340
FXUS65 KRIW 241023
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
423 AM MDT SUN MAY 24 2026
KEY MESSAGES
- REMAINING WARM TODAY WITH AN INCREASED CHANCE (AS HIGH AS A 2
OUT OF 5 CHANCE) OF A SHOWER OR THUNDERSTORM TODAY.
- REMAINING WARM ON MEMORIAL DAY WITH FURTHER CHANCES OF A
SHOWER OR THUNDERSTORM, ESPECIALLY ALONG AND WEST OF THE
DIVIDE.
- MUCH OF NEXT WEEK WILL HAVE DAILY CHANCES OF SHOWERS AND
THUNDERSTORMS, ALTHOUGH PLACEMENT OF THE MOST NUMEROUS STORMS
AND BEST CHANCE OF HEAVIER RAIN REMAINS RATHER UNCERTAIN.
DISCUSSION
ISSUED AT 100 AM MDT SUN MAY 24 2026
AS WITH MOST THINGS WITH FORECASTING THE WEATHER, THERE ARE SOME
THINGS WE KNOW, AND SOME THINGS WE DON'T KNOW. AND, THERE IS NO
EXCEPTION TO THIS AS I WRITE THIS EARLY ON SUNDAY MORNING. I AM
LISTENING TO HAIR METAL THIS MORNING, AND THE SONG DIRTY LOVE JUST
CAME ON. AND THIS TIES INTO THE MAIN HAZARD OVER THE NEXT SEVERAL
DAYS. THE ABOVE MENTIONED SONG IS BY A BRITISH HARD ROCK BAND CALLED
THUNDER (THEY WERE A THING FOR A BRIEF TIME IN THE EARLY 90S). WE
WILL HAVE DAILY CHANCES OF THUNDER FOR THE NEXT SEVERAL DAYS. THAT
IS THE PART WE KNOW. THE PART WE DON'T KNOW, ESPECIALLY A FEW DAYS
OUT, ARE THE COVERAGE AND PLACEMENT OF THE STORMS.
WE CURRENTLY HAVE A FEW SHOWERS OUT THERE, LARGELY IN SOUTHWESTERN
WYOMING. LITTLE IF ANY OF THE PRECIPITATION IS REACHING THE GROUND
THOUGH. THE MAIN DRIVER OF THE THUNDER TODAY WILL BE A SHORTWAVE
MOVING IN FROM THE WEST AND SOME INCREASING MOISTURE FROM THE
SOUTHWEST. THIS SHOULD INCREASE COVERAGE OF SHOWERS AND STORMS THIS
AFTERNOON AND EVENING. THERE IS GOOD MODEL AGREEMENT OF HAVING THE
HIGHEST COVERAGE (ABOUT A 2 IN 5 CHANCE) ACROSS THE SOUTHWEST WITH
TAPERING CHANCES FURTHER TO THE NORTH AND EAST. PRECIPITABLE WATER
VALUES ARE ABOUT 50 PERCENT HIGHER THAN YESTERDAY. HOWEVER, MODEL
SOUNDINGS CONTINUE TO SHOW INVERTED VS ALONG WITH HIGH CLOUD BASES.
DEW POINT DEPRESSIONS ARE ALSO OVER 40 DEGREES IN MANY LOCATIONS
ONCE AGAIN. WHAT THIS MEANS IS THAT ALTHOUGH THERE IS A BETTER
CHANCE FOR SOME RAIN TO REACH THE GROUND, THERE WILL STILL BE A LOT
OF VIRGA SHOWERS AND POSSIBLY DRY THUNDERSTORMS. AND THIS MEANS THAT
WE HAVE THE POTENTIAL OF STRONG WIND GUSTS FROM ANY SHOWER OR
THUNDERSTORM. MOST CONVECTION AGAIN LOOKS DIURNAL AND SHOULD DECREASE
AFTER SUNSET.
MEMORIAL DAY MAY END UP BEING A BIT DRIER THAN TODAY, AS HEIGHTS
RISE BY AROUND 40 DECAMETERS AND PRECIPITABLE WATER VALUES FALL BY
AROUND 25 PERCENT. MOST GUIDANCE IS FAIRLY CONSISTENT WITH THIS.
MOST GUIDANCE IS ALSO IN DECENT AGREEMENT IN MOST OF THE SHOWERS AND
STORMS REMAINING WEST OF THE DIVIDE WITH LESS THAN A 1 OUT OF 5
CHANCE EAST OF THE DIVIDE. WITH THE SOUTHWEST FLOW, TEMPERATURES
SHOULD AVERAGE 5 TO 10 DEGREES ABOVE NORMAL THROUGH THE HOLIDAY
WEEKEND.
