695
FXUS65 KRIW 271014
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
314 AM MST SAT DEC 27 2025
KEY MESSAGES
- A CANADIAN COLD FRONT WILL DROP SOUTHWARD ACROSS WYOMING TODAY
AND TONIGHT, BRING GUSTY WIND, A PERIOD OF SNOW AND SHARPLY
COLDER TEMPERATURES.
- SUNDAY AND MONDAY WILL BE THE COLDEST IN A WHILE, WITH
TEMPERATURES NEAR TO SOMEWHAT BELOW NORMAL FOR LATE DECEMBER.
- MUCH OF NEXT WEEK LOOKS RAIN AND SNOW FREE WITH A RETURN TO
ABOVE NORMAL TEMPERATURES.
DISCUSSION
ISSUED AT 304 AM MST SAT DEC 27 2025
MUCH OF WYOMING IS ABOUT TO GET A SLAP ACROSS THE FACE. AND
THAT SLAP ACROSS THE FACE IS THE REALITY OF WINTER IN WYOMING
USUALLY IS. IF YOU DON'T LIKE COLD WEATHER, IT HAS BEEN A
CHARMED LIFE OVER THE PAST 2 WEEKS, WITH MOST LOCATIONS 15 TO AS
MUCH AS 22 DEGREES ABOVE NORMAL. WE STARTED COOLING YESTERDAY,
AND THAT WILL CONTINUE TODAY. BUT THE SLAP WILL REALLY HIT
TONIGHT AND INTO THE SUNDAY AND MONDAY.
WE DO HAVE SOME SNOW FALLING LARGELY ACROSS THE WESTERN MOUNTAINS.
THERE IS ALSO SOME ACROSS EASTERN SWEETWATER COUNTY. THE LAST ROUND
OF PRECIPITATION WILL OCCUR WITH THE ARRIVAL OF THE NEXT SYSTEM, A
CANADIAN COLD FRONT THAT WILL DROP ACROSS THE AREA TODAY AND
TONIGHT. THIS FRONT WILL HAVE THREE THINGS TO TALK ABOUT: SNOW, WIND
AND COLDER TEMPERATURES.
AS FOR SNOW, THERE SHOULD NOT BE A LOT OF IT. AS WITH MOST CANADIAN
OR ARCTIC FRONTS, THERE IS LITTLE MOISTURE WITH IT. AS WE LOOK INTO
THE PROBABILISTIC REALM OF ENSEMBLES, THE ONLY ARE WITH A GREATER
THAN 1 IN 2 CHANCE OF 6 INCHES OR MORE OF SNOW STARTING AT 5 AM IS
THE TETONS, WITH MOST LOCATIONS HAVING LESS THAN 1 IN 10 CHANCE. THE
CHANCE OF 3 INCHES IS HIGHER BUT AGAIN, ONLY IN THE MOUNTAINS FOR
THE MOST PART. WE DO HAVE WINTER WEATHER ADVISORIES AND WE WILL
LEAVE THESE UP, MAINLY FOR TRAVEL OVER THE PASSES. AS FOR THE LOWER
ELEVATIONS, OTHER THAN THE WESTERN VALLEYS, THE CHANCE OF 2 INCHES
OR MORE OF SNOW IS AT MOST 1 OUT 4, AND THAT IS THE PLACES LIKE
SINKS CANYON AND SOUTH OF WYOMING BOULEVARD WHERE THERE COULD BE A
BRIEF PERIOD OF UPSLOPE ENHANCEMENT. CHANCES OF AN INCH OR SNOW DO
INCREASE TO AS HIGH AS 3 OUT OF 5 THROUGH IN A CRESCENT FROM JOHNSON
COUNTY TO CASPER TO THE WIND RIVER BASIN TO THE CODY FOOTHILLS. THIS
SNOW WILL BE OF THE ANAFRONTAL VARIETY, OCCURRING BEHIND THE FRONT.
