Alert archive / Wyoming / Red Flag Warnings in 2021

Red Flag Warning 22, NWS Riverton, WY

September 16, 202112 counties in Wyoming

NWS Riverton, WY issued this red flag warning at Sep 16, 2021, 1:59 PM MDT for 12 counties in Wyoming. It took effect at Sep 17, 2021, 12:00 PM MDT. It was in force for 32 hr. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Sep 16, 2021, 1:59 PM MDT (19:59 UTC)
In effect from
Sep 17, 2021, 12:00 PM MDT
Expired
Sep 18, 2021, 8:00 PM MDT
In force
32 hr
Issued by
NWS Riverton, WY

Counties Big Horn County, WY, Fremont County, WY, Hot Springs County, WY, Johnson County, WY, Lincoln County, WY, Natrona County, WY, Park County, WY, Sublette County, WY, Sweetwater County, WY, Teton County, WY, Uinta County, WY, Washakie County, WY

The radar

The Riverton/Lander radar (KRIW), 35 km from the middle of the area, began a volume at 19:58 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 18, 4:10 PM MDTNON-TSTM WND GST 633 Nnw Buffalo, WYASOS STATION KBYG BUFFALO AIRPORT. WEAK VIRGA SHOWER PASSED OVER SITE.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Riverton, WY (KRIW), launched 12:00Z, 8.0 hours before the alert went out and 41 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 2021-09-16Temperature 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 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 2021-09-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -3 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3709 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
-3 m²/s²
0-3 km storm-relative helicity
53 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

378 
WWUS85 KRIW 161959
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
159 PM MDT Thu Sep 16 2021

WYZ277>279-288-289-171200-
/O.NEW.KRIW.FW.W.0022.210917T1800Z-210918T0200Z/
/O.CON.KRIW.FW.W.0021.000000T0000Z-210917T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
East Wind River Mountains/South Shoshone NF-
Granite/Green/Ferris/Rattlesnake Mountains-
159 PM MDT Thu Sep 16 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING AND IS ALSO IN EFFECT FROM NOON TO 8 PM MDT FRIDAY...

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

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

* AFFECTED AREA: 
  In Central WY Fire Zones...288...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: As low as 10 percent.

* TEMPERATURES: Highs in the mid to upper 70s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

WYZ280-300-171200-
/O.NEW.KRIW.FW.W.0022.210917T1800Z-210918T0200Z/
/O.CON.KRIW.FW.W.0021.000000T0000Z-210917T0200Z/
Natrona County/Casper BLM-Casper Mountain-
159 PM MDT Thu Sep 16 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS
EVENING AND IS ALSO IN EFFECT FROM NOON TO 8 PM MDT FRIDAY...

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

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

* AFFECTED AREA: 
  In Central WY...Fire Weather Zones 280 and 300.

* COUNTIES AFFECTED: 
  In Central WY...Natrona.

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

* HUMIDITY: As low as 11 percent.

* TEMPERATURES: Highs from the upper 70s to low 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

WYZ281-285-286-414-416-171200-
/O.NEW.KRIW.FW.W.0022.210917T1800Z-210918T0200Z/
Johnson County/Casper BLM-South Bighorn Mountains-
Absaroka Mountains/North Shoshone NF-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
159 PM MDT Thu Sep 16 2021

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

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

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

* AFFECTED AREA: 
  In Central WY Fire Zone....285.
  In North Central WY Fire Zone....281.
  In Northwest WY Fire Zone....286.
  In West Central WY Fire Zones...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Park...Washakie.
  In West Central WY...Lincoln...Sublette.

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

* HUMIDITY: As low as 12 percent in the lower elevations, and 15
  percent in the mountains.

* TEMPERATURES: Highs in the low 80s in the lower elevations, and 
  low 70s in the mountains.

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.

&&

$$

WYZ283-170200-
/O.CON.KRIW.FW.W.0021.000000T0000Z-210917T0200Z/
Upper Wind River Basin/Wind River Basin-
159 PM MDT Thu Sep 16 2021

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

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

* AFFECTED AREA: 
  In Central WY...Fire Weather Zone 283.

* COUNTIES AFFECTED: 
  In Central WY...Fremont.

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

* HUMIDITY: As low as 12 percent.

* TEMPERATURES: Highs in the upper 70s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

http://weather.gov/riverton
7 follow-up statements
236 
WWUS85 KRIW 170232
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
832 PM MDT Thu Sep 16 2021

WYZ277>281-285-286-288-289-300-414-416-171300-
/O.CON.KRIW.FW.W.0022.210917T1800Z-210918T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
Natrona County/Casper BLM-Johnson County/Casper BLM-
South Bighorn Mountains-Absaroka Mountains/North Shoshone NF-
East Wind River Mountains/South Shoshone NF-
Granite/Green/Ferris/Rattlesnake Mountains-Casper Mountain-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
832 PM MDT Thu Sep 16 2021

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

* IMPACTS: Low Humidities...Unseasonably Warm Temperatures...and
  Gusty Winds will create erratic fire behavior if any new fires
  start. 

