Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 105, NWS Salt Lake City, UT

August 18, 2021Kane County, Washington County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Aug 18, 2021, 8:58 AM MDT for Kane County, Washington County, Utah. It was in force for 92 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 18, 2021, 8:58 AM MDT (14:58 UTC)
Expired: Aug 18, 2021, 10:30 AM MDT
In force: 92 min
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Kane County, UT, Washington County, UT

The radar

The Cedar City radar (KICX), 35 km from the middle of the area, began a volume at 14:57 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, 3.0 hours before the alert went out and 250 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: 590 J/kg
Mixed-layer CIN: -3 J/kg
Mixed-layer LCL: 634 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: 23 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

352 
WGUS55 KSLC 181458
FFWSLC
UTC025-053-181630-
/O.NEW.KSLC.FF.W.0105.210818T1458Z-210818T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
858 AM MDT Wed Aug 18 2021

The National Weather Service in Salt Lake City has issued a

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

* Until 1030 AM MDT.

* At 858 AM MDT, The gauge at the North Fork of the Virgin River 
  continues to show very high flows.  Another wave of flood waters 
  is likely to come through the area later this morning.

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

  SOURCE...Gauges reported.

  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, Springdale and Rockville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3734 11300 3734 11291 3739 11281 3733 11278
      3726 11287 3725 11290 3717 11300 3716 11303
      3727 11299

FLASH FLOOD...GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

CRK

2 follow-up statements

484 
WGUS75 KSLC 181528
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
928 AM MDT Wed Aug 18 2021

UTC025-053-181630-
/O.CON.KSLC.FF.W.0105.000000T0000Z-210818T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
928 AM MDT Wed Aug 18 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 AM MDT THIS 
MORNING FOR WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...

At 928 AM MDT, the gauge on the North Fork of the Virgin River 
continues to show very high flows and flash flooding.  Additional 
increases in the flow are possible through late morning.

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

SOURCE...Gauges reported.

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, Springdale and Rockville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3734 11300 3734 11291 3739 11281 3733 11278
      3726 11287 3725 11290 3717 11300 3716 11303
      3727 11299

FLASH FLOOD...GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

CRK

897 
WGUS75 KSLC 181623
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1023 AM MDT Wed Aug 18 2021

UTC025-053-181633-
/O.EXP.KSLC.FF.W.0105.000000T0000Z-210818T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-Washington UT-
1023 AM MDT Wed Aug 18 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1030 AM MDT THIS MORNING FOR 
WEST CENTRAL KANE AND EAST CENTRAL WASHINGTON COUNTIES...

The heavy rain has ended for now. The North Fork of the Virgin River 
continues to see elevated flows.

An areal flood warning is in effect for the Zion National Park area 
through 2 PM MDT.

A Flash Flood Watch remains in effect until 1200 AM MDT Thursday for 
a portion of southwest Utah.

LAT...LON 3734 11300 3734 11291 3739 11281 3733 11278
      3726 11287 3725 11290 3717 11300 3716 11303
      3727 11299

$$

CRK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 17, 6:05 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Millard	3 hr
Aug 17, 6:10 PM MDT	Severe Thunderstorm Warning	SLC	Juab	35 min
Aug 17, 6:31 PM MDT	Severe Thunderstorm Warning	SLC	Millard	59 min
Aug 17, 6:39 PM MDT	Special Weather Statement	SLC	Utah	36 min
Aug 17, 6:49 PM MDT	Severe Thunderstorm Warning	SLC	Utah, Wasatch	26 min
Aug 17, 6:57 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, San Juan	5 hr
Aug 17, 7:14 PM MDT	Severe Thunderstorm Warning	SLC	Summit, Wasatch	31 min
Aug 17, 8:52 PM MDT	Special Weather Statement	SLC	Salt Lake	38 min
Aug 17, 9:30 PM MDT	Special Weather Statement	SLC	Tooele	30 min
Aug 17, 9:55 PM MDT	Special Weather Statement	SLC	Kane	35 min
Aug 17, 9:58 PM MDT	Special Weather Statement	SLC	Juab	32 min
Aug 17, 10:00 PM MDT	Special Weather Statement	SLC	Juab	30 min
Aug 17, 10:17 PM MDT	Special Weather Statement	SLC	Salt Lake	28 min
Aug 18, 12:23 AM MDT	Special Weather Statement	SLC		52 min
Aug 18, 12:31 AM MDT	Special Weather Statement	SLC	Millard	44 min
Aug 18, 12:45 AM MDT	Special Weather Statement	SLC	Juab	45 min
Aug 18, 1:42 AM MDT	Special Weather Statement	SLC	Juab	48 min
Aug 18, 4:38 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron	5 hr
Aug 18, 4:41 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron	3 hr
Aug 18, 6:02 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron, Washington	4 hr
Aug 18, 7:30 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, Washington	90 min
Aug 18, 7:55 AM MDT	Areal Flood Warning	SLC	Garfield, Iron, Kane, Washington	6 hr
Aug 18, 11:05 AM MDT	Severe Thunderstorm Warning	SLC	Tooele	40 min
Aug 18, 11:45 AM MDT	Special Weather Statement	SLC	Salt Lake	45 min
Aug 18, 12:11 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Wayne	6 hr
Aug 18, 12:17 PM MDT	Areal Flood Advisory	SLC	Davis, Salt Lake, Tooele	2 hr
Aug 18, 12:29 PM MDT	Special Weather Statement	SLC		31 min
Aug 18, 12:34 PM MDT	Severe Thunderstorm Warning	SLC	Juab, Tooele	56 min
Aug 18, 12:47 PM MDT	Special Weather Statement	SLC	Piute	28 min
Aug 18, 1:05 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Wayne	3 hr
Aug 18, 1:12 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield	2 hr
Aug 18, 1:14 PM MDT	Special Weather Statement	SLC	Beaver	31 min
Aug 18, 1:24 PM MDT	Areal Flood Warning	SLC	Juab, Salt Lake, Tooele, Utah	3 hr
Aug 18, 1:24 PM MDT	Severe Thunderstorm Warning	SLC	Juab, Tooele, Utah	81 min
Aug 18, 1:39 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, Washington	3 hr
Aug 18, 1:57 PM MDT	Areal Flood Advisory	SLC	Salt Lake, Utah	2 hr
Aug 18, 2:27 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Utah	3 hr
Aug 18, 2:37 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Utah	113 min
Aug 18, 2:51 PM MDT	Special Weather Statement	SLC	Summit	24 min
Aug 18, 2:56 PM MDT	Special Weather Statement	SLC	Garfield	49 min
Aug 18, 3:14 PM MDT	Special Weather Statement	SLC	Kane	46 min
Aug 18, 3:18 PM MDT	Special Weather Statement	SLC	Wasatch	27 min
Aug 18, 3:25 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Utah	3 hr
Aug 18, 3:41 PM MDT	Special Weather Statement	SLC	Sanpete	49 min
Aug 18, 3:46 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Emery, Wayne	3 hr
Aug 18, 4:16 PM MDT	Special Weather Statement	SLC	Kane	44 min
Aug 18, 4:22 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield	3 hr
Aug 18, 5:41 PM MDT	Special Weather Statement	SLC		49 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.