Alert archive / Wyoming / Red Flag Warnings in 2021

Red Flag Warning 19, NWS Riverton, WY

September 9, 20216 counties in Wyoming

NWS Riverton, WY issued this red flag warning at Sep 9, 2021, 2:52 AM MDT for 6 counties in Wyoming. It took effect at Sep 9, 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
Sep 9, 2021, 2:52 AM MDT (08:52 UTC)
In effect from
Sep 9, 2021, 12:00 PM MDT
Expired
Sep 9, 2021, 8:00 PM MDT
In force
8 hr
Issued by
NWS Riverton, WY

Counties Fremont County, WY, Hot Springs County, WY, Lincoln County, WY, Park County, WY, Sublette County, WY, Teton County, WY

The radar

The Riverton/Lander radar (KRIW), 100 km from the middle of the area, began a volume at 08:54 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 00:00Z, 8.9 hours before the alert went out and 106 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 00:00Z on 2021-09-09Temperature 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 00:00Z on 2021-09-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 59 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3864 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
59 m²/s²
0-3 km storm-relative helicity
151 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

375 
WWUS85 KRIW 090852
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
252 AM MDT Thu Sep 9 2021

WYZ286-287-092200-
/O.UPG.KRIW.FW.A.0010.210909T1800Z-210910T0200Z/
/O.NEW.KRIW.FW.W.0019.210909T1800Z-210910T0200Z/
Absaroka Mountains/North Shoshone NF-Owl Creek Mountains-
252 AM MDT Thu Sep 9 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. The Fire Weather Watch is no longer in effect.

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

* AFFECTED AREA: 
  In North Central WY Fire Zone....287.
  In Northwest WY Fire Zone....286.

* COUNTIES AFFECTED: 
  In Central WY...Fremont.
  In North Central WY...Hot Springs...Park.

* WIND: West 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 11 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 strong 
winds...low relative humidity...and warm temperatures can 
contribute to extreme fire behavior.

&&

$$

WYZ276-092200-
/O.UPG.KRIW.FW.A.0010.210909T1800Z-210910T0200Z/
/O.NEW.KRIW.FW.W.0019.210909T1800Z-210910T0200Z/
Cody Foothills-
252 AM MDT Thu Sep 9 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. The Fire Weather Watch is no longer in effect.

* IMPACTS: Low Humidities...Unseasonably Warm Temperatures...and
  Strong Gusty Winds will create erratic fire behavior with any 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 35 mph.

* HUMIDITY: As low as 10 percent.

* TEMPERATURES: Highs around 90.

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.

&&

$$

WYZ415-092200-
/O.UPG.KRIW.FW.A.0010.210909T1800Z-210910T0200Z/
/O.NEW.KRIW.FW.W.0019.210909T1800Z-210910T0200Z/
North Zone Bridger Teton NF and Grand Teton NP-
252 AM MDT Thu Sep 9 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. The Fire Weather Watch is no longer in effect.

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

* AFFECTED AREA: 
  In Northwest WY...Fire Weather Zone 415.

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

* WIND: Southwest 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 13 percent.

* TEMPERATURES: Highs in the mid 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 strong 
winds...low relative humidity...and warm temperatures can 
contribute to extreme fire behavior.

&&

$$

WYZ288-092200-
/O.NEW.KRIW.FW.W.0019.210909T1800Z-210910T0200Z/
East Wind River Mountains/South Shoshone NF-
252 AM MDT Thu Sep 9 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 with any 
  new fire starts. 

* AFFECTED AREA: 
  In Central WY...Fire Weather Zone 288.

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

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

* HUMIDITY: As low as 10 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 strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ282-283-285-289-092200-
/O.NEW.KRIW.FW.A.0011.210910T1800Z-210911T0200Z/
South Big Horn Basin/Worland BLM-
Upper Wind River Basin/Wind River Basin-South Bighorn Mountains-
Granite/Green/Ferris/Rattlesnake Mountains-
252 AM MDT Thu Sep 9 2021

...FIRE WEATHER WATCH IN EFFECT FROM FRIDAY AFTERNOON THROUGH
FRIDAY EVENING...

The National Weather Service in Riverton has issued a Fire Weather
Watch, which is in effect from Friday afternoon through Friday
evening.

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

* AFFECTED AREA: 
  In Central WY Fire Zones...283...285...289.
  In North Central WY Fire Zone....282.

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

* WIND: Southwest 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 10 percent.

* TEMPERATURES: Highs in the mid 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Fire Weather Watch means that critical fire weather conditions
could occur. Listen for later forecasts and possible Red Flag 
Warnings.

&&

$$

WYZ280-281-300-092200-
/O.NEW.KRIW.FW.A.0011.210910T1800Z-210911T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
Casper Mountain-
252 AM MDT Thu Sep 9 2021

...FIRE WEATHER WATCH IN EFFECT FROM FRIDAY AFTERNOON THROUGH
FRIDAY EVENING...

The National Weather Service in Riverton has issued a Fire Weather
Watch, which is in effect from Friday afternoon through Friday
evening.

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

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

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

* WIND: West 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 9 percent.

* TEMPERATURES: Highs in the lower 90s. Highs in the mid 80s across
  Casper Mountain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Fire Weather Watch means that critical fire weather conditions
could occur. Listen for later forecasts and possible Red Flag 
Warnings.

