206
FXUS65 KRIW 271749
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1149 AM MDT WED AUG 27 2025
KEY MESSAGES
- ISOLATED TO SCATTERED RAIN SHOWERS WITH VERY ISOLATED
THUNDERSTORMS WILL CONTINUE THROUGH THE AFTERNOON, ESPECIALLY
AS A LARGE BAND OF PRECIPITATION MOVES INTO NORTHERN WY.
SOUTHWEST INTO CENTRAL WY WILL HAVE A BETTER CHANCE OF
THUNDERSTORMS THIS AFTERNOON.
- MORE ISOLATED SHOWERS AND THUNDERSTORMS ACROSS WESTERN AND
CENTRAL WY ON THURSDAY, WITH BETTER CHANCES ACROSS NORTHERN
WY. TEMPERATURES WILL BE ABOUT 5-8 DEGREES BELOW NORMAL.
- FRIDAY AND SATURDAY WILL CONTINUE TO BE ON THE COOL SIDE, WITH
ISOLATED SHOWERS OVER NORTH-CENTRAL WY.
- HIGH PRESSURE RETURNS SUNDAY AND MONDAY FOR SEASONABLE
TEMPERATURES AND MOSTLY DRY CONDITIONS WITH SOME BREEZY
AFTERNOON SOUTHWEST WIND.
DISCUSSION
ISSUED AT 130 AM MDT WED AUG 27 2025
WV IMAGERY SHOWS THE MAIN FINGER OF THE PFJ PUSHING FURTHER
SOUTH OUT OF CANADA THAT WILL COME INTO PLAY LATER THIS WEEK AND
INTO THE WEEKEND. BROAD RIDGING INDUCED ACROSS THE CWA IS
EVIDENT WITH SOME DRY-SLOTTING THAT HAS INHIBITED MUCH OF THE
FORECASTED QPF AT THIS POINT WAY UNDER-PERFORMING WITH ALL
MODELS. IR SHOWS THE DISORGANIZATION OF THIS SYSTEM WITH THE
MAIN UPPER LEVEL LOW ACROSS WESTERN AND NORTHERN IDAHO ALREADY
MAKING A NORTH TO NORTHWESTWARD RETREAT THAT HAS KEPT MUCH OF
THE MOISTURE WEST OF THE CWA. EVEN THE MONSOONAL MOISTURE
INFLUX IS BEING STOPPED ACROSS NM AND INTO CO WITH THE UPPER
LEVEL HIGH STILL IN PLACE NOT MAKING ITS WAY EAST AS MODELS HAD
BEEN INDICATING DUE TO THE AFOREMENTIONED LOW MAKING MORE OF AN
EASTWARD PROGRESSION.
OTHERWISE, IT IS HARD TO FOLLOW ANY MODEL AT THIS POINT WITH NO
AGREEMENT WITH THE HI-RES MODELS NOR ANY OF THEM GETTING THE
ONGOING RADAR SITUATION CORRECTLY. THE HRRR IS THE ONLY ONE
REMOTELY CLOSE AND THUS WILL FOLLOW IT FOR THE DAY KNOWING QPF
AND POPS STILL NEED SLASHED. THE INDUCED RIDGE OVER THE STATE IS
DEFINITELY DRY-SLOTTING MUCH OF THE AREA WITH HOPES OF THE
ISOLATED RAIN SHOWER ACTIVITY TO BECOME MORE WIDELY SCATTERED
LATER THIS WEDNESDAY MORNING AND INTO THE AFTERNOON HOURS. MUCH
OF THE HEAVIER RAINFALL IS STAYING INTO IDAHO AND WESTERN
PORTIONS OF MT. WEST OF THE DIVIDE STILL SEE MUCH OF THE
ACTIVITY WITH AREAS TO THE EAST SEEING MORE MINIMAL CHANCES AND
QPF AMOUNTS. QPF WEST HAVE BEEN CUT TO WELL UNDER AN INCH AT
THIS POINT, AND STILL PROBABLY COULD SAY IT ISN'T ENOUGH. MODEL
INITIALIZATIONS AREN'T EVEN THAT CLOSE TO THE ONGOING SITUATION
AND HARD TO FOLLOW ANY WITH ANY TYPE OF CONFIDENCE. REGARDLESS,
AMPLE CLOUD COVER AND THE MORE MINIMAL RAIN CHANCES WILL KEEP
TEMPERATURES MORE SEASONABLE TO EVEN BELOW AVERAGE FOR THIS
TIME OF YEAR THIS AFTERNOON AND FOR THE REST OF THE WEEK INTO
SATURDAY. MODELS STILL INDICATE A WEAKER SHORTWAVE THURSDAY AND
MORESO FRIDAY, AND IF THE TREND CONTINUES, THIS WILL NOT BE
IMPACTFUL AS WELL. THE BETTER CHANCES LATER FRIDAY AND INTO
SATURDAY WILL BE FOR THE NORTHERN HALF OF THE CWA AND EAST OF
THE DIVIDE, ALTHOUGH SMALL (20-30% CONFIDENCE AND PROBABLY
LOWER AT THIS POINT). THE NORTHWEST FLOW ALOFT COMES BACK INTO
PLAY WITH A WEAKER FINGER OF THE JET IMPACTING THESE AREAS AS
THE MAIN PFJ PUSHES WELL EAST.
