586
FXUS65 KRIW 230436
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
936 PM MST THU JAN 22 2026
KEY MESSAGES
- A COLD FRONT MOVES IN TONIGHT, BRINGING COLD TEMPERATURES TO
THE AREA FOR FRIDAY. COLDEST TEMPERATURES OCCUR SATURDAY
MORNING, WITH LOWS AROUND AND BELOW 0 DEGREES.
- LIGHT SNOW IS POSSIBLE, MAINLY EAST OF THE DIVIDE FRIDAY INTO
SATURDAY. UP TO 2 INCHES IS POSSIBLE FOR PORTIONS OF THE
BIGHORN BASIN, JOHNSON COUNTY, AND NATORNA COUNTY, WITH LESSER
CHANCES ELSEWHERE.
UPDATE
ISSUED AT 1127 AM MST THU JAN 22 2026
NO CHANGES TO THE OVERALL MESSAGE FOR THE NEXT FEW DAYS. A COLD
FRONT MOVES IN TONIGHT, USHERING IN COLDER TEMPERATURES FOR THE END
OF THE WEEK. WINDS DO NOT LOOK TO BE A MAJOR CONCERN, WITH GUSTS
MAYBE TOPPING AROUND 30 MPH WITH FRONTAL PASSAGE FOR FAVORED AREAS
LIKE THE BIGHORN BASIN AND NATRONA COUNTY, MAINLY THE WESTERN
PORTION OF THE COUNTY. BREEZY WINDS 15 TO 20 MPH BECOME MORE
WIDESPREAD FOR FRIDAY AFTERNOON.
FOR TEMPERATURES, THE COLDEST PERIOD WILL LIKELY BE SATURDAY MORNING
LOWS (THOUGH FRIDAY IS ALSO NOTABLY COLDER). THERE IS A WIDESPREAD
60 TO 100 PERCENT CHANCE FOR SATURDAY MORNING LOWS TO BE 0 DEGREES
OR LESS, WITH THE WARMEST TEMPERATURES ACROSS SOUTHERN SWEETWATER
COUNTY. FOR THE COLDEST AREAS, THERE IS A 20 TO 40 PERCENT CHANCE
FOR BELOW NEGATIVE 10 DEGREES IN THE BIGHORN BASIN AND A 40 TO 60
PERCENT CHANCE FOR JOHNSON AND NATRONA COUNTIES. LOCALIZED COLD
PRONE LOCATIONS (LIKE NEAR RIVERS AND IN LOW SPOTS) COULD BE IN THE
NEGATIVE TEENS FOR THESE LOCATIONS. CLOUD COVER AND SNOW POTENTIAL
WILL BE THE GREATEST INFLUENCE IN THESE TEMPERATURES, ADDING SOME
UNCERTAINTY WITH THE CURRENT TEMPERATURE FORECAST. WIND IS NOT A
GREAT FACTOR SATURDAY MORNING, BUT A LIGHT BREEZE AROUND 10 MPH IN
JOHNSON AND NATRONA COUNTY COULD HAVE FEEL-LIKE TEMPERATURES IN THE
NEGATIVE TEENS.
FOR SNOW, GREATEST ACCUMULATIONS ARE EAST OF THE DIVIDE, MAINLY THE
EASTERN BIGHORN BASIN AND JOHNSON/NATRONA COUNTIES. LATEST GUIDANCE
WOULD SUGGEST 40 TO 60 PERCENT CHANCE FOR AT LEAST HALF AN INCH IN
THE BIGHORN BASIN AND 60 TO 70 PERCENT CHANCE FOR THE LOWER
ELEVATIONS OF JOHNSON AND NATRONA COUNTIES. HIGHER-END AMOUNTS OF 2
INCHES OR MORE IS POSSIBLE FOR BUFFALO (20 PERCENT CHANCE) AND
CASPER (40 PERCENT CHANCE). WITH THE EXPECTED NORTH-NORTHWEST FLOW,
SOUTHERN CASPER WILL LIKELY SEE MORE SNOW THAN NORTHERN PARTS.
DISCUSSION
ISSUED AT 237 AM MST THU JAN 22 2026
FOR THE MOST PART THINGS ARE QUIET AT THE HUMBLE RIVERTON
WEATHER ABODE AS HIGH PRESSURE IS BRINGING DRY, QUIET AND FOR
THE MOST PART SEASONABLY COLD WEATHER TONIGHT. WE HAVE TWO
QUESTIONS TONIGHT THAT WE ARE PONDERING FOR THE FORECAST AS WE
LISTEN TO CLASSIC ROCK TONIGHT (TWO GEN XERS WORKING TONIGHT).
