014
FXUS65 KRIW 252215
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
315 PM MST THU DEC 25 2025
KEY MESSAGES
- THOUGH REMAINING GUSTY, WINDS DECREASE THIS AFTERNOON. RAIN
AND SNOW ALSO DECREASES THIS AFTERNOON.
- RECORD-BREAKING TEMPERATURES TODAY, WITH THE WARM TEMPERATURES CONTINUING
FOR TOMORROW.
- A WEATHER SYSTEM FRIDAY BRINGS WESTERN SNOW AND WIDESPREAD
GUSTY WINDS OVER 30 MPH, WITH MANY AREAS OVER 40 MPH. THIS
SYSTEM ALSO BRINGS A COLD FRONT SATURDAY, WHICH BRINGS MUCH
COOLER (BUT SEASONABLE) TEMPERATURES FOR THE WEEKEND.
UPDATE
ISSUED AT 1232 PM MST THU DEC 25 2025
THE ISOLATED LIGHT RAIN AND SNOW SHOWERS DECREASE THROUGH THE
AFTERNOON, ALONG WITH THE STRONGEST WINDS FROM LAST NIGHT AND THIS
MORNING. GUSTY WINDS ARE STILL EXPECTED OVER THE MOUNTAINS AND THE
USUAL LOCATIONS, LIKE FROM SOUTH PASS TO CASPER. WIDESPREAD WINDS
INCREASE EARLY FRIDAY MORNING. EVIDENCE IS NOT QUITE HIGH ENOUGH FOR
ANY WIND HIGHLIGHTS FRIDAY, WITH 700MB WINDS ONLY PEAKING ABOUT 45
KNOTS. THAT SAID, WIDESPREAD GUSTS 40 TO 50 MPH ARE STILL FORECASTED
ACROSS PORTIONS OF THE AREA, AND LOCALIZED WIND PRONE LOCATIONS,
LIKE OUTER DRIVE IN CASPER, COULD SEE GUSTS MORE IN THE 50 TO 60
MPH RANGE.
FOR SNOW WITH FRIDAY'S SYSTEM, GUIDANCE WOULD SUGGEST AT LEAST
ADVISORY AMOUNTS OVER THE WESTERN MOUNTAINS. WITH RELATIVELY COLDER
TEMPERATURES IN PLACE FRIDAY, (SNOW LEVELS 6000 TO 6500 FEET) WOULD
ACTUALLY HAVE BETTER CONFIDENCE IN SNOW AMOUNTS COMPARED TO THE
RECENT WARMER SYSTEMS WHERE SNOW AMOUNTS GENERALLY UNDERPERFORMED
COMPARED TO WHAT WAS FORECASTED. WINTER WEATHER ADVISORIES HAVE BEEN
ISSUED TO COVER THIS SNOW. MAIN WEATHER IMPACT CONCERNS WOULD BE FOR
ANY TRAVEL OVER MOUNTAIN PASSES, (TETON, TOGWOTEE, SOUTH, ETC.)
WHERE SNOW AND WIND COULD BRING SOME WINTER TRAVEL CONDITIONS.
DISCUSSION
ISSUED AT 152 AM MST THU DEC 25 2025
THE WEATHER HAS BEEN EXCEPTIONALLY ABNORMAL ACROSS WESTERN AND
ESPECIALLY CENTRAL WYOMING FOR MUCH OF THIS MONTH. THIS YEAR,
IT SEEMS LIKE THE SNOW MISER HAS BEEN ON A TWO MONTH LONG LEAVE
OF ABSENCE WITH ONLY CAMEO APPEARANCES AND IS STILL NOWHERE TO
BE FOUND. AT THE OFFICE AS I WRITE THIS, OUR OFFICE IS SITTING
AT 53 DEGREES, WHICH IS THE AVERAGE HIGH TEMPERATURE FOR
RALEIGH, NORTH CAROLINA, WHERE I WENT TO COLLEGE BACK IN THE
DARK AGES CALLED THE 90S. AND IT LOOKS LIKE WE WILL HAVE ANOTHER
DAY OF RECORD WARM TEMPERATURES, MAINLY EAST OF THE CONTINENTAL
DIVIDE. ONE OF THINGS BRINGING THIS THOUGH IS STRONG TO HIGH
WIND, COURTESY OF AN APPROACHING TROUGH AND AN 120 KNOT JET OVER
THE AREA. WE HAVE HIGH WIND WARNINGS OUT ROUGHLY FROM SOUTH
PASS THROUGH CASPER THROUGH 11 AM THIS MORNING. MOST GUIDANCE
SHOWS 700 MILLIBAR WIND REMAINING 50 KNOTS OR MORE THROUGH THIS
PERIOD BEFORE DECREASING, AND BRINGING LIGHTER WIND AS A RESULT.
