368
FXUS65 KRIW 220431
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1031 PM MDT WED OCT 21 2026
KEY MESSAGES
- INCREASING CLOUDS AND ABOVE AVERAGE TEMPERATURES OVERNIGHT
INTO THURSDAY MORNING.
- PRECIPITATION CHANCES INCREASE THURSDAY WITH RAIN AND MOUNTAIN
SNOWFALL EXPECTED THROUGH FRIDAY, MOSTLY ALONG AND WEST OF
THE CONTINENTAL DIVIDE.
- STRONG WIND GUSTS OF 40 TO 55 MPH ARE EXPECTED ON FRIDAY ALONG
THE WIND CORRIDOR FROM SWEETWATER COUNTY THROUGH JOHNSON
COUNTY. THIS WILL LEAD TO NEAR-CRITICAL FIRE WEATHER
CONDITIONS FRIDAY AFTERNOON.
- MUCH COOLER TEMPERATURES ARE EXPECTED THIS WEEKEND BEHIND THE
INCOMING SYSTEM TO NEAR SEASONABLE TO JUST BELOW FOR THIS TIME
OF YEAR.
UPDATE
ISSUED AT 315 PM MDT WED OCT 21 2026
A FEW SHOWERS HAVE POPPED UP OVER THE WESTERN WYOMING MOUNTAINS THIS
AFTERNOON AS MOISTURE AND UPPER LEVEL LIFT INCREASE WITH THE
INCOMING SYSTEM. MOUNTAIN SNOW ACCUMULATION CONTINUES TO
DECREASE WITH THE LATEST GUIDANCE. THIS IS DUE TO BOTH
DECREASING LIQUID PRECIPITATION AND THE FACT THAT THE SYSTEM IS
RELATIVELY WARM; SNOW LEVELS WILL MOSTLY REMAIN ABOVE 8,500 FT.
EAST OF THE DIVIDE, THE MORE NOTABLE CONCERN WITH THIS SYSTEM
WILL BE FIRE WEATHER AS WINDS COME UP ON FRIDAY AHEAD OF THE
COLD FRONT. WHILE HUMIDITY IS EXPECTED TO REMAIN ABOVE 20
PERCENT, SUSTAINED WINDS OF 25 TO 35 MPH WITH GUSTS NEARING 50
MPH WILL LEAD TO NEAR CRITICAL FIRE WEATHER CONDITIONS.
DISCUSSION
ISSUED AT 130 AM MDT WED OCT 21 2026
IR CURRENTLY DEPICTS MID LEVEL CLOUDS PUSHING IN ACROSS WESTERN
AND NORTHERN PARTS OF THE CWA FROM THE SOUTHWEST, EXTENDING FROM
BAJA CALIFORNIAN MOISTURE EXTENDING THROUGH THE FOUR CORNER
REGION. WV IMAGERY SHOWS THE MAIN FINGER OF THE PFJ EXTENDING
ACROSS SOUTHERN CANADA AND A STRONG UPPER LEVEL LOW OFF THE
CENTRAL CALIFORNIAN COASTLINE. THIS LOW WILL BEGIN ITS EASTERN
EXTENT WEDNESDAY NIGHT INTO THURSDAY AS IT BECOMES A MORE OPEN
AND PROGRESSIVE WAVE THAT WILL STRENGTHEN THE SOUTHWEST AND
DIVERGENT FLOW INTO THE CWA OUT OF NORTHERN UTAH. THIS IS WHERE
THE STRONGER PVA ANOMALIES WILL OCCUR EXTENDING MOISTURE CONTENT
INTO SOUTHERN PORTIONS OF THE STATE BY THURSDAY MORNING.
THE AFOREMENTIONED PFJ WILL START TO DIP ACROSS THE PACIFIC
NORTHWEST ALIGNED WITH THE MAIN LOW AS IT BECOMES MORE OPEN LATE
THURSDAY WITH AN INCREASING JET MAX PUSHING 120-130KTS. THIS
DEEPENS THE NORTHERN PORTIONS OF THIS SYSTEM WITH INCREASED
DIVERGENCE ALOFT. THIS INCREASES THE PRESSURE GRADIENT ACROSS
MUCH OF THE CWA ABOUT 5 TO 7 MB ACROSS THE STATE, STRONGEST
ACROSS THE SOUTH. SOUTHWEST WINDS PUSH 40 TO 55 MPH THURSDAY
AFTERNOON DURING PEAK HEATING AND MIXING TO THE SURFACE,
STRONGEST ACROSS THE WIND CORRIDOR FROM SWEETWATER THROUGH
EASTERN FREMONT TO NATRONA COUNTIES. OCCASIONAL GUSTS OVER 60 TO
65 MPH POSSIBLE (40-50%) FOR THE HIGHER TERRAIN AREAS OF SOUTH
PASS AND OUTER DRIVE OF CASPER MOUNTAIN. THERE IS LOW CONFIDENCE
ON HIGH WIND CRITERIA BEING MET FOR THIS PERIOD OF TIME, BUT
WINDS REMAIN ELEVATED OVERNIGHT INTO FRIDAY MORNING WITH WIND
SHIFTS OCCUR DUE TO A PASSING COLD FRONT EXTENDING THROUGH THE
CWA INTO THE AFTERNOON HOURS FRIDAY.
