954
FXUS65 KRIW 092326
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
526 PM MDT WED SEP 9 2026
KEY MESSAGES
- WARM, DRY, AND WINDY CONDITIONS WITH MOSTLY CLEAR SKIES WILL
CONTINUE FROM WEDNESDAY INTO THURSDAY. AFTERNOON HIGH
TEMPERATURES WILL BE JUST ABOVE NORMAL (WED) TO 5 TO 10
DEGREES ABOVE NORMAL (THU).
- ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS PERSIST FOR
PORTIONS OF CENTRAL AND SOUTHWEST WYOMING FROM WED TO THU DUE
TO GUSTY AFTERNOON WEST TO NORTHWEST WIND 20 TO 35 MPH AND
MINIMUM RELATIVE HUMIDITY IN THE TEENS. THURSDAY WILL ALSO SEE
CRITICAL FIRE WEATHER CONDITIONS SPREAD TO THE WIND RIVERS,
DUBOIS AREA, OWL CREEKS, AND ABSAROKAS.
- A WEAK DISTURBANCE FROM THE GREAT BASIN WILL BRING INCREASED
CLOUDS WITH A SLIGHT CHANCE OF SHOWERS FRIDAY MORNING TO THE
EARLY AFTERNOON ACROSS SOUTHERN AND CENTRAL WY.
- CONFIDENCE CONTINUES TO INCREASE FOR A STORM SYSTEM TO ARRIVE
THIS WEEKEND. AN INITIAL COLD FRONT PUSHES ACROSS THE REGION
FRIDAY EVENING, SETTING THE STAGE FOR COOLER AND WETTER
WEATHER SATURDAY AND SUNDAY, ESPECIALLY EAST OF THE
CONTINENTAL DIVIDE. AT THIS TIME, PRECIPITATION FORECASTS
REMAIN ON THE LIGHT SIDE HOWEVER.
UPDATE
ISSUED AT 120 PM MDT WED SEP 9 2026
FORECAST REMAINS ON TRACK FOR VERY WARM, DRY, AND WINDY
CONDITIONS THIS AFTERNOON AND THURSDAY. THURSDAY LOOKS TO BE A
MORE WIDESPREAD DAY WITH SLIGHTLY STRONGER AFTERNOON WINDS, AND
RH VALUES DROPPING A COUPLE PERCENTAGES MORE COMPARED TO
WEDNESDAY. HAVE ADDED THE EAST SIDE OF THE WIND RIVERS, THE
ABSAROKAS, AND THE OWL CREEKS TO THE RED FLAG WARNING FOR
CRITICAL FIRE WEATHER CONDITIONS AS WELL, ESPECIALLY AT
ELEVATIONS BELOW ABOUT 9-10 K FEET. HUMIDITY RECOVERY IS
EXPECTED TO BE FAIR TO POOR TONIGHT IN THESE AREAS AS WELL,
WHICH WILL CREATE MORE HAZARDOUS CONDITIONS ON THURSDAY.
AFTER A NIGHT OF CLEAR SKIES TONIGHT, HIGH CLOUDS ARE EXPECTED
TO MOVE INTO WESTERN WY THURSDAY AFTERNOON IN ADVANCE OF A
DISTURBANCE FROM THE GREAT BASIN. THIS SYSTEM SHOULD BRING
ENOUGH MOISTURE WITH WEAK INSTABILITY FOR SOME LIGHT SHOWERS
OVER SOUTHWEST WY EARLY FRIDAY MORNING. ANOTHER SYSTEM WILL MOVE
ACROSS MONTANA, INCREASING CLOUDS OVER NORTHERN WY LATE FRIDAY,
AND DROPPING A COOL FRONT EAST OF THE DIVIDE FRIDAY EVENING.
MODELS ARE SHOWING AN INTERESTING PATTERN DEVELOPMENT FOR WY
SATURDAY AND SUNDAY, BUT SYNOPTIC SCALE DIFFERENCES ARE CURIOUS
AT THIS TIME, AS ONLY LIGHT PRECIPITATION IS EXPECTED SATURDAY
AFTERNOON INTO SUNDAY MORNING.
