975
FXUS65 KRIW 191847
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1247 PM MDT SUN OCT 19 2025
KEY MESSAGES
- WIND GUSTS 60+ MPH LIKELY (>90% CHANCE) THIS AFTERNOON FROM
SOUTH PASS TO CASPER. LOWER CONFIDENCE IN HIGH WINDS NEAR
KEMMERER (40% CHANCE), CODY FOOTHILLS (30% CHANCE), AND LANDER
FOOTHILLS (20% CHANCE).
- COLD FRONT PASSES THROUGH TONIGHT, BRINGING RAIN AND MOUNTAIN
SNOW. NW WY MOUNTAINS WILL SEE THE HIGHEST SNOWFALL TOTALS (6
TO 10 INCHES) THROUGH MONDAY MORNING.
- SNOW LEVELS DROP TO VALLEY LEVEL OVERNIGHT, RESULTING IN
CHANCES (60 TO 80%) OF SEEING SOME ACCUMULATING SNOW (LESS
THAN AN INCH) ACROSS JACKSON AND STAR VALLEY AND THE UPPER
GREEN RIVER BASIN FOOTHILLS MONDAY MORNING.
- SEASONAL AND TRANQUIL WEATHER IS THEN EXPECTED FOR THE
REMAINDER OF THE WEEK.
UPDATE
ISSUED AT 1246 PM MDT SUN OCT 19 2025
THE FORECAST REMAINS GENERALLY ON TRACK WITH THE INCOMING TROUGH.
WINDS ARE ALREADY GUSTING ACROSS THE GREEN MOUNTAIN AND RATTLESNAKE
RANGES FROM SOUTH PASS TO CASPER, AS EXPECTED. GUSTS THUS FAR (AS OF
1200L) HAVE BEEN GENERALLY 50 TO 60 MPH WITH OCCASIONAL GUSTS TO
NEAR 65 MPH ACROSS THE HIGHER PEAKS AND FAVORED LOCATIONS (SUCH AS
HWY 258/OUTER DRIVE). WINDS ARE EXPECTED TO CONTINUE TO INCREASE
THROUGH THE AFTERNOON, PEAKING AROUND 1500 TO 1800L. CONFIDENCE IN
REACHING HIGH WIND CRITERIA REMAINS ABOUT THE SAME AS WITH THE
OVERNIGHT UPDATE. LANDER FOOTHILLS AND CODY FOOTHILLS ALSO REMAIN
AREAS TO WATCH FOR POSSIBLE HIGH WINDS. CONFIDENCE IN HIGH WINDS FOR
THE CODY FOOTHILLS HAS INCREASED SOMEWHAT WITH THE 12Z MODEL RUNS
AND LATEST HI-RES GUIDANCE. THE JET, ORIENTED SW-NE AHEAD OF THE
TROUGH LOOKS TO PUSH IN RIGHT AROUND 00Z (1800L) THIS EVENING, AND
THIS IS ALSO REFLECTED AT THE 700MB LEVEL WITH 50KTS PROGGED ALONG
THE EAST SLOPES OF THE ABSAROKAS. GREATEST CONCERN FOR HIGH WINDS IN
THAT AREA BASED ON HI-RES GUIDANCE IS AROUND MEETEETSE AND GRASS
CREEK SOUTH OF CODY. I DO EXPECT TO SEE SOME GUSTS 60+ ACROSS SOME
OF THE HIGHER ELEVATION POINTS WEST OF MEETEETSE, HOWEVER IT DOES
NOT LOOK TO BE WIDESPREAD ACROSS THAT ZONE. ALSO, DURATION DOES NOT
LOOK LIKE IT WOULD LAST MORE THAN 1 TO 2 HOURS. GIVEN THIS, HAVE NO
PLANS TO EXTEND THE HIGH WIND WARNING TO THE CODY FOOTHILLS ZONE.
THE LANDER FOOTHILLS ALSO REMAIN A CONCERN, BUT CONFIDENCE HAS
DECREASED FROM THE PREVIOUS DISCUSSION. HI-RES GUIDANCE DOES NOT
SHOW SIGNS OF DOWNSLOPING WINDS ON THE EAST SIDE OF THE WIND RIVER
MOUNTAINS, AND GIVEN THE JET ORIENTATION AS IT PUSHES THROUGH, THERE
LOOKS TO BE TOO MUCH OF A WESTERLY COMPONENT TO THE FLOW AT 700MB TO
TRANSLATE TO A TRUE DOWNSLOPE SCENARIO.
