113
FXUS65 KRIW 271112
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
512 AM MDT WED AUG 27 2025
KEY MESSAGES
- ONGOING SCATTERED RAIN SHOWERS AND A COUPLE ISOLATED
THUNDERSTORMS WILL CONTINUE TODAY BEING THE PEAK OF ACTIVITY.
- LESS WIDESPREAD AND MORE ISOLATED COVERAGE THURSDAY AND EVEN
LESS FOR FRIDAY AND SATURDAY, MORE FOR THE NORTHERN HALF OF
THE CWA.
- SEASONABLE TEMPERATURES THROUGH SATURDAY WITH A WARMING AND
DRY TREND SUNDAY AND INTO NEXT WEEK.
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 /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 511 AM MDT WED AUG 27 2025
WEST OF THE DIVIDE...
SHOWERS ARE FORECAST TO INCREASE IN COVERAGE FROM THE SOUTH-
SOUTHWEST AND CONTINUE TO IMPACT ALL WEST OF THE DIVIDE TERMINALS
UNTIL AT LEAST 00Z THURSDAY. SHOWER COVERAGE IS EXPECTED TO BE
SCATTERED TO WIDESPREAD WITH INTERMENT PERIODS OF DRY CONDITIONS.
THERE IS POTENTIAL FOR EMBEDDED THUNDERSTORMS, AND ASSOCIATED GUSTS
AROUND 20-25KTS, AFTER 20Z. WHERE CONFIDENCE IS AROUND 30% IN DIRECT
IMPACTS AND OCCURRENCE, A PROB30 GROUP IS MAINTAINED. THUNDERSTORM
POTENTIAL DIMINISHES AFTER 02Z AT THE LATEST. CONFIDENCE IS HIGHEST
(70% CHANCE) IN MVFR TO IFR CEILINGS AT KJAC, KPNA, AND KBPI THROUGH
20Z AT THE LATEST. HOWEVER, MVFR CEILINGS AND VISIBILITIES COULD
ACCOMPANY ANY SHOWERS OR THUNDERSTORMS THAT DIRECTLY IMPACT ANY
TERMINAL. SHOWER CHANCES DIMINISH BETWEEN 03Z AND 06Z THURSDAY.
OUTSIDE OF ANY THUNDERSTORMS, WINDS REMAIN AROUND OR LESS THAN 10KTS.
EAST OF THE DIVIDE...
SHOWERS ARE FORECAST TO INCREASE IN COVERAGE FROM THE SOUTH-
SOUTHWEST THIS TAF PERIOD, BEGINNING WITH KLND AND KCPR AROUND 12Z
AND KRIW AFTER 13Z. SHOWER CHANCES ARE AROUND 30% AT KCOD AND KWRL
STARTING BETWEEN 19Z AND 20Z AND THIS IS REFLECTED AS A PROB30
GROUP. SHOWER COVERAGE IS EXPECTED TO BE SCATTERED TO WIDESPREAD
WITH INTERMENT PERIODS OF DRY CONDITIONS. AT KCPR, KRIW, AND KLND
THERE IS POTENTIAL FOR EMBEDDED THUNDERSTORMS AFTER 20Z.
THUNDERSTORM POTENTIAL DIMINISHES AFTER 02Z AT THE LATEST. THERE IS
A 40% CHANCE FOR MFVR CEILINGS BETWEEN 13Z AND 17Z AT KRIW SO OPTED
TO KEEP OUT OF TAF AT THIS TIME BUT THE CHANCES ARE REFLECTED AS A
SCT025 GROUP. MVFR CEILINGS AND VISIBILITIES COULD ACCOMPANY ANY
SHOWERS OR THUNDERSTORMS THAT DIRECTLY IMPACT ANY TERMINAL. SHOWER
CHANCES DIMINISH AROUND 03Z AT ALL EAST OF THE DIVIDE TERMINALS
EXCEPT KCPR, WHERE RAIN CHANCES CONTINUE THE ENTIRE TAF PERIOD.
OUTSIDE OF ANY THUNDERSTORMS, WINDS REMAIN AROUND OR LESS THAN 10KTS.
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...GERHARDT
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