THE AREA STILL LOOKS GOOD WITH MOST AREAS HAVING AT LEAST A 3
OUT OF 5 CHANCE OF WIND GUSTS PAST 55 MPH. THERE COULD BE A FEW
HIGH GUSTS AROUND LANDER AS WELL, BUT THESE WOULD BE ISOLATED.
WE WILL ISSUE A SPECIAL WEATHER STATEMENT TO COVER FOR THIS.
AND WE HAVE A SNOWY PART OF THE SYSTEM AS WELL. SNOW HAS BEEN
FALLING LARGELY ABOVE 8000 FEET TODAY, BRINGING SLICK CONDITIONS TO
THE MOUNTAIN PASSES, MAINLY TETON AND TOGWOTEE PASSES. THE CURRENT
ADVISORY LOOKS TO BE IN GOOD SHAPE RIGHT NOW, ALTHOUGH A BULK
OF THE SNOW SHOULD FALL BEFORE NOON AS THE BEST FORCING MOVES
EAST OF THE AREA BY THAT TIME. WE WILL CONTINUE AS IS FOR NOW.
SNOW LEVELS MAY FALL TO AROUND 7000 FEET THIS AFTERNOON, SO
THERE COULD BE SOME LIGHT ACCUMULATION IN THE VALLEYS, BUT
NOTHING TO WRITE HOME ABOUT.
THERE SHOULD BE A LULL IN THE SNOW AND WIND LATER THIS AFTERNOON AND
THROUGH TONIGHT. THEN, ANOTHER PACIFIC TROUGH WILL APPROACH THE
AREA. THERE IS A BIT MORE UNCERTAINTY WITH THIS ONE, AS THE
MODELS HAVE DIFFERENT PLACEMENT OF THE HEAVIEST QPF. ENSEMBLE
GUIDANCE GIVES A GREATER THAN 4 OUT OF 5 CHANCE OF OVER 6 INCHES
OF SNOW IN THE WESTERN MOUNTAINS THROUGH SATURDAY. CHANCES OF
12 INCHES ARE MORE LIMITED THOUGH, GENERALLY LESS THAN 1 OUT OF
2. AND AREAS THAT HAVE THE GREATEST CHANCE ARE THE WIND RIVER
RANGE AND SOUTHWESTERN YELLOWSTONE, AREAS WHERE IMPACTS ARE
FAIRLY LIMITED. I COULD SEE SOME MORE HIGHLIGHTS HERE, BUT WILL
HOLD OFF FOR NOW WITH THE CURRENT ADVISORIES SO AS NOT TO
CONFUSE PEOPLE. ONE DIFFERENCE HERE IS THAT COLDER AIR WILL BE
IN PLACE, WITH 700 MILLIBAR TEMPERATURES FALLING TO MINUS 9
CELSIUS BY FRIDAY EVENING ACROSS THE WESTERN VALLEYS, MAKING
MOST OF THE PRECIPITATION IN THE FORM OF SNOW. CHANCES OF OVER
3 INCHES IN THE VALLEYS REMAIN SMALL, GENERALLY 1 OUT OF 3 OR
LESS THOUGH. ALTHOUGH THERE WILL NOT BE A WHITE CHRISTMAS, IT
COULD BE A WHITE BOXING DAY, AT LEAST LATE IN THE DAY. SOME SNOW
COULD EVEN MAKE IT IN SOUTHERN WYOMING IN THE AFTERNOON OR
EVENING, BUT ACCUMULATIONS HERE SHOULD REMAIN ON THE LIGHT SIDE.
