587
FXUS65 KRIW 271022
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
422 AM MDT WED MAY 27 2026
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS WILL BE AROUND TODAY BUT LESS
NUMEROUS THAN ON TUESDAY (AROUND A 1 IN 4 CHANCE). OTHERWISE
REMAINING WARM WITH A GUSTY WIND, ESPECIALLY IN NORTHERN
WYOMING.
- THE CHANCE OF THUNDERSTORMS REACHES A MINIMUM ON THURSDAY
WITH ONLY ISOLATED STORMS (LESS THAN A 1 IN 5 CHANCE) IN AND
NEAR THE MOUNTAINS.
- A WEATHER SYSTEM APPROACHES THE AREA ON FRIDAY NIGHT AND
SATURDAY AND BRINGS A BETTER CHANCE OF SHOWERS, WITH THE
GREATEST CHANCE ACROSS WESTERN WYOMING.
DISCUSSION
ISSUED AT 1254 AM MDT WED MAY 27 2026
I AM THINKING OF ANOTHER CHILDHOOD MEMORY HAS I WAS COMPOSING THE
FORECAST TONIGHT. ONE OF THE TRADITIONS OF BEING HOME SICK FROM
SCHOOL IN THE PRE-INTERNET AGE WAS WATCHING DAYTIME TV. AND ONE OF
THE MOST POPULAR SHOWS WAS (AND STILL IS), THE PRICE IS RIGHT. AND
OUR WEATHER PATTERN THIS MORNING REMAINS ME OF ONE OF THE GAMES ON
THAT VENERABLE GAME SHOW, SQUEEZE PLAY. IT RELATES TO THE WEATHER IS
WE ARE TRAPPED BETWEEN THE CUT OFF UPPER LEVEL LOW ROTATING NEAR THE
SIERRA NEVADA'S AND A STRONG RIDGE TO THE EAST.
FOR TODAY, IT IS SHOWING OFF WITH OUR PRECIPITABLE WATER VALUES.
THEY ARE PROJECTED TO BE ABOVE NORMAL AS MUCH AS 150 PERCENT IN SOME
LOCATIONS EAST OF THE DIVIDE. MEANWHILE, AREAS WEST OF THE DIVIDE
ARE BELOW NORMAL. THIS WOULD IMPLY THE GREATER CHANCE OF CONVECTION
SHIFTS HERE TODAY. BUT, THERE ARE A COUPLE MORE FACTORS. INSTABILITY
IS LESS, AS HEIGHTS HAVE RISEN BY AROUND 50 DECAMETERS. THERE IS
ALSO ONLY HALF AS MUCH PROJECTED CAPE AS YESTERDAY (350 J/KG TODAY
VERSUS 700 J/KG YESTERDAY, SO COVERAGE MAY BE LESS. THE LASTING
THING WE LOOK AT IS THE MEAN FLOW, AND THAT IS LARGELY SOUTH-
SOUTHEAST WITH THE SQUEEZE PLAY BETWEEN THE LOW AND THE RIDGE. THIS
LEADS ME TO THINK THAT THE BEST CHANCE OF CONVECTION WOULD BE
CLOSE TO AREAS WHERE THIS FLOW IS UPSLOPE. THIS MEANS LOCATIONS
LIKE ALONG AND EAST OF THE ABSAROKAS AND THE BIG HORNS, FOR
PLACES LIKE PARK. JOHNSON AND NATRONA COUNTY AS WELL AS PORTIONS
OF THE WIND RIVER BASIN AND YELLOWSTONE PARK. BUT GIVEN THE
MORE LIMITED INSTABILITY, COVERAGE LOOKS LESS, GENERALLY LESS
THAN 1 OUT OF 4 OR LESS. AN THE SQUEEZE PLAY WILL HAVE ONE MORE
IMPACT, THE WIND. THERE IS A DECENT PRESSURE GRADIENT IN THE
EASTERN PORTIONS OF THE AREA. THE NBM ENSEMBLE IS SHOWING A
GREATER THAN 2 IN 3 CHANCE OF WIND GUSTS PAST 30 MPH IN THE
BIGHORN BASIN AND JOHNSON COUNTY. THE STRONGEST WIND WOULD BE IN
JOHNSON COUNTY, WHERE THERE IS 1 IN 2 CHANCE OF GUSTS AROUND 40
MPH THIS AFTERNOON AS WE REACHING PEAK MIXING. TEMPERATURES
SHOULD BE SIMILAR TO YESTERDAY, ABOUT 5 TO 10 DEGREES ABOVE
NORMAL BUT NO EXTREMELY HOT CONDITIONS. MOST CONVECTION LOOKS
DIURNAL TODAY, WITH MOST SHOWERS AND STORMS ENDING AFTER SUNSET.