* AFFECTED AREA: 
  In Central WY Fire Zones...280...285...288...289...300.
  In North Central WY Fire Zone....281.
  In Northwest WY Fire Zone....286.
  In Southwest WY Fire Zones...277...279.
  In West Central WY Fire Zones...278...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Park...Washakie.
  In Southwest WY...Sweetwater...Uinta.
  In West Central WY...Lincoln...Sublette.

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

* HUMIDITY: As low as 11 percent.

* TEMPERATURES: Highs in the mid 70s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

http://weather.gov/riverton
955 
WWUS85 KRIW 170801
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
201 AM MDT Fri Sep 17 2021

WYZ280-281-172300-
/O.EXT.KRIW.FW.W.0022.210917T1800Z-210919T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
201 AM MDT Fri Sep 17 2021

...RED FLAG WARNING NOW IN EFFECT FROM NOON TODAY TO 8 PM MDT
SATURDAY...

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

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

* COUNTIES AFFECTED: 
  In Central WY...Natrona.
  In North Central WY...Johnson.

* WIND: Zone 281: South 20 to 25 mph with gusts up to 45 mph.
        Zone 280: Southwest 15 to 20 mph with gusts up to 25 mph.

* HUMIDITY: As low as 12 percent.

* TEMPERATURES: Today: Highs in the lower 80s. 
                Saturday: Highs in the middle to upper 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

WYZ277>279-285-286-288-289-300-414-416-172300-
/O.CON.KRIW.FW.W.0022.210917T1800Z-210918T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
South Bighorn Mountains-Absaroka Mountains/North Shoshone NF-
East Wind River Mountains/South Shoshone NF-
Granite/Green/Ferris/Rattlesnake Mountains-Casper Mountain-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
201 AM MDT Fri Sep 17 2021

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

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

* AFFECTED AREA: 
  In Central WY Fire Zones...285...288...289...300.
  In Northwest WY Fire Zone....286.
  In Southwest WY Fire Zones...277...279.
  In West Central WY Fire Zones...278...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Park...Washakie.
  In Southwest WY...Sweetwater...Uinta.
  In West Central WY...Lincoln...Sublette.

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

* HUMIDITY: As low as 12 percent.

* TEMPERATURES: Highs in the lower 70s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

http://weather.gov/riverton
717 
WWUS85 KRIW 172015
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
215 PM MDT Fri Sep 17 2021

WYZ277>279-285-286-288-289-300-414-416-180200-
/O.CON.KRIW.FW.W.0022.000000T0000Z-210918T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
South Bighorn Mountains-Absaroka Mountains/North Shoshone NF-
East Wind River Mountains/South Shoshone NF-
Granite/Green/Ferris/Rattlesnake Mountains-Casper Mountain-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
215 PM MDT Fri Sep 17 2021

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

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

* AFFECTED AREA: 
  In Central WY Fire Zones...285...288...289...300.
  In Northwest WY Fire Zone....286.
  In Southwest WY Fire Zones...277...279.
  In West Central WY Fire Zones...278...414...416.

* COUNTIES AFFECTED: 
  In Central WY...Fremont...Natrona.
  In North Central WY...Hot Springs...Johnson...Park...Washakie.
  In Southwest WY...Sweetwater...Uinta.
  In West Central WY...Lincoln...Sublette.

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

* HUMIDITY: As low as 15 percent in the higher elevations, and as
  low as 10 to 12 percent in the lower elevations.

* TEMPERATURES: Highs in the upper 60s in the higher elevations,
  and in the upper 70s to around 80 in the lower elevations.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

WYZ280-281-180200-
/O.CON.KRIW.FW.W.0022.000000T0000Z-210919T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
215 PM MDT Fri Sep 17 2021

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

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

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

* COUNTIES AFFECTED: 
  In Central WY...Natrona.
  In North Central WY...Johnson.

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

* HUMIDITY: As low as 10 percent.

