242
FXUS65 KRIW 292323
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
423 PM MST MON DEC 29 2025
KEY MESSAGES
- CHILLY TEMPERATURES AND LINGER ACROSS MUCH OF THE COWBOY
STATE TODAY ESPECIALLY FOR WESTERN VALLEYS.
- TEMPERATURES WILL GRADUALLY WARM THROUGH THE WEEK WITH HIGHS
RETURNING TO ABOVE NORMAL VALUES BY NEW YEARS EVE.
- DRY CONDITIONS PREVAIL FOR MUCH OF THE WEEK WITH THE NEXT
CHANCE FOR PRECIPITATION POSSIBLY ARRIVING BY THURSDAY WITH
THE BEST CHANCES BEING OVER WESTERN WY.
UPDATE
ISSUED AT 1212 PM MST MON DEC 29 2025
NOTHING TO UPDATE REGARDING THE PREVIOUS DISCUSSION AS THE
OVERALL PATTERN REMAINS QUIET AND MILD THROUGH THE NEXT FEW
DAYS. CHILLY TEMPERATURES ARE FORECAST ACROSS THE STATE TODAY
WITH HIGHS IN THE 30S EAST OF THE DIVIDE AND 20S TO LOW 30S WEST
OF THE DIVIDE. COLDER AIR IS PERSISTING IN SOME WESTERN VALLEYS
WHERE RECENT SNOWFALL OCCURRED SUCH AS STAR VALLEY, WHERE HIGHS
MAY STRUGGLE TO GET INTO THE 20S TODAY. OTHERWISE, NOT MUCH
MORE TO ADD IN TERMS OF THE SHORT TERM FORECAST. THE NEXT CHANCE
FOR PRECIPITATION LOOKS TO POSSIBLY ARRIVE BY THE SECOND HALF
OF THE WEEK WITH CHANCES FAVORING WESTERN WY. MODELS ARE NOT
SHOWING ALL THE IMPRESSIVE OF A SYSTEM SO IMPACTS AT THIS TIME
ARE LOOKING MINIMAL.
DISCUSSION
ISSUED AT 132 AM MST MON DEC 29 2025
HIGH PRESSURE WILL BE HOLDING CONTROL ALONG THE NORTHERN ROCKIES
DURING THE NEXT SEVERAL DAYS, DEFLECTING THE STORM TRACK BACK
INTO CANADA AND KEEPING MILD TEMPERATURES GOING FOR WYOMING.
LOWS THIS MORNING HAVE BEEN COLD, WITH TEMPS WELL BELOW ZERO FOR
THE WESTERN VALLEYS, AND IN THE SINGLE DIGITS ABOVE ZERO EAST OF
THE DIVIDE. SOUTHWEST FLOW RETURNS TODAY, HELPING TO CARVE OUT
SOME OF THE COLD POOL THAT HAS SETTLED IN THE REGION. WITH THE
COLD POOL NOT OVERLY STRONG AND NOT REINFORCED BY ANY SNOWPACK,
EXPECT A GOOD RECOVERY OF TEMPERATURES INTO THE 30S THIS
AFTERNOON. WESTERN VALLEYS THAT DO HAVE SNOWPACK AND ARE
STARTING A LOWER TEMPERATURES WILL HAVE MORE TROUBLE GETTING
OUT OF THE TEENS THIS AFTERNOON. THIS PATTERN WILL CONTINUE
THROUGH THE REMAINDER OF THE WEEK, AS THE RIDGE HOLDS IN PLACE,
PUSHING SYSTEMS OFF TO THE NORTH AND CONTINUING TO CARVE UP ANY
REMAINING COLD POOL. MOST AREAS WILL BE BACK IN THE 40S BY
WEDNESDAY, WITH JACKSON HOLE AND STAR VALLEY HOLDING BACK A BIT
DEPENDING ON HOW FAST SURFACE SNOW THINS OUT.
THE RIDGE TRIES TO SHIFT MORE EAST LATE IN THE WEEK, OPENING THE
DOOR FOR SOME MOISTURE TO GET BACK INTO THE WESTERN MOUNTAINS,
BUT A LACK OF SIGNIFICANT SUPPORTING STORM SYSTEMS WILL KEEP ANY
SNOWFALL ON THE LIGHTER SIDE FOR THE TIME BEING.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 423 PM MST MON DEC 29 2025
UPPER-LEVEL HIGH PRESSURE CONTINUES OVER THE GREAT BASIN THIS
EVENING AND OVERNIGHT, WITH NORTH-NORTHWEST MID- AND UPPER-
LEVEL FLOW OVER WESTERN AND CENTRAL WY. AS A RESULT, VFR
CONDITIONS WILL PERSIST AT ALL TAF SITES THROUGH LATE TUESDAY
AFTERNOON WITH A 10- 20% POSSIBILITY OF MVFR CONDITIONS AT KJAC
AND OTHER SITES DUE TO A WEAK MID-LEVEL DISTURBANCE MOVING
THROUGH THE AREA TUESDAY. SOME HIGH CLOUDS ALSO CONTINUE TO
STREAM FROM NORTH TO SOUTH OVER THE AREA THIS AFTERNOON AND
EVENING. BREEZY WIND GUSTS AT SEVERAL TAF SITES (KBPI, KPNA,
KRKS, AND KCPR) WILL DECREASE AROUND SUNSET.
CLOUDS INCREASE FROM NORTH TO SOUTH STARTING AROUND 30/09Z
TUESDAY ACROSS NORTHERN WY DUE TO A WEAK WEATHER SYSTEM PASSING
BY. MID- TO HIGH- LEVEL CEILINGS WILL CONTINUE THROUGH
30/21Z BEFORE SKIES BECOME MOSTLY CLEAR TUESDAY EVENING. NO
PRECIPITATION IS EXPECTED THOUGH THE TAF PERIOD AT THE TAF
SITES, THOUGH LIGHT SHOWERS COULD DEVELOP TUESDAY MIDDAY OVER
THE NORTHERN WY MOUNTAINS. THE HIGHER TERRAIN ABOVE 10K FT MAY
BE OBSCURED THROUGH THIS PERIOD. GUSTY WEST-SOUTHWEST WINDS
WILL AGAIN DEVELOP AT KCPR AND KRKS LATE TUESDAY MORNING AND
CONTINUE THROUGH SUNSET TUESDAY.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...DZIEWALTOWSKI
DISCUSSION...STRAUB
AVIATION...MCDONALD/VANDENBOOGART
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