AT THIS TIME, CONVECTION LOOKS TO REACH A NADIR ON THURSDAY, AS
DRIER AIR SURGES FURTHER EASTWARD ACROSS THE STATE, WITH THE 0.50
INCH PRECIPITABLE WATER LINE ENVELOPING MOST OF WESTERN AND CENTRAL
WYOMING. ANY CONVECTION THIS DAY WOULD LIKELY REMAIN CLOSE TO THE
MOUNTAINS WITH HIGH LEVEL HEAT SOURCE AND UPSLOPE FLOW, MAINLY OF
THE SOUTH TO SOUTHEASTERN VARIETY AGAIN. THE VAST MAJORITY OF
LOCATIONS, ESPECIALLY IN THE LOWER ELEVATIONS, SHOULD REMAIN RAIN
FREE. WIND SHOULD ALSO BE LIGHTER EXCEPT FOR JOHNSON COUNTY, WHERE A
GUSTY WIND WILL CONTINUE. HIGH TEMPERATURES SHOULD RUN NEAR TO A
COUPLE OF DEGREES WARMER THAN WEDNESDAY.
CHANCES OF SHOWERS SHOULD BEGIN TO RISE SOMEWHAT ON FRIDAY AS THE
CUT OFF LOW BEGINS TO GET KICKED EASTWARD BY THE NEXT TROUGH
APPROACHING THE WEST COAST. THE ATMOSPHERE WILL BE VERY DRY TO START
THOUGH, SO THIS COULD END UP BEING A LATER SHOW. PLACEMENT IS ALSO
UNCERTAIN AS A LOT DEPENDS ON HOW QUICKLY DEEPER MOISTURE CAN BE
ADVECTED INTO THE AREA. THE CURRENT FORECAST LOOKS LIKE A REASONABLE
COMPROMISE, ALTHOUGH MOST OF THE DAY SHOULD BE RAIN FREE.
THERE IS NOW DECENT AGREEMENT IN THE LOW OPENING UP A BIT AND
LIFTING NORTHWARD FRIDAY NIGHT AND MOVING INTO WESTERN WYOMING ON
SATURDAY. THIS LOOKS LIKE THE WETTEST DAY AS A RESULT. THE EXACT
PATH OF THE LOW WILL BE CRITICAL THOUGH. IF IT TRACKS FURTHER WEST,
MANY AREAS EAST OF THE DIVIDE MAY HAVE A SOUTHWESTERLY DOWNSLOPING
FLOW WHICH WOULD KEEP SHOWERS AND THUNDERSTORMS TO A MINIMUM. THE
CURRENT FORECAST HAS THIS SHOWN FAIRLY WELL, WITH THE HIGHEST POPS
IN THE NORTHWEST THEN TAPERING THEM DOWN THE FURTHER SOUTH AND EAST
YOU GO.
THEN MORE UNCERTAINTY CREEPS INTO THE FORECAST FOR SUNDAY AND EARLY
NEXT WEEK. SOME MODELS AND ENSEMBLE MEMBERS SHOW THE LOW CUTTING OFF
AGAIN AND LINGERING NEAR THE AREA INTO EARLY NEXT WEEK, KEEPING THE
FORECAST COOLER AND UNSETTLED. OTHERS LIFT IT OUT AND BRING A
SOUTHWEST FLOW WHICH WOULD BRING WARMER WEATHER AND MAINLY CHANCES
OF DIURNAL CONVECTION. IT IS A COIN FLIP WHICH ONE WILL WIN OUT AT
THIS TIME THOUGH.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 417 AM MDT WED MAY 27 2026
LARGELY VFR CONDITIONS SHOULD CONTINUE THROUGH 12Z FOR THE MOST
PART. MOISTURE WILL CONTINUE TO FEED INTO THE AREA FROM THE
SOUTH TODAY BUT THE MAIN CHANCE OF STORMS SHIFTS LARGELY EAST OF
THE DIVIDE TODAY. WE CONTINUED THE PROB30 GROUP FOR
THUNDERSTORMS IN CASPER. WE ALSO ADDED A PROB30 CODY WHERE
SOUTHEASTERLY UPSLOPE FLOW MAY BRING SOME AFTERNOON AND EVENING
CONVECTION AS WELL. ELSEWHERE, THE CHANCE IS LESS THAN 20
PERCENT SO WE KEPT IT OUT OF THE TAFS FOR NOW. THERE IS A 20
PERCENT CHANCE OF BRIEF MVFR CONDITIONS WITH ANY SHOWER OR
THUNDERSTORM.
GUSTY WIND WILL ALSO CONTINUE TODAY. THE STRONGEST WIND WILL BE
FOUND ACROSS NORTHERN WYOMING, WHERE GUSTS OVER 25 KNOTS WILL BE
POSSIBLE IN VICINITY OF KWRL. MANY OTHER TERMINALS COULD SEE
GUSTS BETWEEN 15 AND 25 KNOTS AFTER 18Z BEFORE WIND BEGINS TO
DECREASE AFTER SUNSET.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HATTINGS
AVIATION...HATTINGS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page