438
FXUS65 KRIW 020510
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1010 PM MST THU JAN 1 2026
KEY MESSAGES
- SNOW CONTINUES ACROSS PORTIONS OF WESTERN AND SOUTHERN WY
TONIGHT AND PERSISTS THROUGH FRIDAY.
- LOCATIONS EAST OF THE DIVIDE REMAIN MILD AND MOSTLY DRY
THROUGH MUCH OF THE UPCOMING WEEKEND EXCEPT FOR AN ISOLATED
SHOWER OR TWO.
- ANOTHER DISTURBANCE LOOKS TO POSSIBLY BRING MORE SNOW TO
WESTERN WY STARTING SUNDAY INTO MONDAY.
UPDATE
ISSUED AT 1205 PM MST THU JAN 1 2026
NOT MUCH TO ADD REGARDING THE PREVIOUS DISCUSSION. TIMING AND
IMPACTS FOR THE INCOMING SYSTEM HAVE REMAINED MOSTLY UNCHANGED.
PRECIPITATION BEGINS THIS AFTERNOON AND WILL SPREAD FROM THE
SOUTHWEST INTO PORTIONS OF WESTERN AND CENTRAL WY. THE HEAVIEST
SNOWFALL LOOKS TO OCCUR ACROSS THE MOUNTAINS OF WESTERN WY THIS
EVENING INTO FRIDAY MORNING WITH SNOWFALL RATES OF 1 INCH OR
MORE POSSIBLE AT TIMES. AS MENTIONED IN THE PREVIOUS DISCUSSION
TEMPERATURES WILL BE ON THE FRINGE LEADING TO SOME LOWER
ELEVATIONS SEEING MIXING OF RAIN/SNOW OR RAIN. A FEW ISOLATED
SHOWERS MAY MAKE THEIR WAY ACROSS THE DIVIDE BY THE LATE EVENING
HOURS. HOWEVER, CHANCES REMAIN LOW, RANGING FROM 20-40% WITH
THE BEST CHANCES EAST OF THE DIVIDE BEING IN PORTIONS OF FREMONT
AND NATRONA COUNTIES. PRECIPITATION GRADUALLY DIMINISHES
THROUGH THE DAY FRIDAY WITH MAINLY QUIET AND MILD CONDITIONS
RETURNING FOR SATURDAY. ANOTHER DISTURBANCE HAS THE POTENTIAL TO
BRING MORE SNOW TO THE MOUNTAINS OF WESTERN STARTING SUNDAY INTO
MONDAY. CURRENTLY THERE IS STILL UNCERTAINTY WITH IMPACTS AND
TIMING BUT THAT SHOULD BE IRONED OUT OVER THE NEXT DAY OR SO.
DISCUSSION
ISSUED AT 117 AM MST THU JAN 1 2026
MID TO HIGH LEVEL CLOUDS WILL CONTINUE TO INCREASE FROM THE WEST-
SOUTHWEST THIS MORNING, AS AN UPPER LEVEL LOW MOVES ONSHORE OVER
CENTRAL CA. PRECIPITATION CHANCES WILL INCREASE ACROSS AREAS WEST OF
THE DIVIDE THROUGH THE DAY AND INTO TONIGHT, AS THE LOW MOVES OVER
THE GREAT BASIN. THE FORECAST CHALLENGE THIS AFTERNOON INTO THE
EVENING WILL BE WHETHER PRECIPITATION FALLS AS SNOW, A RAIN/SNOW MIX
OR FREEZING RAIN. SOUTHERN PORTIONS, SUCH AS KEMMERER, ROCK SPRINGS
AND FARSON, WILL HAVE A SNOW TO RAIN/SNOW MIX BY 21Z WITH SNOW
LEVELS STAYING AROUND 6500FT. SIMILAR CONDITIONS ARE EXPECTED IN THE
JACKSON/STAR VALLEYS. TEMPERATURES ARE EXPECTED TO RISE ABOVE
FREEZING (35F TO 37F) IN THE AFTERNOON, WITH ONLY A 10 TO 20% CHANCE
OF STAYING BELOW FREEZING THROUGH 00Z. SNOW LEVELS WILL STAY AROUND
6200FT BY THIS TIME IN THE JACKSON VALLEY AND TOWARD ALPINE, WITH
THE SOUTHERN PORTIONS OF THE STAR VALLEY STARTING AT 6800FT AT 00Z
AND DROPPING TO 6400FT BY 06Z FRIDAY. A RAIN/SNOW MIX OR VERY WET
SNOW IS EXPECTED AS A RESULT, WITH SFC TEMPERATURES BEING AT OR JUST
ABOVE FREEZING THROUGH MUCH OF THE NIGHT. THERE IS A 30 TO 40%
CHANCE FOR FREEZING TEMPERATURES IN THE CITY OF JACKSON AND THE REST
OF STAR VALLEY. SNOW IS MORE LIKELY IN FOOTHILL LOCATIONS LIKE TETON
VILLAGE, AS WELL AS THE REST OF JACKSON VALLEY NORTH OF JACKSON.
