240
FXUS65 KRIW 260735
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
135 AM MDT TUE AUG 26 2025
KEY MESSAGES
- SCATTERED RAIN SHOWERS AND ISOLATED THUNDERSTORMS THIS TUESDAY
MORNING AND AFTERNOON BECOMING MORE WIDESPREAD OVERNIGHT INTO
WEDNESDAY.
- AMPLY RAINFALL WILL CONTINUE WEDNESDAY AND THURSDAY.
- MORE SEASONABLE TEMPERATURES AND ISOLATED RAIN SHOWERS FRIDAY
AND INTO THE WEEKEND.
DISCUSSION
ISSUED AT 130 AM MDT TUE AUG 26 2025
WV IMAGERY SHOWS THE CONTINUED NORTHWEST FLOW ALOFT ACROSS THE
CWA AS THE UPPER LEVEL RIDGE WEAKENS WITH ITS SOUTHWARD RETREAT
DUE TO DECREASING CONVERGENCE. IR SHOWS THE AMPLE CLOUD COVER
ACROSS MUCH OF THE STATE WITH THE FIRST OF MANY SHORTWAVES TO
PUSH IN FROM NORTHERN UTAH LATER THIS TUESDAY MORNING. RADAR IS
QUIET FOR NOW BUT WILL SOON PICK UP AROUND SUNRISE PUSHING INTO
FAR WESTERN AREAS SPREADING TO THE DIVIDE THROUGH THE MORNING
AND AFTERNOON.
CURRENTLY, HI-RES MODEL AGREEMENT IS FAR AND FEW BETWEEN ON
COVERAGE AND TIMING BUT THE NAMNEST HAS BEST HANDLED RECENT
RAINFALL, SO WILL RELY MORE HEAVILY ON IT IN THE NEXT COUPLE OF
DAYS UNTIL PROVEN OTHERWISE. TUESDAY'S RAINFALL AMOUNTS LOOK TO
BE MORE MINIMAL COMPARED TO THE UPCOMING EVENTS FOR WEDNESDAY
AND THURSDAY, BUT STILL LOOKS TO BE DECENT FOR THE FIRES WEST OF
THE DIVIDE TODAY. ENSEMBLE DATA GIVES A 30-40% CHANCES FOR OVER
A QUARTER INCH FOR SOME OF THE WESTERN HIGHER TERRAIN WITH
10-20% POSSIBLE THROUGH STAR VALLEY CLOSER TO HALF AN INCH.
REGARDLESS, DECENT RAINFALL WILL BE HAD FOR MANY WEST OF THE
DIVIDE AND TOWARDS THE SOUTHERN BORDER FOR SWEETWATER COUNTY
WHILE TO THE EAST REMAINS DRY. THIS ACTIVITY WILL NOT SPREAD
OVER THE DIVIDE UNTIL AFTER SUNSET AND OVERNIGHT INTO WEDNESDAY
MORNING. THE GOOD THING ABOUT THE UPCOMING RAINFALL IS THE
INSTABILITY LOOKS TO BE ON THE WEAKER SIDE IN THE PEAK HEATING
OF THE AFTERNOON DUE TO COOLER HIGH TEMPERATURES THAN RECENT
DAYS. AS SUCH, EXPECT ONLY SOME ISOLATED THUNDERSTORMS,
ESPECIALLY THAT FOR SWEETWATER COUNTY TUESDAY.
AS THE MAIN PACIFIC NORTHWEST LOW DEEPENS AND PUSHES FURTHER
EAST INTO WEDNESDAY, AN INCREASE OF DIVERGENCE WILL PUSH IN FOR
THE UPPER ROCKIES. IT IS HARD TO DECIPHER WITH THE MULTITUDE OF
WAVES WITH VARYING MODEL OUTPUTS WEDNESDAY AND THURSDAY WITH
SOME SHOWING A STEADY PUSH OF MONSOONAL MOISTURE AIDING IN THE
AFOREMENTIONED UPPER LEVEL LOWS AND ITS SHORTWAVES. RAINFALL
AMOUNTS ARE TRENDING A BIT UPWARD WITH THE LATEST MODEL RUNS,
WITH THE LIKELIHOOD OF OVER AN INCH WEST OF THE DIVIDE BECOMING
MORE 70-80% TO OCCUR. AREAS TO THE EAST ARE LOWER IN
PROBABILITIES OF 40-50% FOR HALF AN INCH OF MORE, WITH THE OPEN
TERRAIN WITH THE SOUTHWEST MOISTURE PLUME ACROSS THE WIND
CORRIDOR FROM RKS TO CPR SEEING THE HIGHEST QPF AMOUNTS
POSSIBLE. WITH THE AMPLE INCONSISTENCY WITH MANY MODELS AND
BETWEEN RUNS, THE FORECAST IS HIGHER IN SUBJECTIVITY TO CHANGE
THROUGHOUT THE DAY AND INTO THE EVENT ITSELF.