THE BEST CHANCE WOULD BE FROM THE AFTERNOON INTO THE NIGHT TIME
HOURS. THE SYSTEM IS A FAST MOVING ONE THOUGH, WITH ALL SNOW LIKELY
DONE BY SUNRISE SUNDAY. WITH THE LIGHT AMOUNTS OF SNOW, NO FURTHER
HIGHLIGHTS WILL BE ISSUED AT THIS TIME.
NOW WE MOVE ON TO WIND. THERE WILL BE A GUSTY WEST TO SOUTHWEST WIND
AHEAD OF THE FRONT, BUT WITH 700 MILLIBAR GENERALLY REMAINING BELOW
50 KNOTS, ANY HIGH WIND GUST WOULD BE ISOLATED. IT COULD WARM THINGS
UP A BIT, AND IT IS NOT OUT OF THE QUESTION THAT A PLACE LIKE
RIVERTON, WHICH HAS LOW RECORD HIGHS, COULD SET ANOTHER ONE TODAY.
THE CONCERN FOR WIND THEN SHIFTS THE NORTHWEST FLOW / COLD ADVECTION
LOCATIONS POST FRONTAL, FIRST IN PLACES LIKE BUFFALO AND GREYBULL IN
THE AFTERNOON. THEN INTO CENTRAL WYOMING AFTER SUNSET. LIKE PRE
FRONTAL, MID LEVEL WIND DOES NOT SUPPORT HIGH WIND. HOWEVER,
PROBABILISTIC GUIDANCE DOES SHOW AROUND A 1 IN 2 CHANCE OF WIND
GUSTS PAST 50 MPH IN THE FAVORED AREAS AFTER THE FRONTAL PASSAGE.
THIS WOULD BE A BRIEF PERIOD OF STRONGER WIND, GENERALLY LESS THAN 6
HOURS. WE WILL NOT ISSUE ANY WIND HIGHLIGHTS FOR NOW, BUT MAY
ISSUE A SPECIAL WEATHER STATEMENT, ESPECIALLY FOR JOHNSON COUNTY
WHERE THE WIND MAY BE THE STRONGEST WITH A BETTER CHANCE OF SOME
ACCUMULATING SNOW.
AND NOW ON TO TEMPERATURES. THERE IS A NAME FOR THE TEMPERATURES
THAT WILL BE FOUND BEHIND THE FRONT, SEASONABLE. LOWS SUNDAY AND
MONDAY NIGHT WILL BE FAIRLY CLOSE OR SOMEWHAT BELOW SEASONAL
AVERAGES, BUT FAIRLY TYPICAL FOR THE LAST DAYS OF DECEMBER. IT WILL
FEEL QUITE COLD THOUGH, THAT SLAP IN THE FACE COMPARED TO MILD
WEATHER WE HAVE HAD OVER THE PAST COUPLE OF WEEKS. SOME PORTIONS OF
NORTHERN WYOMING WILL HAVE AROUND A 1 IN 3 CHANCE OF LOW
TEMPERATURES BELOW ZERO, ESPECIALLY AREAS THAT GET SOME SNOW THIS
AFTERNOON AND EVENING. IT WILL FEEL BELOW ZERO THOUGH WITH THE GUSTY
WIND, BUT NOT COLD ENOUGH FOR WIND HIGHLIGHTS. AND THERE IS ANOTHER
CONCERN. WITH THE RECENT WARM TEMPERATURES, THE GROUND IS FAIRLY
WARM. THIS IS A FAIRLY GOOD SETUP FOR A FLASH FREEZE WITH THE SNOW
INITIALLY MELTING ON ROADS AND RAPIDLY FALLING TEMPERATURES BEHIND
THE FRONT.
COLD TEMPERATURES WILL STICK AROUND INTO SUNDAY AND SUNDAY NIGHT.