THE FIRST IS HOW MUCH SNOW WE WILL GET OVER THE NEXT THREE DAYS,
AND THE SECOND, MORE IMPORTANT QUESTION, IS HOW COLD WILL IT
GET AS WE HAVE THE COLDEST AIR OF THE SEASON MOVING IN FOR THE
WEEKEND AND WILL PEOPLE BE STONE COLD, COLD AS ICE OR SO COLD (I
THREW IN BREAKING BENJAMIN FOR THE MILLENNIALS). WE WILL DO
SOMETHING DIFFERENT AND ADDRESS THESE INDIVIDUALLY.
WE WILL START WITH SNOW. DRY CONDITIONS ARE EXPECTED TODAY, BUT THE
NEXT COLD FRONT (THE THIRD WE HAVE SEEN THIS WEEK) WILL CROSS
THE AREA TONIGHT AND INTO FRIDAY. AND, I'M GOING TO SOUND LIKE A
BROKEN RECORD, WITH THE ARCTIC ORIGINS OF THE AIR, IT HAS
LITTLE MOISTURE TO WORK WITH. AS A RESULT, SNOWFALL AMOUNTS ARE
EXPECTED TO BE LIGHT. IN THE DETERMINISTIC MODEL REALM, THE
ECMWF BRINGS A FAIRLY BROAD AREA OF LIGHT QPF (LESS THAN A
TENTH OF AN INCH) ACROSS MOST AREAS EAST OF THE DIVIDE. THE GFS
IS MUCH DRIER WITH ONLY SOME LIGHT SNOW SHOWERS ACROSS AREAS
EAST OF THE DIVIDE. THEN WE TRANSITION INTO THE PROBABILISTIC
REALM OF ENSEMBLE GUIDANCE. THE SNOW IS STILL EXPECTED TO BE OF
THE ANAFRONTAL VARIETY, FALLING BEHIND THE FRONT. AND WITH THE
NORTHERLY FLOW BEHIND THE FRONT, THE HEAVIEST SNOW (A RELATIVE
TERM WITH THIS SYSTEM) WOULD FALL IN THE FAVORED NORTHERLY
UPSLOPE LOCATIONS. THIS LOOKS TO BE FURTHER EAST AS WELL,
GENERALLY AROUND CASPER AND FROM THERMOPOLIS AND EASTWARD INTO
THE SOUTHEASTERN BIGHORN BASIN. EVEN HERE, THE CHANCE OF OVER AN
INCH OF SNOW IN THE LOWER ELEVATIONS IS ONLY 1 OUT OF 2. WHEN
WE BUMP THE TOTALS TO ADVISORY LEVEL (3 INCHES), THE ONLY
POSSIBLE AREA IS AROUND CASPER, WHERE THERE WILL BE A BIT OF
RIGHT REAR QUADRANT JET ENERGY TO ENHANCE LIFT A BIT. EVEN HERE,
THE CHANCE IS ONLY 1 OUT OF 5 AT THE MOST. THIS, PLUS THE FACT
THE COLD AIR WILL OOZE IN RATHER THAN MOVE IN QUICKLY, WIND
SHOULD NOT BE TOO STRONG. SO, NO ADVISORIES HERE. ELSEWHERE, THE
CHANCE OF AN INCH OF SNOW IS LESS THAN 1 OUT OF 10. THIS ROUND
OF SNOW SHOULD END FRIDAY NIGHT. AFTER A DRY SATURDAY, THE
FOURTH AND LAST FRONT WILL MOVE INTO THE AREA SATURDAY NIGHT.
THIS SYSTEM IS EVEN DRIER AND WILL BRING EVEN LESS SNOW, WITH
ONLY SOME SHOWERS EXPECTED AND ANY ACCUMULATION EXPECTED TO BE
LIGHT.
THE MAIN STORY LOOKS TO BE THE COLD AIR, THE COLDEST OF THE SEASON.