DISCUSSION
ISSUED AT 223 AM MDT WED SEP 9 2026
A FREEZE WARNING REMAINS IN EFFECT FOR THE WESTERN VALLEYS, THE
UPPER GREEN RIVER BASIN AND SOUTHERN LINCOLN COUNTY THIS MORNING.
TEMPERATURES OF 26 TO 32 DEGREES ARE EXPECTED AGAIN IN THESE AREAS,
WITH MORE COLD PRONE LOCATIONS POSSIBLY DROPPING AS LOW AS 22
DEGREES.
OTHERWISE, DRY CONDITIONS, CLEAR SKIES AND SEASONAL TEMPERATURES
WILL BE IN THE FORECAST AGAIN TODAY. THE MAIN HAZARD WILL ONCE AGAIN
BE FIRE WEATHER. THE LIGHTEST WINDS OF THE WEEK ARE EXPECTED TODAY,
HOWEVER ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS WILL BE IN PLACE
DUE TO CRITICALLY LOW RH VALUES AND WIND GUSTS UP TO 25 MPH. THESE
WINDS WILL BE PRIMARILY LOCATED FROM SOUTHERN LINCOLN COUNTY TO
NATRONA COUNTY THROUGH THE AFTERNOON. THE FIRE WEATHER WATCH THAT
WAS ISSUED FOR THESE AREAS HAS BEEN UPGRADED TO RED FLAG WARNINGS AS
A RESULT. HAVE ALSO EXTENDED THESE NEW WARNINGS INTO THURSDAY.
BURNING OF ANY KIND IS HIGHLY DISCOURAGED DUE TO THE VERY DRY
CONDITIONS, REGARDLESS OF HOW LIGHT THE WINDS MIGHT BE.
CRITICAL FIRE WEATHER CONDITIONS WILL BECOME MORE WIDESPREAD ACROSS
THE CWA AGAIN THURSDAY, AS WINDS INCREASE. WIND GUSTS OF 25 TO 35
MPH WILL RETURN FOR MOST AREAS IN THE AFTERNOON. EXCEPTIONS WILL BE
FOR LOCATIONS LIKE EASTERN PORTIONS OF THE BIGHORN BASIN AND
NORTHERN PORTIONS OF JOHNSON COUNTY. THESE WINDS WILL RETURN FOR
FRIDAY AFTERNOON AS WELL. THE MAIN DIFFERENCE WILL BE ANOTHER DRY
COLD FRONT WILL MOVE ACROSS NORTHERN AREAS EAST OF THE DIVIDE.
INITIAL INDICATIONS ARE THIS FRONT WILL BECOME STATIONARY ALONG
SOUTHERN PORTIONS OF THE BIGHORN BASIN AND JOHNSON COUNTY BY MIDDAY
FRIDAY. MODELS REMAIN SPLIT WHETHER THE FRONT WILL PUSH FURTHER
SOUTHWARD THROUGH THE OVERNIGHT HOURS FRIDAY AND ALLOW FOR THE
ASSOCIATED COLD POOL TO INFILTRATE INTO THE BIGHORN BASIN AND
JOHNSON COUNTY.
MOISTURE WILL BEGIN TO INCREASE SATURDAY AHEAD OF THE INCOMING STORM
SYSTEM, WITH THE WESTERN MOUNTAINS AND CENTRAL PORTIONS OF THE CWA
HAVING THE BEST CHANCES FOR PRECIPITATION SATURDAY AFTERNOON INTO
SATURDAY NIGHT. SNOW LEVELS WILL STAY AROUND 10KFT THROUGH THE
NIGHT, SO HUNTERS/BACKCOUNTRY ENTHUSIASTS SHOULD PREPARE FOR SNOW.
THE STORM ITSELF WILL MOVE OVER THE COWBOY STATE DURING THE DAY
SUNDAY, WITH THE COLDEST AIR STAYING OVER NORTHWESTERN PORTIONS.
SNOW LEVELS WILL RANGE BETWEEN 7000 AND 8500FT IN THIS AREA AND MOST
OF THE PRECIPITATION WILL STAY OVER NORTHERN PORTIONS OF THE STATE.
