060
FXUS65 KRIW 011747
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1147 AM MDT SUN JUN 1 2025
KEY MESSAGES
- ONE MORE WARM DAY TODAY WITH SCATTERED AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS WITH STRONG WIND GUSTS.
- HIGH ELEVATION SNOW MELT MAY BRING MINOR FLOODING OF CREEKS
AND RIVERS TODAY AND TOMORROW.
- CLOUD COVER TONIGHT MAY MAKE VIEWING OF A POSSIBLE DISPLAY OF
THE NORTHERN LIGHTS DIFFICULT.
- COOLER AND UNSETTLED FROM MONDAY THROUGH WEDNESDAY, WITH A FEW
INCHES OF SNOW POSSIBLE IN THE MOUNTAINS.
DISCUSSION
ISSUED AT 311 AM MDT SUN JUN 1 2025
WELCOME TO SUMMER! WELL, METEOROLOGICAL SUMMER, (THE SOLSTICE IS ON
JUNE 20TH FOR ASTRONOMICAL SUMMER). AND IN TRUE WYOMING FASHION, WE
WILL HAVE MORE THAN ONE SEASON IN THIS FORECAST PERIOD, SUMMER,
SPRING AND, FOR SOME OF THE MOUNTAINS, WINTER. FIRST, I WANT TO
APOLOGIZE FOR THE LATENESS OF THE DISCUSSION, AS WE HAD A REALLY
GOOD DISPLAY OF THE NORTHERN LIGHTS, WITH KP INDICES OF 8 AND
SOME REALLY BRILLIANT COLORS. THERE COULD BE A REPEAT
PERFORMANCE TONIGHT, BUT THERE WILL LIKELY BE SOME COMPLICATIONS
IN SEEING THEM. DETAILS WILL BE BELOW.
IT WILL FEEL LIKE SUMMER TODAY. SOUTHWEST FLOW WILL INCREASE AHEAD
OF AN ADVANCING COLD FRONT AND UPPER LEVEL LOW AND BRING SOME VERY
WARM TEMPERATURES. WE FELL SHORT OF 90 YESTERDAY, BUT THERE IS A
BETTER CHANCE TODAY. AGAIN, THE BEST CHANCES WILL BE ACROSS THE BIG
HORN BASIN AND PLACES LIKE CASPER AND RIVERTON. BUT THERE IS ANOTHER
SIDE OF THIS SUMMER PART OF THE FORECAST. AND THIS IS SHOWERS AND
THUNDERSTORMS. THE APPROACHING FRONT WILL BRING SOME LIFT AND
INCREASING MOISTURE WILL LEAD TO SCATTERED SHOWERS AND
THUNDERSTORMS. MODELS HAVE TRENDED DRIER THOUGH, WITH THE BEST
CHANCE OF CONVECTION ACROSS NORTHWESTERN WYOMING (ABOUT A 1 IN 2
CHANCE) TAPERING TO 1 OUT OF 6 FURTHER SOUTH AND EAST. WE CONTINUE
TO HAVE A MARGINAL CHANCE OF SEVERE WEATHER ACROSS THE NORTHWEST.
STRONG WIND WILL BE THE MAIN THREAT, BUT THERE WILL BE ENOUGH LOW
LEVEL MOISTURE FOR SOME HAIL AS WELL. FURTHER EAST, THE LOW LEVEL
WILL REMAIN VERY DRY THROUGH THE DAY. DEW POINT DEPRESSIONS WILL BE
AS HIGH AS 50 TO 55 DEGREES THIS AFTERNOON AND MODEL SOUNDING ARE
SHOWING VERY OBVIOUS INVERTED VS. THIS MEANS HIGH BASED SHOWERS AND
THUNDERSTORMS AND THE CHANCE OF WIND GUSTS PAST 50 MPH WITH ANY
PRECIPITATION, EVEN INNOCENT LOOKING SHOWERS. YES, THIS LOOKS LIKE
IT COULD BE A "LITTLE GREEN BLOB" DAY ACROSS MUCH OF THE AREA EAST
OF THE DIVIDE. AND, WITH THE WARM WEATHER, WE HAVE SOME CREEKS AND
RIVERS APPROACHING ACTION STAGE SO WE COULD SEE SOME FLOOD
ADVISORIES AT TIMES TODAY AS THE HIGH ELEVATION SNOW MELT CONTINUES.
NOW FOR THE POSSIBLE NORTHERN LIGHTS VIEWING. THIS COULD BE A VERY
GOOD DISPLAY, WITH A G4 WATCH IN EFFECT (THE SPACE WEATHER
PREDICTION CENTER DOESN'T ISSUE G5 WATCHES). IT LOOKS LIKE WE WILL
HAVE SOME CLOUDS AROUND THROUGH MUCH OF THE AREA THROUGH THE NIGHT.
IF YOU WANT TO TAKE A LOOK, THE EASTERN PORTIONS OF THE AREA,
ESPECIALLY NATRONA, EASTERN SWEETWATER AND EASTERN SWEETWATER LOOK
LIKE THE BEST LOCATION. THEY WOULD LIKELY NOT BE VISIBLE UNTIL AT
LEAST 10:30 PM GIVEN THE LONG JUNE DAYS.