* TEMPERATURES: Highs in the lower 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

http://weather.gov/riverton
872 
WWUS85 KRIW 180143
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
743 PM MDT Fri Sep 17 2021

WYZ277>279-285-286-288-289-300-414-416-180245-
/O.EXP.KRIW.FW.W.0022.000000T0000Z-210918T0200Z/
Lincoln and Uinta Counties/Lower Elevations-
Upper Green River Basin/Rock Springs BLM-
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
South Bighorn Mountains-Absaroka Mountains/North Shoshone NF-
East Wind River Mountains/South Shoshone NF-
Granite/Green/Ferris/Rattlesnake Mountains-Casper Mountain-
Salt and Wyoming Ranges/West Zone Bridger Teton NF-
West Wind River Mountains/East Zone Bridger Teton NF-
743 PM MDT Fri Sep 17 2021

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

Wind speeds will decrease into the overnight hours with increasing
humidity values as temperatures decrease. As a result red flag 
conditions will no longer occur tonight, so the red flag warning 
will be allowed to expire at 8PM MDT.

$$

WYZ280-281-181345-
/O.CON.KRIW.FW.W.0022.000000T0000Z-210919T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
743 PM MDT Fri Sep 17 2021

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

* IMPACTS: Low Humidities...Unseasonably Warm Temperatures...and
  Strong Gusty Winds will create erratic fire behavior if new fires
  start. 

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

* COUNTIES AFFECTED: 
  In Central WY...Natrona.
  In North Central WY...Johnson.

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

* HUMIDITY: As low as 9 percent.

* TEMPERATURES: Lows in the lower 50s. Highs in the mid 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

http://weather.gov/riverton
084 
WWUS85 KRIW 180917
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
317 AM MDT Sat Sep 18 2021

WYZ275-276-282-285-287-182300-
/O.EXB.KRIW.FW.W.0022.210918T1800Z-210919T0200Z/
North Big Horn Basin/Worland BLM-Cody Foothills-
South Big Horn Basin/Worland BLM-South Bighorn Mountains-
Owl Creek Mountains-
317 AM MDT Sat Sep 18 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...Unseasonably Warm Temperatures...and 
  Strong Gusty Winds will create erratic fire behavior and new 
  fire starts. 

* AFFECTED AREA: 
  In Central WY Fire Zone....285.
  In North Central WY Fire Zones...275...276...282...287.

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

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

* HUMIDITY: As low as 13 percent.

* TEMPERATURES: Highs around 80 in the higher elevations. Highs in
  the middle to upper 80s in the basin. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

WYZ280-281-182300-
/O.CON.KRIW.FW.W.0022.000000T0000Z-210919T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
317 AM MDT Sat Sep 18 2021

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

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

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

* COUNTIES AFFECTED: 
  In Central WY...Natrona.
  In North Central WY...Johnson.

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

* HUMIDITY: 10 to 14 percent.

* TEMPERATURES: Highs in the middle to upper 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

http://weather.gov/riverton
287 
WWUS85 KRIW 182033
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
233 PM MDT Sat Sep 18 2021

WYZ275-276-282-285-287-190200-
/O.CON.KRIW.FW.W.0022.000000T0000Z-210919T0200Z/
North Big Horn Basin/Worland BLM-Cody Foothills-
South Big Horn Basin/Worland BLM-South Bighorn Mountains-
Owl Creek Mountains-
233 PM MDT Sat Sep 18 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....285.
  In North Central WY Fire Zones...275...276...282...287.

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

* WIND: Southwest 20 to 30 mph with gusts up to 45 mph.

* HUMIDITY: As low as 12 percent.

* TEMPERATURES: Highs in the upper 70s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

WYZ280-281-190200-
/O.CON.KRIW.FW.W.0022.000000T0000Z-210919T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
233 PM MDT Sat Sep 18 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....280.
  In North Central WY Fire Zone....281.

* COUNTIES AFFECTED: 
  In Central WY...Natrona.
  In North Central WY...Johnson.

* WIND: Southwest 20 to 30 mph with gusts up to 45 mph.

* HUMIDITY: As low as 10 percent.

* TEMPERATURES: Highs in the mid 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

http://weather.gov/riverton
947 
WWUS85 KRIW 190139
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
739 PM MDT Sat Sep 18 2021

WYZ275-276-282-285-287-190245-
/O.EXP.KRIW.FW.W.0022.000000T0000Z-210919T0200Z/
North Big Horn Basin/Worland BLM-Cody Foothills-
South Big Horn Basin/Worland BLM-South Bighorn Mountains-
Owl Creek Mountains-
739 PM MDT Sat Sep 18 2021

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

Humidity has risen as temperatures have cooled. It will remain
breezy to windy through much of the night. Red Flag conditions are
not expected overnight, so the Red Flag Warning will be allowed to
expire at 8 PM MDT. 

$$

WYZ280-281-190245-
/O.EXP.KRIW.FW.W.0022.000000T0000Z-210919T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
739 PM MDT Sat Sep 18 2021

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

Humidity has risen as temperatures have cooled. It will remain
breezy to windy through much of the night. Red Flag conditions are
not expected overnight, so the Red Flag Warning will be allowed to
expire at 8 PM MDT. 

$$

http://weather.gov/riverton

Nearby

Red Flag Warnings in Wyoming, 2021Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.