Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 125, NWS Salt Lake City, UT

August 21, 2021Salt Lake County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Aug 21, 2021, 9:59 PM MDT for Salt Lake County, Utah. It was in force for 91 min. 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 21, 2021, 9:59 PM MDT (03:59 UTC)
Expired
Aug 21, 2021, 11:30 PM MDT
In force
91 min
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Salt Lake County, UT

The radar

The Salt Lake City radar (KMTX), 89 km from the middle of the area, began a volume at 04:02 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

Salt Lake City I, UT (KSLC), launched 00:00Z, 4.0 hours before the alert went out and 22 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 00:00Z on 2021-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 422 joules per kilogram.LCLEL10008507005003002001001 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 00:00Z on 2021-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 84 square meters per square second.1939587897Sfc1 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
422 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
2862 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
84 m²/s²
0-3 km storm-relative helicity
171 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.1

Open this sounding in Storm Lab

The text

As transmitted.

331 
WGUS55 KSLC 220359
FFWSLC
UTC035-220530-
/O.NEW.KSLC.FF.W.0125.210822T0359Z-210822T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
959 PM MDT Sat Aug 21 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  The Parleys Canyon burn scar in...
  Northeastern Salt Lake County in northern Utah...

* Until 1130 PM MDT.

* At 959 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain over the Parleys Canyon Burn Scar. Up to 0.5 inches of 
  rain have fallen and additional rainfall is expected. Flash 
  flooding is ongoing or expected to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Parleys Canyon Burn Scar. The debris flow can 
consist of rock, mud, vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Parleys
           Canyon Burn Scar.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Parleys Canyon Burn Scar.

* Some locations that will experience flash flooding include...
  mainly rural areas of Northeastern Salt Lake County

This includes the following highways...
	Interstate 80 in Utah between mile markers 137 and 138.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4074 11166 4075 11164 4073 11163 4073 11164
      4074 11167

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

$$

CRK
2 follow-up statements
145 
WGUS75 KSLC 220444
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1044 PM MDT Sat Aug 21 2021

UTC035-220530-
/O.CON.KSLC.FF.W.0125.000000T0000Z-210822T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Salt Lake UT-
1044 PM MDT Sat Aug 21 2021

...FLASH FLOOD WARNING FOR THE PARLEYS CANYON BURN SCAR REMAINS IN 
EFFECT UNTIL 1130 PM MDT THIS EVENING FOR NORTHEASTERN SALT LAKE 
COUNTY...

At 1044 PM MDT, Doppler radar indicated thunderstorms producing 
heavy rain over the Parleys Canyon Burn Scar. Between 0.5 and 0.75 
inches of rain have fallen. Flash flooding is ongoing or expected to 
begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Parleys Canyon Burn Scar. The debris flow can 
consist of rock, mud, vegetation and other loose materials.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding in and around the Parleys Canyon Burn
         Scar.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Parleys Canyon Burn Scar.

Some locations that will experience flash flooding include...
  mainly rural areas of Northeastern Salt Lake County

This includes the following highways...
	Interstate 80 in Utah near mile marker 138.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4074 11166 4075 11164 4073 11163 4073 11164
      4074 11167

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

$$

CRK
631 
WGUS75 KSLC 220521
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
1121 PM MDT Sat Aug 21 2021

UTC035-220531-
/O.EXP.KSLC.FF.W.0125.000000T0000Z-210822T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Salt Lake UT-
1121 PM MDT Sat Aug 21 2021

...FLASH FLOOD WARNING FOR THE PARLEYS CANYON BURN SCAR WILL EXPIRE 
AT 1130 PM MDT THIS EVENING FOR NORTHEASTERN SALT LAKE COUNTY...

The heavy rain has ended. Be careful for debris on I-80 near the 
burn scar through the overnight period.

LAT...LON 4074 11166 4075 11164 4073 11163 4073 11164
      4074 11167

$$

CRK

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 21, 6:06 PM MDTSevere Thunderstorm Warning Considerable damage threatSLCBox Elder, Cache, Davis, Morgan, Rich, Salt Lake and 3 more39 min
Aug 21, 6:29 PM MDTSevere Thunderstorm WarningSLCCache, Rich61 min
Aug 21, 6:40 PM MDTSevere Thunderstorm Warning Considerable damage threatSLCBox Elder, Cache, Davis, Morgan, Rich, Salt Lake and 3 more50 min
Aug 21, 6:59 PM MDTAreal Flood AdvisorySLCDavis, Weber2 hr
Aug 21, 7:08 PM MDTSevere Thunderstorm Warning Considerable damage threatSLCSummit37 min
Aug 21, 7:23 PM MDTSpecial Weather StatementSLCSalt Lake37 min
Aug 21, 7:33 PM MDTAreal Flood AdvisorySLCDavis, Morgan, Salt Lake, Summit117 min
Aug 21, 7:41 PM MDTSpecial Weather StatementSLCSummit49 min
Aug 21, 7:49 PM MDTSpecial Weather StatementSLCDuchesne41 min
Aug 21, 8:09 PM MDTSpecial Weather StatementSLCSummit51 min
Aug 21, 8:14 PM MDTSpecial Weather StatementSLC31 min
Aug 21, 8:19 PM MDTSevere Thunderstorm WarningSLCDuchesne, Summit26 min
Aug 21, 8:32 PM MDTHigh Wind WarningSLCUtah3 hr

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.