AS THE MAIN UPPER LEVEL LOW OFF THE PACIFIC NORTHWEST COAST
MOVES A BIT NORTHEAST, IT FILLS WITH TIME WITH DECREASING
DIVERGENCE ALOFT. THIS WILL ALLOW INDUCED RIDGING TO BUILD IN
ACROSS THE UPPER ROCKIES FROM THE BERMUDA HIGH OVER SOUTHERN NM
INTO MEXICO ALLOWING THE LOW TO BE BLOCKED FROM ANY INFLUENCE TO
THE CWA FOR THE LATER HALF OF THE WEEKEND INTO NEXT WEEK. THIS
WILL BRING A WARMING AND DRY TREND SUNDAY AND THROUGH THE LONG
TERM WITH TEMPERATURES BACK TO ABOVE AVERAGE AND MINIMAL STORM
CHANCES OUTSIDE OF THE HIGHER TERRAIN AND AIRMASS DEVELOPMENT
WITH THE WEAK UPPER LEVEL FLOW.
ALL IN ALL, HOPES ARE STILL DECENT FOR AT LEAST SOME RAINFALL
LATER TODAY AND INTO THURSDAY ESPECIALLY WEST OF THE DIVIDE.
HOWEVER, QPF AMOUNTS ARE NOT COMING TO FRUITION AT THIS POINT IN
TIME AS EVEN THE ENSEMBLE DATA HAS BEEN OUT TO LUNCH AS WELL.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1149 AM MDT WED AUG 27 2025
A BAND OF STRATIFORM RAIN SHOWERS CONTINUES TO PUSH ACROSS THE
REGION AT THE START OF THE PERIOD, AS OF 18Z, LOCATED ALONG A LINE
FROM KJAC TO KCPR. AS IT CROSSES THE OWL CREEK AND BRIDGER
MOUNTAINS, IT IS EXPECTED TO START TO BREAK UP A BIT, HOWEVER RAIN
SHOWERS AT KCOD AND KWRL ARE EXPECTED DURING THE AFTERNOON AS THE
BAND MOVES THROUGH. SOME ISOLATED LOW CLOUDS ACROSS THE WIND RIVER
BASIN (INCLUDING AT KRIW AND KLND) HAVE BEEN OBSERVED BEHIND THE
LINE OF SHOWERS BUT ARE EXPECTED TO BREAK UP INTO THE EARLY
AFTERNOON. SOME CLEARING WEST OF THE DIVIDE HAS ALREADY BEGUN, WHICH
WILL PROMPT CONVECTIVE DEVELOPMENT DURING THE AFTERNOON. PROB30
GROUPS HAVE BEEN INCLUDED FOR KBPI, KPNA, AND KRKS FOR THIS
CONVECTION.
OVERNIGHT, LOW CLOUDS AND PERHAPS EVEN FOG ARE EXPECTED TO DEVELOP
AT SEVERAL TERMINALS (10 TO 30% CHANCES) WITH GREATEST CHANCES AT
KBPI, KPNA, KJAC, AND KCPR. THERE IS NOT ENOUGH CONFIDENCE TO DROP
CIGS OR VSBY IN THE TAFS BELOW MVFR AT THIS TIME, BUT IF FOG
DEVELOPS (10 TO 15% CHANCE), EXPECT TO SEE IFR TO LIFR CONDITIONS
THROUGH MUCH OF THURSDAY MORNING (10Z THROUGH 16Z TIMEFRAME). BY
LATE MORNING, MORE SIGNIFICANT CLEARING IS EXPECTED AHEAD OF THE
NEXT SHORTWAVE.
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 WYZ014-015-
025.
DISCUSSION...LOWE
AVIATION...HENSLEY
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