740
FXUS65 KRIW 290401
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1001 PM MDT WED MAY 28 2025
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THIS EVENING,
MAINLY OVER CENTRAL WYOMING.
- DRIER AND WARMER TOMORROW. ISOLATED RAIN CHANCES (15%-40%)
OVER WESTERN WYOMING, MAINLY THE MOUNTAINS.
- WARMING TREND THROUGH THE END OF THE WEEK. WARMEST DAY IS
SUNDAY, WHERE SOME AREAS MAY SEE HIGHS AROUND 90 DEGREES.
UPDATE
ISSUED AT 1224 PM MDT WED MAY 28 2025
SCATTERED SHOWERS AND THUNDERSTORMS ARE ONGOING OVER PORTIONS OF
WYOMING, MAINLY CENTRAL. THESE ARE STILL EXPECTED TO CONTINUE
THROUGH THIS AFTERNOON AND EVENING, DIMINISHING AFTER SUNSET.
ALL BUT A FEW MOUNTAIN SHOWERS SHOULD BE DONE ABOUT MIDNIGHT
TONIGHT.
HIGH TEMPERATURES ARE AROUND SEASONAL FOR MOST AREAS THIS
AFTERNOON, THE EXCEPTION IS FOR EASTERN FREMONT, NATRONA, AND
JOHNSON COUNTIES, WHERE CLOUD COVER AND RAIN KEEPS TEMPERATURES
COOLER. THE STORY THE REST OF THE WEEK CONTINUES TO BE THE
WARMER TEMPERATURES, WITH SUNDAY LOOKING TO HAVE THE PEAK
HEATING, WHERE SOME OF THE AREA COULD SEE HIGHS AROUND 90
DEGREES.
DISCUSSION
ISSUED AT 150 AM MDT WED MAY 28 2025
SOME SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE ACROSS CENTRAL
WYOMING EARLY THIS MORNING. I TOOK A BRIEF BREAK TO GO OUTSIDE
EARLIER AND SAW A COUPLE OF THE MOST BEAUTIFUL DISPLAYS OF WEATHER,
AT LEAST IN MY OPINION. THOSE ARE NIGHTTIME CLOUD TO GROUND
LIGHTNING STRIKES, TO THE NORTH OF OUR OFFICE OVER THE OWL CREEK
RANGE. THIS WILL CONTINUE TODAY AS A TROUGH AXIS ROTATING AROUND A
LARGE UPPER LEVEL LOW LOCATED OVER THE WESTERN GREAT LAKES MOVES
THROUGH THE AREA, BRINGING ANOTHER DAY OF SCATTERED SHOWERS AND
THUNDERSTORMS, MAINLY TO AREAS EAST OF THE DIVIDE. THERE IS A BIT
LESS INSTABILITY TODAY, WITH AROUND 25 PERCENT LESS CAPE THAN
YESTERDAY AND LIFTED INDICES ONLY GO DOWN TO MINUS 1, LIKELY DUE THE
COOLER TEMPERATURES AND MORE CLOUD COVER. PRECIPITABLE WATER LEVELS
REMAIN AROUND 125 PERCENT ABOVE CLIMATOLOGICAL NORMALS THOUGH, SO
THERE COULD BE SOME LOCALLY HEAVY RAIN. WITH LOWER WET BULB ZEROS,
THERE COULD ALSO BE SOME SMALL HAIL. COVERAGE SHOULD BE SMALLER
THOUGH. AS FOR AMOUNTS, THE AREAS WITH THE GREATEST CHANCE OF A
QUARTER OF AN INCH OR RAIN OR MORE SHIFT INTO CENTRAL WYOMING, WITH
THE EASTERN SLOPES OF THE WIND RIVER RANGE AND THE SOUTH SIDE OF
CASPER HAVING AROUND A 1 IN 3 CHANCE. SHOWERS SHOULD WANE THIS
EVENING AND LARGELY END BY AROUND MIDNIGHT.
THINGS LOOK QUIETER FOR THURSDAY AS RIDGING BUILDS ACROSS THE STATE.
THERE WILL STILL BE A FEW SHOWERS AND THUNDERSTORMS AROUND, BUT
THESE WOULD BE OF THE DIURNAL VARIETY AND LARGELY RESTRICTED TO THE
MOUNTAINS AND ADJACENT FOOTHILLS, MAINLY IN THE WESTERN HALF OF THE
STATE. THE CHANCE IS ONLY AROUND 1 OUT OF 4 AT ANY GIVEN SPOT.
