559
FXUS65 KRIW 170210
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
810 PM MDT THU OCT 16 2025
KEY MESSAGES
- PRECIPITATION ENDS AROUND MIDNIGHT. LIGHT MOUNTAIN SNOW
LINGERS THROUGH ABOUT SUNRISE FRIDAY.
- WARMER AND DRIER CONDITIONS ON FRIDAY.
- SATURDAY THROUGH EARLY NEXT WEEK WILL REMAIN UNSETTLED WITH AN ADDITIONAL
SYSTEM OR TWO BRINGING PRECIPITATION CHANCES TO THE AREA.
UPDATE
ISSUED AT 1242 PM MDT THU OCT 16 2025
FORECAST REMAINS ON TRACK, WITH LOWER ELEVATION RAIN AND MOUNTAIN
SNOW THROUGH TONIGHT. HEAVIEST MOUNTAIN SNOW OCCURS LATE MORNING
THROUGH THIS AFTERNOON, IMPACTING MOUNTAIN PASSES AND HIGH ELEVATION
ROADS. PRECIPITATION CHANCES END FOR MOST LOCATIONS BY ABOUT
MIDNIGHT, WITH LINGERING SNOW OVER THE MOUNTAINS THROUGH FRIDAY
MORNING. PRECIPITATION CHANCES AND AMOUNTS HAVE BEEN ADJUSTED WITH
LATEST MODEL TRENDS, BUT NO NOTABLE CHANGES WERE MADE WITH THIS
UPDATE.
DISCUSSION
ISSUED AT 434 AM MDT THU OCT 16 2025
THE FORECAST IN THE SHORT TERM WILL CONTINUE TO BE DOMINATED BY A
HIGHLY AMPLIFIED TROUGH AND ASSOCIATED UPPER LOW THAT IS NOW MOVING
INTO SOUTHERN WYOMING. ONGOING JET-INDUCED SHOWERS AND THUNDERSTORMS
WILL BE BOLSTERED BY SUNRISE AS THE LOW MOVES FARTHER NORTHEASTWARD
INTO CENTRAL WYOMING. COLDER AIR IS CONCURRENTLY MOVING EAST ACROSS
THE STATE THIS MORNING. PRECIPITATION IS EXPECTED TO BECOME FAIRLY
WIDESPREAD BY MID-MORNING, WRAPPING CYCLONICALLY AROUND THE LOW AND
STEADIEST ACROSS CENTRAL WYOMING AND OVER ANY MOUNTAINS.
SNOW LEVELS WILL DROP TO AROUND OR JUST UNDER 7,000 FT THIS MORNING,
WHICH COULD AT LEAST BRIEFLY BRING LIGHT ACCUMULATIONS TO ELEVATED
SURFACES ACROSS WESTERN WYOMING AND THE GREEN RIVER BASIN. WINTER
WEATHER ADVISORIES REMAIN IN EFFECT FOR MOST OF THE MOUNTAINS
THROUGH THIS EVENING. THE BIGHORNS CONTINUE TO BE THE EXCEPTION,
WITH MOST OF THE ACCUMULATION THERE EXPECTED TO BE ALONG THE HIGHER
PEAKS OF THE CLOUD PEAK WILDERNESS. TRAVEL IMPACTS DUE TO SNOW
SHOULD REMAIN LIMITED TO THE MOUNTAIN PASSES ACROSS THE AREA.
PRECIPITATION WILL BEGIN TO WANE BY SUNSET TODAY AS THE LOW MOVES
INTO NORTHEASTERN WYOMING AND DRIER AIR PUSHES IN BEHIND IT. JOHNSON
COUNTY AND THE EASTERN BIGHORN BASIN WILL LIKELY HOLD ON TO
PRECIPITATION THE LATEST BEFORE MOST OF THIS ACTIVITY COMES TO AN
END BY MIDNIGHT. LIGHT SNOW MAY CONTINUE OVERNIGHT ACROSS THE
MOUNTAINS OF NORTHWESTERN WYOMING THOUGH WITH LITTLE TO NO
ADDITIONAL ACCUMULATION. TOTAL LIQUID PRECIPITATION AMOUNTS THROUGH
THE REST OF THIS SYSTEM WILL BE HIGHEST ALONG THE TRACK OF THE
LOW FROM NORTHERN SWEETWATER COUNTY THROUGH JOHNSON COUNTY.
