Alert archive / Wyoming / Red Flag Warnings in 2021

Red Flag Warning 11, NWS Riverton, WY

August 9, 20216 counties in Wyoming

NWS Riverton, WY issued this red flag warning at Aug 9, 2021, 1:17 PM MDT for 6 counties in Wyoming. It took effect at Aug 10, 2021, 12:00 PM MDT. It was in force for 8 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 9, 2021, 1:17 PM MDT (19:17 UTC)
In effect from: Aug 10, 2021, 12:00 PM MDT
Expired: Aug 10, 2021, 8:00 PM MDT
In force: 8 hr
Issued by: NWS Riverton, WY

Counties Fremont County, WY, Hot Springs County, WY, Johnson County, WY, Natrona County, WY, Park County, WY, Washakie County, WY

The radar

The Riverton/Lander radar (KRIW), 82 km from the middle of the area, began a volume at 19:16 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, 7.3 hours before the alert went out and 79 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 2362 m above ground
0-6 km bulk shear: 62 kt
0-1 km storm-relative helicity: -17 m²/s²
0-3 km storm-relative helicity: 226 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

871 
WWUS85 KRIW 091917
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
117 PM MDT Mon Aug 9 2021

WYZ280-281-285-300-101215-
/O.NEW.KRIW.FW.W.0011.210810T1800Z-210811T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
South Bighorn Mountains-Casper Mountain-
117 PM MDT Mon Aug 9 2021

...RED FLAG WARNING IN EFFECT FROM NOON TO 8 PM MDT TUESDAY...

The National Weather Service in Riverton has issued a Red Flag
Warning, which is in effect from noon to 8 PM MDT Tuesday.

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zones...280...285...300.
  In North Central WY Fire Zone....281.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Washakie.

* WIND: West 15 to 20 mph with gusts up to 30 mph.

* HUMIDITY: 9 to 14 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ277>279-289-101215-
/O.EXT.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
Granite/Green/Ferris/Rattlesnake Mountains-
117 PM MDT Mon Aug 9 2021

...RED FLAG WARNING NOW IN EFFECT UNTIL 8 PM MDT TUESDAY...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zone....289.
  In Southwest WY Fire Zones...277...279.
  In West Central WY Fire Zone....278.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In Southwest WY...Sweetwater...Uinta.
  In West Central WY...Lincoln...Sublette.

* WIND: Monday: West 15 to 25 mph with gusts up to 40 mph.
        Tuesday: West 15 to 25 mph with gusts up to 35 mph.

* HUMIDITY: Monday: 12 to 14 percent.
            Tuesday: 7 to 10 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ288-414-416-101215-
/O.EXT.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
East Wind River Mountains/South Shoshone NF-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
117 PM MDT Mon Aug 9 2021

...RED FLAG WARNING NOW IN EFFECT UNTIL 8 PM MDT TUESDAY...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zone....288.
  In West Central WY Fire Zones...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont.
  In West Central WY...Lincoln...Sublette.

* WIND: Monday: West 15 to 25 mph with gusts up to 35 mph.
        Tuesday: West 15 to 25 mph with gusts up to 30 mph.

* HUMIDITY: Monday: 12 to 16 percent over southern portions of the
            zones.
            Tuesday: 8 to 14 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

http://weather.gov/riverton

4 follow-up statements

135 
WWUS85 KRIW 100155
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
755 PM MDT Mon Aug 9 2021

WYZ277>279-289-101300-
/O.CON.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
Granite/Green/Ferris/Rattlesnake Mountains-
755 PM MDT Mon Aug 9 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT TUESDAY...

Wind speeds decrease late Monday evening, but relative humidity 
recovery will be poor again overnight.

* IMPACTS: Low relative humidity and strong gusty wind will create
  erratic fire behavior and cause wildfires to rapidly spread.

* AFFECTED AREA: 
  In Central WY Fire Zone....289.
  In Southwest WY Fire Zones...277...279.
  In West Central WY Fire Zone....278.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In Southwest WY...Sweetwater...Uinta.
  In West Central WY...Lincoln...Sublette.