REGARDLESS, ACCUMULATIONS WILL BE MORE MUTED AS SNOW RATIOS WILL BE
CLOSER TO 8:1 DUE TO THE PACIFIC AIRMASS FROM THE UPPER LOW. WILL
ISSUE A WINTER WEATHER ADVISORY FOR THE TETONS/GROS VENTRES AND
SALT/WYOMING ZONES WITH MOST AREAS RECEIVING UP TO 8 INCHES THROUGH
FRIDAY. LOCALLY HIGHER AMOUNTS UP TO 16 INCHES WILL OCCUR IN THE
TETONS AND THE SALT RIVER RANGE. WILL OPT FOR THE ADVISORY VS A
WARNING DUE TO THE MORE LOCALIZED HIGHER AMOUNTS.
PRECIPITATION EAST OF THE DIVIDE WILL MOSTLY BE ISOLATED, WITH
FOOTHILL LOCATIONS LIKE LANDER, DUBOIS AND CODY HAVING A 20 TO 40%
CHANCE. RAIN IS MORE LIKELY TO OCCUR, WITH DUBOIS HAVING THE BETTER
CHANCE FOR SNOW DUE TO ITS HIGHER ELEVATION. TEMPERATURES ARE
EXPECTED TO STAY ABOVE FREEZING ACROSS I-80, BUT SLICK SPOTS CANNOT
BE RULED OUT. HOWEVER, PRECIPITATION AMOUNTS ARE EXPECTED TO REMAIN
VERY LIGHT SO NOT OVERLY CONCERNED WITH THIS HAZARD.
SNOW WILL CONTINUE OVER THE WESTERN MOUNTAINS THROUGH FRIDAY
MORNING, GRADUALLY DECREASING THROUGH THE AFTERNOON, AS THE UPPER
LOW MOVES OVER THE CENTRAL AND SOUTHERN ROCKIES. ANY PRECIPITATION
EAST OF THE DIVIDE AND OVER SOUTHERN PORTIONS OF THE CWA WILL BE
ISOLATED AND (RELATIVELY) SHORT-LIVED. AREAS NEAR GREEN RIVER/ROCK
SPRINGS AND WAMSUTTER LOOK TO HAVE THE BEST CHANCES THESE SHOWERS
LATE IN THE MORNING TO EARLY AFTERNOON.
A TRANSITORY RIDGE WILL BUILD BACK OVER THE REGION DURING THE DAY
FRIDAY, AS A STRONG CLOSED UPPER LOW MOVES OVER THE EPAC TOWARD THE
WEST COAST. DRY CONDITIONS AND ABOVE NORMAL TEMPERATURES WILL BE IN
PLACE ONCE AGAIN AS A RESULT. STRONG TO HIGH WINDS COULD OCCUR OVER
THE WIND CORRIDOR SUNDAY NIGHT INTO MONDAY MORNING, AS THE RIDGE
TRANSITIONS EASTWARD AND INCREASING THE SOUTHWEST FLOW ALOFT. THIS
IN TURN WILL LEAD TO A LEESIDE TROUGH TO DEVELOP OVER EASTERN WY,
TIGHTENING THE SFC PRESSURE GRADIENT. THE FIRST ROUND OF SNOW COULD
ALSO RETURN TO WESTERN PORTIONS DURING THIS TIME AS WELL, AS THE
FIRST SHORTWAVE FROM THE UPPER LOW MOVES OVER THE REGION.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1000 PM MST THU JAN 1 2026
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
SNOW CONTINUES TO FALL ACROSS KJAC TONIGHT, AND LIKELY WILL
CONTINUE THROUGH A GOOD PORTION OF THE DAY FRIDAY. INTENSITY
WILL BEGIN TO DECREASE AFTER 12Z, WITH LIGHTER SNOW DURING THE
AFTERNOON, BUT CONTINUING TO OBSCURE LOCAL MOUNTAINS. KBPI/KPNA
ALREADY HAVE LOW CLOUDS AND FOG, WHICH WILL CONTINUE THROUGH
THE NIGHT. FOG WILL LIFT SLOWLY DURING THE MORNING, BUT CLOUD
CIGS WILL REMAIN NEAR 3000 THROUGH THE AFTERNOON. KRKS WILL
CONTINUE WITH LIGHT RAIN AND SNOW, BUT INTENSITY REMAIN LIGHT
AND VIS WILL BE MINIMALLY AFFECTED THROUGH THE NIGHT. CIGS WILL
REMAIN LOW THROUGH MIDMORNING BEFORE LIFTING AROUND 18Z. WINDS
AT KRKS WILL AGAIN BE GUSTY ON FRIDAY, WITH FREQUENT GUSTS ABOVE
35KTS.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
MOST SITES EAST OF THE DIVIDE ARE NOT EXPECTED TO SEE
PRECIPITATION THROUGH THE NEXT 24 HOURS. THE ONLY EXCEPTION IS
KCPR, WHICH IS CURRENTLY SEEING LIGHT RAIN, WHICH WILL CONTINUE
ONLY FOR A COUPLE MORE HOURS. OTHERWISE MIDLEVEL CLOUDS HOLD
THROUGH THE DAY, BUT WELL ABOVE MVFR LIMITS.
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
WINTER WEATHER ADVISORY UNTIL 5 PM MST FRIDAY FOR WYZ012-024.
UPDATE...DZIEWALTOWSKI
DISCUSSION...LAVOIE
AVIATION...STRAUB
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