422
FXUS65 KRIW 111700
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1100 AM MDT SAT APR 11 2026
KEY MESSAGES
- AT LEAST A 20 PERCENT CHANCE OF A RAIN SHOWER OR THUNDERSTORM TODAY,
WITH THE BEST CHANCES REMAINING WEST OF THE CONTINENTAL
DIVIDE. GUSTY OUTFLOW WINDS UP TO 60 MPH ARE POSSIBLE.
- ELEVATED TO NEAR CRITICAL FIRE WEATHER TODAY FOR PORTIONS OF
THE AREA, AS DRY AND WINDY CONDITIONS ARE IN PLACE.
- SUNDAY IS SIMILAR TO TODAY, THOUGH PRECIPITATION CHANCES WILL
BE MORE LIMITED TO THE WESTERN MOUNTAINS.
- LIMITED PRECIPITATION CHANCES OCCUR FOR THE FIRST HALF OF NEXT
WEEK. A COLD WEATHER SYSTEM MOVES IN LATE NEXT WEEK, POSSIBLY
BRINGING MORNING LOW TEMPERATURES INTO THE LOW 20S.
DISCUSSION
ISSUED AT 145 AM MDT SAT APR 11 2026
AS AN ADVANCING TROUGH MAKES IT TO NORTHERN CALIFORNIA TODAY,
SOUTHWEST FLOW ALOFT INCREASES ACROSS WYOMING, BRINGING BETTER
MOISTURE TO THE AREA. IN ADDITION, A TROUGH IN ADVANCE OF THE MAIN
SYSTEM PASSES THROUGH TODAY. THESE FACTORS COMBINE TO BRING
INCREASED PRECIPITATION CHANCES TODAY, WITH SHOWERS BEING ABLE
TO PRODUCE RAIN THAT REACHES THE GROUND. THE MAIN PUSH OF THIS
SHORTWAVE STARTS LATE THIS MORNING, WITH SHOWER AND THUNDERSTORM
CHANCES INCREASING FROM THE SOUTHWEST THROUGH THE AFTERNOON,
AND THEN DECREASING FROM THE SOUTHWEST TO NORTHEAST BETWEEN
ABOUT 6PM AND MIDNIGHT. EVERYWHERE WILL HAVE A CHANCE FOR RAIN
TODAY (SNOW LEVELS AROUND 9000 FEET). THE BEST CHANCES WILL BE
WEST OF THE CONTINENTAL DIVIDE, WHERE THE BETTER MOISTURE WILL
BE. THE CURRENT FORECAST DEPICTS OF BLEND OF HI-RES MODELS, WITH
THE REALITY BEING THAT IT IS NEARLY IMPOSSIBLE TO DETERMINE
EXACTLY WHERE A SHOWER OR STORM COULD OCCUR TODAY, BUT THEY WILL
BE AROUND. EVERYWHERE HAS AT LEAST A 20 PERCENT CHANCE, THOUGH
ACTUAL CHANCES VARY TO BE AS HIGH AS 80 PERCENT (MAINLY WEST OF
THE DIVIDE). MANY MODELS SEEM TO DEPICT A CLUSTER OF RAIN
SHOWERS OVER SWEETWATER COUNTY THIS AFTERNOON, SO CONFIDENCE IN
RAIN IS BETTER THERE. THE MAIN HAZARD WITH ANY SHOWERS OR STORMS
WOULD BE OUTFLOW GUSTS, WHICH COULD BE UP TO ABOUT 60 MPH.
THE OTHER HAZARD TODAY WILL BE WIND, AND SOME FIRE WEATHER CONCERNS
WITH IT. MOISTURE DOES INCREASE TODAY, ESPECIALLY WEST OF THE
DIVIDE, BUT MINIMUM HUMIDITY VALUES AROUND 20 PERCENT ARE LIKELY FOR
BASINS EAST OF THE DIVIDE, DRIEST FOR JOHNSON COUNTY. IT IS ALSO
GOING TO BE WINDY TODAY, A RESULT OF A TIGHTENING PRESSURE GRADIENT.
GUSTS 25 TO 40 MPH WILL BE COMMON, AND FOR THESE DRIER PLACES, NEAR
CRITICAL FIRE WEATHER CONDITIONS COULD OCCUR.