AS FOR EAST OF THE DIVIDE, THERE WILL BE ONE MORE MILD DAY.
HOWEVER, THE PEAK OF THE HEAT WILL BE TODAY WITH TEMPERATURES
ABOUT 10 DEGREES COOLER ON FRIDAY THAN CHRISTMAS DAY AS 700
MILLIBAR TEMPERATURES FALL ABOUT 5 DEGREES CELSIUS. IT WILL
STILL BE WELL ABOVE NORMAL THOUGH. THERE COULD BE ANOTHER PERIOD
OF HIGH WIND AS WELL, AS THE PRESSURE GRADIENT TIGHTENS AHEAD
OF THE TROUGH AND SOUTHWEST FLOW INCREASES WITH 700 MILLIBAR
WIND AGAIN REACHING 50 TO 55 KNOTS. ENSEMBLES ARE GIVING A
GREATER THAN 1 OUT OF 2 CHANCE OF WIND GUSTS PAST 55 MPH FROM
SOUTH PASS THROUGH CASPER AND ALSO IN THE LEE OF THE ABSAROKAS.
WE WILL HOLD OFF ON ANY HIGHLIGHTS FOR THIS, GIVEN THE CURRENT
ONES IN EFFECT. IF CONDITIONS LOOK LIKELY, WE CAN ISSUE ON THE
DAY SHIFT TODAY OR EARLY FRIDAY MORNING. AS FOR PRECIPITATION,
CHANCES LOOK SMALL AGAIN WITH THE DOWNSLOPING FLOW.
THERE WILL BE ONE MORE SYSTEM FOR SATURDAY, AND THAT WILL REALLY PUT
AN END TO THE MILD WEATHER, AT LEAST TEMPORARILY. THIS WILL BE
IN THE FORM OF A CANADIAN COLD FRONT THAT WILL BRING A COLDER
AIRMASS FROM, YOU GUESSED IT, CANADA. AS FOR PRECIPITATION,
GIVEN THE CONTINENTAL ORIGIN, MOISTURE IS LIMITED AND WITH THE
FRONT'S FAST MOVEMENT, AMOUNTS WOULD BE LIGHT. MANY AREAS EAST
OF THE DIVIDE COULD SEE SOME SNOWFLAKES FOR THE FIRST TIME IN A
WHILE THOUGH ON SATURDAY INTO SATURDAY NIGHT.
TEMPERATURES THEN RETURN TO LEVELS MORE NORMAL FOR LATE DECEMBER ON
SUNDAY. THE NUMBERS WE HAVE IN THE FORECAST MAY BE THE COLDEST
THEY COULD GET THOUGH. IF THERE IS LITTLE OR NO SNOW ON THE
GROUND, ALBEDO WOULD BE LIMITED. IT WILL FEEL RATHER COLD
THOUGH, GIVEN THE RECENT BALMY WEATHER. THE COLD WEATHER WON'T
LAST LONG THOUGH, AS RIDGING BUILDS BACK OVER THE AREA AND FLOW
TURNS WESTERLY AGAIN FOR MUCH OF NEXT WEEK. THIS WILL BRING A
RETURN TO ABOVE NORMAL TEMPERATURES, ALTHOUGH NOT AS WARM AS
THIS PAST WEEK. IT WILL ALSO LIKELY BE RATHER WINDY AT TIMES
GIVEN THE FAST ZONAL FLOW.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 315 PM MST THU DEC 25 2025
WEST OF THE CONTINENTAL DIVIDE...KJAC/KRKS/KPNA/KBPI TERMINALS
BREAKS IN THE CLOUD COVER COMBINED WITH FAVORABLE INSTABILITY HAS
ALLOWED FOR SCATTERED CONVECTIVE SHOWERS THURSDAY AFTERNOON. EVEN A
FEW RUMBLES OF THUNDER HAVE BEEN OBSERVED. THE CONVECTION TRACKS
NORTHEAST UNTIL 01Z-03Z/FRIDAY WHEN INSTABILITY WANES AND SHOWERS
DISSIPATE. BRIEF MVFR IS POSSIBLE WITH THESE SHOWERS, BUT THESE WILL