THESE AREAS WILL GENERALLY HAVE AROUND A 50 TO 70 PERCENT CHANCE
OF AT LEAST A QUARTER OF AN INCH AND A 30 TO 50 PERCENT CHANCE
OF AT LEAST A HALF INCH.
WESTERLY WIND WILL INCREASE FRIDAY MORNING IN THE WAKE OF THE SYSTEM
AS SURFACE PRESSURE DECREASES TO OUR EAST. TEMPERATURES WILL
MODERATE FRIDAY AFTERNOON AND NO PRECIPITATION IS EXPECTED. GUIDANCE
IS THEN KEYING IN ON A GLANCING BLOW FROM A TROUGH TO OUR NORTH
ARRIVING FRIDAY NIGHT. THIS SHOULD BRING A COLD FRONT AND A QUICK
SHOT OF MOISTURE THROUGH SATURDAY MORNING ALONG AND EAST OF THE
CONTINENTAL DIVIDE. BY SATURDAY AFTERNOON THIS FEATURE SHOULD
ALREADY BE EAST OF THE AREA, WITH RIDGING SETTLING IN BEHIND IT.
ACCORDINGLY, SUNDAY IS FAVORED TO BE WARMER AND DRIER. HOWEVER,
GUIDANCE IS SHOWING YET ANOTHER SYSTEM ARRIVING SUNDAY EVENING. THIS
ONE APPEARS A LITTLE MORE SUBSTANTIAL AND MAY RETURN MORE WIDESPREAD
PRECIPITATION CHANCES TO THE AREA EARLY NEXT WEEK, INCLUDING
MOUNTAIN SNOW.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 501 PM MDT THU OCT 16 2025
THE CURRENT STORM SYSTEM IS MOVING TOWARD THE NORTHEAST THIS
AFTERNOON AND EVENING, AFTER BRINGING MODERATE TO HEAVY RAIN AND
SNOW TO MOST OF THE FORECAST AREA LAST NIGHT AND TODAY. CONDITIONS
ARE GENERALLY IMPROVING AT THE TAF SITES WITH MOST SITES MVFR TO
VFR. SCATTERED SHOWERS WILL CONTINUE THROUGH 17/01-02Z AS WEST-
NORTHWEST WINDS GRADUALLY DECREASE. KCPR AND KRKS THOUGH SHOULD SEE
GUSTY (~20 KTS) WIND REMAIN THROUGH ABOUT 17/06Z. AREAS OF FOG ARE
LIKELY EARLY IN THE MORNING, WITH THE FEELING THAT KJAC AND KWRL
HAVE THE BEST CHANCES, THOUGH OTHER TAF SITES MAY ALSO BE IMPACTED
(WITH LOW CERTAINTY AT THIS TIME). THUS, MVFR TO IFR CONDITIONS MAY
LINGER THROUGH FRIDAY MORNING, DEPENDING.
GUSTY WEST-NORTHWEST WINDS ARE EXPECTED AT MOST TAF SITES ON FRIDAY
IN THE POST-STORM ENVIRONMENT. THE TIMING OF THE GUSTY WEST WINDS IS
UNCERTAIN THOUGH AS MODELS ARE WIDELY VARYING ON PUSHING THE
BOUNDARY AWAY FROM THE FOOTHILLS. KCPR AND KRKS SHOULD SEE GUSTS
ABOVE 25 KTS EARLY FRIDAY AFTERNOON WITH THE STRONG PRESSURE
GRADIENT. CLOUDS WILL INCREASE AGAIN IN COVERAGE FROM THE NORTHWEST
TO SOUTHEAST LATE FRIDAY INTO FRIDAY NIGHT AS A WEAK STORM SYSTEM
APPROACHES FROM THE PACNW. ISOLATED SHOWERS ARE POSSIBLE OVER THE
NORTHWEST MOUNTAINS MIDDAY FRIDAY AND WITH A HIGHER LIKELIHOOD
ACROSS NORTHERN WY FRIDAY NIGHT INTO SATURDAY MORNING AS A WEAK
SYSTEM MOVES THROUGH SOUTHERN MONTANA.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 11 PM MDT THIS EVENING FOR
WYZ002-012-014-015-024.
UPDATE...WITTMANN
DISCUSSION...MYERS
AVIATION...MCDONALD
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