&&

$$

WYZ279-092200-
/O.NEW.KRIW.FW.A.0011.210910T1800Z-210911T0200Z/
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
252 AM MDT Thu Sep 9 2021

...FIRE WEATHER WATCH IN EFFECT FROM FRIDAY AFTERNOON THROUGH
FRIDAY EVENING...

The National Weather Service in Riverton has issued a Fire Weather
Watch, which is in effect from Friday afternoon through Friday
evening.

* IMPACTS: Low Humidities...Unseasonably Warm Temperatures...Strong
  Gusty Winds...and Dry Thunderstorms with gusty and erratic
  outflow winds will create erratic fire behavior and possible new
  fire starts. 

* AFFECTED AREA: 
  In Southwest WY...Fire Weather Zone 279.

* COUNTIES AFFECTED: 
  In Southwest WY...Sweetwater.

* WIND: West 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 12 percent.

* TEMPERATURES: Highs in the mid 80s.

* THUNDERSTORMS: Isolated dry thunderstorms will develop during 
  the afternoon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Fire Weather Watch means that critical fire weather conditions
could occur. Listen for later forecasts and possible Red Flag 
Warnings.

&&

$$

http://weather.gov/riverton
1 follow-up statement
504 
WWUS85 KRIW 091841
RFWRIW

URGENT - FIRE WEATHER MESSAGE
National Weather Service Riverton WY
1241 PM MDT Thu Sep 9 2021

WYZ286>288-100200-
/O.CON.KRIW.FW.W.0019.000000T0000Z-210910T0200Z/
Absaroka Mountains/North Shoshone NF-Owl Creek Mountains-
East Wind River Mountains/South Shoshone NF-
1241 PM MDT Thu Sep 9 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....288.
  In North Central WY Fire Zone....287.
  In Northwest WY Fire Zone....286.

* COUNTIES AFFECTED: 
  In Central WY...Fremont.
  In North Central WY...Hot Springs...Park.
  In West Central WY...Sublette.

* WIND: West 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 11 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 strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ276-100200-
/O.CON.KRIW.FW.W.0019.000000T0000Z-210910T0200Z/
Cody Foothills-
1241 PM MDT Thu Sep 9 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 North Central WY...Fire Weather Zone 276.

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

* WIND: Northwest 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 10 percent.

* TEMPERATURES: Highs around 90.

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.

&&

$$

WYZ415-100200-
/O.CON.KRIW.FW.W.0019.000000T0000Z-210910T0200Z/
North Zone Bridger Teton NF and Grand Teton NP-
1241 PM MDT Thu Sep 9 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 Northwest WY...Fire Weather Zone 415.

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

* WIND: Southwest 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 13 percent.

* TEMPERATURES: Highs in the mid 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 strong
winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

WYZ282-283-285-289-100600-
/O.CON.KRIW.FW.A.0011.210910T1800Z-210911T0200Z/
South Big Horn Basin/Worland BLM-
Upper Wind River Basin/Wind River Basin-South Bighorn Mountains-
Granite/Green/Ferris/Rattlesnake Mountains-
1241 PM MDT Thu Sep 9 2021

...FIRE WEATHER WATCH REMAINS IN EFFECT FROM FRIDAY AFTERNOON
THROUGH FRIDAY 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...283...285...289.
  In North Central WY Fire Zone....282.

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

* WIND: Southwest 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 10 percent.

* TEMPERATURES: Highs in the mid 80s.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Fire Weather Watch means that critical fire weather conditions
could occur. Listen for later forecasts and possible Red Flag
Warnings.

&&

$$

WYZ280-281-300-100600-
/O.CON.KRIW.FW.A.0011.210910T1800Z-210911T0200Z/
Natrona County/Casper BLM-Johnson County/Casper BLM-
Casper Mountain-
1241 PM MDT Thu Sep 9 2021

...FIRE WEATHER WATCH REMAINS IN EFFECT FROM FRIDAY AFTERNOON
THROUGH FRIDAY 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...280...300.
  In North Central WY Fire Zone....281.

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

* WIND: West 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 9 percent.

* TEMPERATURES: Highs in the lower 90s. Highs in the mid 80s 
  across Casper Mountain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Fire Weather Watch means that critical fire weather conditions
could occur. Listen for later forecasts and possible Red Flag
Warnings.

&&

$$

WYZ279-100600-
/O.CON.KRIW.FW.A.0011.210910T1800Z-210911T0200Z/
Sweetwater County/Rock Springs BLM/Flaming Gorge NRA-
1241 PM MDT Thu Sep 9 2021

...FIRE WEATHER WATCH REMAINS IN EFFECT FROM FRIDAY AFTERNOON
THROUGH FRIDAY EVENING...

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

* AFFECTED AREA: 
  In Southwest WY...Fire Weather Zone 279.

* COUNTIES AFFECTED: 
  In Southwest WY...Sweetwater.

* WIND: West 10 to 20 mph with gusts up to 35 mph.

* HUMIDITY: As low as 12 percent.

* TEMPERATURES: Highs in the mid 80s.

* THUNDERSTORMS: Isolated dry thunderstorms will develop during 
  the afternoon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Fire Weather Watch means that critical fire weather conditions
could occur. Listen for later forecasts and possible Red Flag
Warnings.

&&

$$

http://weather.gov/riverton

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 9, 2:52 AM MDTFire Weather WatchRIWFremont, Hot Springs, Johnson, Natrona, Sweetwater, Washakie23 hr

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.