Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 42, NWS Salt Lake City, UT

July 24, 2021Iron County, Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 24, 2021, 4:12 PM MDT for Iron County, 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 24, 2021, 4:12 PM MDT (22:12 UTC)
Expired: Jul 24, 2021, 7:15 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Iron County, UT, Washington County, UT

The radar

The Cedar City radar (KICX), 31 km from the middle of the area, began a volume at 22:14 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 243 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 335 J/kg
Mixed-layer CIN: -191 J/kg
Mixed-layer LCL: 2063 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 121 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

031 
WGUS55 KSLC 242212
FFWSLC
UTC021-053-250115-
/O.NEW.KSLC.FF.W.0042.210724T2212Z-210725T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
412 PM MDT Sat Jul 24 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Southeastern Iron County in southern Utah...
  East Central Washington County in southwestern Utah...

* Until 715 PM MDT.

* At 412 PM MDT, Zion National Park Rangers reported flash flooding 
  across the warned area. Between 1.5 and 2.5 inches of rain have 
  fallen across the headwaters of the La Verkin Creek drainage. 
  Additionally, between 0.5 and 0.75 inches of rain have fallen 
  across the headwaters of Taylor Creek. Flash flooding is already 
  occurring.

  HAZARD...Life threatening flash flooding. Heavy rain producing
           flash flooding.

  SOURCE...Public reported.

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

* Some locations that will experience flash flooding include...
  La Verkin Creek draining through Zion National Park. Additional 
  flows have been observed through Taylor Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3748 11314 3748 11313 3751 11310 3751 11305
      3747 11305 3743 11307 3743 11309 3743 11312
      3741 11315 3740 11318 3735 11318 3736 11320
      3739 11320 3745 11319 3746 11322 3745 11325
      3746 11325 3746 11324 3748 11317

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

SW

2 follow-up statements

698 
WGUS75 KSLC 250033
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
633 PM MDT Sat Jul 24 2021

UTC021-053-250115-
/O.CON.KSLC.FF.W.0042.000000T0000Z-210725T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-Washington UT-
633 PM MDT Sat Jul 24 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 715 PM MDT THIS 
EVENING FOR SOUTHEASTERN IRON AND EAST CENTRAL WASHINGTON COUNTIES...

At 633 PM MDT, Zion National Park Rangers reported flash flooding 
across the warned area. Between 1.5 and 2.5 inches of rain have 
fallen across the headwaters of the La Verkin Creek drainage. 
Additionally, between 0.5 and 0.75 inches of rain have fallen across 
the headwaters of Taylor Creek. Flash flooding is already occurring.

HAZARD...Life threatening flash flooding. Heavy rain producing
         flash flooding.

SOURCE...Public reported.

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

Some locations that will experience flash flooding include...
  La Verkin Creek draining through Zion National Park. Additional 
  flows have been observed through Taylor Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3748 11314 3748 11313 3751 11310 3751 11305
      3747 11305 3743 11307 3743 11309 3743 11312
      3741 11315 3740 11318 3735 11318 3736 11320
      3739 11320 3745 11319 3746 11322 3745 11325
      3746 11325 3746 11324 3748 11317

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

SW

324 
WGUS75 KSLC 250114
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
714 PM MDT Sat Jul 24 2021

UTC021-053-250124-
/O.EXP.KSLC.FF.W.0042.000000T0000Z-210725T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-Washington UT-
714 PM MDT Sat Jul 24 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 715 PM MDT THIS EVENING FOR 
SOUTHEASTERN IRON AND EAST CENTRAL WASHINGTON COUNTIES...

Flood waters have receded. 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 Sunday for 
portions of southern Utah and southwest Utah.

LAT...LON 3748 11314 3748 11313 3751 11310 3751 11305
      3747 11305 3743 11307 3743 11309 3743 11312
      3741 11315 3740 11318 3735 11318 3736 11320
      3739 11320 3745 11319 3746 11322 3745 11325
      3746 11325 3746 11324 3748 11317

$$

SW

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 23, 6:14 PM MDT	Areal Flood Advisory	SLC	Washington	61 min
Jul 24, 3:23 AM MDT	Flash Flood Watch	SLC	Beaver, Garfield, Iron, Kane, Piute, Washington and 1 more	42 hr
Jul 24, 12:56 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	3 hr
Jul 24, 12:58 PM MDT	Special Weather Statement	SLC	Kane	32 min
Jul 24, 1:34 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane	4 hr
Jul 24, 2:13 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Washington	3 hr
Jul 24, 2:24 PM MDT	Severe Thunderstorm Warning	SLC	Washington	21 min
Jul 24, 3:16 PM MDT	Severe Thunderstorm Warning	SLC	Washington	29 min
Jul 24, 3:40 PM MDT	Severe Thunderstorm Warning	SLC	Iron, Washington	35 min
Jul 24, 4:04 PM MDT	Severe Thunderstorm Warning	SLC	Washington	26 min
Jul 24, 4:07 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, Washington	3 hr
Jul 24, 4:30 PM MDT	Severe Thunderstorm Warning	SLC	Washington	30 min
Jul 24, 5:24 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Washington	3 hr

Nearby

Flash Flood Warnings in Utah, 2021 Every 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.