AS FOR PRECIPITATION, TOTAL QPF/SNOW AMOUNTS HAVE NOT CHANGED MUCH
SINCE THE PREVIOUS FORECAST, SO ADVISORIES REMAIN ON TRACK FOR
TONIGHT. TOGWOTEE PASS DOES CONTINUE TO BE THE PRIMARY LOCATION OF
CONCERN FOR SNOW, GIVEN THAT IT IS A SIGNIFICANT TRAVEL CORRIDOR.
WINDS WILL REMAIN ELEVATED (40+ MPH) THROUGH THE NIGHT, SO BLOWING
SNOW WILL BE A CONCERN AS WELL ACROSS TOGWOTEE PASS, BUT ALSO OTHER
MOUNTAIN PASSES INCLUDING TETON PASS AND POWDER RIVER PASS AND
GRANITE PASS IN THE BIGHORNS. SOUTH PASS ALSO WILL BE A LOCATION TO
WATCH, AS IT IS ALSO A MAJOR TRAVEL CORRIDOR. HIGH WIND WILL BE THE
MORE LIKELY CONCERN, AS DISCUSSED ABOVE, BUT A BAND OF PRECIPITATION
DOES LOOK TO PUSH THROUGH WITH THE COLD FRONT THIS EVENING.
TEMPERATURES SHOULD BE WARM ENOUGH THAT PRECIPITATION WILL FALL AS
RAIN, HOWEVER, EVAPORATIVE COOLING COULD DROP TEMPERATURES QUICKLY
ENOUGH WITH FALLING PRECIPITATION, THAT A TRANSITION TO SNOW MAY BE
POSSIBLE BY AROUND 2000L THIS EVENING. WITH WINDS STILL GUSTING
LIKELY 50+ MPH, THIS COULD LEAD TO BRIEF WHITEOUT CONDITIONS ON SOUTH
PASS. CONFIDENCE IS LOW (LESS THAN 20%) THAT ACCUMULATING SNOW WILL
FALL AND LEAD TO IMPACTS. THUS, WILL LEAVE THAT AREA OUT OF ANY
WINTER WEATHER HIGHLIGHTS. SNOW LEVELS WILL DROP QUICKLY FROM WEST
TO EAST THROUGH THE NIGHT. EXPECT A TRANSITION TO SNOW ACROSS THE
WESTERN VALLEYS SOMETIME SHORTLY AFTER SUNSET. THOUGH LIGHT SNOW IS
EXPECTED TO CONTINUE OVERNIGHT, ACCUMULATIONS IN THE LOWER
ELEVATIONS SHOULD REMAIN LESS THAN AN INCH.
SNOW ACROSS THE MOUNTAINS (MAINLY NW WY RANGES AND THE BIGHORNS)
CONTINUES THROUGH MONDAY MORNING, AS DO THE GUSTY WINDS. AS THE
TROUGH PUSHES OUT AND FLOW TRANSITIONS TO NORTHWESTERLY MONDAY,
NORTHERN JOHNSON COUNTY BECOMES THE GREATER FOCUS FOR POTENTIAL FOR
HIGH WIND. THE JET LOOKS TO WEAKEN SLIGHTLY BY THAT TIME, SO
CONFIDENCE IN REACHING HIGH WIND CRITERIA IS LOW (LESS THAN 30%) FOR
ANY LOCATIONS ON MONDAY, BUT WORTH KEEPING AN EYE ON.
DISCUSSION
ISSUED AT 332 AM MDT SUN OCT 19 2025
WE HAVE AROUND 36 HOURS OF ACTIVE WEATHER BEFORE WE ENTER IN A MORE
TRANQUIL PATTERN. CONCERNS TODAY REMAIN THE SAME AS YESTERDAY, SNOW
AND WIND. WE WILL ADDRESS EACH ONE OF THOSE INDIVIDUALLY.
WE WILL START WITH SNOW. THINGS ARE DRY RIGHT NOW, AND WILL REMAIN
SO THROUGH THE MORNING HOUR. AND HERE, THINGS ARE IN FAIRLY GOOD
SHAPE SO WE MADE FEW CHANGES. THE WINTER WEATHER ADVISORIES COVER
THE AREA OF GREATER CONCERN. THE MOST SNOW CONTINUES TO BE ACROSS
THE SOUTHERN ABSAROKAS, WITH A GREATER THAN 4 OUT OF 5 CHANCE OF 6
INCHES OR MORE IN SOME LOCATIONS. THE TETONS ARE MORE LIMITED,
GENERALLY 1 OUT OF 2 OR LESS. HOWEVER, THE MAIN AREA WITH A LARGER
CHANCE, ABOUT 2 OUT OF 3, IS TOGWOTEE PASS WHICH IS A MAJOR TRAVEL
CORRIDOR. SO, WE WILL CONTINUE THE ADVISORIES AS IS. THE WORST
CONDITIONS WOULD LIKELY OCCUR FROM LATE THIS AFTERNOON UNTIL AROUND
MIDNIGHT AS THE TROUGH AND COLD FRONT MOVE THROUGH THE AREA,
COMBINED WITH THE STRONGEST WIND WITH THE FRONTAL PASSAGE.
