197
FXUS65 KRIW 180002
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
602 PM MDT FRI OCT 17 2025
KEY MESSAGES
- GUSTY WEST WINDS CONTINUE OVERNIGHT, LESSENING SOME SATURDAY
MORNING AND AFTERNOON.
- SHOWERS WILL RETURN TO NORTHERN WYOMING TONIGHT AS THE NEXT
SYSTEM ARRIVES. THIS BRINGS LIGHT RAIN AND MOUNTAIN SNOW
SHOWERS TO AREAS ALONG AND EAST OF THE CONTINENTAL DIVIDE
THROUGH SATURDAY MORNING.
- UNSETTLED CONDITIONS CONTINUE ON SUNDAY AS ANOTHER SYSTEM
ARRIVES. WIDESPREAD GUSTY TO STRONG WINDS ARE POSSIBLE
THROUGH THE DAY, WITH RAIN AND MOUNTAIN SNOW SHOWERS EXPECTED
SUNDAY AFTERNOON THROUGH MONDAY MORNING.
UPDATE
ISSUED AT 106 PM MDT FRI OCT 17 2025
HIGH CLOUDS CONTINUE TO SWEEP ACROSS CENTRAL WY THIS AFTERNOON
AHEAD OF THE NEXT WEATHER SYSTEM. WITH THE GRADIENT TIGHTENING
WITH THE APPROACHING STORM, SOUTHWEST WINDS ARE RAMPING UP
ACROSS CENTRAL AND SOUTHERN WY. FREQUENT GUSTS OF 25 TO 30 MPH
WILL CONTINUE, WITH A FEW GUSTS APPROACHING 40MPH AROUND GREATER
CASPER.
THIS NEXT SYSTEM IS POISED TO RACE THROUGH OVERNIGHT
TONIGHT,BRINGING SOME LIGHT PRECIPITATION MAINLY FOR THE
ABSAROKAS, THE BIGHORN BASIN, AND INTO THE I-25 CORRIDOR. PRECIP
AMOUNTS WILL BE LIMITED, DUE TO BOTH THE QUICK SPEED OF THE
SYSTEM AND THE MINIMAL AMOUNT OF MOISTURE AVAILABLE. THE SYSTEM
WILL BE THROUGH THE AREA BY AROUND NOON SATURDAY, WITH THE LOWER
ELEVATIONS OF THE BIGHORN BASIN AND JOHNSON COUNTY ONLY
RECEIVING A FEW HUNDREDTHS OF RAINFALL, WHILE THE ABSAROKAS AND
BIGHORN RANGE GENERALLY 2 TO 4 INCHES OF SNOWFALL.
ONCE THE SYSTEM DEPARTS SATURDAY, EXPECT MOSTLY CLEAR SKIES AND
COLDER TEMPERATURES ONLY PEAKING IN THE UPPER 40S TO MID 50S.
DISCUSSION
ISSUED AT 354 AM MDT FRI OCT 17 2025
WITH THE PREVIOUS SYSTEM NOW WELL OFF TO OUR NORTHEAST, FRIDAY WILL
BE DRY AND MILD AS TEMPERATURES RETURN TO SEASONABLE NORMS. HOWEVER,
IT WON'T BE A CALM DAY FOR MOST AS WESTERLY WINDS INCREASE THIS
MORNING DUE TO A BUILDING SURFACE PRESSURE AND THERMAL GRADIENT. THE
STRONGEST WINDS WILL LIKELY BE SEEN ALONG THE CODY FOOTHILLS AND IN
THE UPPER WIND RIVER BASIN AS A DOWNSLOPING FLOW IS ESTABLISHED OUT
OF THE ABSAROKAS AND WINDS. GUSTS OF 35 TO 45 MPH CAN BE EXPECTED
HERE THROUGH THE DAY WITH GENERALLY LESSER MAGNITUDES ELSEWHERE.
THE MOSTLY CLEAR SKIES EXPECTED THIS AFTERNOON WON'T LAST LONG AS
THE NEXT SYSTEM DROPS SOUTH INTO THE AREA THIS EVENING. THIS
TROUGH AND ASSOCIATED UPPER LEVEL 120 KNOT JET WILL BRING A
QUICK SHOT OF MOISTURE AND COLDER AIR ALONG AND EAST OF THE
CONTINENTAL DIVIDE THIS EVENING THROUGH SATURDAY MORNING. GIVEN
THE SPEED OF THIS SYSTEM AND A LACK OF DEEPER MOISTURE, QPF
AMOUNTS ARE GENERALLY UNDER A TENTH OF AN INCH ACROSS LOWER
ELEVATIONS, FOCUSED MOSTLY IN THE BIGHORN BASIN AND JOHNSON AND
NATRONA COUNTIES. THE ABSAROKAS AND BIGHORNS SHOULD PICK UP A
QUICK FEW INCHES OF SNOW OVERNIGHT WITH MINIMAL TRAVEL IMPACTS
EXPECTED. THIS TROUGH WILL ALREADY BE ON ITS WAY OUT BY MID-
SATURDAY MORNING, AND ANY LINGERING SHOWERS SHOULD QUICKLY GIVE
WAY TO WIDESPREAD SUNNY SKIES AROUND NOON AS DRIER AIR MOVES IN
BEHIND IT.