BE QUICK-HITTING IN NATURE. THE NEXT WAVE OF PACIFIC MOISTURE
REACHES WESTERN WYOMING BETWEEN 05Z-08Z/FRIDAY, WITH KJAC SEEING THE
EARLIEST PRECIPITATION. INITIAL LIGHT RAIN AROUND 06Z/FRIDAY CHANGES
TO SNOW AT KJAC LATE TONIGHT BEFORE INTENSITY INCREASES AND IFR
CONDITIONS DEVELOP AROUND 12Z-14Z/FRIDAY. MVFR LIGHT SNOW HOLDS OFF
UNTIL CLOSER TO 18Z/FRIDAY AT KPNA/KBPI. GUSTY SURFACE SOUTHWEST
WIND 15-30KTS RETURNS TO KRKS LATE FRIDAY MORNING AND CONTINUES
THROUGH THE REMAINDER OF THE PERIOD. KJAC SEES AN INCREASE IN SOUTH-
SOUTHWEST WIND 10-18KTS IN ASSOCIATION WITH THE FRIDAY MORNING
SNOWFALL. MOUNTAIN TOPS OCCASIONALLY OBSCURED, WITH MOUNTAINS
OBSCURED AFTER 06Z/FRIDAY.
EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KRIW/KLND/KWRL TERMINALS
PASSAGE OF A MIDDAY SHORTWAVE AND CONVECTIVE OUTFLOWS HAVE PLAYED
HAVOC WITH SURFACE WIND SPEEDS AND DIRECTIONS ACROSS CENTRAL WYOMING
THURSDAY AFTERNOON, IMPACTING KCPR, KRIW, AND KLND. IN GENERAL, KCPR
AND KCOD TO KEEP A GUSTY 12-25KT SOUTHWESTERLY WIND OVERNIGHT, WHILE
DOWNSLOPING WIND OF SIMILAR INTENSITY RETURNS TO KLND EARLY IN THE
PERIOD. SPEEDS INCREASE AGAIN AT KCPR, KCOD, AND KLND LATE FRIDAY
MORNING, WHILE KRIW AND KWRL HOLD OFF UNTIL 18Z-19Z/FRIDAY BEFORE
WESTERLY WIND PICKS-UP. LINGERING THURSDAY LATE DAY CONVECTIVE
SHOWERS FADE BETWEEN 01Z-03Z/FRIDAY. A FEW SHOWERS DRIFT EAST OFF
THE ABSAROKA AND WIND RIVER MOUNTAINS FRIDAY AFTERNOON, BUT IMPACTS
WOULD BE LIMITED IN DURATION AT KCOD AND KLND SO HAVE LEFT OUT
PROB30 AT THIS RANGE. MOUNTAIN TOPS OCCASIONALLY OBSCURED.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZLC AND ZDV FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
CLIMATE
ISSUED AT 152 AM MST THU DEC 25 2025
ANOTHER DAY OF RECORD HIGH TEMPERATURES ARE LIKELY TODAY ACROSS
MUCH OF THE AREA. THERE WERE EIGHT RECORD HIGH TEMPERATURES AT
OUR NINE OFFICIAL CLIMATE SITES YESTERDAY, WITH ONLY BIG PINEY
NOT HAVING A RECORD HIGH. TWO LOCATIONS, THE RIVERTON AIRPORT
AND GREYBULL HAD THEIR ALL-TIME WARMEST DECEMBER TEMPERATURE ON
THE AFTERNOON OF THE 24TH. THIS BRINGS THE TOTAL OF RECORD HIGH
TEMPERATURES THIS MONTH SO FAR AT OUR NINE OFFICIAL CLIMATE
SITES TO 59.
RIW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 5 AM TO 11 PM MST FRIDAY FOR
WYZ001-002-012-014-024.
UPDATE...WITTMANN
DISCUSSION...HATTINGS
AVIATION...CNJ
CLIMATE...
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