THE UNCERTAINTY REALLY INCREASES AS WE HEAD INTO TUESDAY AND THE
REST OF THE WEEK. AND WHAT HAPPENS IS DEPENDENT ON THE POSITION OF
TWO FEATURES. ONE, IS A STRONG RIDGE THAT WILL BE FOUND ACROSS THE
MIDWEST. THE SECOND, WHICH HAS MORE IMPACT ON US, IS ONE OF THE
FEATURES THAT LEADS MANY METEOROLOGISTS TO EARLY HAIR LOSS. IT IS A
STACKED UPPER LEVEL LOW THAT WILL MOVE ONSHORE IN THE PACIFIC
NORTHWEST MONDAY NIGHT AND TUESDAY AND DRIFT TOWARD THE GREAT BASIN
FOR THE MIDDLE OF THE WEEK. IF LOOKS LIKE IT WILL CUT OFF FROM THE
MAIN LOW AND SIT FOR A FEW DAYS, BUT EXACTLY WHERE WILL BE THE
DETERMINING FACTOR FOR OUR WEATHER. ENSEMBLE GUIDANCE IS ALL OVER
THE PLACE. WITH THE DETERMINISTIC MODELS, THE GFS, WHICH HAS BEEN
FLIP-FLOPPING MORE THAN A FISH OUT OF WATER, NOW KEEPS THE LOW WEST
OF WYOMING BEFORE OPENING IT UP INTO A TROUGH FOR THE END OF THE
WEEK. THE EUROPEAN MODEL HAS BEEN MORE CONSISTENT, KEEPING THE LOW A
BUT FURTHER SOUTH DURING THE MIDDLE OF THE WEEK BEFORE MOVING IT
NORTHWARD ABOUT 24 HOURS LATER, AGAIN WEST OF WYOMING. AS FOR THE
FORECAST, THE LOW WILL CONTINUE TO FEED MOISTURE INTO THE AREA, AND
AS A RESULT THERE SHOULD BE SOME SHOWERS AND THUNDERSTORMS AROUND
EACH DAY. HOWEVER, THE MOISTURE MAY BE MORE OF THE MID AND HIGH
LEVEL VARIETY. MODEL SOUNDINGS AT THIS TIME SHOW LARGELY INVERTED VS
WHICH WOULD IMPLY MORE HIGH BASED SHOWERS AND STORMS. BUT A LOT
DEPENDS ON THE ULTIMATE PATH OF THE LOW, AND CUT OFF LOWS ARE ONE OF
THE MOST DIFFICULT THINGS TO FORECAST. IF IT MOVES FURTHER EAST, WE
HAVE A BETTER CHANCE OF SOME STILL NEEDED RAIN. AND AS FAR AS
PLACEMENT AND TIMING OF THE SHOWERS AND STORMS, A LOT DEPENDS ON
SHORTWAVES ROTATING AROUND IT AND THESE ARE DIFFICULT TO TIME THIS
FAR OUT. FOR NOW, WE KEPT THE FORECAST LARGELY BROADBRUSHED WITH
MORE POPS IN THE MOUNTAINS AND WESTERN WYOMING AND PRECIPITATION
LARGELY DIURNAL. TEMPERATURES LOOK TO BE NEAR TO SLIGHTLY ABOVE
NORMAL THROUGH THE PERIOD.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 418 AM MDT SUN MAY 24 2026
LARGELY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. A
FEW SHOWERS ARE MOVING INTO THE WESTERN MOUNTAINS AT THIS TIME,
SO WE ADDED VCSH IN VICINITY OF KJAC UNTIL AROUND 15Z. INCREASED
INSTABILITY WILL LEAD TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THIS AFTERNOON, WITH THE GREATEST COVERAGE IN
SOUTHWESTERN WYOMING. WITH INCREASES IN INSTABILITY ACROSS THE
WESTERN MOUNTAINS, WE ALSO ADDED A PROB30 GROUP FOR KJAC
STARTING AT 19Z. A FEW LOCATIONS MAY SEE A THUNDERSTORM, BUT
WITH CHANCES GENERALLY LESS THAN 20 PERCENT, NOT ENOUGH
CONFIDENCE FOR A PROB30 GROUP. BREEZY CONDITIONS ARE POSSIBLE
THIS AFTERNOON WITH GUSTS TO AROUND 20 TO 25 KNOTS IN THE
NORMALLY WINDIER SITES. WIND GUSTS TO 35 TO 40 KNOTS WILL BE
POSSIBLE AROUND ANY SHOWER OR THUNDERSTORM. MOST ACTIVITY SHOULD
END AFTER 03Z TONIGHT AS THE SUN SETS AND INSTABILITY DECREASES.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HATTINGS
AVIATION...HATTINGS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page