352
FXUS65 KRIW 250720
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
120 AM MDT MON MAY 25 2026
KEY MESSAGES
- A WARM MEMORIAL DAY ACROSS WESTERN AND CENTRAL WYOMING WITH
SCATTERED SHOWERS AND THUNDERSTORMS, MAINLY ACROSS WESTERN
WYOMING AS WELL AS IN AND NEAR THE MOUNTAINS.
- INCREASED MOISTURE MAY BRING AN INCREASED CHANCE OF SHOWERS
AND THUNDERSTORMS FOR TUESDAY AFTERNOON AND EVENING.
- ABOVE NORMAL TEMPERATURES LIKELY CONTINUE MUCH OF THE WEEK.
THERE WILL BE DAILY CHANCES OF AFTERNOON SHOWERS AND
THUNDERSTORMS, BUT DETAILS OF PLACEMENT AND THE MOST ACTIVE
DAY REMAIN UNCERTAIN.
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, AND 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 /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.
DISCUSSION...HATTINGS
AVIATION...CNJ
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