Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 94, NWS Salt Lake City, UT

August 17, 2021Garfield County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Aug 17, 2021, 2:50 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 17, 2021, 2:50 PM MDT (20:50 UTC)
Expired: Aug 17, 2021, 5:45 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), 68 km from the middle of the area, began a volume at 20:54 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, 8.8 hours before the alert went out and 267 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: 984 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 829 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 135 m²/s²
0-3 km storm-relative helicity: 154 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.8

Open this sounding in Storm Lab

The text

As transmitted.

111 
WGUS55 KSLC 172050
FFWSLC
UTC017-172345-
/O.NEW.KSLC.FF.W.0094.210817T2050Z-210817T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
250 PM MDT Tue Aug 17 2021

The National Weather Service in Salt Lake City has issued a

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

* Until 545 PM MDT.

* At 250 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the upper headwaters of the Paria River 
  watershed. Between 1 and 1.75 inches of rain have fallen. 
  Additional rainfall amounts of 0.5 to 1 inch are possible. 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...
  Bryce Canyon National Park, Tropic, and Cannonville.

This includes the following highways...
	Utah Route 12 between mile markers 17 and 26.

This includes the following streams and drainages...
  Paria River.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3763 11217 3767 11214 3769 11208 3767 11204
      3764 11202 3761 11205 3755 11203 3754 11205
      3761 11207 3761 11212 3762 11215

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

$$

SW

2 follow-up statements

106 
WGUS75 KSLC 172216
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
416 PM MDT Tue Aug 17 2021

UTC017-172345-
/O.CON.KSLC.FF.W.0094.000000T0000Z-210817T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-
416 PM MDT Tue Aug 17 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM MDT THIS 
AFTERNOON FOR SOUTHERN GARFIELD COUNTY...

At 416 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the upper headwaters of the Paria River watershed. 
Between 1.5 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...
  Bryce Canyon National Park, Tropic, and Cannonville.

This includes the following highways...
	Utah Route 12 between mile markers 17 and 26.

This includes the following streams and drainages...
  Paria River.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3763 11217 3767 11214 3769 11208 3767 11204
      3764 11202 3761 11205 3755 11203 3754 11205
      3761 11207 3761 11212 3762 11215

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

$$

SW

970 
WGUS75 KSLC 172343
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
543 PM MDT Tue Aug 17 2021

UTC017-172353-
/O.EXP.KSLC.FF.W.0094.000000T0000Z-210817T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-
543 PM MDT Tue Aug 17 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 545 PM MDT THIS AFTERNOON FOR 
SOUTHERN GARFIELD COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Runoff from earlier 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 1200 AM MDT Thursday for 
portions of central Utah, northern Utah and southern Utah.

LAT...LON 3763 11217 3767 11214 3769 11208 3767 11204
      3764 11202 3761 11205 3755 11203 3754 11205
      3761 11207 3761 11212 3762 11215

$$

SW

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 17, 1:31 PM MDT	Special Weather Statement	SLC	Kane	44 min
Aug 17, 1:50 PM MDT	Severe Thunderstorm Warning	SLC	Garfield, Kane	20 min
Aug 17, 2:23 PM MDT	Severe Thunderstorm Warning	SLC	Beaver, Garfield, Piute	52 min
Aug 17, 3:14 PM MDT	Special Weather Statement	SLC	Juab	31 min
Aug 17, 3:20 PM MDT	Special Weather Statement	SLC	Tooele	25 min
Aug 17, 3:29 PM MDT	Severe Thunderstorm Warning	SLC	Sevier	46 min
Aug 17, 3:51 PM MDT	Severe Thunderstorm Warning	SLC	Tooele	24 min
Aug 17, 4:12 PM MDT	Severe Thunderstorm Warning Considerable damage threat	SLC	Tooele	48 min
Aug 17, 4:18 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Emery, Wayne	3 hr
Aug 17, 4:29 PM MDT	Severe Thunderstorm Warning	SLC	Tooele	46 min
Aug 17, 4:39 PM MDT	Severe Thunderstorm Warning Considerable damage threat	SLC	Millard	66 min
Aug 17, 4:53 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield	3 hr
Aug 17, 4:56 PM MDT	Severe Thunderstorm Warning	SLC	Garfield	24 min
Aug 17, 5:00 PM MDT	Severe Thunderstorm Warning	SLC	Davis, Salt Lake, Tooele	30 min
Aug 17, 5:10 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane	4 hr
Aug 17, 5:12 PM MDT	Severe Thunderstorm Warning	SLC	Tooele	63 min
Aug 17, 5:30 PM MDT	Severe Thunderstorm Warning Considerable damage threat	SLC	Davis, Salt Lake	45 min
Aug 17, 5:37 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield, Kane	6 hr
Aug 17, 5:40 PM MDT	Severe Thunderstorm Warning	SLC	Millard	50 min
Aug 17, 5:48 PM MDT	Special Weather Statement	SLC	Sanpete	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.