ONE DISCLAIMER HERE, THIS WILL NOT BE A RECORD BREAKING COLD
OUTBREAK. TEMPERATURES WILL GENERALLY BE 10 TO 15 DEGREES BELOW
NORMAL AS THE CORE OF THE COLD AIR WILL REMAIN WELL TO THE
EAST, OVER THE NORTHERN PLAINS AND GREAT LAKES, WITH WYOMING
SEEING MORE OF A GLANCING BLOW. THE 700 MILLIBAR TEMPERATURES
WILL BE GENERALLY DOWN TO AROUND MINUS 21C, AS OPPOSED TO THE
MINUS 30S FURTHER EAST. FRIDAY WILL BE THE COLDEST DAY IN A LONG
TIME FOR AREAS EAST OF THE DIVIDE, WITH HIGHS REMAINING IN THE
TEENS AND SINGLE DIGITS. AS OF NOW, IT IS LOOKING MORE LIKELY
THAT MANY AREAS WILL SEE LOWS IN BELOW ZERO EAST OF THE DIVIDE,
WITH MOST AREAS HAVING AT LEAST A 4 OUT OF 5 CHANCE. THERE ARE
STILL A COUPLE OF WILD CARDS THOUGH. ONE IS IF THE CLOUDS DON'T
CLEAR QUICKLY ENOUGH, KEEPING TEMPERATURES UP JUST A BIT. THE
OTHER IS SNOW COVER. AREAS FURTHER WEST MAY NOT HAVE ANY SNOW
COVER, KEEPING TEMPERATURES A BIT WARMER. THE COLDEST
TEMPERATURES MAY END UP BEING IN NATRONA COUNTY, WHERE SNOW
COVER SHOULD BE THE DEEPEST, AIDING IN COOLING. HERE, THERE IS A
2 OUT OF 5 CHANCE OF LOWS LOWER THAN MINUS 10. AS FOR COLD
HIGHLIGHTS, DON'T THINK THEY ARE NEEDED NOW SINCE MINUS 20 IS
NOT EXPECTED AND THE WIND SHOULD BE FAIRLY CALM. SATURDAY LOOKS
COLD AS WELL.
THE COLD SHOULD NOT LAST THOUGH, AS THE COLD AIR MOVES TO THE EAST
AS FLOW TURNS MORE NORTHWESTERLY AND WESTERLY. A SLOW MODERATION
BEGINS ON SUNDAY, BUT SHOULD REALLY BE FELT ON MONDAY AS A WEAK
SHORTWAVE APPROACHES AND MIXES OUT THE ATMOSPHERE. TEMPERATURES
SHOULD RETURN TO ABOVE NORMAL LEVELS AGAIN ON MONDAY. THE FORECAST
GETS MUDDIER AFTER THAT, BUT NO ARCTIC AIR IS EXPECTED AS WE
HAD TOWARD THE END OF JANUARY.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 930 PM MST THU JAN 22 2026
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS
BKN-OVC FL100-180 WILL BE IN PLACE FOR MUCH OF THE AREA AND
PROGRESS SOUTHWARD THROUGH 13Z. THESE CLOUDS DECKS WILL DROP TO
AROUND FL070 FROM NORTH TO SOUTH THROUGH THIS TIME FRAME. LOWER
CEILINGS WILL LEAD TO MOUNTAIN OBSCURATIONS OVER PORTIONS OF
YELLOWSTONE AND THE ABSAROKAS. CONDITIONS ARE EXPECTED TO
REMAIN DRY THROUGH THE TAF PERIOD, ALONG WITH LIGHT WINDS (11KT
OR LESS).
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS
MVFR CONDITIONS HAVE DEVELOPED FROM KCOD TO KCPR, WITH LIGHT
POSSIBLE. THE BEST CHANCES LOOK TO OCCUR BY 14Z, WITH A 30%
CHANCE FOR IFR VISIBILITIES BETWEEN 15Z AND 18Z. MVFR CEILINGS
WILL BE COMMON ACROSS THE BIGHORN BASIN BY 12Z, WITH A 30%
CHANCE FOR LIGHT SNOW BETWEEN 15 AND 18Z ALSO FOR KCOD. CEILINGS
ARE EXPECTED TO STAY VFR AT KRIW/KLND THROUGH THE PERIOD.
MOUNTAIN OBSCURATIONS WILL BE COMMON OVER THE BIGHORNS AND
CASPER MOUNTAIN, WITH IMPROVING CONDITIONS AS CLOUDS BEGIN TO
CLEAR FROM NORTH TO SOUTH TOWARD THE END OF THE TAF PERIOD.
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
NONE.
UPDATE...WITTMANN
DISCUSSION...HATTINGS
AVIATION...LAVOIE
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