Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 55, NWS Salt Lake City, UT

July 26, 2021Kane County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 26, 2021, 5:30 PM MDT for Kane County, Utah. It was in force for 6 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 26, 2021, 5:30 PM MDT (23:30 UTC)
Expired
Jul 26, 2021, 11:30 PM MDT
In force
6 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Kane County, UT

The radar

The Cedar City radar (KICX), 117 km from the middle of the area, began a volume at 23:31 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

TimeReportWhereRemark
Jul 26, 9:42 PM MDTFLASH FLOODBig Water, UTSTORM CHASER SENT A VIDEO OF A FLOOD WAVE MOVING THROUGH BIG WATER, UT.

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

The nearest sounding before it

Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 11.5 hours before the alert went out and 216 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-pSkew-T log-p diagram, Flgstf/Belemont, AZ at 12:00Z on 2021-07-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 20 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Flgstf/Belemont, AZ at 12:00Z on 2021-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
20 J/kg
Mixed-layer CIN
-105 J/kg
Mixed-layer LCL
954 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
37 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

170 
WGUS55 KSLC 262330
FFWSLC
UTC025-270530-
/O.NEW.KSLC.FF.W.0055.210726T2330Z-210727T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
530 PM MDT Mon Jul 26 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  Central Kane County in southern Utah...

* Until 1130 PM MDT.

* At 530 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the mid and upper portions of Wahweep Creek. 
  Between 0.75 and 1 inch of rain has fallen, and additional heavy 
  rainfall is expected over the next hour. Flash flooding is ongoing 
  or expected to begin shortly, with the flash flood wave eventually 
  tracking downstream through Big Water later this evening, prior to 
  reaching its terminus in the Lake Powell.

  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...
  Wahweep Creek through Big Water.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3700 11148 3701 11153 3701 11159 3703 11164
      3711 11170 3713 11176 3720 11180 3731 11187
      3738 11184 3744 11175 3738 11169 3731 11169
      3725 11168 3718 11163 3710 11156 3700 11146

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

$$

GM
3 follow-up statements
611 
WGUS75 KSLC 270209
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
809 PM MDT Mon Jul 26 2021

UTC025-270530-
/O.CON.KSLC.FF.W.0055.000000T0000Z-210727T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-
809 PM MDT Mon Jul 26 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1130 PM MDT THIS 
EVENING FOR CENTRAL KANE COUNTY...

At 809 PM MDT, Doppler radar indicated between 0.75 and 1.75 inches 
of rain fell across the the mid and upper portions of the Wahweep 
Creek Basin from earlier thunderstorms. Flash flooding is ongoing or 
expected to begin shortly. The flood wave is expected to travel 
downstream and through Big Water later this evening prior to 
reaching its terminus at Lake Powell.

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...
  Wahweep Creek running through Big Water.

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.

Flooding is occurring or is imminent. It is important to know where 
you are relative to streams, rivers, or creeks which can become 
killers in heavy rains. Campers and hikers should avoid streams or 
creeks.

&&

LAT...LON 3700 11148 3701 11153 3701 11159 3703 11164
      3711 11170 3713 11176 3720 11180 3731 11187
      3738 11184 3744 11175 3738 11169 3731 11169
      3725 11168 3718 11163 3710 11156 3700 11146

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

$$

GM
844 
WGUS75 KSLC 270353
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
953 PM MDT Mon Jul 26 2021

UTC025-270530-
/O.CON.KSLC.FF.W.0055.000000T0000Z-210727T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-
953 PM MDT Mon Jul 26 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1130 PM MDT THIS 
EVENING FOR CENTRAL KANE COUNTY...

At 953 PM MDT, storm chaser reported flash flooding in Wahweep Creek 
at Big Water. Between 0.75 and 1.75 inches of rain have fallen. 
Flash flooding is already occurring.

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

SOURCE...Storm chaser reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Wahweep Creek through Big Water.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3700 11148 3701 11153 3701 11159 3703 11164
      3711 11170 3713 11176 3720 11180 3731 11187
      3738 11184 3744 11175 3738 11169 3731 11169
      3725 11168 3718 11163 3710 11156 3700 11146

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

$$

Church
728 
WGUS75 KSLC 270528
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1128 PM MDT Mon Jul 26 2021

UTC025-270538-
/O.EXP.KSLC.FF.W.0055.000000T0000Z-210727T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane UT-
1128 PM MDT Mon Jul 26 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1130 PM MDT THIS EVENING FOR 
CENTRAL KANE COUNTY...

Flooding will continue to diminish overnight and the heavy rain has 
ended. Please continue to heed higher water levels on Wahweep Creek 
and any remaining road closures.

LAT...LON 3700 11148 3701 11153 3701 11159 3703 11164
      3711 11170 3713 11176 3720 11180 3731 11187
      3738 11184 3744 11175 3738 11169 3731 11169
      3725 11168 3718 11163 3710 11156 3700 11146

$$

Church

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 25, 6:06 PM MDTSpecial Weather StatementSLCWashington39 min
Jul 25, 6:16 PM MDTSpecial Weather StatementSLCWashington44 min
Jul 26, 3:37 AM MDTFlash Flood WatchSLCBeaver, Garfield, Iron, Kane, Piute, Washington and 1 more20 hr
Jul 26, 1:13 PM MDTFlash Flood Warning Considerable damage threatSLCKane, Washington3 hr
Jul 26, 1:37 PM MDTSevere Thunderstorm WarningSLCWashington23 min
Jul 26, 1:40 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield3 hr
Jul 26, 1:47 PM MDTSpecial Weather StatementSLCPiute43 min
Jul 26, 2:00 PM MDTSpecial Weather StatementSLCWashington45 min
Jul 26, 2:07 PM MDTAreal Flood AdvisorySLCWashington53 min
Jul 26, 2:12 PM MDTAreal Flood AdvisorySLCIron2 hr
Jul 26, 2:35 PM MDTFlash Flood Warning Considerable damage threatSLCIron115 min
Jul 26, 2:45 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield4 hr
Jul 26, 2:53 PM MDTFlash Flood Warning Considerable damage threatSLCIron, Washington3 hr
Jul 26, 3:01 PM MDTSevere Thunderstorm WarningSLCBeaver, Iron29 min
Jul 26, 3:07 PM MDTSevere Thunderstorm WarningSLCBeaver, Iron23 min
Jul 26, 3:20 PM MDTSevere Thunderstorm WarningSLCBeaver, Iron2 min
Jul 26, 3:26 PM MDTSpecial Weather StatementSLCWashington49 min
Jul 26, 3:30 PM MDTSevere Thunderstorm WarningSLCWashington30 min
Jul 26, 3:32 PM MDTAreal Flood AdvisorySLCWashington118 min
Jul 26, 3:32 PM MDTFlash Flood Warning Considerable damage threatSLCBeaver3 hr
Jul 26, 4:00 PM MDTSevere Thunderstorm WarningSLCWashington30 min
Jul 26, 4:34 PM MDTSpecial Weather StatementSLCWashington41 min
Jul 26, 4:55 PM MDTSpecial Weather StatementSLCBeaver50 min

Nearby

Flash Flood Warnings in Utah, 2021Every 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.