234
FXUS65 KRIW 221655
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1055 AM MDT THU OCT 22 2026
KEY MESSAGES
- SHOWER CHANCES (30-60%) ARE EXPECTED ACROSS SOUTH AND
SOUTHWEST WYOMING THROUGH MIDNIGHT TONIGHT. GREATER
PRECIPITATION CHANCES (40- 90%) ARRIVE OVERNIGHT THROUGH MUCH
OF FRIDAY FOR WEST AND NORTHWEST WYOMING. SNOW WILL LARGELY BE
CONFINED TO THE MOUNTAINS.
- STRONG GUSTY WINDS OF 35 TO 55 MPH ARE FORECAST ON FRIDAY
ACROSS THE WIND CORRIDOR, BIGHORN BASIN, WIND RIVER BASIN,
AND JOHNSON COUNTY.
- LOW RELATIVE HUMIDITY VALUES AROUND 20 PERCENT WILL RESULT IN
NEAR- CRITICAL FIRE WEATHER CONDITIONS ACROSS JOHNSON COUNTY
ON FRIDAY.
- MUCH COOLER TEMPERATURES ARE FORECAST THIS WEEKEND BEHIND THIS
WEATHER SYSTEM WITH NEAR SEASONABLE TO BELOW NORMAL FOR THIS
TIME OF YEAR.
DISCUSSION
ISSUED AT 100 AM MDT THU OCT 22 2026
IR CONTINUES TO DEPICT AMPLE CLOUD COVER EXTENDING FROM THE
EASTERN PACIFIC, BRINGING IN TROPICAL MOISTURE THROUGH MUCH OF
THE ROCKIES AND PUSHING TO THE NORTH. THERE HAS BEEN A BIT
FURTHER EASTERN PUSH OF THIS MOISTURE, AND AS SUCH, ANY SHOWER
ACTIVITY LOOKS TO BE MORE ALONG AND EAST OF THE DIVIDE EXTENDING
FROM SWEETWATER TO NATRONA COUNTIES THROUGHOUT THE DAY THURSDAY.
IMPACTS NEGLIGIBLE AT THIS TIME, BRINING IN CONTINUED NEEDED
PRECIPITATION CHANCES IN THE COMING DAYS. WV SHOWS THE MAIN
FINGER OF THE PFJ PUSHING FURTHER SOUTH ACROSS THE PACIFIC
NORTHWEST AND EXTENDING INTO SOUTHERN CANADA. THE CLOSED LOW HAS
PUSHED ACROSS SOUTHERN CALIFORNIA WITH ITS EASTERN PROGRESSION
STARTING AS IT NEARS THE CWA AND UPPER ROCKIES LATER THURSDAY.
THIS WILL INTERACT WITH THE AFOREMENTIONED TROPICAL MOISTURE
THAT WILL PROVIDE BETTER PRECIPITATION CHANCES ON FRIDAY.
WINDS WILL INCREASE LATE THURSDAY MORNING AS THE GRADIENT STARTS
TO STRENGTHEN AHEAD OF THIS SYSTEM, SEEING SOUTHWEST WIND GUSTS
UP TO 25 TO 35 MPH ACROSS THE WIND CORRIDOR, AND 20 TO 30 MPH
FOR OTHER AREAS EAST OF THE DIVIDE. 15 TO 25 MPH EXPECTED TO THE
WEST, BUT THE STRONGER WIND COMES LATE FRIDAY MORNING AND INTO
THE AFTERNOON AND EVENING HOURS. WINDS REMAIN ELEVATED OVERNIGHT
THURSDAY, BUT THE STRONGEST WINDS UP TO 40 TO 60 MPH EXPECTED,
HIGHEST FROM SOUTH PASS TO OUTER DRIVE OF CASPER MOUNTAIN, WHERE
AN OCCASIONAL HIGHER GUST IS POSSIBLE. REGARDLESS, THE MAIN
CONCERN COMES WITH FRONTAL PASS LATE FRIDAY AFTERNOON AND INTO
THE EVENING HOURS OUT OF THE WEST TO NORTHWEST BEHIND IT. WINDS
SLOWLY DIMINISH WITH THE WIND SHIFT CHANGE BUT REMAIN ELEVATED
FOR 2 TO 3 HOURS BEHIND FROPA BEFORE BECOMING RELATIVELY LIGHT
OVERNIGHT. WINDS ACROSS NORTHERN NATRONA AND MUCH OF JOHNSON,
WILL STAY ELEVATED THROUGH SUN-UP SATURDAY MORNING BEFORE
BECOMING RELATIVELY LIGHT.
