADAR ESTIMATES 0.75 TO 1 INCH OF RAIN HAS FALLEN ACROSS DRAINAGES 
  LEADING INTO THE NORTH FORK OF THE VIRGIN RIVER OVER THE PAST HOUR.
  RUNOFF FROM THIS RAINFALL WILL RESULT IN FLASH FLOODING. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO THE NORTH
  FORK OF THE VIRGIN RIVER INCLUDING THE ZION NARROWS AND TELEPHONE
  CANYON. 

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 3726 11300 3734 11301 3735 11290 3727 11290
      3715 11297 3716 11310

$$

CHENG
2 follow-up statements
256 
WGUS75 KSLC 120441
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1041 PM MDT MON JUL 11 2011

UTC053-120600-
/O.CON.KSLC.FF.W.0008.000000T0000Z-110712T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
1041 PM MDT MON JUL 11 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL MIDNIGHT MDT FOR 
THE NORTH FORK OF THE VIRGIN RIVER IN EAST CENTRAL WASHINGTON 
COUNTY...

AT 1024 PM MDT...ZION NATIONAL PARK RANGERS REPORTED FLASH FLOODING 
OCCURRING ALONG THE NORTH FORK OF THE VIRGIN RIVER...IN REFRIGERATOR 
CANYON...AND NEAR THE TEMPLE OF SINAWAVA. RUNOFF FROM THE HEAVY RAIN 
EARLIER WILL CONTINUE TO PRODUCE FLASH FLOODING ALONG THE NORTH FORK 
OF THE VIRGIN RIVER...INCLUDING THE ZION NARROWS...THROUGH MIDNIGHT 
TONIGHT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3726 11300 3734 11301 3735 11290 3727 11290
      3715 11297 3716 11310

$$

CHENG
254 
WGUS75 KSLC 120546
FFSSLC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1146 PM MDT MON JUL 11 2011

UTC053-120547-
/O.CAN.KSLC.FF.W.0008.000000T0000Z-110712T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WASHINGTON UT-
1146 PM MDT MON JUL 11 2011

...THE FLASH FLOOD WARNING FOR THE NORTH FORK OF THE VIRGIN RIVER IN 
ZION NATIONAL PARK IN EAST CENTRAL WASHINGTON COUNTY HAS BEEN 
CANCELLED...

THE THUNDERSTORM THAT BROUGHT HEAVY RAIN AND FLASH FLOODING TO 
REFRIGERATOR CANYON IN ZION NATIONAL PARK HAS MOVED OUT OF THE 
REGION AND DISSIPATED. WATERS HAVE RECEDED ON THE NORTH FORK OF THE 
VIRGIN AND ARE NO LONGER A THREAT TO FLOODING.

LAT...LON 3726 11300 3734 11301 3735 11290 3727 11290
      3715 11297 3716 11310

$$

STRUTHWOLF

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 12, 3:07 PM MDTSevere Thunderstorm WarningSLCEmery38 min
Jul 12, 3:30 PM MDTFire Weather WatchSLC37 hr

Nearby

Flash Flood Warnings in Utah, 2011Every flash flood warning in 2011

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.