Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 131, NWS Salt Lake City, UT

September 11, 2021Carbon County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Sep 11, 2021, 1:40 PM MDT for Carbon 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
Sep 11, 2021, 1:40 PM MDT (19:40 UTC)
Expired
Sep 11, 2021, 4:30 PM MDT
In force
3 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Carbon County, UT

The radar

The Salt Lake City radar (KMTX), 212 km from the middle of the area, began a volume at 19:40 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
Sep 11, 1:47 PM MDTFLASH FLOOD5 Nnw Helper, UTUDOT REPORTS FLOODING AND DEBRIS FLOWS ACROSS HIGHWAY 6 WITH AN ASSOCIATED ROAD CLOSURE OF WESTBOUND LANES AT MP 229 AND EASTBOUND LANES CLOSED AT MP 220

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, 7.7 hours before the alert went out and 142 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 2021-09-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 25 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 2021-09-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -26 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
25 J/kg
Mixed-layer CIN
-278 J/kg
Mixed-layer LCL
1449 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
-26 m²/s²
0-3 km storm-relative helicity
135 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

920 
WGUS55 KSLC 111940
FFWSLC
UTC007-112230-
/O.NEW.KSLC.FF.W.0131.210911T1940Z-210911T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
140 PM MDT Sat Sep 11 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  The Bear burn scar in...
  Northwestern Carbon County in central Utah...

* Until 430 PM MDT.

* At 140 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain over the Bear burn scar. Flash flooding is ongoing or 
  expected to begin shortly.

Intense rainfall is falling over the Bear burn scar. Flash flooding 
and debris flows are expected out of Crandall and Bear Canyons which 
will impact US 6 between mm226 and mm230 near Castle Gate. 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 Bear burn
           scar.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Bear burn scar.

* Some locations that will experience flash flooding include...
  Helper and Castle Gate.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3980 11093 3974 11086 3969 11086 3972 11096
      3975 11097

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

$$

GM
2 follow-up statements
682 
WGUS75 KSLC 112017
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
217 PM MDT Sat Sep 11 2021

UTC007-112230-
/O.CON.KSLC.FF.W.0131.000000T0000Z-210911T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Carbon UT-
217 PM MDT Sat Sep 11 2021

...FLASH FLOOD WARNING FOR THE BEAR BURN SCAR REMAINS IN EFFECT 
UNTIL 430 PM MDT THIS AFTERNOON FOR NORTHWESTERN CARBON COUNTY...

At 217 PM MDT, UDOT has reported a debris flow off of the Bear burn 
scar out of Crandall Canyon that is currently impacting US 6 near 
Castle Gate. The highway has been closed in both directions in this 
area.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding in and around the Bear burn scar.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Bear burn scar.

Some locations that will experience flash flooding include...
  Helper and Castle Gate.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3980 11093 3974 11086 3969 11086 3972 11096
      3975 11097

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

$$

GM
415 
WGUS75 KSLC 112235
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
435 PM MDT Sat Sep 11 2021

UTC007-112245-
/O.EXP.KSLC.FF.W.0131.000000T0000Z-210911T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Carbon UT-
435 PM MDT Sat Sep 11 2021

...FLASH FLOOD WARNING FOR THE BEAR BURN SCAR HAS EXPIRED FOR 
NORTHWESTERN CARBON COUNTY...

The heavy rain has ended over the Bear burn scar, but Highway 6 
remains closed in both directions between Emma Park Road (MP 220) 
and US 191 (MP 229) due to significant debris on the roadway from an 
earlier debris flow. Please visit the UDOT Traffic website for the 
latest information on this road closure and ongoing clean up efforts.

LAT...LON 3980 11093 3974 11086 3969 11086 3972 11096
      3975 11097

$$

GM

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 10, 6:06 PM MDTSevere Thunderstorm WarningSLCBox Elder, Weber39 min
Sep 10, 6:20 PM MDTSevere Thunderstorm WarningSLCDavis, Morgan, Weber25 min
Sep 10, 6:42 PM MDTSpecial Weather StatementSLCMorgan, Weber33 min
Sep 10, 6:42 PM MDTSpecial Weather StatementSLCDavis33 min
Sep 10, 6:50 PM MDTSevere Thunderstorm WarningSLCDavis, Salt Lake, Tooele25 min
Sep 10, 7:10 PM MDTSpecial Weather StatementSLCSalt Lake, Utah50 min
Sep 10, 7:10 PM MDTSevere Thunderstorm WarningSLCDavis, Morgan, Salt Lake, Weber35 min
Sep 10, 7:16 PM MDTSevere Thunderstorm WarningSLCDavis, Salt Lake29 min
Sep 10, 7:24 PM MDTSpecial Weather StatementSLCRich51 min
Sep 10, 7:24 PM MDTSpecial Weather StatementSLCCache51 min
Sep 10, 7:38 PM MDTSpecial Weather StatementSLCCache, Morgan, Rich, Weber52 min
Sep 11, 12:50 PM MDTFlash Flood Warning Considerable damage threatSLCWayne3 hr
Sep 11, 12:54 PM MDTSpecial Weather StatementSLCCarbon51 min
Sep 11, 1:39 PM MDTSpecial Weather StatementSLCDuchesne51 min
Sep 11, 3:17 PM MDTSpecial Weather StatementSLCDuchesne43 min
Sep 11, 4:25 PM MDTSpecial Weather StatementSLCMillard35 min
Sep 11, 5:10 PM MDTSpecial Weather StatementSLCJuab35 min
Sep 11, 5:19 PM MDTSpecial Weather StatementSLCMillard26 min
Sep 11, 5:44 PM MDTSpecial Weather StatementSLCMillard46 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.