334
FXUS65 KRIW 050012
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
612 PM MDT SUN OCT 4 2026
KEY MESSAGES
- THERE IS HIGH CONFIDENCE IN UNSEASONABLY WARM TEMPERATURES AND
MOSTLY DRY WEATHER THIS WORK WEEK. THE WARMEST DAY WILL BE
MONDAY, WITH MONTHLY RECORD HIGHS POSSIBLE.
- LOW RELATIVE HUMIDITY, ABOVE NORMAL TEMPERATURES, AND GUSTY
WINDS WILL RESULT IN CRITICAL TO NEAR CRITICAL FIRE WEATHER
CONDITIONS ACROSS THE STATE ON MONDAY.
- A RED FLAG WARNING IS IN EFFECT FROM NOON TO 6 PM ON MONDAY
FOR PORTIONS OF NATRONA, SWEETWATER, AND SOUTHEAST FREMONT
COUNTIES.
UPDATE
ISSUED AT 1136 AM MDT SUN OCT 4 2026
ONE THING TO UPDATE REGARDING THE NEAR TERM FORECAST. FIRE
WEATHER WATCHES HAVE BEEN UPGRADED TO RED FLAG WARNINGS STARTING
MONDAY AT NOON THROUGH 6PM MDT. THIS IS DUE TO CONFIDENCE
GROWING IN MIN RH'S HITTING CRITICAL VALUES, WINDS GUSTING ABOVE
25 MPH, AND UNSEASONABLY WARM TEMPERATURES IN THE LOW TO MID
80S. OTHER PORTIONS OF THE STATE ARE LIKELY TO NEAR OR MEET
ELEVATED FIRE WEATHER CONDITIONS AS WELL DURING THE AFTERNOON
AND EVENING. OTHERWISE, NOT MUCH ELSE TO UPDATE AS WARM NEAR
RECORD BREAKING TEMPERATURES REMAIN LIKELY FOR MONDAY. WELL
ABOVE NORMAL TEMPERATURES ARE FORECAST TO PREVAIL THROUGH THE
REMAINDER OF THE WEEK. A FEW VERY ISOLATED VIRGA SHOWERS CANNOT
BE RULED OUT OVER HIGHER ELEVATIONS AND FAR SOUTHWESTERN WY ON MONDAY
AFTERNOON/EVENING. HOWEVER, LITTLE TO NO CHANCES FOR
PRECIPITATION ARE FORECAST THROUGH THE REST OF THE WEEK.
DISCUSSION
ISSUED AT 1253 AM MDT SUN OCT 4 2026
THIS IS AROUND THE TIME OF YEAR WHEN THOSE OF US WHO HAVE BEEN IN
WYOMING FOR A WHILE START THINKING ABOUT WHEN THE FIRST SNOW IS
GOING TO FLY. I CAN REMEMBER A FEW SNOWSTORMS BEFORE THIS DATE,
INCLUDING A FEW DAMAGING ONES. THAT MAKES DAYS LIKE THIS ONE EVEN
MORE PRECIOUS. TODAY MAY BE THE PERFECT EARLY AUTUMN DAY. HIGH
PRESSURE WILL BE OVER THE AREA TODAY. THE RESULT WILL BE A COOL,
CRISP MORNING FOLLOWED BY A COMFORTABLY WARM AFTERNOON WITH LOTS OF
SUNSHINE. WIND SHOULD ALSO REMAIN FAIRLY LIGHT AS WELL, ESPECIALLY
BY WYOMING STANDARDS. AND, IT FALLS ON A WEEKEND, SO MOST PEOPLE
WILL GET TO EXPERIENCE IT. ENJOY!
THINGS GET A BIT MORE ACTIVE ON MONDAY. A PACIFIC TROUGH WILL BEGIN
TO APPROACH THE AREA FROM THE WEST. THIS WILL TIGHTEN THE PRESSURE
GRADIENT SOMEWHAT AND BRING A GUSTY BREEZE, ESPECIALLY TO THE
FAVORED SOUTHWEST FLOW AREAS FROM EAST OF ROCK SPRINGS THROUGH
CASPER. THIS AREA HAS AT LEAST A 3 OUT OF 4 CHANCE OF WIND GUSTS
PAST 30 MPH ACCORDING TO THE NBM ENSEMBLE FORECAST, ALONG WITH
AREAS LIKE THE UPPER WIND RIVER BASIN AND THE LEE OF THE ABSAROKAS.
