585
FXUS65 KRIW 200350
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
950 PM MDT MON OCT 19 2026
KEY MESSAGES
- CLOUD COVER INCREASES ACROSS THE FAR WEST AND SOUTHWEST MONDAY
NIGHT WITH A FEW LIGHT SHOWERS POSSIBLE BY SUNRISE TUESDAY.
- A WEAK SYSTEM PUSHES ACROSS THE REGION TUESDAY WITH ISOLATED
SHOWER ACTIVITY (~20%) ACROSS HIGHER TERRAIN, MAINLY WEST OF
THE CONTINENTAL DIVIDE. NO SIGNIFICANT IMPACTS EXPECTED.
- A WEATHER SYSTEM GENERATES GUSTY SOUTHWEST WIND THURSDAY AND
ESPECIALLY FRIDAY, WITH RAIN AND HIGH ELEVATION SNOW LATE
THURSDAY THROUGH FRIDAY. CONFIDENCE IN PRECIPITATION TOTALS
AND SNOW LEVELS IS LOW AT THIS TIME.
- MUCH ABOVE NORMAL HIGH TEMPERATURES PREVAIL THROUGH THURSDAY
BEFORE BEGINNING TO COOL FRIDAY. WEEKEND DAYTIME HIGHS WILL BE
AROUND OR SLIGHTLY BELOW SEASONAL AVERAGES.
UPDATE
ISSUED AT 1232 PM MDT MON OCT 19 2026
THE NEXT FEW DAYS REMAIN SEASONABLE AND MOSTLY DRY. LATEST HI-RES
MODELS CONTINUE TO PUT WEAK, ISOLATED (15-30% CHANCES) RAIN SHOWERS
OVER THE WESTERN MOUNTAINS FROM ABOUT SUNRISE TUESDAY THROUGH LATE
EVENING. OTHERWISE, FOCUS REMAINS ON THE BIGGER SYSTEM FOR LATE THIS
WEEK. DETAILS STILL HAVE LOW CONFIDENCE, BUT HIGH ELEVATION SNOW
(9000+ FEET) IS STILL LOOKING LIKELY, WITH THE MAIN IMPACTS BEING TO
WESTERN MOUNTAIN PASSES FRIDAY MORNING; IMPACTS LOOK MINOR AT
THIS TIME HOWEVER. DETAILS SHOULD BECOME CLEARER OVER THE NEXT
COUPLE DAYS.
DISCUSSION
ISSUED AT 130 AM MDT MON OCT 19 2026
IR CURRENTLY DEPICTS MAINLY CLEAR SKIES INTO MONDAY MORNING
WITH SOME PASSING CLOUDS THROUGH SWEETWATER COUNTY PUSHING EAST
BY SUNRISE. WATER VAPOR SHOWS WEAK UPPER LEVEL SOUTHWEST FLOW
ACROSS THE CWA WITH THE MAIN FINGER OF THE PFJ WELL TO THE NORTH
SUPPORTING A LOW OFF THE PACIFIC NORTHWEST COAST. THIS WILL
DEEPEN WITH ITS SOUTHWARD PROGRESSION MONDAY INTO TUESDAY WITH
INCREASING DIVERGENCE ALOFT. SEASONABLE TEMPERATURES AND
RELATIVELY LIGHT OR MODEST WINDS 10 TO 20 MPH THROUGH MID WEEK
EXPECTED. A WEAK SHORTWAVE WILL PROPAGATE ACROSS THE SOUTHWEST
FLOW TUESDAY AFTERNOON AND EVENING THAT WILL BRING ISOLATED
SHOWER ACTIVITY FOR HIGHER TERRAIN, MAINLY WEST OF THE DIVIDE.
LOW COVERAGE IS EXPECTED ~20 PERCENT WITH NO SIGNIFICANT IMPACTS
EXPECTED.