REGARDLESS, MUCH NEEDED RAINFALL WILL OCCUR FOR THE ENTIRE AREA
AND HOPE TO RENDER AID TO THE MANY FIRES ONGOING. ALL GOOD
THINGS DO COME TO AN END OR AT LEAST TAPER OFF. FRIDAY AND INTO
THE WEEKEND WILL SEE LESS CHANCES FOR RAINFALL AS INDUCED
RIDGING BUILDS IN FROM THE SOUTHWEST THAT WILL DRY SLOT MUCH OF
THE SOUTHERN HALF OF THE CWA AND WEST OF THE DIVIDE. NORTHWEST
FLOW ALOFT WILL CONTINUE FOR THE AREAS EAST OF THE DIVIDE AND
NORTHERN HALF OF THE CWA TO INCLUDE YELLOWSTONE THAT WILL KEEP
POPS IN THROUGH SATURDAY NIGHT BUT MORE ISOLATED IN NATURE AT
THAT POINT. THE EC INDICATES LONG TERM THE AFOREMENTIONED UPPER
LEVEL TO FILL WITH DECREASED DIVERGENCE ALOFT AS IT RETREATS
BACK OFF THE NORTHWEST COAST AND POSSIBLE EMBEDDING BACK INTO
ANOTHER LOW THAT EVENTUALLY PUSHES SOUTH. THIS WILL ALLOW UPPER
LEVEL RIDGING TO BUILD BACK IN OVER THE UPPER ROCKIES BY
WEEKEND'S END AND INTO NEXT WEEK. SEASONABLE TO JUST BELOW
AVERAGE TEMPERATURES WILL SEE A SLIGHT WARMING TREND AT THAT
TIME WITH MAINLY DRY CONDITIONS TO BE EXPECTED HEADING INTO THE
LONGER TERM FORECAST.
IN ALL, CONFIDENCE STILL WAVERS IN THE SHORT TERM IN REGARDS TO
PRECIPITATION TIMING AND COVERAGE. HOWEVER, RAINFALL IS
EXPECTED, IT JUST MIGHT VARY IN OUTPUT BASED ON HOW THIS SHAPES
OUT.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1043 PM MDT MON AUG 25 2025
MONSOONAL MOISTURE CONTINUES TO FUNNEL INTO THE REGION. VFR
CONDITIONS ARE EXPECTED TO PREVAIL THROUGH MUCH OF THE TAF PERIOD.
CHANCES FOR SHOWERS AND THUNDERSTORMS GRADUALLY SPREAD FARTHER EAST
THROUGHOUT THE PERIOD. KJAC WILL SEE PRECIPITATION CHANCES FIRST
STARTING AROUND 14Z THEN SPREADING TO KBPI AND KPNA BY 17/18Z
TUESDAY. KRKS MAY SEE SHOWERS AND THUNDERSTORMS DEVELOP SLIGHTLY
LATER NEAR 20Z. SHOWERS LOOK TO BECOME MORE PREVAILING AT KBPI,
KPNA, AND KRKS BY AROUND 01Z WEDNESDAY PERSISTING INTO THE END OF
THE PERIOD. AROUND THE SAME TIME LOWER CLOUD DECKS MAY BEGIN TO FORM
AT KJAC, KBPI, KPNA, AND KRKS. EASTERN TERMINALS REMAIN DRY THROUGH
MUCH OF THE PERIOD WITH LIGHT WINDS. SHOWERS AND THUNDERSTORMS BEGIN
TO DEVELOP SHORTLY AFTER 00Z WEDNESDAY WITH THE BEST CHANCES BEING
AT KLND AND KRIW. KCPR LOOKS TO SEE PRECIPITATION CHANCES ARRIVE BY
THE END OF THE PERIOD. KCOD AND KWRL ARE EXPECTED TO HAVE LESSER
CHANCES FOR PRECIPITATION BUT THE OCCASIONAL SHOWER OR STORM CANNOT
BE RULED OUT. LIGHT WINDS PERSIST ACROSS ALL TERMINALS WITH A FEW
GUSTS NEAR 20 KNOTS POSSIBLE AT KCPR AND KRKS. WILDFIRE SMOKE MAY
CAUSE SOME OBSCURATION MAINLY ALONG THE WIND RIVER RANGE THROUGH THE
TAF PERIOD.
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
AIR QUALITY ALERT UNTIL 1 PM MDT THIS AFTERNOON FOR WYZ012>016-
025-026.
DISCUSSION...LOWE
AVIATION...DZIEWALTOWSKI
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