PRECIPITATION WISE, THURSDAY WILL SEE ISOLATED SHOWER ACTIVITY,
WITH THE BEST CHANCES FOR SWEETWATER AND NATRONA COUNTIES INTO
THE AFTERNOON AND EARLY EVENING HOURS. A RUMBLE OF THUNDER
CANNOT BE RULED OUT WITH INSTABILITY VALUES UP TO 100-200 J/KG
EXPECTED BUT MUCH OF THIS ACTIVITY WILL BE EAST INTO THE CYS
CWA. THIS WILL HELP AID THE STRONGER WINDS AS WELL WITH ANY
OUTFLOWS WITH THIS SHOWER ACTIVITY, BUT MINIMAL IMPACTS (IF ANY)
WILL BE EXPECTED. INCREASING CHANCES COME FRIDAY MORNING WITH
FIRST WAVE OF MOISTURE COMING OUT OF EASTERN IDAHO AND NORTHERN
UTAH PUSHING INTO THE WEST BY SUNRISE. AN ISOLATED STORM IS
POSSIBLE WITH ANY STRONGER OUTFLOWS THE MAIN HAZARD. SNOWFALL
LOOKS TO BE MINIMAL FOR THE HIGHEST OF THE PEAKS ALONG AND WEST
OF THE DIVIDE, THROUGH MID TO LATE MORNING WITH DRY CONDITIONS
EXPECTED TO THE EAST. THE NEXT ROUND OF SHOWER ACTIVITY WILL
COME WITH FRONTAL PASSAGE AS THE COLD FRONT PUSHES INTO
YELLOWSTONE BY 3 TO 5PM AND PUSHING SOUTHEAST AND THROUGH THE
CWA BY MIDNIGHT. THIS IS WHEN FREEZING LEVELS LOOK TO DROP
BETWEEN 8-9KFT, ALLOWING FOR SNOW TO FALL ACROSS THE HIGHER
TERRAIN OF THE WESTERN MOUNTAINS, AND AS WELL AS THE BIGHORNS.
MINIMAL IMPACTS EXPECTED FOR THE BIGHORNS AS MODELS HAVE
DIMINISHED IN QPF AMOUNTS, WITH THE PASSES LOOKING TO STAY
MINIMALLY IMPACTED AT THIS TIME. WEST OF THE DIVIDE WILL BE A
DIFFERENT STORY, EVEN THROUGH LESS SNOWFALL NOW LIKELY. TETON
AND TOGWOTEE HAS THE BEST CHANCES FOR A COUPLE OF INCHES TO FALL
LATE FRIDAY AFTERNOON INTO THE OVERNIGHT HOURS (30-40%) WITH
ANYTHING HIGHER IN ELEVATION PUSHING UP TO 6 INCHES (50-60%).
THIS COULD CONTINUE ITS DOWNWARD TREND, AND AS SUCH, EVEN
ADVISORY LEVEL SNOWFALL DOES NOT LOOK TO BE GREAT AT THIS TIME.
THIS IS FOLLOWING IN LINE WITH LAST WINTER WITH SYSTEMS THAT
LOOK GOOD A FEW DAYS OUT, LOOKING TO WEAKEN AS IT NEARS THE CWA
BEFORE MODELS DO ANYTHING GOOD ON HOW IT TURNS OUT. THIS COULD
BE A PRE-CURSOR OF THE WINTER TO COME, ESPECIALLY WITH THE
STRONGER EL-NINO EXPECTED AS WELL.
AS THIS MORE OPEN WAVE PROGRESSES NORTHEAST AND GETS EMBEDDED
BACK INTO THE JET STREAM FOR THE NORTHERN DAKOTAS, ANOTHER
TROUGH BEGINS TO DEEPEN ALONG THE PACIFIC NORTHWEST OUT OF THE
GULF OF ALASKA WITH INCREASING DIVERGENCE ALOFT. THIS BEGINS TO
NEAR THE CWA BY LATE SUNDAY AND INTO EARLY NEXT WEEK WITH A
BETTER TRACK FOR THE WESTERN MOUNTAINS FOR ANY SIGNIFICANT
SNOWFALL. AGAIN, TIME WILL TELL AS WE ARE FINDING OUT CURRENTLY
AND FROM LAST WINTER. IF ANYTHING, IT WILL REINFORCE THE COLDER
AIR FROM THIS LATE WORK WEEK SYSTEM WITH MORE SEASONABLE TO JUST
BELOW AVERAGE TEMPERATURES HEADING INTO THE LAST WEEK OF
OCTOBER. IN ALL, A MORE ACTIVE PATTERN HAS COMMENCED WITH MORE
FALL LIKE WEATHER AS THE JET GETS CLOSER AND CLOSER WITH ITS
SOUTHWARD AND STANDARD PROGRESSION (EVEN IF A MONTH LATE).
