971
FXUS65 KRIW 260834
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
234 AM MDT MON OCT 26 2026
KEY MESSAGES
- ANY SHOWERS ENDING EARLY, THEN A SOMEWHAT WARMER AND MAINLY
DRY DAY TODAY WITH MORE SUNSHINE.
- AN APPROACHING WEATHER SYSTEM WILL BRING A PERIOD OF SNOW TO
WESTERN WYOMING TONIGHT, AND STRONG TO POTENTIALLY HIGH WIND
EAST OF THE DIVIDE ON TUESDAY.
- ANOTHER FAST MOVING SYSTEM MAY BRING SOME SNOW TO SOUTHWESTERN
WYOMING LATER TUESDAY NIGHT.
- MAINLY DRY AND SOMEWHAT WARMER FROM WEDNESDAY THROUGH MOST OF
FRIDAY.
DISCUSSION
ISSUED AT 232 AM MDT MON OCT 26 2026
I HAVE TO APOLOGIZE FOR THE FORECAST YESTERDAY, THE RAIN SHOWERS
REACHED A BIT FURTHER NORTH THAN I OR MOST OF THE GUIDANCE THOUGHT.
HOWEVER, MOST AREAS NEED RAIN SO COMPLAINTS WERE FEW. AND, MANY
AREAS WILL AN ADDITIONAL COUPLE OF CHANCES OF PRECIPITATION OVER
THE NEXT WEEK OR SO.
WE STILL HAVE A FEW LIGHT SHOWERS OUT THERE EARLY THIS MORNING, BUT
THESE SHOULD BE GONE BY SUNRISE, WHICH IS GETTING RATHER LATE (AFTER
7:30 AM). ALL IN ALL, TODAY LOOKS LIKE A FAIRLY LOW IMPACT DAY AS
SHORTWAVE RIDGING SHOULD BRING A MAINLY DRY AND SOMEWHAT WARMER DAY
TO THE AREA. WE HAVE A COUPLE OF SMALL CONCERNS. THE FIRST IS THAT
MAYBE THE FOG MONSTER COULD COME CRAWLING OUT OF HIS LAIR AND BRING
SOME REDUCED VISIBILITY. HE IS STILL SLEEPING AT THIS TIME BUT WE
WILL SEE IF HE WAKES UP. THE OTHER WILL BE SOME GUSTY WIND
DEVELOPING IN THE FAVORED MUDDY GAP TO CASPER AREA, BUT NOTHING
UNUSUAL THROUGH AROUND MIDNIGHT. THERE SHOULD BE MORE SUN TODAY AS
WELL, AND THIS SHOULD ALLOW FOR TEMPERATURES TO BE A BIT WARMER THAN
OVER THE WEEKEND.
THE FIRST WEATHER MAKER, AN AREA OF LOW PRESSURE NOW MOVING ONSHORE
IN THE PACIFIC NORTHWEST, WILL BE THE FIRST CONCERN OF THE FORECAST.
CONCERNS REMAIN THE SAME AS YESTERDAY, WITH A PERIOD OF SNOW,
POTENTIALLY HEAVY IN WESTERN WYOMING, AND POTENTIAL STRONG TO HIGH
WIND IN AREAS EAST OF THE DIVIDE. WE WILL START WITH THE SNOW. SNOW
SHOULD HOLD OFF UNTIL AFTER SUNSET THIS EVENING. WE ALSO HAVE DECENT
MODEL AGREEMENT IN HAVING THE HEAVIEST PRECIPITATION BETWEEN 9 PM
AND 3 AM TONIGHT, WHEN THE TROUGH AXIS AND COLD FRONT MOVE THROUGH
THE AREA. SNOW LEVELS WILL START FAIRLY HIGH, ABOVE 8500 FEET, AS
700 MILLIBAR TEMPERATURES ARE EXPECTED TO BE AT 0 CELSIUS OR ABOVE.
THESE WILL QUICKLY DROP TO AROUND MINUS 4 TO MINUS 6, DROPPING SNOW
LEVELS TO THE VALLEY FLOORS. THERE WILL ALSO BE AN APPROACHING 100
KNOT JET STREAK, ENHANCING LIFT. THE LIMITING FACTOR WILL BE SPEED
OF THE SYSTEM, AS THE HEAVIEST PRECIPITATION SHOULD ONLY LAST AT
MOST SIX HOURS, POSSIBLY AS FEW AS THREE. THIS SHOULD LIMIT AMOUNTS
SOMEWHAT. MOST AREAS SHOULD SEE AT LEAST A COATING IN THE WEST.
HOWEVER, THE AREA THAT HAS A GREATER THAN 1 OUT OF 2 CHANCE OF 3
INCHES OR MORE IS LARGELY RESTRICTED TO AREAS ABOVE 9500 FEET. AS
FOR AREAS WITH ADVISORY LEVEL AMOUNTS (6 INCHES IN THE MOUNTAINS),
THIS IS LARGELY RESTRICTED TO AREAS ABOVE 10500 FEET AND IN PLACES
LIKE SOUTHWESTERN YELLOWSTONE PARK, WHERE IMPACTS WOULD BE MINIMAL.
SO, WE WILL NOT ISSUE ADVISORIES AT THIS TIME. HOWEVER, THERE COULD
BE A PERIOD OF A FEW HOURS LATER THIS EVENING WHEN THERE COULD BE A
PERIOD OF HEAVY SNOW AND GUSTY WIND THAT COULD MAKE TRAVEL
DIFFICULT, ESPECIALLY OVER THE MOUNTAIN PASSES. THE STEADIEST SNOW
SHOULD END BY SUNRISE, WITH ONLY A FEW LEFTOVER SHOWERS AFTER
SUNRISE TUESDAY.
