Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 48, NWS Salt Lake City, UT

July 25, 2021Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 25, 2021, 5:16 PM MDT for 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 25, 2021, 5:16 PM MDT (23:16 UTC)
Expired: Jul 25, 2021, 8:15 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
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 23:20 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, 11.3 hours before the alert went out and 240 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: 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.

801 
WGUS55 KSLC 252316
FFWSLC
UTC053-260215-
/O.NEW.KSLC.FF.W.0048.210725T2316Z-210726T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Salt Lake City has issued a

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

* Until 815 PM MDT.

* At 516 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.75 and 1 inch of rain 
  has 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...
  Zion National Park, specifically the Subway canyon. Flows are 
  expected to continue down North Creek to the confluence with the 
  Virgin River.

This includes the following streams and drainages...
  Right Fork North Creek, North Creek, and the Virgin River.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3719 11317 3720 11319 3726 11315 3727 11312
      3734 11310 3736 11308 3741 11308 3744 11305
      3738 11302 3734 11300 3728 11300 3724 11307
      3722 11310 3721 11313

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

$$

SW

2 follow-up statements

144 
WGUS75 KSLC 260144
FFSSLC

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

UTC053-260215-
/O.CON.KSLC.FF.W.0048.000000T0000Z-210726T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington UT-
744 PM MDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 815 PM MDT THIS 
EVENING FOR EAST CENTRAL WASHINGTON COUNTY...

At 744 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 0.75 and 1 inch of rain has 
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...
  Zion National Park, specifically the Subway canyon. Flows are 
  expected to continue down North Creek to the confluence with the 
  Virgin River.

This includes the following streams and drainages...
  Right Fork North Creek, North Creek, and the Virgin River.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3719 11317 3720 11319 3726 11315 3727 11312
      3734 11310 3736 11308 3741 11308 3744 11305
      3738 11302 3734 11300 3728 11300 3724 11307
      3722 11310 3721 11313

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

$$

SW

442 
WGUS75 KSLC 260211
FFSSLC

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

UTC053-260221-
/O.EXP.KSLC.FF.W.0048.000000T0000Z-210726T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington UT-
811 PM MDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 815 PM MDT THIS EVENING FOR 
EAST CENTRAL WASHINGTON COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Runoff from previous heavy rainfall will continue to 
diminish through the evening hours. Please continue to heed any road 
closures.
 
A Flash Flood Watch remains in effect until 1000 PM MDT for portions 
of southern Utah and southwest Utah.

LAT...LON 3719 11317 3720 11319 3726 11315 3727 11312
      3734 11310 3736 11308 3741 11308 3744 11305
      3738 11302 3734 11300 3728 11300 3724 11307
      3722 11310 3721 11313

$$

SW

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 24, 7:17 PM MDT	Special Weather Statement	SLC	Garfield	28 min
Jul 24, 8:08 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane	3 hr
Jul 25, 2:25 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron	3 hr
Jul 25, 2:49 PM MDT	Special Weather Statement	SLC	Piute	26 min
Jul 25, 2:53 PM MDT	Special Weather Statement	SLC	Beaver	37 min
Jul 25, 3:11 PM MDT	Special Weather Statement	SLC	Piute	34 min
Jul 25, 3:18 PM MDT	Special Weather Statement	SLC	Sevier	27 min
Jul 25, 3:33 PM MDT	Special Weather Statement	SLC	Iron	27 min
Jul 25, 3:49 PM MDT	Severe Thunderstorm Warning	SLC	Iron	26 min
Jul 25, 4:11 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron	3 hr
Jul 25, 4:21 PM MDT	Special Weather Statement	SLC	Washington	24 min
Jul 25, 4:29 PM MDT	Areal Flood Advisory	SLC	Iron	3 hr
Jul 25, 4:41 PM MDT	Special Weather Statement	SLC	Washington	19 min
Jul 25, 4:41 PM MDT	Special Weather Statement	SLC	Iron	49 min
Jul 25, 4:52 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron, Kane, Washington	4 hr
Jul 25, 5:26 PM MDT	Severe Thunderstorm Warning	SLC	Washington	19 min
Jul 25, 5:42 PM MDT	Severe Thunderstorm Warning	SLC	Washington	33 min
Jul 25, 5:44 PM MDT	Special Weather Statement	SLC	Washington	31 min
Jul 25, 5:52 PM MDT	Special Weather Statement	SLC	Washington	23 min

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.