PRECIPITATION WISE, EXPECT SHOWER ACTIVITY TO INCREASE OUT OF
NORTHERN UTAH INTO SOUTHERN PORTIONS OF THE CWA THURSDAY
MORNING PUSHING NORTH THROUGHOUT THE DAY. MUCH OF THE QPF WILL
FALL WEST OF THE DIVIDE WITH SOME HIGHER TERRAIN MOUNTAIN SNOW
EXPECTED BY LATE THURSDAY AFTERNOON AND ESPECIALLY OVERNIGHT AS
TEMPERATURES FALL. THIS WILL BE REINFORCED WITH FROPA ON FRIDAY,
LOWERING FREEZING LEVELS TO 8-9KFT AS THE SYSTEM SHIFTS EAST OF
THE DIVIDE, AND THUS, IMPACTING THE BIGHORNS WITH MOUNTAIN
SNOW. MOUNTAIN PASSES, TO INCLUDE TETON, TOGWOTEE, AND SOUTH
PASS, EXTENDING TO GRANITE/POWDER RIVER, WILL SEE THE IMPACTS
AND HAZARDS LATE FRIDAY AND INTO SATURDAY MORNING AS THE TROUGH
SHIFTS NORTHEAST BY DAY'S END SATURDAY. PROBABILITIES FOR
SNOWFALL TOTALS LOOK TO BE OF HIGHER CONFIDENCE ACROSS WESTERN
MOUNTAINS, TO INCLUDE THE WINDS, OF 6 INCHES OR MORE AROUND
60-70%. THE BIGHORNS ARE OF LOWER CONFIDENCE AROUND 30-40% FOR
LATER FRIDAY AND INTO THE OVERNIGHT HOURS. WITH SNOWFALL TOTALS
OF NOT GREAT CONFIDENCE, AND BEING FRIDAY FOR IMPACTS, IT HAS
BEEN DECIDED TO INCLUDE SURROUNDING OFFICES TO NOT ISSUE ANY
HEADLINES AT THIS TIME. MODEL GUIDANCE HAS BEEN UP AND DOWN THE
PAST COUPLE OF DAYS WITH THIS ROUND BUMPING TOTALS UP ONCE AGAIN
AND WILL NEED HIGHER CONFIDENCE TO DO SO MOVING FORWARD.
BEYOND THAT, EXPECT MORE SEASONABLE TO JUST BELOW AVERAGE
TEMPERATURES POST FROPA FRIDAY AND INTO THE WEEKEND TO FELL MORE
FALL-LIKE FOR THIS TIME OF YEAR MOVING TOWARDS THE LATER HALF OF
OCTOBER. ANOTHER LOW EXTENDING OUT OF THE GULF OF ALASKA LOOKS
TO PUSH DOWN ALONG THE L/W PATTERN INTO THE PACIFIC NORTHWEST
LATE SUNDAY THAT WILL NEAR THE CWA EARLY NEXT WEEK. THIS WILL
NOT ONLY REINFORCE THIS COOLER AIR BUT CONTINUE THE ACTIVE
PATTERN THAT HAS A BETTER TRACK FOR STRONGER SNOW TOTALS. TOO
SOON TO JUDGE THE IMPACTS AT THIS POINT IN TIME, BUT THIS LOOKS
TO HAVE A BETTER TRACK FOR HIGHER MOUNTAIN SNOW ALONG AND WEST
OF THE DIVIDE. STAY TUNED FOR FORECAST UPDATES AND ANY HEADLINE
ISSUANCE LATER WEDNESDAY OR WEDNESDAY NIGHT AS CONFIDENCE GROWS
FOR IMPACTS ON FRIDAY INTO SATURDAY.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1030 PM MDT WED OCT 21 2026
VFR CONDITIONS ACROSS ALL TERMINALS THROUGH AT LEAST THE FIRST 12
HOURS OF THE TAF PERIOD. SOME PATCHY AREAS OF MID LEVEL CLOUDS MAY
MOVE THROUGH DURING THE OVERNIGHT INTO THE MORNING HOURS ON
THURSDAY. HOWEVER, IMPACTS FROM CEILINGS LOOK TO BE MINIMAL AT THIS
TIME. MOSTLY ALL TERMINALS EAST OF THE DIVIDE ARE FORECAST TO SEE
QUIET AND DRY CONDITIONS THROUGH THE TAF PERIOD WITH A BREEZY WIND
(10 TO 20 KNOTS) DEVELOPING BETWEEN 18Z THURSDAY AND 00Z FRIDAY.
WEST OF THE DIVIDE WILL SEE CLOUDS GRADUALLY MOVING IN AS A RESULT
OF THE NEXT WEATHER SYSTEM. MOST TERMINALS WILL REMAIN DRY THROUGH
THIS PERIOD BUT A STRAY SHOWER CANNOT BE RULED OUT FOR KJAC, KBPI,
AND KPNA DURING THE AFTERNOON AND EVENING THURSDAY. KRKS LOOKS TO
HAVE BETTER CHANCES FOR SEEING SOME SCATTERED SHOWERS BETWEEN 19Z
THURSDAY AND 00Z FRIDAY. A PROB 30 GROUP IS IN PLACE DUE TO GROWING
CONFIDENCE IN THESE SHOWERS OCCURRING. KCPR MAY SEE SOME SHOWERS
MOVE THROUGH AFTER 00Z FRIDAY INTO THE END OF THE TAF PERIOD. AS A
RESULT A PROB 30 GROUP IS IN PLACE FOR THIS TIME PERIOD FOR KCPR.
PRECIPITATION CHANCES INCREASE WEST OF THE DIVIDE AFTER THE END OF
THE TAF PERIOD WITH WINDS INCREASING EAST OF THE DIVIDE AROUND THE
SAME TIME.
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...MYERS
DISCUSSION...LOWE
AVIATION...DZIEWALTOWSKI
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page