TEMPERATURES WILL WARM AS WELL, LIKELY RETURNING TO NEAR NORMAL
LEVELS.
THERE IS A NEW WRINKLE IN THE FORECAST FOR FRIDAY AS A SHORTWAVE
MOVES BY TO THE NORTH. THE MODELS DO HAVE SOME DIFFERENCES IN THE
DETAILS WITH THIS IN REGARDS TO POSSIBLE COVERAGE OF CONVECTION. FOR
NOW, WE PLAYED THE MIDDLE GROUND WITH THE BEST CHANCE OF SHOWERS AND
STORMS ACROSS EASTERN PORTIONS OF THE AREA. IN ADDITION, IT COULD
BECOME RATHER WINDY AFTER THE PASSAGE IN THE FAVORED NORTHWEST FLOW
AREAS LIKE BUFFALO, BUT THE PRESSURE GRADIENT AND MID LEVEL WINDS DO
NOT SUPPORT HIGH WIND AT THIS TIME.
DRY WEATHER THEN RETURNS FOR SATURDAY AS WE TURN UP THE HEAT ACROSS
THE AREA. MANY AREAS WILL BE WELL INTO THE 80S. THE HEAT LOOKS TO
PEAK ON SUNDAY AS SOUTHWEST FLOW INCREASES AHEAD OF AN UPPER LEVEL
LOW. THIS COULD BE THE DAY WE SEE THE FIRST 90 DEGREE HIGH
TEMPERATURES ACROSS THE AREA IN THE WARMEST LOCATIONS. A FEW
THUNDERSTORMS WILL THEN BE POSSIBLE AS MOISTURE INCREASES ACROSS THE
WEST AHEAD OF THE UPPER LEVEL LOW. WE WILL THEN ENTER INTO A COOLER
AND WETTER PATTERN AS AN UPPER LEVEL LOW APPROACHES THE AREA,
BRINGING AN INCREASED CHANCE OF SHOWERS. DETAILS ARE IMPOSSIBLE TO
GIVE THIS FAR OUT, BUT THERE IS GREATER THAN A 1 IN 2 CHANCE OF
BELOW NORMAL TEMPERATURES AND ABOVE NORMAL PRECIPITATION FOR THE
FIRST PART OF NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1000 PM MDT WED MAY 28 2025
SHOWERS CONTINUE TO WANE ACROSS THE AREA THIS EVENING AND ARE
EXPECTED TO AROUND AROUND THE START OF THE TAF PERIOD. WITH
LIGHT WINDS AND AMPLE LOW- LEVEL MOISTURE, FOG WILL BE A
POSSIBILITY THROUGH 15Z. MOST LIKELY CHANCES (30 TO 40%) ARE AT
KCPR, WITH LOW-LEVEL EASTERLY WINDS FILTERING MOISTURE AND LOW
CLOUDS IN FROM EASTERN WY AND INTO THE CASPER AREA. MODEL
GUIDANCE INDICATES THAT ANY FOG/LOW CLOUD IMPACTS SHOULD ONLY
LAST A FEW HOURS. HAVE CONTINUED WITH THE FEW005 GROUP TO HEDGE
TOWARDS THE FOG CHANCES, AS THERE IS NOT ENOUGH CONFIDENCE TO
INCLUDE A PREVAILING IFR OR MVFR GROUP.
PARTLY CLOUDY SKIES WILL BE IN PLACE ACROSS AREAS WEST OF THE
DIVIDE IN THE MORNING AND MOSTLY CLEAR ELSEWHERE. CLOUDS WILL
INCREASE OVER THE WESTERN MOUNTAINS AFTER 19Z, WITH SHOWERS AND
THUNDERSTORMS BECOMING OVER THE ABSAROKA AND WIND RIVER
MOUNTAINS, AS WELL AS YELLOWSTONE NP LATE IN THE AFTERNOON.
ISOLATED SHOWERS AND THUNDERSTORMS WILL ALSO BE POSSIBLE OVER
THE GREEN RIVER BASIN. KCOD, KPNA AND KRKS LOOK TO HAVE THE
MOST LIKELY CHANCES FOR SHOWERS OR THUNDERSTORMS (15 TO 20%
CHANCES), BUT NOT ENOUGH CONFIDENCE TO INCLUDE MENTIONS IN THE
TAFS AT THIS TIME. THIS CONVECTION WILL WANE THROUGH THE EVENING
HOURS ONCE AGAIN AND END BY THE END OF THE TAF PERIOD.
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...LAVOIE/HENSLEY
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page