558
FXUS65 KRIW 251427
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
827 AM MDT MON MAY 25 2026
KEY MESSAGES
- A WARM DAY, WITH HIGHS IN THE UPPER 70S TO UPPER 80S. SHOWERS
AND THUNDERSTORMS ARE POSSIBLE (15 TO 50 PERCENT), WITH THE
BEST CHANCES ALONG AND WEST OF THE DIVIDE. GUSTY OUTFLOW WINDS
30 TO 50 MPH ARE THE MAIN HAZARD WITH ANY SHOWER OR STORM.
- INCREASED MOISTURE BRINGS THE CHANCE OF SHOWERS AND
THUNDERSTORMS TUESDAY. STRONG WINDS ARE THE MAIN HAZARD WITH
THESE STORMS.
- A FAIRLY STAGNANT WEATHER PATTERN KEEPS ABOVE NORMAL
TEMPERATURES MUCH OF THE WEEK, WITH DAILY CHANCES OF AFTERNOON
SHOWERS AND THUNDERSTORMS.
DISCUSSION
ISSUED AT 114 AM MDT MON MAY 25 2026
THE OVERALL THEME OF THE FORECAST REMAINS LARGELY THE SAME AS THIS
TIME YESTERDAY. THINGS ARE LARGELY QUIET AT THIS TIME AROUND WESTERN
AND CENTRAL WYOMING. AND THE MAIN PLAYERS IN THE FORECAST REMAIN THE
SAME, AN APPROACHING UPPER LEVEL LOW THAT WILL MOVE ONSHORE IN
THE PACIFIC NORTHWEST TODAY AND A RIDGE THAT WILL BUILD ACROSS
THE PLAINS STATES FOR MUCH OF THE WEEK. AND THEIR POSITIONS WILL
HAVE THE MAIN INFLUENCE ON OUR WEATHER EACH DAY, AS WE WILL
LIKELY BE BETWEEN THE TWO OF THEM.
AS FOR TODAY, THE AXIS OF THE MOST SHOWERS AND STORMS SHOULD SHIFT
TO WESTERN WYOMING. DEW POINTS SHOULD RUN AROUND 5 TO 10 DEGREES
ABOVE YESTERDAY AND CAPE IS MAXIMIZED IN THIS LOCATION, WITH UP TO
1000 J/KG. WE DID INCREASE POPS HERE SOMEWHAT, BUT THE CHANCE OF ANY
LOCATION SEEING A SHOWER OR THUNDERSTORM GENERALLY RANGES FROM 1 OUT
OF 5 IN THE LOWER ELEVATIONS TO UP TO 2 OUT OF 5 IN THE MOUNTAINS.
MOST THUNDERSTORMS SHOULD BE OF THE RUN OF MILL VARIETY, ALTHOUGH A
STRONGER STORM OR TWO CAN'T BE RULED OUT. THERE IS MORE OF A
QUESTION EAST OF THE DIVIDE, WHERE THE LOWER ATMOSPHERE WILL BE
DRIER, AND SOUTHWEST FLOW SHOULD BRING SOME DOWNSLOPING FLOW. WE DID
BUMP POPS UP A BIT, WITH THE BEST CHANCE ACROSS NORTHERN WYOMING,
WHERE THE ATMOSPHERE IS A BIT MORE UNSTABLE, ESPECIALLY THE CODY
FOOTHILLS. MOST OF ANY ACTIVITY IN THIS AREA WOULD LIKELY BE NEAR
THE MOUNTAINS, AND THE CHANCE IS GENERALLY LOWER THAN 1 OUT OF 3. WE
CAN'T RULE A SHOWER OUT ANYWHERE, BUT ELSEWHERE THE CHANCE IS LESS
THAN 1 OUT OF 10. SOUTHWEST FLOW WILL BRING A WARM DAY AS WELL, WITH
TEMPERATURES RUNNING AROUND 10 DEGREES ABOVE NORMAL, AND MAYBE A FEW
90S IN THE BIGHORN BASIN. LIKE PREVIOUS DAYS, ACTIVITY WILL BE
LARGELY DIURNAL AND MOST WILL END SHORTLY AFTER SUNSET.
THINGS MAY GET A BIT MORE ACTIVE TOMORROW. THE UPPER LEVEL LOW WILL
BE ONSHORE BY THIS TIME AND THE FIRST SHORTWAVE WILL BE MOVING
ACROSS THE AREA FROM SOUTH TO NORTH. LOW LEVEL FLOW WILL ALSO BE
TURNING MORE TO THE SOUTH AND EAST, BRINGING IN MORE LOW LEVEL
MOISTURE. PRECIPITABLE WATER RISE SOMEWHAT AS WELL, TO AS HIGH AS AN
INCH IN EASTERN PORTIONS OF THE AREA, WHICH IS GREATER THAN 175
PERCENT OF NORMAL AND ABOVE THE 90TH PERCENTILE WITH CLIMATOLOGY.
