Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 27, NWS Salt Lake City, UT

July 20, 2021Garfield County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 20, 2021, 4:58 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: Jul 20, 2021, 4:58 PM MDT (22:58 UTC)
Expired: Jul 20, 2021, 8:00 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), 163 km from the middle of the area, began a volume at 23:00 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

Grand Junction, CO (KGJT), launched 12:00Z, 11.0 hours before the alert went out and 263 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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2685 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: -7 m²/s²
0-3 km storm-relative helicity: 31 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

989 
WGUS55 KSLC 202258
FFWSLC
UTC017-210200-
/O.NEW.KSLC.FF.W.0027.210720T2258Z-210721T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Eastern Garfield County in southern Utah...

* Until 800 PM MDT.

* At 458 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...
  Upper and Lower Muley Twist Canyon and Burr Trail Road in Capitol 
  Reef National Park. Additional flows in Halls Creek near Burr 
  Trail Road will be possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3785 11107 3786 11105 3786 11104 3786 11102
      3785 11101 3785 11100 3783 11098 3782 11100
      3780 11099 3780 11100 3782 11101 3782 11102
      3782 11103 3782 11104 3781 11107 3783 11109
      3785 11108

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

$$

SW

2 follow-up statements

611 
WGUS75 KSLC 210041
FFSSLC

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

UTC017-210200-
/O.CON.KSLC.FF.W.0027.000000T0000Z-210721T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-
641 PM MDT Tue Jul 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS EVENING 
FOR EASTERN GARFIELD COUNTY...

At 641 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 0.75 and 1.25 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...
  Capitol Reef National Park.

This includes the following streams and drainages...
  Upper and Lower Muley Twist Canyon and Burr Trail Road Road in 
  Capitol Reef National Park. Additional flows in Halls Creek near 
  Burr Trail Road will be possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3785 11107 3786 11105 3786 11104 3786 11102
      3785 11101 3785 11100 3783 11098 3782 11100
      3780 11099 3780 11100 3782 11101 3782 11102
      3782 11103 3782 11104 3781 11107 3783 11109
      3785 11108

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

$$

SW

310 
WGUS75 KSLC 210157
FFSSLC

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

UTC017-210207-
/O.EXP.KSLC.FF.W.0027.000000T0000Z-210721T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-
757 PM MDT Tue Jul 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 8 PM MDT THIS EVENING FOR 
EASTERN GARFIELD COUNTY...

The heavy rain has ended over the southern portions of Capitol Reef 
National Park. Flooding is no longer expected to pose a threat. 
Runoff from earlier heavy rain will continue to decrease through 
this evening. Please continue to heed any road closures.

LAT...LON 3785 11107 3786 11105 3786 11104 3786 11102
      3785 11101 3785 11100 3783 11098 3782 11100
      3780 11099 3780 11100 3782 11101 3782 11102
      3782 11103 3782 11104 3781 11107 3783 11109
      3785 11108

$$

LC

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, 1:18 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron, Washington	4 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

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.