ELSEWHERE, CHANCES OF ADVISORY LEVEL AMOUNTS ARE LESS THAN 1 OUT OF
10. WE DID MAKE A FEW ADJUSTMENTS TO SNOW RATIOS THIS MORNING
THOUGH. I HAVE MY DOUBTS OF A 20 TO 1 SNOW RATIO IN MID OCTOBER
WITH AN AIR MASS OF PACIFIC ORIGIN. AS FOR THE VALLEYS, THE WESTERN
ONES COULD SEE UP TO AN INCH AS THE SNOW LEVELS FALL TO AROUND 6000
FEET, BUT THE CHANCE OF MORE THAN THAT IS 1 OUT OF 4 AT THE MOST. AS
FOR THE BIGHORNS, THE CHANCE OF MORE THAN 4 INCHES IS ONLY 1 OUT OF
6 AT THE HIGHEST PEAKS. SO, PARAPHRASING THE SOUP MAN FROM THE 90S
SITCOM SEINFELD, "NO ADVISORIES FOR YOU." THE STEADIEST SNOW
SHOULD BE OVER BY SUNRISE MONDAY, BUT WESTERLY UPSLOPE FLOW WILL
KEEP SHOWERS GOING TO THE MORNING. ALL SNOW SHOULD END BY LATER
MONDAY AFTERNOON AS THE SYSTEM MOVES AWAY.
NOW FOR THE MORE WIDESPREAD PART OF THE THREAT, STRONG TO
POTENTIALLY HIGH WIND. WE HAVE MORE POTENTIAL FOR THIS. ONE OF THE
MOST USEFUL THINGS TO LOOK AT ARE THE 700 MILLIBAR WINDS.A GOOD RULE
OF THUMB HERE IS 50 KNOTS OR GREATER, AND THIS RUNS ACROSS SOUTHERN
LINCOLN COUNTY AND INTO SOUTHEASTERN FREMONT AND NATRONA COUNTIES.
THE OTHER THING IS THE POSITION OF THE JET, WHICH IS QUITE STRONG AT
AROUND 130 KNOTS. THIS WILL BE ACROSS SOUTHERN WYOMING, WHICH IS
WHERE THE STRONGEST WIND WILL SET UP. WE HAVE UPGRADED THE HIGH WIND
WATCHES TO WARNINGS, THESE LINEUP FAIRLY WELL WITH THE GREATER THAN
1 OUT OF 2 CHANCE OF MAXIMUM WIND GUSTS OVER 55 MPH. WE THOUGHT
ABOUT A COUPLE OF OTHER LOCATIONS AS WELL. WE THOUGHT ABOUT THE
LANDER FOOTHILLS FOR THE AFTERNOON, AS THERE IS A BRIEF PERIOD OF 50
KNOT 700 MILLIBAR WIND AND SOUTHWEST FLOW. HOWEVER, THE ENSEMBLES
GIVE AN AVERAGE OF A 1 OUT OF 3 CHANCE OF GUSTS OVER 55 MPH RIGHT
NOW, WITH MOST OF THESE IN THE HIGHER SPOTS WHERE FEW PEOPLE LIVE.
SO, WE HELD OFF FOR NOW. AS FOR THE CODY FOOTHILLS, WE FEEL THE
JET IS TOO FAR SOUTH FOR THE STRONGEST WIND WITH THE CHANCE OF
GREATER THAN 55 MPH GUSTS ONLY AROUND 1 IN 4. IT IS HIGHER AROUND
CLARK, BUT THIS IS A WIND PRONE AREA WITH HIGHER WARNING CRITERIA.