FREEZING TEMPERATURES WILL RETURN TO WESTERN PORTIONS MONDAY AND
TUESDAY MORNINGS IN THE WAKE OF THIS SYSTEM, WITH READINGS IN THE
MIDDLE 30S TO LOWER 40S ELSEWHERE. MONDAY WILL BE A CRISP AUTUMN
DAY, WITH HIGHS IN THE 60S TO NEAR 70S DEGREES UNDER MOSTLY CLEAR
SKIES.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 525 PM MDT WED SEP 9 2026
TERMINALS REMAIN VFR WITH ONLY A FEW PASSING HIGH CLOUDS THROUGH
00Z/FRIDAY. WESTERLY SURFACE WIND REMAINS THE PRIMARY AVIATION
HAZARD. ONGOING WESTERLY SURFACE WIND DECREASES TO LESS THAN 10 KTS
BETWEEN 01Z-03Z/THURSDAY. CONDITIONS APPEAR A BIT MORE FAVORABLE FOR
INCREASED SPEEDS AND AN EARLIER START TIME FOR WINDS TO MIX TO THE
SURFACE AROUND MIDDAY THURSDAY. MOST TERMINALS TO SEE WESTERLY WIND
11-16KT GUSTING 22-28KTS BY MID-AFTERNOON THURSDAY.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZLC AND ZDV FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE FORECASTS.
FIRE WEATHER
ISSUED AT 120 PM MDT MON SEP 7 2026
UPDATE: A RED FLAG WARNING HAS NOW BEEN ISSUED FOR PORTIONS OF
THE WIND RIVERS, ABSAROKAS, AND OWL CREEKS FOR THURSDAY FROM
NOON TO 900 PM. RH RECOVERY WILL BE POOR TONIGHT IN THE LOWER
ELEVATIONS OF THESE ZONES, AND AFTERNOON HUMIDITY VALUES WILL
DROP TO 12-15 PERCENT ACCOMPANIED BY WIND GUSTS OVER 30 MPH.
PREVIOUS DISCUSSION: FIRE WEATHER WATCHES IN ZONES 277/278/279
HAVE BEEN UPGRADED TO RED FLAG WARNINGS AND HAVE BEEN EXTENDED
INTO THURSDAY. WINDS WILL BE THE LIGHTEST ACROSS THE AREA TODAY,
WITH GUSTS OF 25 MPH OCCURRING FROM ZONE 277 TO 280/300 AND THE
MOUNTAIN ZONES 285, 286 AND 288. RH RECOVERY WILL BE FAIR TO
POOR FOR MOST ZONES TONIGHT. THE ONLY AREAS WILL GOOD RECOVERY
WILL BE ZONES 140/278 AND THE JACKSON/STAR VALLEYS.
WINDS WILL INCREASE ACROSS THE AREA THURSDAY, WITH GUSTS OF 25
TO 35 MPH OCCURRING ACROSS MOST ZONES. THE EXCEPTIONS WILL BE
ZONES 275, 282 AND THE NORTHERN HALF OF 281. RH RECOVERY WILL BE
FAIR TO POOR AGAIN FOR MOST AREAS AGAIN THURSDAY NIGHT. ANOTHER
COLD FRONT WILL MOVE OVER NORTHERN WY FRIDAY MORNING AND LOOKS
TO BECOME STATIONARY ALONG SOUTHERN PORTIONS OF THE BIGHORN
BASIN AND ZONE 281 BY MIDDAY. WIND GUSTS OF 25 TO 35 MPH WILL
ONCE AGAIN BE WIDESPREAD, HOWEVER RHS ARE FORECASTED TO BE JUST
ABOVE THE CRITICAL THRESHOLD.
RIW WATCHES/WARNINGS/ADVISORIES
RED FLAG WARNING FROM NOON TO 9 PM MDT THURSDAY FOR WYZ286>288.
RED FLAG WARNING UNTIL 9 PM MDT THURSDAY FOR WYZ277>280-289-
300.
UPDATE...MCDONALD
DISCUSSION...LAVOIE
AVIATION...CNJ
FIRE WEATHER...MCDONALD/LAVOIE
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