Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 34, NWS Salt Lake City, UT

July 22, 2021Utah County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 22, 2021, 5:58 PM MDT for Utah 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 22, 2021, 5:58 PM MDT (23:58 UTC)
Expired
Jul 22, 2021, 9:00 PM MDT
In force
3 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Utah County, UT

The radar

The Salt Lake City radar (KMTX), 169 km from the middle of the area, began a volume at 00:05 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 22, 6:15 PM MDTFLASH FLOOD12 Ene Birdseye, UTSOLDIER CREEK FLOODED OVER RAILROAD TRACKS AND ONTO SOUTH SHOULDER OF US-6.

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

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 12.0 hours before the alert went out and 100 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, Salt Lake City I, UT at 12:00Z on 2021-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 56 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Salt Lake City I, UT at 12:00Z on 2021-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 21 square meters per square second.193958Sfc1 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
56 J/kg
Mixed-layer CIN
-151 J/kg
Mixed-layer LCL
2355 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
21 m²/s²
0-3 km storm-relative helicity
40 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

687 
WGUS55 KSLC 222358
FFWSLC
UTC049-230300-
/O.NEW.KSLC.FF.W.0034.210722T2358Z-210723T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
558 PM MDT Thu Jul 22 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  South Central Utah County in northern Utah...

* Until 900 PM MDT.

* At 558 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the Cole Hollow Burnscar. Between 0.75 and 1.5 
  inches of rain have fallen. Flash flooding is ongoing.

Excessive rainfall over the burn scar will result in debris flow 
moving through Dairy Fork and into Soldier Creek. The debris flow 
can consist of rock, mud, vegetation and other loose materials.

  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 Utah County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3996 11138 3999 11140 3999 11143 3999 11150
      4000 11150 4000 11139 3997 11132 3990 11130
      3991 11138

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

$$

GM
2 follow-up statements
296 
WGUS75 KSLC 230214
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
814 PM MDT Thu Jul 22 2021

UTC049-230300-
/O.CON.KSLC.FF.W.0034.000000T0000Z-210723T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Utah UT-
814 PM MDT Thu Jul 22 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 9 PM MDT THIS EVENING 
FOR SOUTH CENTRAL UTAH COUNTY...

At 814 PM MDT, UDOT and local law enforcement earlier reported 
debris flows and flash flooding off the Cole Hollow burn scar out of 
Dairy Fork and into Soldier Creek. Some of this flood water impacted 
the Union Pacific Railway near Sheep Creek, with water reaching the 
shoulder of US 6. Between 0.75 and 1.5 inches of rain fell from 
earlier thunderstorms.

Additional rainfall is now moving over the burn scar once again, 
with an additional .25 to .50 inches possible over the next hour.

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

SOURCE...Law enforcement reported.

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 Utah County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3996 11138 3999 11140 3999 11143 3999 11150
      4000 11150 4000 11139 3997 11132 3990 11130
      3991 11138

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

$$

GM
371 
WGUS75 KSLC 230302
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
902 PM MDT Thu Jul 22 2021

UTC049-230312-
/O.EXP.KSLC.FF.W.0034.000000T0000Z-210723T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Utah UT-
902 PM MDT Thu Jul 22 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR SOUTH CENTRAL UTAH COUNTY...

Flood waters are beginning to recede. The heavy rain has ended, but 
periods of light to moderate rainfall remains possible into the 
overnight hours. Flooding is no longer expected to pose a threat.

LAT...LON 3996 11138 3999 11140 3999 11143 3999 11150
      4000 11150 4000 11139 3997 11132 3990 11130
      3991 11138

$$

GM

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 8:41 PM MDTFlash Flood Warning Considerable damage threatSLCKane6 hr
Jul 22, 2:43 AM MDTFlash Flood WatchSLCEmery, Garfield, Kane, Sevier, Washington, Wayne20 hr
Jul 22, 11:16 AM MDTSpecial Weather StatementSLCPiute29 min
Jul 22, 11:41 AM MDTSpecial Weather StatementSLC49 min
Jul 22, 11:54 AM MDTFlood WatchSLCBeaver, Garfield, Iron, Kane, Piute, Washington and 1 more11 hr
Jul 22, 1:02 PM MDTSpecial Weather StatementSLCIron43 min
Jul 22, 1:13 PM MDTSpecial Weather StatementSLCGarfield32 min
Jul 22, 1:18 PM MDTAreal Flood AdvisorySLCIron117 min
Jul 22, 1:20 PM MDTSevere Thunderstorm WarningSLCGarfield25 min
Jul 22, 1:45 PM MDTSpecial Weather StatementSLCKane45 min
Jul 22, 2:00 PM MDTSpecial Weather StatementSLCBeaver30 min
Jul 22, 2:13 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Kane3 hr
Jul 22, 2:13 PM MDTSevere Thunderstorm WarningSLCBeaver32 min
Jul 22, 2:34 PM MDTFlash Flood Warning Considerable damage threatSLCKane, Washington3 hr
Jul 22, 2:42 PM MDTAreal Flood AdvisorySLCBeaver2 hr
Jul 22, 2:58 PM MDTSevere Thunderstorm WarningSLCWashington32 min
Jul 22, 3:08 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Wayne3 hr
Jul 22, 3:14 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Kane5 hr
Jul 22, 3:14 PM MDTSpecial Weather StatementSLCWashington46 min
Jul 22, 3:30 PM MDTSevere Thunderstorm WarningSLCGarfield
Jul 22, 3:46 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Kane7 hr
Jul 22, 4:02 PM MDTSevere Thunderstorm WarningSLCIron28 min
Jul 22, 4:15 PM MDTSpecial Weather StatementSLCBox Elder30 min
Jul 22, 4:28 PM MDTSevere Thunderstorm WarningSLCIron32 min
Jul 22, 4:48 PM MDTSpecial Weather StatementSLCWashington27 min
Jul 22, 5:51 PM MDTSpecial Weather StatementSLC39 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.