* WIND: West 15 to 25 mph with gusts up to 35 mph.

* HUMIDITY: 7 to 10 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ288-414-416-101300-
/O.CON.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
East Wind River Mountains/South Shoshone NF-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
755 PM MDT Mon Aug 9 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT TUESDAY...

Wind speeds decrease late Monday evening, but relative humidity 
recovery will only be poor to fair overnight.

* IMPACTS: Low relative humidity and strong gusty wind will create
  erratic fire behavior and cause wildfires to rapidly spread.

* AFFECTED AREA: 
  In Central WY Fire Zone....288.
  In West Central WY Fire Zones...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont.
  In West Central WY...Lincoln...Sublette.

* WIND: West 15 to 25 mph with gusts up to 30 mph.

* HUMIDITY: 8 to 14 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ280-281-285-300-101300-
/O.CON.KRIW.FW.W.0011.210810T1800Z-210811T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
South Bighorn Mountains-Casper Mountain-
755 PM MDT Mon Aug 9 2021

...RED FLAG WARNING IN EFFECT FROM NOON TO 8 PM MDT TUESDAY...

* IMPACTS: Low relative humidity and strong gusty wind will create
  erratic fire behavior and cause wildfires to rapidly spread.

* AFFECTED AREA: 
  In Central WY Fire Zones...280...285...300.
  In North Central WY Fire Zone....281.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Washakie.

* WIND: West 15 to 20 mph with gusts up to 30 mph.

* HUMIDITY: 9 to 14 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

http://weather.gov/riverton

524 
WWUS85 KRIW 100734
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
134 AM MDT Tue Aug 10 2021

WYZ276-110200-
/O.EXA.KRIW.FW.W.0011.210810T1800Z-210811T0200Z/
Cody Foothills-
134 AM MDT Tue Aug 10 2021

...RED FLAG WARNING IN EFFECT FROM NOON TODAY TO 8 PM MDT THIS
EVENING...

The National Weather Service in Riverton has issued a Red Flag
Warning, which is in effect from noon today to 8 PM MDT this
evening.

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In North Central WY...Fire Weather Zone 276.

* COUNTIES AFFECTED: 
  In North Central WY...Park.

* WIND: Northwest 10 to 20 mph with gusts up to 30 mph.

* HUMIDITY: 10 to 15 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ277>279-289-110200-
/O.CON.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
Granite/Green/Ferris/Rattlesnake Mountains-
134 AM MDT Tue Aug 10 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zone....289.
  In Southwest WY Fire Zones...277...279.
  In West Central WY Fire Zone....278.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In Southwest WY...Sweetwater...Uinta.
  In West Central WY...Lincoln...Sublette.

* WIND: West 15 to 25 mph with gusts up to 35 mph.

* HUMIDITY: 7 to 10 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ288-414-416-110200-
/O.CON.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
East Wind River Mountains/South Shoshone NF-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
134 AM MDT Tue Aug 10 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zone....288.
  In West Central WY Fire Zones...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont.
  In West Central WY...Lincoln...Sublette.

* WIND: West 15 to 25 mph with gusts up to 30 mph.

* HUMIDITY: 8 to 14 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ280-281-285-300-110200-
/O.CON.KRIW.FW.W.0011.210810T1800Z-210811T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
South Bighorn Mountains-Casper Mountain-
134 AM MDT Tue Aug 10 2021

...RED FLAG WARNING REMAINS IN EFFECT FROM NOON TODAY TO 8 PM MDT
THIS EVENING...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zones...280...285...300.
  In North Central WY Fire Zone....281.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Washakie.

* WIND: West 10 to 20 mph with gusts up to 30 mph.