AND IN THE ABSAROKAS, THIS IS COVERED BY THE WINTER WEATHER
ADVISORY. JUST ABOUT ALL AREAS SHOULD SEE AT LEAST A 1 OUT OF 2
CHANCE OF WIND GUSTS PAST 35 MPH THOUGH. THROUGH TONIGHT, STRONG
WIND WILL CONTINUE IN THE NORTHWEST / POST FRONTAL LOCATIONS
LIKE THE WIND RIVER BASIN, SWEETWATER COUNTY AND JOHNSON COUNTY,
BUT PLACES LIKE CASPER SHOULD SEE A DECREASE IN WIND. GUSTY WIND
WILL CONTINUE TOMORROW AS WELL, ALTHOUGH THE CHANCE FOR STRONG
WIND WOULD BE RESTRICTED TO JOHNSON COUNTY AND EASTERN SWEETWATER
COUNTY. A FEW AREAS HAVE AROUND A 1 IN 4 CHANCE OF WIND GUSTS
PAST 55 MPH, SO NOT ENOUGH CONFIDENCE FOR A WATCH. ALL GUSTY TO
STRONG WIND SHOULD REALLY DECREASE AFTER DARK MONDAY. AS A QUICK
NOTE FOR TEMPERATURES, TODAY WILL BE QUIET MILD EAST OF THE
DIVIDE, WITH SOME AREAS LIKE CASPER MAKING A RUN AT 70.
TEMPERATURES ON MONDAY WILL BE GENERALLY 15 TO 20 DEGREES COLDER
AND WITH THE GUSTY WIND IT WILL FEEL AS MUCH AS 30 DEGREES
COOLER WHEN COMPARED TO TODAY.
THE REST OF THE FORECAST LOOKS LARGELY TRANQUIL THE ONE FLY IN THE
OINTMENT IS A WEAK FLOW THAT WILL BE MOVING ACROSS COLORADO. IT MAY
BRING A FEW SHOWERS TO SOUTHERN WYOMING WEDNESDAY NIGHT OR
THURSDAY BUT IT HAS LIMITED MOISTURE TO WORK WITH. OTHER THAN THAT,
EXPECT DRY WEATHER THROUGH THE WORKWEEK. THE NEXT CHANCE FOR MORE
WIDESPREAD IMPACTFUL WEATHER WOULD BE NEXT WEEKEND WHEN THE NEXT
PACIFIC SYSTEM APPROACHES, BUT DETAILS WITH PLACEMENT OF
PRECIPITATION ARE STILL UP IN THE AIR THIS FAR OUT. TEMPERATURES
LOOK TO AVERAGE FAIRLY CLOSE TO SEASONAL NORMALS.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1123 AM MDT SUN OCT 19 2025
TWO MAIN AVIATION CONCERNS TODAY ACROSS WESTERN WY. FIRST IS THE
STRONG SOUTHWEST WINDS THIS AFTERNOON. ALL SITES WILL SEE GUSTS
ABOVE 20KTS THIS AFTERNOON, WITH THE MOST PRONE AREAS AT KCPR
AND KRKS GUSTING ABOVE 40KTS THROUGH THIS EVENING. THE WEATHER
SYSTEM THIS EVENING WILL KEEP GUSTY WINDS GOING OVERNIGHT, BUT
SHIFTING MORE FROM THE NORTHWEST THROUGH THE NIGHT. THESE GUSTY
WINDS WILL CONTINUE WELL INTO THE DAY MONDAY.
THE OTHER WEATHER CONCERN IS INCOMING PRECIPITATION FROM THE
NEXT FAST-MOVIGNN WEATHER SYSTEM. PRECIP IS STILL TIMED TO
START AT KJAC MIDAFTERNOON BEFORE SPREADING QUICKLY EAST THROUGH
THE EVENING. MAIN ROUND OF RAIN IS NOT EXPECTED TO LAST MORE
THAN ABOUT 4 HOURS AT ANY LOCATION. ALL SITES WILL STAY AS RAIN,
BUT SOME SNOW MAY MIX IN BRIEFLY AT KCPR JUST BEFORE SUNRISE
MONDAY. ONCE THE PRECIP ENDS, SKIES WILL SCATTER OUT PRETTY
QUICKLY, BUT SOME CU MAY STILL MOVE THROUGH AT TIMES, REMAINING
WELL ABOVE THE LOWER VFR THRESHOLD.
RIW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL NOON MDT MONDAY FOR WYZ002-012.
HIGH WIND WARNING UNTIL 6 AM MDT MONDAY FOR WYZ019.
HIGH WIND WARNING UNTIL 11 PM MDT THIS EVENING FOR WYZ020-027.
UPDATE...HENSLEY
DISCUSSION...HATTINGS
AVIATION...STRAUB
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page