Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 23, NWS Salt Lake City, UT

July 20, 2021Wayne County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 20, 2021, 12:11 PM MDT for Wayne County, Utah. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 20, 2021, 12:11 PM MDT (18:11 UTC)
Expired: Jul 20, 2021, 3:15 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Wayne County, UT

The radar

The Cedar City radar (KICX), 158 km from the middle of the area, began a volume at 18:12 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.

What was reported inside it

Time	Report	Where	Remark
Jul 20, 1:40 PM MDT	FLASH FLOOD	Capitol Reef Np, UT	ACTIVE FLOODING IN CAPITOL REEF, SULFUR CREEK 6-12 INCHES HIGH, FLOODING IN THE FREMONT RIVER. HEADWALL OF WATER MOVED THROUGH GRAND WASH.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Grand Junction, CO (KGJT), launched 12:00Z, 6.2 hours before the alert went out and 259 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.

680 
WGUS55 KSLC 201811
FFWSLC
UTC055-202115-
/O.NEW.KSLC.FF.W.0023.210720T1811Z-210720T2115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
1211 PM MDT Tue Jul 20 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Western Wayne County in southern Utah...

* Until 315 PM MDT.

* At 1211 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...
  Capitol Reef National Park and Fruita.

This includes the following streams and drainages...
  Fremont River, Carcass Creek, Rock Creek, and Grand Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Remain alert for flooding even in locations not receiving rain. Dry 
washes, streams, and rivers can become raging killer currents in a 
matter of minutes, even from distant rainfall.

&&

LAT...LON 3825 11134 3826 11132 3827 11129 3829 11124
      3829 11122 3829 11119 3828 11118 3827 11120
      3826 11122 3825 11123 3822 11127 3821 11129
      3821 11131 3822 11134

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

$$

SW

2 follow-up statements

180 
WGUS75 KSLC 201950
FFSSLC

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

UTC055-202115-
/O.CON.KSLC.FF.W.0023.000000T0000Z-210720T2115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Wayne UT-
150 PM MDT Tue Jul 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 PM MDT THIS 
AFTERNOON FOR WESTERN WAYNE COUNTY...

At 150 PM MDT, the public reported flash flooding across the warned 
area. Between 0.75 and 1.1 inches of rain have fallen. Flash 
flooding is already occurring.

HAZARD...Life threatening flash flooding. Heavy rain producing
         flash flooding.

SOURCE...Public reported.

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 and Fruita.

This includes the following streams and drainages...
  Fremont River, Sulphur Creek, Carcass Creek, Rock Creek, and Grand 
  Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Remain alert for flooding even in locations not receiving rain. Dry 
washes, streams, and rivers can become raging killer currents in a 
matter of minutes, even from distant rainfall.

&&

LAT...LON 3825 11134 3826 11132 3827 11129 3829 11124
      3829 11122 3829 11119 3828 11118 3827 11120
      3826 11122 3825 11123 3822 11127 3821 11129
      3821 11131 3822 11134

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

SW

679 
WGUS75 KSLC 202113
FFSSLC

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

UTC055-202123-
/O.EXP.KSLC.FF.W.0023.000000T0000Z-210720T2115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Wayne UT-
313 PM MDT Tue Jul 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 315 PM MDT THIS AFTERNOON FOR 
WESTERN WAYNE COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures. Additional 
heavy rainfall may enter the warned area and warrant another warning.

LAT...LON 3825 11134 3826 11132 3827 11129 3829 11124
      3829 11122 3829 11119 3828 11118 3827 11120
      3826 11122 3825 11123 3822 11127 3821 11129
      3821 11131 3822 11134

$$

SW

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, 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
Jul 20, 4:58 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Garfield	3 hr

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.