* HUMIDITY: 10 to 15 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

http://weather.gov/riverton

616 
WWUS85 KRIW 101947
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
147 PM MDT Tue Aug 10 2021

WYZ277>279-289-110200-
/O.CON.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
Granite/Green/Ferris/Rattlesnake Mountains-
147 PM MDT Tue Aug 10 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zone....289.
  In Southwest WY Fire Zones...277...279.
  In West Central WY Fire Zone....278.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In Southwest WY...Sweetwater...Uinta.
  In West Central WY...Lincoln...Sublette.

* WIND: West 15 to 25 mph with gusts up to 40 mph.

* HUMIDITY: 8 to 12 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ288-414-416-110200-
/O.CON.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
East Wind River Mountains/South Shoshone NF-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
147 PM MDT Tue Aug 10 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zone....288.
  In West Central WY Fire Zones...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont, including the Dubois area.
  In West Central WY...Lincoln...Sublette.

* WIND: West 15 to 20 mph with gusts up to 35 mph.

* HUMIDITY: 8 to 11 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ280-281-285-300-110200-
/O.CON.KRIW.FW.W.0011.000000T0000Z-210811T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
South Bighorn Mountains-Casper Mountain-
147 PM MDT Tue Aug 10 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zones...280...285...300.
  In North Central WY Fire Zone....281.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Washakie.

* WIND: West 15 to 25 mph with gusts up to 35 mph.

* HUMIDITY: 10 to 14 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ276-110200-
/O.CON.KRIW.FW.W.0011.000000T0000Z-210811T0200Z/
Cody Foothills-
147 PM MDT Tue Aug 10 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING...

* IMPACTS: Low Humidities and Strong Gusty Winds will create 
  erratic fire behavior and new fire starts. 

* AFFECTED AREA: 
  In North Central WY...Fire Weather Zone 276.

* COUNTIES AFFECTED: 
  In North Central WY...Park.

* WIND: West to Northwest 10 to 20 mph with gusts up to 30 mph.

* HUMIDITY: 12 to 14 percent.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions are
either occurring now....or will shortly. A combination of strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

http://weather.gov/riverton

584 
WWUS85 KRIW 110158
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
758 PM MDT Tue Aug 10 2021

WYZ277>279-289-110300-
/O.EXP.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
Granite/Green/Ferris/Rattlesnake Mountains-
758 PM MDT Tue Aug 10 2021

...RED FLAG WARNING WILL EXPIRE AT 8 PM MDT THIS EVENING...

Gusty west wind will continue to decrease Tuesday evening.
Therefore, the warning will be allowed to expire. Overnight relative
humidity recovery will be poor.

$$

WYZ288-414-416-110300-
/O.EXP.KRIW.FW.W.0010.000000T0000Z-210811T0200Z/
East Wind River Mountains/South Shoshone NF-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
758 PM MDT Tue Aug 10 2021

...RED FLAG WARNING WILL EXPIRE AT 8 PM MDT THIS EVENING...

Gusty west wind will continue to decrease Tuesday evening.
Therefore, the warning will be allowed to expire. Overnight relative
humidity recovery will be fair.

$$

WYZ280-281-285-300-110300-
/O.EXP.KRIW.FW.W.0011.000000T0000Z-210811T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
South Bighorn Mountains-Casper Mountain-
758 PM MDT Tue Aug 10 2021

...RED FLAG WARNING WILL EXPIRE AT 8 PM MDT THIS EVENING...

Wind speeds have decreased and will continue to trend downward this
evening. Therefore, the warning will be allowed to expire. 
Overnight relative humidity recovery will be poor to fair.

$$

WYZ276-110300-
/O.EXP.KRIW.FW.W.0011.000000T0000Z-210811T0200Z/
Cody Foothills-
758 PM MDT Tue Aug 10 2021

...RED FLAG WARNING WILL EXPIRE AT 8 PM MDT THIS EVENING...

Gusty west wind will continue to decrease Tuesday evening.
Therefore, the warning will be allowed to expire. Overnight relative
humidity recovery will be fair.

$$

http://weather.gov/riverton

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 12:29 AM MDT	Special Weather Statement	RIW	Park	31 min

Nearby

Red Flag Warnings in Wyoming, 2021 Every red flag 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.