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 430 AM MDT THU OCT 22 2026
VFR CONDITIONS EXPECTED THROUGHOUT THE ENTIRETY OF THE PERIOD.
LIGHT WINDS AND MID LEVEL CLOUDS TO START THE PERIOD AS SHOWER
ACTIVITY INCREASES AT RKS AFTER 20Z, PUSHING TO CPR BY 01Z FOR
A FEW HOUR PERIOD OF LIGHT RAIN AND BREEZY WINDS. HIGHEST WIND
GUSTS UP TO 25KTS AT CPR IN THE AFTERNOON DURING PEAK HEATING
AND MIXING TO THE SURFACE WITH ALL OTHER SITES AROUND 10KTS AND
OCCASIONAL 18KT GUSTS. THE NEXT ROUND OF PRECIPITATION PUSHES IN
FROM THE WEST, FIRST AT JAC AFTER 08Z, SPREADING TO BPI/PNA BY
09Z THROUGH THE END OF THE PERIOD. THE GRADIENT TIGHTENS THERE
AFTER, WITH A POSSIBLE STRONGER PUSH OF MOUNTAIN AIR ACROSS LND
DURING THAT TIME WITH HIRES MODELS PICKING UP ON A 35KT GUST.
ALL OTHER LOCATIONS WILL START TO SEE A STRONGER WIND FOR FRIDAY
INTO THE NEXT TAF CYCLE AS PRECIPITATION SPREADS EASTWARD.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE
FORECASTS.
FIRE WEATHER
ISSUED AT 100 AM MDT THU OCT 22 2026
ELEVATED FIRE WEATHER CONCERNS THURSDAY AFTERNOON AND EARLY
EVENING. SOUTHWEST WIND GUSTS UP TO 25 TO 35 MPH ACROSS THE WIND
CORRIDOR OF SWEETWATER TO NATRONA COUNTIES, EXTENDING UP TO
JOHNSON. MINIMUM RELATIVE HUMIDITY VALUES, HOWEVER, WILL REMAIN
ABOVE CRITICAL THRESHOLDS ABOVE 30 TO 40 PERCENT.
STRONGER WINDS EXPECTED FRIDAY AFTERNOON, WITH SOUTHWEST WIND
GUSTS UP TO 40 TO 60 MPH POSSIBLE, HIGHEST ACROSS SWEETWATER TO
NATRONA COUNTIES, TO INCLUDE SOUTH PASS TO OUTER DRIVE OF CASPER
MOUNTAIN. OTHER AREAS EAST OF THE DIVIDE WILL SEE WIND GUSTS
OVER 30 TO 40 MPH. LOWEST HUMIDITY VALUES WILL REMAIN ACROSS
EASTERN COUNTIES IN THE 20 TO 25 PERCENT, GIVING WAY TO NEAR
CRITICAL FIRE WEATHER CONCERNS DUE TO THE STRONG WINDS.
THE BIGGEST CONCERN, IF ANY FIRES DEVELOP, WILL BE A SUDDEN WIND
SHIFT BY LATE AFTERNOON THROUGH MIDNIGHT AS A COLD FRONT DROPS
THROUGH THE STATE NORTHWEST TO SOUTHEAST. SOUTHWEST WINDS WILL
SHIFT OUT OF THE WEST TO NORTHWEST BEHIND FRONTAL PASSAGE WITH
WINDS SLOWLY DIMINISHING BEHIND IT BUT REMAINING ELEVATED INTO
THE OVERNIGHT HOURS, ESPECIALLY FOR NORTHERN NATRONA AND MUCH OF
JOHNSON COUNTIES, BEFORE BECOMING RELATIVELY LIGHT BY SUNRISE
SATURDAY MORNING.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...LOWE
AVIATION...LOWE
FIRE WEATHER...
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