Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 24, NWS Salt Lake City, UT

July 20, 2021Iron County, Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 20, 2021, 1:18 PM MDT for Iron County, Washington County, Utah. It was in force for 4 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 20, 2021, 1:18 PM MDT (19:18 UTC)
Expired: Jul 20, 2021, 5:15 PM MDT
In force: 4 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), 81 km from the middle of the area, began a volume at 19:18 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

Time	Report	Where	Remark
Jul 20, 1:24 PM MDT	FLASH FLOOD	6 Wnw Enterprise, UT	FAST RUNNING WATER THROUGH TRIBUTARY OF SHOAL CREEK. AN ABANDONED PICKUP TRUCK WAS OBSERVED SUBMERGED IN THE WATER.

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 12:00Z, 7.3 hours before the alert went out and 206 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: 33 J/kg
Mixed-layer CIN: -208 J/kg
Mixed-layer LCL: 2439 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: -26 m²/s²
0-3 km storm-relative helicity: -8 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

111 
WGUS55 KSLC 201918
FFWSLC
UTC021-053-202315-
/O.NEW.KSLC.FF.W.0024.210720T1918Z-210720T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
118 PM MDT Tue Jul 20 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Southwestern Iron County in southern Utah...
  Northwestern Washington County in southwestern Utah...

* Until 515 PM MDT.

* At 118 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2.5 and 3 inches of 
  rain have 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...
  Shoal Creek through Enterprise.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3763 11389 3764 11385 3761 11376 3759 11374
      3758 11371 3759 11371 3761 11371 3761 11370
      3759 11370 3757 11371 3756 11377 3757 11382
      3755 11383 3755 11387 3759 11389

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

$$

SW

2 follow-up statements

619 
WGUS75 KSLC 202142
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
342 PM MDT Tue Jul 20 2021

UTC021-053-202315-
/O.CON.KSLC.FF.W.0024.000000T0000Z-210720T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-Washington UT-
342 PM MDT Tue Jul 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 515 PM MDT THIS 
AFTERNOON FOR SOUTHWESTERN IRON AND NORTHWESTERN WASHINGTON 
COUNTIES...

At 342 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 2.5 and 3.25 inches of rain 
have 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...
  Enterprise.

This includes the following streams and drainages...
  Little Pine Creek, Shoal Creek and Spring Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3763 11389 3764 11385 3761 11376 3759 11374
      3758 11371 3759 11371 3761 11371 3761 11370
      3759 11370 3757 11371 3756 11377 3757 11382
      3755 11383 3755 11387 3759 11389

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

$$

SW

587 
WGUS75 KSLC 202310
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
510 PM MDT Tue Jul 20 2021

UTC021-053-202320-
/O.EXP.KSLC.FF.W.0024.000000T0000Z-210720T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Iron UT-Washington UT-
510 PM MDT Tue Jul 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 515 PM MDT THIS AFTERNOON FOR 
SOUTHWESTERN IRON AND NORTHWESTERN WASHINGTON COUNTIES...

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

LAT...LON 3763 11389 3764 11385 3761 11376 3759 11374
      3758 11371 3759 11371 3761 11371 3761 11370
      3759 11370 3757 11371 3756 11377 3757 11382
      3755 11383 3755 11387 3759 11389

$$

SW

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 19, 6:01 PM MDT	Special Weather Statement	SLC	Tooele	59 min
Jul 19, 6:10 PM MDT	Special Weather Statement	SLC	Juab	65 min
Jul 19, 6:13 PM MDT	Special Weather Statement	SLC	Washington	47 min
Jul 19, 8:19 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	86 min
Jul 20, 12:11 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Wayne	3 hr
Jul 20, 2:21 PM MDT	Special Weather Statement	SLC	Iron	39 min
Jul 20, 3:26 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane	6 hr
Jul 20, 3:41 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane	3 hr
Jul 20, 4:03 PM MDT	Special Weather Statement	SLC	Sevier	27 min
Jul 20, 4:58 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield	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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.