RIDGING BUILDS IN SATURDAY NIGHT, KEEPING DRY AND CLEAR CONDITIONS
THROUGH SUNDAY MORNING. HOWEVER, THE UNSETTLED PATTERN WILL CONTINUE
AS THE NEXT SYSTEM APPROACHES SUNDAY AFTERNOON. THIS IS NOW LOOKING
MORE SIMILAR TO TONIGHT'S SYSTEM, WITH THE MAJORITY OF PRECIPITATION
EXPECTED ALONG AND EAST OF THE DIVIDE AS AN OPEN TROUGH SLIDES
ACROSS THE NORTHERN ROCKIES THROUGH MONDAY MORNING. THIS ONE SHOULD
DROP A LITTLE FARTHER SOUTH, HOWEVER, WITH PRECIPITATION ALSO
EXTENDING TO WESTERN WYOMING. AMOUNTS ARE LOOKING FAIRLY SIMILAR AS
WELL, WITH THE MOUNTAINS AGAIN PICKING UP SOME LIGHT SNOW
ACCUMULATION. THIS SYSTEM MAY ALSO BRING WIDESPREAD STRONG
WINDS ON SUNDAY AHEAD OF A COLD FRONT THAT WILL PUSH IN SUNDAY
EVENING. THIS WARRANTS WATCHING FOR POTENTIAL WIND HIGHLIGHTS,
BUT CURRENTLY GUIDANCE KEEPS GUSTS BELOW CRITERIA.
GENERALLY DRY CONDITIONS AND SEASONABLE TO SLIGHTLY ABOVE NORMAL
TEMPERATURES ARE THEN EXPECTED MONDAY THROUGH AT LEAST THE MIDDLE OF
NEXT WEEK AS UPPER FLOW BECOMES MORE ZONAL. FURTHER OUT, ENSEMBLE
CLUSTER ANALYSIS CURRENTLY FAVORS ABOVE AVERAGE 500 MB HEIGHTS
THROUGH THE END OF THE WEEK, KEEPING MILD AND DRIER CONDITIONS
ACROSS THE AREA INTO NEXT WEEKEND.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 437 PM MDT FRI OCT 17 2025
GUSTY WINDS WILL DIMINISH AFTER 00Z EXCEPT AT KRKS WHERE GUSTS
AROUND 30KTS WILL CONTINUE THROUGH MUCH OF THE PERIOD.
A QUICK-MOVING SHORTWAVE WILL MOVE THROUGH OVERNIGHT. WITH IT, THE
JET STREAM WILL BRIEFLY BRING A PERIOD OF STRONGER WINDS AROUND
FL020 TO FL030 AT AROUND 35 TO 45KTS, WHICH ARE NOT EXPECTED TO
TRANSLATE TO THE SURFACE. THIS WILL LIKELY TRANSLATE TO LLWS AT
SEVERAL TERMINALS FOR SEVERAL HOURS OVERNIGHT, WITH MOST LIKELY
TIMING BEING 03Z TO 09Z. MENTIONS OF LLWS CONTINUE FOR THE KBPI,
KCOD, AND KJAC TAFS TO ACCOUNT FOR THIS CONCERN.
WITH THE AFOREMENTIONED SHORTWAVE, THERE WILL ALSO BE SOME SHOWERS,
MAINLY IMPACTING EAST OF THE DIVIDE TERMINALS. KCOD, KCPR, AND KWRL
ALL CAN EXPECT AT LEAST A BRIEF PERIOD OF NEAR MVFR CONDITIONS
OVERNIGHT TOWARDS SATURDAY MORNING AS A RESULT OF THE SHOWER
ACTIVITY. KRIW ALSO HAS A SLIGHT CHANCE OF SHOWERS (10 TO 20%
CHANCE) BUT NOT ENOUGH CONFIDENCE TO INCLUDE MENTIONS IN THE TAF.
ALL SITES ARE EXPECTED TO RETURN TO VFR CONDITIONS SATURDAY MORNING.
GUSTY WINDS RETURN AT SEVERAL LOCATIONS LATE SATURDAY MORNING AS
WELL, BUT WILL NOT BE AS STRONG AS TODAY.
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
NONE.
UPDATE...STRAUB
DISCUSSION...MYERS
AVIATION...HENSLEY
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