FOR SUNDAY, PRECIPITATION CHANCES REMAIN (THOUGH MUCH MORE LIMITED
COMPARED TO TODAY), MOSTLY ALONG AND WEST OF THE DIVIDE, THOUGH SOME
"SPILL-OVER" IS LIKELY. CURRENT PROJECTED POSITIONING OF THE
INCOMING LOW WOULD FAVOR THE WESTERN MOUNTAINS (I.E. ABSAROKAS,
TETONS, YELLOWSTONE) THE MOST. GUSTY SOUTHWEST WINDS 25 TO 40 MPH
CONTINUE DURING THE DAY AS WELL, SO ELEVATED TO NEAR CRITICAL FIRE
WEATHER CONDITIONS REMAIN A CONCERN.
FOR MONDAY AND TUESDAY, THE MODEL TREND CONTINUES TO BE FOR A WEAKER
AND DRIER SYSTEM, UNFORTUNATE NEWS FOR THOSE WISHING FOR
PRECIPITATION. LIQUID TOTALS HAVE DROPPED ONCE AGAIN, WITH VERY
LIMITED CHANCES FOR LOW ELEVATION BASIN LOCATIONS. ELEVATED TO NEAR
CRITICAL FIRE WEATHER LOOKS TO CONTINUE AS WELL AS GUSTY WINDS OCCUR.
LOOKING FURTHER AHEAD, THERE IS GROWING CONFIDENCE IN A COLDER SYSTEM
TOWARDS THE END OF NEXT WEEK (THURSDAY-SATURDAY). THIS SYSTEM HAS
THE POTENTIAL TO BRING MORNING LOW TEMPERATURES IN THE LOW 20S, WITH
MULTIPLE MORNINGS IN A ROW UNDER 30 DEGREES. THIS IS A HEADS UP TO
THOSE WITH SPRINKLERS OR VULNERABLE VEGETATION.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1059 AM MDT SAT APR 11 2026
VFR FLIGHT CONDITIONS ARE LARGELY EXPECTED THROUGH 18Z SUNDAY WITH
SCATTERED SHOWER AND THUNDERSTORM CHANCES THIS AFTERNOON. AT ALL
TERMINALS, THERE IS A 30 PERCENT CHANCE OF THUNDERSTORMS BEGINNING
AS EARLY AS 19Z AT KJAC FOLLOWED BY ALL OTHER TERMINALS. BECAUSE
SHOWERS AND THUNDERSTORMS WILL MOVE SOUTHWEST TO NORTHEAST, IT IS
EXPECTED THAT WEST OF THE DIVIDE TERMINALS (KJAC, KRKS, KPNA, AND
KBPI) WILL GENERALLY SEE CHANCES BEFORE EAST OF THE DIVIDE TERMINALS
(KRIW, KCPR, KCOD, KLND, AND KWRL). SHOWERS OR THUNDERSTORMS SHOULD
ALSO END FROM SOUTHWEST TO NORTHEAST BETWEEN 01Z AND 04Z. GUSTY 40KT
TO 50KT WINDS ARE POSSIBLE AT ANY TERMINAL IN OR WITH NEARBY SHOWERS
OR THUNDERSTORMS. ISOLATED SEVERE GUSTS NEAR 60KTS CANNOT BE RULED
OUT. MVFR CONDITIONS WILL BE POSSIBLE IN THE HEAVIER SHOWERS AND
THUNDERSTORMS WITH OCCASIONAL MOUNTAIN OBSCURATIONS.
GUSTY SOUTHWEST WINDS ARE ALSO EXPECTED OUTSIDE OF ANY SHOWERS OR
THUNDERSTORMS WITH GUSTS GENERALLY BETWEEN 25KTS AND 35KTS. THESE
GUSTY WINDS SHOULD DIMINISH AROUND OR SHORTLY AFTER SUNSET WITH
RELATIVELY LIGHT WINDS OVERNIGHT AT MOST TERMINALS. KCPR IS THE
EXCEPTION WITH WINDS REMAINING BREEZY THE ENTIRE TAF PERIOD.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...WITTMANN
AVIATION...GERHARDT
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