852
FXUS65 KRIW 250355
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
955 PM MDT SUN MAY 24 2026
KEY MESSAGES
- WARM TEMPERATURES CONTINUE FOR MONDAY AND TUESDAY, ALONG WITH SHOWER
AND THUNDERSTORM CHANCES (15 TO 45 PERCENT). BEST CHANCES
OCCUR ALONG AND WEST OF THE CONTINENTAL DIVIDE.
- DAILY SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH THE
REST OF THE WEEK. THE AREAS WITH THE BEST CHANCES CHANGE DAY-
TO-DAY.
UPDATE
ISSUED AT 1238 PM MDT SUN MAY 24 2026
NOT MUCH CHANGE TO THE FORECAST FOR TODAY. SHOWERS, AND SOME
THUNDERSTORMS, WILL BE FAIRLY WIDESPREAD ACROSS THE AREA TODAY,
AT LEAST IN COVERAGE, BUT SPECIFIC LOCATIONS ONLY HAVE A 15 TO
40 PERCENT CHANCE OF ACTUALLY GETTING CONVECTION OVER THEM. THE
MAIN HAZARD WITH THIS WILL BE GUSTY OUTFLOW WINDS. GIVEN DEW
POINT DEPRESSIONS AROUND 50 DEGREES, WOULD EXPECT OUTFLOW GUSTS
UP TO 55 MPH BEING A POSSIBILITY, WITH A 30 TO 50 MPH RANGE
BEING THE MOST LIKELY. OTHERWISE, TEMPERATURES CLIMB AGAIN
TODAY, REACHING THE 70S FOR MOST LOCATIONS, WITH LOW-TO-MID 80S
FOR THE BIGHORN BASIN AND JOHNSON COUNTY. CONVECTION SHOULD
QUICKLY DIMINISH AFTER SUNSET, WITH THE LAST FEW SHOWERS WANING
BETWEEN 10PM AND MIDNIGHT.
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. IT 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 SCATTERED RAIN SHOWERS AND STORMS CONTINUE THROUGH THIS
EVENING, WITH THE MAIN HAZARD BEING GUSTY OUTFLOW WINDS 30 TO
55 MPH. THIS CONVECTIVE ACTIVITY WILL END BY MIDNIGHT.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 /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 955 PM MDT SUN MAY 24 2026
LINGERING ISOLATED SHOWERS ARE FADING LATE SUNDAY EVENING WITH THE
LOSS OF SOLAR HEATING AND SHORTWAVE ENERGY. THE PRIMARY MOISTURE
FEED FROM THE WEST BEGINS TO BACK TO THE SOUTH OVERNIGHT AND MONDAY
MORNING. THIS SHOULD LIMIT ANY OVERNIGHT SHOWERS WHILE SHIFTING
ATTENTION TO AREAS WEST OF A KRKS-KCOD LINE FOR EARLY MONDAY
AFTERNOON CONVECTION. EMBEDDED SHORTWAVE ENERGY AND THE BETTER MID-
LEVEL MOISTURE WILL INITIALLY BE ACROSS THE FAR WEST THROUGH MID-
AFTERNOON SUNDAY. SCATTERED SHOWERS AND ISOLATED STORMS THEN SLIP TO
THE EASTERN BASINS LATE IN THE AFTERNOON AND EARLY EVENING. THE
EXCEPTION LOOKS TO BE KCPR WHICH SEES LESS THAN A 15 PERCENT CHANCE
FOR CONVECTION. ONCE AGAIN, THE PRIMARY AVIATION HAZARD WILL BE
GUSTY OUTFLOW WIND 30-45KTS GIVEN THE HIGH-BASED NATURE OF DAYTIME
CONVECTION. HOWEVER, MOISTURE DEEPENS AND DEW POINTS RISE OVER THE
FAR WEST MONDAY AFTERNOON LEADING TO A BETTER CHANCE OF BRIEF,
HEAVIER SHOWERS. OTHERWISE, ALL TERMINALS REMAIN VFR THROUGH MONDAY
EVENING. MOST TERMINALS SEE SURFACE WIND SPEEDS 8-13KTS FROM MIDDAY
MONDAY UNTIL AROUND 02Z/TUESDAY.
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.
UPDATE...WITTMANN
DISCUSSION...HATTINGS
AVIATION...CNJ
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