005
FXUS65 KRIW 261317
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
717 AM MDT MON OCT 26 2026
KEY MESSAGES
- DRY WITH SEASONAL TEMPERATURES TODAY. LOW CLOUDS AND FOG
DECREASES THROUGH THE MORNING.
- A WEATHER SYSTEM BRINGS A PERIOD OF SNOW TO WESTERN WYOMING
TONIGHT, AND STRONG TO POTENTIALLY HIGH WIND EAST OF THE
DIVIDE INTO EARLY TUESDAY AFTERNOON. MINOR IMPACTS TO TETON
AND TOGWOTEE PASSES ARE POSSIBLE.
- ANOTHER FAST MOVING SYSTEM MAY BRING SOME LIGHT SNOW TO
SOUTHWESTERN WYOMING 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 HAVE 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
TOO 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 FLOW SHOULD BRING NEAR TO SOMEWHAT ABOVE NORMAL
TEMPERATURES THROUGH THE END OF THE WORKWEEK AND POSSIBLY TO
SATURDAY AS WELL.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 443 AM MDT MON OCT 26 2026
AREAS OF LOW CLOUDS WILL PERSIST INTO THE MORNING FOR PORTIONS
OF THE AREA, WITH THE HIGHEST LIKELIHOOD IN VICINITY OF KCPR,
KBPI, KPNA AND KRIW. AT KRIW, AREAS OF FOG HAVE FORMED AND WILL
BE AROUND FROM TIME TO TIME THROUGH AROUND 16Z WITH PERIODS OF
IFR TO LIFR CONDITIONS BEFORE IT GRADUALLY BURNS OFF. LARGELY
VFR CONDITIONS ARE THEN EXPECTED AT ALL TAF SITES FROM AROUND
16Z MONDAY THROUGH 04Z TUESDAY. WIND SHOULD REMAIN UNDER 11
KNOTS AT ALL TERMINALS THROUGH 06Z TONIGHT, WITH THE EXCEPTION
OF KCPR WHICH WILL SEE A GUSTY WIND DEVELOP THIS AFTERNOON AND
PERSIST THROUGH THE NIGHT, WITH GUSTS OVER 30 KNOTS LIKELY (70
PERCENT CHANCE) AFTER 08Z TUESDAY.
A WEATHER SYSTEM WILL MOVE INTO WESTERN WYOMING AFTER 04Z
TONIGHT AND BRING A PERIOD OF SNOW AND RAIN CHANGING TO SNOW.
THE RAIN AND SNOW WILL MAINLY IMPACT KJAC, KPNA AND KBPI BETWEEN
05Z AND 12Z, WITH THE HIGHEST CHANCE OF IFR CONDITIONS (AROUND
50 PERCENT) IN VICINITY OF KJAC. MOUNTAIN OBSCURATIONS ARE
EXPECTED DURING THE TIME OF THIS PERIOD OF RAIN AND SNOW.
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...HATTINGS
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