Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 59, NWS Salt Lake City, UT

July 27, 2021Garfield County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 27, 2021, 1:55 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 27, 2021, 1:55 PM MDT (19:55 UTC)
Expired
Jul 27, 2021, 5:00 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), 161 km from the middle of the area, began a volume at 19:59 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, 7.9 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-pSkew-T log-p diagram, Grand Junction, CO at 12:00Z on 2021-07-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 28 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, Grand Junction, CO at 12:00Z on 2021-07-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -20 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
28 J/kg
Mixed-layer CIN
-304 J/kg
Mixed-layer LCL
1735 m above ground
0-6 km bulk shear
5 kt
0-1 km storm-relative helicity
-20 m²/s²
0-3 km storm-relative helicity
-8 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

690 
WGUS55 KSLC 271955
FFWSLC
UTC017-272300-
/O.NEW.KSLC.FF.W.0059.210727T1955Z-210727T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
155 PM MDT Tue Jul 27 2021

The National Weather Service in Salt Lake City has issued a

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

* Until 500 PM MDT.

* At 155 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across portions of Upper Muley Twist Canyon and 
  drainages leading into the canyon. Between 1.25 and 1.75 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, specifically Upper Muley Twist Canyon 
  through the intersection with Burr Trail Road.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3790 11110 3791 11109 3792 11107 3790 11105
      3786 11103 3784 11102 3783 11102 3785 11104
      3788 11105 3787 11108 3788 11110

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

$$

SW
1 follow-up statement
607 
WGUS75 KSLC 272258
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
458 PM MDT Tue Jul 27 2021

UTC017-272308-
/O.EXP.KSLC.FF.W.0059.000000T0000Z-210727T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-
458 PM MDT Tue Jul 27 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 5 PM MDT THIS AFTERNOON FOR 
EASTERN GARFIELD COUNTY...

The heavy rain has ended. Flash flooding was previously observed 
across portions of Capitol Reef National Park, however, flooding is 
no longer expected to pose a threat. Runoff from earlier heavy 
rainfall will continue to decreases through the evening hours. 
Please continue to heed remaining road closures.

LAT...LON 3790 11110 3791 11109 3792 11107 3790 11105
      3786 11103 3784 11102 3783 11102 3785 11104
      3788 11105 3787 11108 3788 11110

$$

SW

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 26, 6:39 PM MDTFlash Flood Warning Considerable damage threatSLCKane3 hr
Jul 26, 7:08 PM MDTSpecial Weather StatementSLCSalt Lake37 min
Jul 27, 12:35 PM MDTFlash Flood Warning Considerable damage threatSLCWayne3 hr
Jul 27, 1:23 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Wayne3 hr
Jul 27, 2:46 PM MDTFlash Flood Warning Considerable damage threatSLCGarfield, Kane3 hr
Jul 27, 4:40 PM MDTSpecial Weather StatementSLCRich50 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.