Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 129, NWS Salt Lake City, UT

September 2, 2021Garfield County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Sep 2, 2021, 5:33 PM MDT for Garfield 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
Sep 2, 2021, 5:33 PM MDT (23:33 UTC)
Expired
Sep 2, 2021, 8:45 PM MDT
In force
3 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Garfield County, UT

The radar

The Cedar City radar (KICX), 127 km from the middle of the area, began a volume at 23:35 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

Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 11.6 hours before the alert went out and 274 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, Flgstf/Belemont, AZ at 12:00Z on 2021-09-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 14 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Flgstf/Belemont, AZ at 12:00Z on 2021-09-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 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
14 J/kg
Mixed-layer CIN
-65 J/kg
Mixed-layer LCL
833 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
14 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

471 
WGUS55 KSLC 022333
FFWSLC
UTC017-030245-
/O.NEW.KSLC.FF.W.0129.210902T2333Z-210903T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
533 PM MDT Thu Sep 2 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  South Central Garfield County in southern Utah...

* Until 845 PM MDT.

* At 533 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain along Harris Wash. Radar estimates up to one inch of 
  rain has already fallen. Flash flooding is ongoing or expected to 
  begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Harris Wash to its terminus at the Escalante River. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3768 11124 3763 11120 3760 11147 3760 11154
      3768 11160 3775 11161 3775 11146

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

MT
1 follow-up statement
262 
WGUS75 KSLC 030101
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
701 PM MDT Thu Sep 2 2021

UTC017-030245-
/O.CON.KSLC.FF.W.0129.000000T0000Z-210903T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-
701 PM MDT Thu Sep 2 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM MDT THIS 
EVENING FOR SOUTH CENTRAL GARFIELD COUNTY...

At 701 PM MDT, Doppler radar indicated earlier thunderstorms 
produced heavy rain over Harris Wash. Flash flooding is ongoing or 
expected to begin shortly.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Harris Wash to its terminus at the Escalante River.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3768 11124 3763 11120 3760 11147 3760 11154
      3768 11160 3775 11161 3775 11146

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

MT

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 1, 9:26 PM MDTAreal Flood WarningSLCWayne10 hr
Sep 1, 9:51 PM MDTAreal Flood WarningSLCGarfield, San Juan, Wayne7 hr
Sep 2, 4:53 AM MDTAreal Flood WarningSLCGarfield, Wayne3 hr
Sep 2, 4:35 PM MDTSpecial Weather StatementSLCDuchesne25 min
Sep 2, 4:38 PM MDTSpecial Weather StatementSLCGarfield37 min
Sep 2, 4:40 PM MDTSpecial Weather StatementSLCTooele35 min
Sep 2, 5:52 PM MDTSpecial Weather StatementSLCSalt Lake23 min
Sep 2, 5:58 PM MDTSpecial Weather StatementSLCDavis32 min

Nearby

Flash Flood Warnings in Utah, 2021Every flash flood warning in 2021

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.