Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 116, NWS Salt Lake City, UT

August 18, 2021Garfield County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Aug 18, 2021, 8:01 PM MDT for Garfield 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: Aug 18, 2021, 8:01 PM MDT (02:01 UTC)
Expired: Aug 18, 2021, 11:00 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Garfield County, UT

The radar

The Cedar City radar (KICX), 130 km from the middle of the area, began a volume at 02:04 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 00:00Z, 2.0 hours before the alert went out and 274 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: 605 J/kg
Mixed-layer CIN: -17 J/kg
Mixed-layer LCL: 745 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 109 m²/s²
0-3 km storm-relative helicity: 108 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

As transmitted.

132 
WGUS55 KSLC 190201
FFWSLC
UTC017-190500-
/O.NEW.KSLC.FF.W.0116.210819T0201Z-210819T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  South Central Garfield County in southern Utah...

* Until 1100 PM MDT.

* At 801 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.25 and 1 inch of rain 
  has fallen, with lower end amounts near the Egypt slot canyons and 
  higher end amounts along the Upper Escalante River. 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...
  mainly rural areas of South Central Garfield County

This includes the following highways...
	Utah Route 12 between mile markers 63 and 75.

This includes the following streams and drainages...
  Escalante River, Boulder Creek, Harris Wash, Death Hollow, Pine 
  Creek, Willow Patch Creek, Sand Creek, Alvey Wash, The Gulch, 
  Twentyfive Mile Wash, Calf Creek, and the Egypt Slot Canyons.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3778 11158 3783 11150 3776 11134 3768 11121
      3758 11112 3755 11113 3755 11128 3756 11133
      3760 11136 3763 11137 3765 11144 3769 11152
      3773 11157 3777 11156

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

$$

SW

1 follow-up statement

171 
WGUS75 KSLC 190458
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1058 PM MDT Wed Aug 18 2021

UTC017-190508-
/O.EXP.KSLC.FF.W.0116.000000T0000Z-210819T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-
1058 PM MDT Wed Aug 18 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 11 PM MDT THIS EVENING FOR 
SOUTH CENTRAL GARFIELD COUNTY...

Flooding is no longer expected to pose an imminent threat. Please 
continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 600 AM MDT Thursday for 
portions of central Utah, northern Utah and southern Utah.

LAT...LON 3778 11158 3783 11150 3776 11134 3768 11121
      3758 11112 3755 11113 3755 11128 3756 11133
      3760 11136 3763 11137 3765 11144 3769 11152
      3773 11157 3777 11156

$$

MPS

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 7:43 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	4 hr
Aug 18, 8:46 PM MDT	Special Weather Statement	SLC	Iron	44 min
Aug 18, 9:39 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron, Washington	3 hr
Aug 18, 9:48 PM MDT	Areal Flood Advisory	SLC	Iron	5 min
Aug 18, 9:53 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron	3 hr
Aug 18, 10:07 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron	3 hr
Aug 18, 11:11 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, Washington	5 hr
Aug 19, 1:43 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Wayne	3 hr
Aug 19, 2:03 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane, San Juan	6 hr
Aug 19, 2:31 AM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	3 hr
Aug 19, 3:50 AM MDT	Special Weather Statement	SLC		25 min
Aug 19, 9:39 AM MDT	Special Weather Statement	SLC	Kane	36 min
Aug 19, 10:16 AM MDT	River Flood Warning	SLC	Duchesne	4 hr
Aug 19, 10:54 AM MDT	Special Weather Statement	SLC	Juab	51 min
Aug 19, 11:15 AM MDT	Areal Flood Advisory	SLC	Millard	2 hr
Aug 19, 11:42 AM MDT	Special Weather Statement	SLC	Sanpete	48 min
Aug 19, 12:29 PM MDT	Special Weather Statement	SLC	Sanpete	46 min
Aug 19, 12:49 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Wayne	3 hr
Aug 19, 1:04 PM MDT	Special Weather Statement	SLC	Utah	56 min
Aug 19, 1:25 PM MDT	Special Weather Statement	SLC	Carbon	50 min
Aug 19, 2:12 PM MDT	Special Weather Statement	SLC	Carbon, Duchesne	63 min
Aug 19, 2:59 PM MDT	Special Weather Statement	SLC	Duchesne	61 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.