Alert archive / Wyoming / Flash Flood Warnings in 2021

Flash Flood Warning 5, NWS Riverton, WY

August 2, 2021Lincoln County, Wyoming

NWS Riverton, WY issued this flash flood warning at Aug 2, 2021, 4:46 PM MDT for Lincoln County, Wyoming. It was in force for 2 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
Aug 2, 2021, 4:46 PM MDT (22:46 UTC)
Expired
Aug 2, 2021, 6:55 PM MDT
In force
2 hr
Issued by
NWS Riverton, WY
Area
Storm-based polygon
Flood severity
None

County Lincoln County, WY

The radar

The Pocatello radar (KSFX), 146 km from the middle of the area, began a volume at 22:45 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

Riverton, WY (KRIW), launched 12:00Z, 10.8 hours before the alert went out and 202 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, Riverton, WY at 12:00Z on 2021-08-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Riverton, WY at 12:00Z on 2021-08-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 5 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2380 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
14 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

611 
WGUS55 KRIW 022246
FFWRIW
WYC023-030145-
/O.NEW.KRIW.FF.W.0005.210802T2246Z-210803T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Riverton WY
446 PM MDT Mon Aug 2 2021

The National Weather Service in Riverton has issued a

* Flash Flood Warning for...
  Northwestern Lincoln County in west central Wyoming...

* Until 745 PM MDT.

* At 446 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Snake River and Greys River Canyons could have debris
           flows consisting of mainly mud and rock.

Motorists should use extreme caution through Snake River Canyon as 
there could be debris on the road.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4323 11077 4315 11077 4312 11102 4321 11100
      4322 11100

FLASH FLOOD...RADAR INDICATED

$$

Murrell
2 follow-up statements
504 
WGUS75 KRIW 022351
FFSRIW

Flash Flood Statement
National Weather Service Riverton WY
551 PM MDT Mon Aug 2 2021

WYC023-030145-
/O.CON.KRIW.FF.W.0005.000000T0000Z-210803T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lincoln WY-
551 PM MDT Mon Aug 2 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 745 PM MDT THIS 
EVENING FOR NORTHWESTERN LINCOLN COUNTY...

At 551 PM MDT, Doppler radar indicated thunderstorms producing 
moderate rain continues in the Snake River Canyon. Doppler radar 
estimates between 0.75 and 1 inch of rain has fallen.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar.

IMPACT...Debris flows remain possible in the Snake River Canyon.

Motorists need to slow down, and be prepared for debris on the road 
through the Snake River Canyon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4323 11077 4315 11077 4312 11102 4321 11100
      4322 11100

FLASH FLOOD...RADAR INDICATED

$$

Murrell
944 
WGUS75 KRIW 030055
FFSRIW

Flash Flood Statement
National Weather Service Riverton WY
655 PM MDT Mon Aug 2 2021

WYC023-030105-
/O.CAN.KRIW.FF.W.0005.000000T0000Z-210803T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lincoln WY-
655 PM MDT Mon Aug 2 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN LINCOLN 
COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat.



LAT...LON 4323 11077 4315 11077 4312 11102 4321 11100
      4322 11100

$$

Murrell

The office that day

Everything else NWS Riverton, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 2, 1:55 PM MDTAreal Flood AdvisoryRIWLincoln3 hr
Aug 2, 3:06 PM MDTAreal Flood AdvisoryRIWLincoln114 min
Aug 2, 3:20 PM MDTSpecial Weather StatementRIW25 min
Aug 2, 3:36 PM MDTSpecial Weather StatementRIW24 min
Aug 2, 3:48 PM MDTSpecial Weather StatementRIWTeton27 min
Aug 2, 4:05 PM MDTAreal Flood AdvisoryRIWPark, Teton2 hr
Aug 2, 4:13 PM MDTAreal Flood AdvisoryRIWTeton2 hr
Aug 2, 4:28 PM MDTSpecial Weather StatementRIWTeton32 min
Aug 2, 4:57 PM MDTAreal Flood AdvisoryRIWTeton48 min
Aug 2, 5:05 PM MDTSpecial Weather StatementRIWTeton25 min
Aug 2, 5:26 PM MDTFlash Flood WarningRIWPark3 hr

Nearby

Flash Flood Warnings in Wyoming, 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.