WITH MEAN RELATIVE HUMIDITY ON THE NBM ENSEMBLE GENERALLY LESS
THAN 15 PERCENT IN THESE AREAS, WE HOISTED FIRE WEATHER WATCHES
FOR THIS AREA FROM 12 PM TO 6 PM MONDAY. HOWEVER, ELEVATED FIRE
WEATHER WILL BE POSSIBLE ELSEWHERE. AND, WITH THE WARMING,
DOWNSLOPING FLOW, IT WILL BE AN ABNORMALLY WARM DAY FOR THE
FIFTH OF OCTOBER. MOST LOCATIONS EAST OF THE DIVIDE UNDER 6000
FEET IN ELEVATION HAVE AT LEAST A 3 OUT OF 4 CHANCE OF HIGH
TEMPERATURES OVER 80 DEGREES. MOST LOCATIONS UNDER 5000 FEET
HAVE A 1 IN 2 CHANCE OF HIGHS OF 85 DEGREES OR HIGHER. THERE
WILL LIKELY BE SOME DAILY RECORD HIGH TEMPERATURES. A FEW
LOCATIONS COULD GET CLOSE OR POSSIBLY BREAK ALL TIME MONTHLY
RECORD HIGH TEMPERATURES AT WELL, WHICH ARE GENERALLY IN THE MID
TO UPPER 90S.
THE PRESSURE GRADIENT SHOULD RELAX SOMEWHAT ON TUESDAY, SO THE
RESULT WILL BE LESS WIND AND AS A RESULT SOME IMPROVEMENT IN FIRE
CONDITIONS, THIS SHOULD ALLOW FOR TEMPERATURES TO BE A BIT COOLER,
BUT STILL WELL ABOVE AVERAGE AND POSSIBLY BREAK SOME MORE DAILY
RECORDS. THE TROUGH WILL BE PASSING TO THE SOUTH ON THIS DAY. THERE
MAY BE JUST ENOUGH MOISTURE FOR A STRAY SHOWER OR THUNDERSTORM IN
SWEETWATER COUNTY IN THE AFTERNOON, BUT THE CHANCE IS LESS THAN 1
OUT OF 8 SO WE LEFT IT OUT OF THE FORECAST FOR NOW.
WARM AND DRY WEATHER SHOULD CONTINUE THROUGH THE REMAINDER OF THE
WORKWEEK. THE NEXT CHANCE FOR CRITICAL FIRE WEATHER LOOKS TO BE
FRIDAY AS A SHORTWAVE TROUGH MOVES THROUGH THE AREA AND COULD
BRING SOME GUSTY WIND AND LOW HUMIDITY. WE MAY HAVE A PATTERN
CHANGE FOLLOWING THIS AS THE TROUGH BREAKS DOWN AND A MORE
POTENT PACIFIC SYSTEM APPROACHES FROM THE WEST. IT COULD ARRIVE
AS EARLY AS SATURDAY, BUT EXPERIENCE TELLS ME THE MODELS ARE
USUALLY TOO FAST WITH PACIFIC SYSTEMS THIS FAR OUT, SO IT IS
MORE LIKELY FOR SUNDAY. THIS IS NOT CERTAIN, BUT ODDS ARE
INCREASING OF SEEING SOME COOLER AND POSSIBLY WETTER WEATHER FOR
NEXT WEEKEND OR EARLY THE FOLLOWING WEEK.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 345 PM MDT SUN OCT 4 2026
VFR CONDITIONS FOR ALL TAF SITES DURING THE ENTIRETY OF THE
PERIOD. LIGHT WINDS TOWARDS SUNSET AFTER 02Z DUE TO RADIATIONAL
COOLING THROUGH THE OVERNIGHT HOURS INTO MONDAY MORNING. SOME
PASSING HIGH CLOUDS FOR JAC/RKS OVERNIGHT, AND EASTWARD BY
17-19Z MONDAY. WINDS INCREASE AS WELL DURING THIS TIME FRAME
WITH DAYTIME HEATING AND MIXING TO THE SURFACE. GUSTY WINDS UP
TO 18KTS, WITH CPR UP TO 25KTS THROUGH THE END OF THE PERIOD,
NOT TO DIMINISH UNTIL THE NEXT TAF CYCLE TOWARDS SUNSET ONCE
AGAIN. OTHERWISE, NO OTHER WEATHER ELEMENTS ARE EXPECTED AT THIS
TIME.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE
FORECASTS.
FIRE WEATHER
ISSUED AT 1253 AM MDT SUN OCT 4 2026
LOW HUMIDITY WILL BE AROUND TODAY, BUT WIND SHOULD REMAIN LIGHT
TO MODERATE. A COMBINATION OF HUMIDITY FALLING INTO THE TEENS
AND A GUSTY SOUTHWESTERLY BREEZE WILL BRING ELEVATED TO POSSIBLY
CRITICAL FIRE WEATHER MONDAY AFTERNOON, WITH SWEETWATER, NATRONA
AND EASTERN FREMONT COUNTIES THE AREA OF GREATEST CONCERN.
RIW WATCHES/WARNINGS/ADVISORIES
RED FLAG WARNING FROM NOON TO 6 PM MDT MONDAY FOR WYZ279-280-
289-300.
UPDATE...DZIEWALTOWSKI
DISCUSSION...HATTINGS
AVIATION...LOWE
FIRE WEATHER...HATTINGS
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