AS THE AFOREMENTIONED LOW STARTS TO MOVE EAST ACROSS SOUTHERN
CALIFORNIA WEDNESDAY, MODELS INDICATE IT BECOMING MORE OF AN
OPEN AND MORE PROGRESSIVE WAVE. THIS WILL THEN PUSH ALONG THE
SOUTHWEST FLOW ACROSS THE UPPER ROCKIES NOT OF HIGH OF AN IMPACT
WITH ITS QUICKER MOVEMENT. HOWEVER, MODELS ARE NOT IN THE BEST
OF AGREEMENT AND QPF AMOUNTS FLUCTUATE WITH EACH MODEL RUN.
WITH THIS RUN, IT HAS BUMPED UP FOR MOUNTAIN SNOW, ESPECIALLY
FOR WESTERN MOUNTAINS BUT DOES INCLUDE THE BIGHORNS. WITH THE
SEASONABLE TO JUST ABOVE TEMPERATURES, EXPECT VALLEY/BASIN
RAIN, EVEN WEST OF THE DIVIDE BELOW 8-9KFT. THIS WILL BE THE
BIGGEST WEATHER EVENT TO KEEP AN EYE ON FOR HEADLINES GOING
FORWARD FOR LATE THURSDAY INTO FRIDAY, STRETCHING INTO THE
WEEKEND, ALL DEPENDENT ON HOW QUICKLY IT PROGRESSES WITH ITS
EAST TO NORTHEASTWARD MOVEMENT. BEYOND THAT, INDUCED RIDGING
WILL BE SHORT LIVED AHEAD OF ANOTHER LOW OFF THE PACIFIC
NORTHWEST EXTENDING IN FROM THE GOA THAT COULD BE MORE IMPACTFUL
WITH A MORE REINFORCED COLDER AIR AND LOWER FREEZING LEVELS.
STAY TUNED FOR UPDATED FORECASTS IN THE COMING DAYS, BUT ENJOY
THE QUIETER WEATHER LEADING UP TO LATER IN THE WORK WEEK.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 950 PM MDT MON OCT 19 2026
ALL TERMINALS TO BE VFR THROUGH 06Z/WEDNESDAY. THE UPPER FLOW
BACKS TO THE SOUTH-SOUTHWEST TUESDAY IN RESPONSE TO A DIGGING
TROUGH ALONG THE US WEST COAST. MID-LEVEL MOISTURE SPREADS NORTH
ACROSS FAR WEST WYOMING OVERNIGHT AND TUESDAY MORNING, LEADING
TO ISOLATED LIGHT SHOWERS WITHIN A BKN MID-LEVEL CLOUD DECK.
KJAC HAS A LESS THAN 30 PERCENT CHANCE OF SEEING A FEW SPRINKLES,
MAINLY BETWEEN 09Z-15Z/TUESDAY. WITH THE MID-LEVEL MOISTURE IN
PLACE, DAYTIME HEATING HELPS TO INITIATE CONVECTION OVER THE
WESTERN WYOMING MOUNTAINS BY EARLY TUESDAY AFTERNOON. THE CHANCE
OF PRECIPITATION REMAINS LESS THAN 30 PERCENT WITH MINIMAL
IMPACTS IF A SHOWER DID MOVE ACROSS A TERMINAL. TERMINALS WEST
OF THE CONTINENTAL DIVIDE, AND PERHAPS KCOD, HAVE THE BEST
CHANCE AT SEEING A LATE TUESDAY SHOWER BEFORE SUNSET ARRIVES.
OTHER THAN A 4- TO 6-HOUR PERIOD OF 10-18KT WINDS AT KCPR DURING
THE MORNING AND EARLY AFTERNOON, WIND SPEEDS AT ALL TERMINALS
SHOULD BE LESS THAN 10KTS THROUGH THE PERIOD.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZLC AND ZDV FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...WITTMANN
DISCUSSION...LOWE
AVIATION...CNJ
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