502
FXUS65 KRIW 191729
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1129 AM MDT SUN OCT 19 2025
KEY MESSAGES
- A WEATHER SYSTEM WILL CROSS THE AREA WITH SNOW IN THE WESTERN
MOUNTAINS AND GUSTY TO STRONG WIND FOR MOST OF THE AREA.
- MUCH COOLER ON MONDAY WITH SCATTERED SHOWERS AND A GUSTY WIND
CONTINUING.
- SEASONAL AND TRANQUIL WEATHER IS THEN EXPECTED FOR THE MOST OF
THE REMAINDER OF THE WEEK.
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.
DISCUSSION...HATTINGS
AVIATION...STRAUB
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