BUT FOR THOSE PEOPLE WHO DON'T LIKE COLD WEATHER, THERE IS GOOD
NEWS. NORTHERLY FLOW WILL START TO TURN MORE ZONAL AND BRING IN
MILDER AIR FROM THE PACIFIC. AND, ONCE AGAIN, LEAD TO ANOTHER PERIOD
OF ABOVE NORMAL TEMPERATURES. IT WILL NOT BE AS WARM AS BEFORE
CHRISTMAS, BUT TEMPERATURES 10 TO 15 DEGREES ABOVE NORMAL MAY APPEAR
AS EARLY AS TUESDAY AND ALMOST CERTAINLY BY WEDNESDAY INTO THE REST
OF THE WEEK. THIS ALSO LOOKS LIKE A DRY PATTERN. THE NEXT CHANCE OF
PRECIPITATION WOULD NOT ARRIVE UNTIL THE END OF THE WEEK IN THE FORM
OF A PACIFIC TROUGH, BUT DETAILS THIS FAR OUT ARE STILL DIFFICULT TO
NAIL DOWN.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 930 PM MST FRI DEC 26 2025
WEST OF THE CONTINENTAL DIVIDE...KJAC/KRKS/KPNA/KBPI TERMINALS
LIGHT SNOW CONTINUES TO PUSH MVFR CONDITIONS AT JAC/BPI/PNA/RKS
OVERNIGHT LINGERING AT JAC ALL DAY SATURDAY. MUCH LOWER
CONFIDENCE AT BPI/PNA/RKS FOR ADDITIONAL SHOWERS AFTER 12Z WITH
LOW BUT VFR CEILINGS LINGERING. GUSTY WINDS AFTER 18-19Z,
HIGHEST AT RKS UP TO 25KTS AHEAD OF THE COLD FRONT PUSHING TO
30KTS AFTER 00Z AS IT PUSHES SOUTHEAST. OTHERWISE, JAC SHOULD
END WITH THE SHOWER ACTIVITY AFTER 03Z, ALTHOUGH LINGERING OVER
THE HIGHER TERRAIN, AND THUS, MOUNTAIN OBSCURATION CONTINUES
THROUGHOUT THE ENTIRE PERIOD FOR ALL LOCATIONS.
EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KRIW/KLND/KWRL TERMINALS
SNOW SHOWERS HAVE ENDED BUT LINGERING AROUND CPR THROUGH 10Z
CARRYING VCSH DUE TO LOWER CONFIDENCE ON STATION (10-20%). WINDS
REMAIN ELEVATED AT CPR THROUGH THE ENTIRE PERIOD PEAKING AT
30KTS IN THE AFTERNOON BEFORE DIMINISHING AFTER 02Z AS THE
FRONT PUSHES THROUGH. ALL OTHER LOCATIONS WILL SEE GUSTY WINDS
UP TO 25KTS AFTER 16Z ENDING BY AROUND 01Z. ANY SNOW SHOWER
ACTIVITY AT COD/CPR WILL BE POST FRONTAL AFTER 01-02Z BUT LESS
MOISTURE TO WORK WITH, AND HENCE, LOWER CONFIDENCE CARRYING
VCSH AT THIS TIME. OTHERWISE, MOUNTAIN OBSCURATION CONTINUES
WITH THE LOW BUT CONTINUED VFR CEILINGS THROUGHOUT THE PERIOD.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZLC AND ZDV FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
CLIMATE
ISSUED AT 304 AM MST SAT DEC 27 2025
ALTHOUGH IT WAS NOT AS WARM AS ON CHRISTMAS DAY, IT WAS STILL
WARM ENOUGH FOR 4 MORE RECORD HIGH TEMPERATURES, PUTTING THE
MONTHLY TOTAL UP TO 70, WITH 69 OCCURRING IN THE PAST TWO
WEEKS. THROUGH DECEMBER 26TH, ALL 9 MAJOR CLIMATE SITES EXCEPT
BUFFALO ARE AT LEAST 10 DEGREES FAHRENHEIT ABOVE NORMAL SO FAR
THE MONTH, WITH THE MOST ANOMALOUS BEING THE RIVERTON AIRPORT
WHICH IS 17.7 DEGREES FAHRENHEIT ABOVE NORMAL FOR THE MONTH.
RIW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR
WYZ001-002-012-014-024.
DISCUSSION...HATTINGS
AVIATION...LOWE
CLIMATE...HATTINGS
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