ONE LIMITING FACTOR MAY BE CLOUD COVER THOUGH, AS THIS MAY LIMIT
INSTABILITY. THE TWO MOST LIKELY ZONES LOOK TO AGAIN BE THE WESTERN
MOUNTAINS, WHERE CAPE VALUES CLIMB TO HIGHER THAN 1000 J/KG AND
LIFTED INDICES FALL TO MINUS 3. THE OTHER IS ACROSS JOHNSON AND
NATRONA COUNTIES, WHERE UPSLOPE MAY BRINGING CONVECTIVE INITIATION
AGAINST THE BIGHORNS. AS FOR STRONGER STORMS, THE BEST CHANCE OF
THAT WOULD BE IN WESTERN WYOMING WHERE THERE IS MORE DIRECTIONAL
SHEAR PRESENT. LOCALLY HEAVY RAIN IS POSSIBLE WITH ANY STORM PUT
THERE WILL BE AROUND 20 KNOTS OF STORM MOTION, SO THIS SHOULD LIMIT
ANY FLOODING POTENTIAL. STORM CHANCES RANGE FROM AROUND 1 OUT OF 2
IN THE WESTERN MOUNTAINS TO LESS THAN 1 OUT 6 IN PORTIONS OF THE
BIGHORN AND WIND RIVER BASINS WHERE THE LEAST ACTIVITY WILL BE
FOUND. AGAIN, MOST ACTIVITY SHOULD END AFTER SUNSET, BUT A FEW
SHOWERS MAY LINGER THROUGH THE NIGHT.
UNCERTAINTY INCREASES AFTER THIS, AS THE GUIDANCE CONTINUES TO
STRUGGLE WITH THE EVOLUTION OF THE MOVEMENT OF THE UPPER LEVEL LOW.
HOWEVER, THERE HAS BEEN A TREND IN THE RIDGE BEING A BIT STRONGER
AND KEEPING THE LOW FURTHER TO THE WEST. THIS WOULD MEAN A SOMEWHAT
DRIER AND WARMER FORECAST. THE FORECAST FOR WEDNESDAY IS LIKELY THE
WETTEST IT COULD BE. THE MOST ACTIVE DAYS MAY END UP BRING FRIDAY OR
SATURDAY, BUT AGAIN A LOT DEPENDS ON THE TRACK OF THE LOW AND HOW
THE TROUGH AXIS MOVES AS THE LOW EVENTUALLY OPENS UP. THE TREND FOR
NOW IS FOR CONTINUED ABOVE NORMAL TEMPERATURES AND SOME CHANCES OF
CONVECTION EACH DAY, WITH THE BEST CHANCE IN WESTERN WYOMING.
DETERMINING WHICH DAY WILL BE THE MOST ACTIVE AND WHERE THE HEAVIER
RAIN FALLS REMAINS UNCERTAIN. WE MAY ALSO HAVE TO DEAL WITH SOME
RISING CREEKS, STREAMS AND RIVERS AS THE WARM SPELL MAY BE ABLE TO
MELT OUT SOME OF THE HIGHER LEVEL SNOWPACK.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 408 AM MDT MON MAY 25 2026
LARGELY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. THE
FOCUS OF CONVECTION WILL SHIFT TO LARGELY WESTERN WYOMING, WITH
ALL TERMINALS WEST OF THE CONTINENTAL DIVIDE HAVING PROB30
GROUPS FOR SHOWERS BETWEEN ROUGHLY 20Z AND 02Z THIS AFTERNOON
AND EVENING. WIND GUSTS OVER 35 KNOTS ARE POSSIBLE WITH ANY
SHOWER WITH THE HIGH BASED CONVECTION. A FEW SPOTS WILL ALSO
SEE A THUNDERSTORM BUT WITH THE CHANCE LESS THAN 20 PERCENT NOT
ENOUGH CONFIDENCE TO INTRODUCE INTO THE TAF FORECASTS. IN AREAS
EAST OF THE DIVIDE, KCOD COULD SEE A SHOWER ROLL OF THE
ABSAROKAS. WE ALSO ADDED A PROB30 GROUP TO KLND WHERE A SHOWER
COULD MAKE IT OFF ON THE WIND RIVER RANGE THIS AFTERNOON. BRIEF
MVFR CONDITIONS CAN'T BE RULED OUT IN A HEAVIER SHOWER, BUT THE
CHANCE IS LESS THAN 10 PERCENT. SUSTAINED WIND SHOULD REMAIN
AROUND 12 KNOTS OR LESS THROUGH THE PERIOD EXCEPT IN AND AROUND
CONVECTION.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HATTINGS
AVIATION...HATTINGS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page