THE OTHER CONCERN IS STRONG TO POTENTIALLY HIGH WIND. IT WILL BE A
DECENT SETUP FOR STRONG WIND WITH AN 100 TO 110 KNOT JET STREAK
MOVING ACROSS THE AREA AND A TROUGH TO HELP MIX STRONG WIND TO THE
SURFACE. THERE IS ALSO A DECENT AREA OF 50 TO 55 KNOT WIND AT 700
MILLIBAR WIND IN THE FAVORED SOUTHWEST FLOW AREAS, MAINLY FROM MUDDY
GAP THROUGH NATRONA COUNTY, WITH THE STRONGEST WIND BETWEEN 6 AM AND
NOON ON TUESDAY. PROBABILISTIC GUIDANCE IS STILL BORDERLINE THOUGH.
THERE IS A 1 IN 2 CHANCE OF WIND GUSTS PAST 55 MPH IN PORTIONS OF
THE AREA. HOWEVER, MUCH OF THIS AREA IS OVER AREAS THAT HAVE HIGHER
THRESHOLDS (65 MPH FOR EAST CASPER, 75 MPH FOR THE HIGHER
ELEVATIONS). SO, WE WILL CONTINUE THE WATCH FOR NOW AND LET THE DAY
CREW TAKE ONE MORE LOOK AT IT. WIND SHOULD DECREASE LATE TUESDAY
INTO TUESDAY NIGHT AS THE LOW MOVES AWAY AND THE PRESSURE GRADIENT
DECREASES.
THERE IS ONE MORE CONCERN FOR TUESDAY NIGHT, ESPECIALLY LATE IN THE
FORM OF A TRAILING SHORTWAVE THAT WOULD MAINLY IMPACT SOUTHWESTERN
WYOMING. THERE IS NOT A TON OF MOISTURE WITH IT. HOWEVER, THERE WILL
BE SOME RIGHT REAR QUADRANT JET ENERGY TO PRODUCE MORE LIFT. THE
CURRENT FORECAST MAY BE TOO DRY. THIS WILL BE ANOTHER QUICK SYSTEM
WHICH SHOULD LIMIT AMOUNTS BUT THE POTENTIAL FOR AN INCH OR TWO OF
SNOW IN PLACES LIKE KEMMERER, FARSON, PINEDALE OR EVEN ROCK SPRINGS
LATER TUESDAY NIGHT. AGAIN, WITH THE FAST MOVEMENT OF THE SYSTEM,
ALL PRECIPITATION SHOULD END BY SUNRISE WEDNESDAY.
FLAT RIDGING SHOULD THEN BRING MAINLY DRY WEATHER WEDNESDAY THROUGH
MOST OF FRIDAY. MY GUT FEELING IS THAT THE FORECAST FOR FRIDAY LOOKS
TO WET. THE NEXT SYSTEM IN THE FORM OF A LOW MOVING IN FROM THE
SOUTHWEST WILL BRING THE NEXT CHANCE OF SHOWERS FOR NEXT WEEKEND.
THERE ARE STILL DIFFERENCES IN THE DETAILS, WITH SOME MODELS SHOWING
A DEEP TROUGH DEVELOPING ACROSS THE WESTERN UNITED STATES AND OTHERS
SHOWING THE TROUGH FLATTER AND FURTHER NORTH. SO, DETAILS ARE STILL
DIFFICULT TO HASH OUT AT THIS TIME. SOUTHWEST SHOULD BRING NEAR TO
SOMEWHAT ABOVE NORMAL TEMPERATURES THROUGH THE END OF THE WORKWEEK
AND POSSIBLY TO SATURDAY AS WELL.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 948 PM MDT SUN OCT 25 2026
A WEAKENING WEATHER SYSTEM WILL CONTINUE TO SLIDE THROUGH THE AREA
TONIGHT EXITING MONDAY MORNING. THERE WILL BE VERY ISOLATED SHOWERS
TONIGHT, WITH NO IMPACTS EXPECTED. THERE WILL BE AREAS OF LOW CLOUDS
IN THE AREA TONIGHT INTO MONDAY MORNING. THE BEST CHANCE FOR MVFR TO
IFR CIGS WILL BE AT KCPR THROUGH MONDAY MORNING. THERE IS A LOW
CHANCE (15%) OF PATCHY FOG AND LOW CLOUDS AT KJAC, KBPI, AND KPNA
MONDAY MORNING.
WIND WILL REMAIN BELOW 10 KNOTS THROUGH THE TAF PERIOD WITH THE
EXCEPTION OF KCPR WHERE WIND WILL BE 10-15 KNOTS WITH GUSTS UP TO 20
KNOTS MONDAY AFTERNOON. PERIODS OF MOUNTAIN OBSCURATION WILL OCCUR
THROUGH MONDAY MORNING. THE NEXT WEATHER SYSTEM WILL PUSH INTO
WESTERN PORTIONS OF THE AREA NEAR THE END OF THE TAF PERIOD. BY
05Z/TUES CONDITIONS SHOULD DROP TO MVFR AT KJAC DUE TO A BAND OF
SNOW/RAIN MOVING INTO WESTERN WYOMING.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
HIGH WIND WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR WYZ019-020.
DISCUSSION...HATTINGS
AVIATION...ROWE
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