Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 46, NWS Salt Lake City, UT

July 25, 2021Iron County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 25, 2021, 4:11 PM MDT for Iron 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 25, 2021, 4:11 PM MDT (22:11 UTC)
Expired
Jul 25, 2021, 7:00 PM MDT
In force
3 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Iron County, UT

The radar

The Cedar City radar (KICX), 21 km from the middle of the area, began a volume at 22:11 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.

The nearest sounding before it

Las Vegas, NV (KVEF), launched 12:00Z, 10.2 hours before the alert went out and 287 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 2021-07-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 97 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 12:00Z on 2021-07-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 18 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
97 J/kg
Mixed-layer CIN
-248 J/kg
Mixed-layer LCL
2117 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
18 m²/s²
0-3 km storm-relative helicity
69 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

029 
WGUS55 KSLC 252211
FFWSLC
UTC021-260100-
/O.NEW.KSLC.FF.W.0046.210725T2211Z-210726T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
411 PM MDT Sun Jul 25 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  The Brian Head burn scar in...
  East Central Iron County in southern Utah...

* Until 700 PM MDT.

* At 411 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain over the Brian Head Burn Scar. Between 0.75 and 1.5 
  inches of rain have fallen. Flash flooding is ongoing or expected 
  to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Parowan Creek drainage. The debris flow can 
consist of rock, mud, vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Brian Head
           Burn Scar.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Brian Head Burn Scar.

* Some locations that will experience flash flooding include...
  Parowan.

This includes the following highways...
Interstate 15 between mile markers 74 and 75. Additionally, flows 
are expected over state route 143 between mile markers 6 an 10.


This includes the following streams and drainages...
  Center Creek and Parowan Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3778 11284 3779 11283 3782 11282 3783 11283
      3783 11289 3784 11289 3784 11282 3782 11280
      3780 11280 3778 11276 3776 11277 3773 11277
      3771 11280 3771 11282 3773 11284 3774 11284
      3776 11284 3776 11285 3777 11285

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

$$

SW
2 follow-up statements
687 
WGUS75 KSLC 260016
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
616 PM MDT Sun Jul 25 2021

UTC021-260100-
/O.CON.KSLC.FF.W.0046.000000T0000Z-210726T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-
616 PM MDT Sun Jul 25 2021

...FLASH FLOOD WARNING FOR THE BRIAN HEAD BURN SCAR REMAINS IN 
EFFECT UNTIL 7 PM MDT THIS EVENING FOR EAST CENTRAL IRON COUNTY...

At 616 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain over the Brian Head Burn Scar. Between 0.75 and 1.5 inches of 
rain have fallen. Flash flooding is ongoing or expected to begin 
shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Parowan Creek drainage. The debris flow can 
consist of rock, mud, vegetation and other loose materials.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding in and around the Brian Head Burn Scar.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Brian Head Burn Scar.

Some locations that will experience flash flooding include...
  Parowan.

This includes the following highways...
Interstate 15 between mile markers 74 and 75. Additionally, flows 
are expected over state route 143 between mile markers 6 an 10.


This includes the following streams and drainages...
  Center Creek and Parowan Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3778 11284 3779 11283 3782 11282 3783 11283
      3783 11289 3784 11289 3784 11282 3782 11280
      3780 11280 3778 11276 3776 11277 3773 11277
      3771 11280 3771 11282 3773 11284 3774 11284
      3776 11284 3776 11285 3777 11285

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

$$

SW
949 
WGUS75 KSLC 260056
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
656 PM MDT Sun Jul 25 2021

UTC021-260106-
/O.EXP.KSLC.FF.W.0046.000000T0000Z-210726T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-
656 PM MDT Sun Jul 25 2021

...FLASH FLOOD WARNING FOR THE BRIAN HEAD BURN SCAR WILL EXPIRE AT 7 
PM MDT THIS EVENING FOR EAST CENTRAL IRON COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed any road closures. Runoff from 
earlier heavy rainfall will continue to diminish through the evening 
hours.

A Flash Flood Watch remains in effect until 1000 PM MDT for portions 
of southern Utah and southwest Utah.

LAT...LON 3778 11284 3779 11283 3782 11282 3783 11283
      3783 11289 3784 11289 3784 11282 3782 11280
      3780 11280 3778 11276 3776 11277 3773 11277
      3771 11280 3771 11282 3773 11284 3774 11284
      3776 11284 3776 11285 3777 11285

$$

SW

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 24, 7:17 PM MDTSpecial Weather StatementSLCGarfield28 min
Jul 24, 8:08 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Kane3 hr
Jul 25, 2:25 PM MDTFlash Flood Warning Considerable damage threatSLCIron3 hr
Jul 25, 2:49 PM MDTSpecial Weather StatementSLCPiute26 min
Jul 25, 2:53 PM MDTSpecial Weather StatementSLCBeaver37 min
Jul 25, 3:11 PM MDTSpecial Weather StatementSLCPiute34 min
Jul 25, 3:18 PM MDTSpecial Weather StatementSLCSevier27 min
Jul 25, 3:33 PM MDTSpecial Weather StatementSLCIron27 min
Jul 25, 3:49 PM MDTSevere Thunderstorm WarningSLCIron26 min
Jul 25, 4:21 PM MDTSpecial Weather StatementSLCWashington24 min
Jul 25, 4:29 PM MDTAreal Flood AdvisorySLCIron3 hr
Jul 25, 4:41 PM MDTSpecial Weather StatementSLCWashington19 min
Jul 25, 4:41 PM MDTSpecial Weather StatementSLCIron49 min
Jul 25, 4:52 PM MDTFlash Flood Warning Considerable damage threatSLCIron, Kane, Washington4 hr
Jul 25, 5:16 PM MDTFlash Flood Warning Considerable damage threatSLCWashington3 hr
Jul 25, 5:26 PM MDTSevere Thunderstorm WarningSLCWashington19 min
Jul 25, 5:42 PM MDTSevere Thunderstorm WarningSLCWashington33 min
Jul 25, 5:44 PM MDTSpecial Weather StatementSLCWashington31 min
Jul 25, 5:52 PM MDTSpecial Weather StatementSLCWashington23 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.