THE FRONT WILL MOVE THROUGH THE AREA TONIGHT AND BRING AN END
TO THE WELL ABOVE NORMAL TEMPERATURES. THE CHANCE FOR A
WIDESPREAD HEAVY RAIN EVENT IS LOOKING LESS LIKELY AS WELL. THE
QUESTION WAS WHEN WOULD THE SYSTEMS PHASE. AND NOW IT LOOKS LIKE
IT WILL OCCUR EAST OF OUR AREA, HENCE THE SLIGHT RISK THERE. AS
FOR PRECIPITATION AMOUNTS IN OUR NECK OF THE WOODS, THE CHANCE
OF A HALF AN INCH OR MORE FROM MONDAY MORNING THROUGH WEDNESDAY
NIGHT TAPERED TO AT MOST 1 OUT OF 3 FOR AREAS EAST OF THE DIVIDE
EXCEPT FOR THE MOUNTAINS. WE ARE STILL CONFIDENT OF A FEW
THINGS. ONE, IT WILL BE A MUCH COOLER PATTERN THROUGH AT LEAST
WEDNESDAY, WITH THE COOLEST TEMPERATURES EXPECTED ON TUESDAY
WHEN SOME OF THE LOWER ELEVATIONS WILL STRUGGLE TO GET OUT OF
THE 50S, UP TO 20 DEGREES BELOW NORMAL. THERE WILL BE A SERIES
OF SHORTWAVES MOVING ACROSS THE AREA THROUGH THE AT LEAST
WEDNESDAY, BRING SOME ROUNDS OF SHOWERS AND ISOLATED
THUNDERSTORMS. THERE ARE DIFFERENT SOLUTIONS THOUGH FOR TIMING
OF THE WAVES, SO PINPOINTING A TIME REMAINS DIFFICULT. NOW FOR
THE WINTERY PART OF THE SYSTEM, MUCH COOLER AIR WILL MOVE IN,
WITH THE COOLEST MONDAY NIGHT AND TUESDAY. MODELS ARE NOW
SHOWING 700 MILLIBAR TEMPERATURES AS LOW AS MINUS 3, WHICH COULD
LOWER SNOW LEVELS DOWN TO 7500 TO EVEN 7000 FEET. THERE REMAINS
A GREATER THAN 1 IN 2 CHANCE OF OVER 3 INCHES OF SNOW IN THE
HIGHER ELEVATIONS OF THE BIGHORNS, WIND RIVER RANGE AND
ABSAROKAS. THE CHANCE OF 6 INCHES OR MORE IS GENERALLY LESS THAN
2 OUT 5 AND ONLY AT THE HIGHEST ELEVATIONS WHERE IMPACTS WOULD
BE MINIMAL.
FLOW THEN BECOMES LARGELY ZONAL THURSDAY AND INTO THE BEGINNING OF
NEXT WEEK, WHICH SHOULD BRING A RETURN TO NEAR NORMAL
TEMPERATURES. WE WILL CONTINUE TO HAVE A FEW WAVES MOVING
THROUGH THE FLOW AS WELL, BRINGING CHANCES OF SHOWERS AND
STORMS. AGAIN, TIMING IS UNCERTAIN BUT THE RULE FOR LATER IN THE
WEEK IS UNSETTLED WITH NEAR NORMAL TEMPERATURES.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1146 AM MDT SUN JUN 1 2025
VFR CONDITIONS CONTINUE AT ALL TERMINALS WITH MOSTLY LIGHT WINDS AND
CLEAR SKIES. CLOUD COVER WILL INCREASE THROUGH THE AFTERNOON, WITH
SHOWERS AND THUNDERSTORMS BECOMING POSSIBLE BY 21Z. NEARLY ALL
TERMINALS WILL HAVE CHANCES TO SEE SHOWERS AND THUNDERSTORMS WITH
THE MOST LIKELY CHANCES (30 TO 40%) BEING EAST OF THE DIVIDE OVER
NORTHERN AND CENTRAL WY. THE MAIN CONCERN WITH ANY SHOWERS OR
THUNDERSTORMS THAT DEVELOP NEARBY TERMINALS WILL BE STRONG GUSTY
OUTFLOW WINDS POSSIBLY OF 40 OR MORE KNOTS. THIS IS ESPECIALLY THE
CASE FOR TERMINALS SUCH AS KCOD, KWRL, KLND, KRIW, AND KCPR. IF ANY
SHOWERS TO TRACK OVER TERMINALS THERE COULD BE A BRIEF PERIOD OF
MODERATE TO HEAVY RAINFALL WITH CONDITIONS DROPPING TO MVFR. THE
TIMEFRAME FOR THESE SHOWERS AND THUNDERSTORMS LOOKS TO BE FROM 21Z
SUNDAY THROUGH 06Z MONDAY. MIDLEVEL SCT TO BKN CLOUD DECKS WILL ALSO
LINGER THROUGH THE END OF THE MORNING FOR MOST TERMINALS. KCOD (50%
CHANCE) AND KCPR (20% CHANCE) COULD SEE MVFR CONDITIONS DEVELOP
EARLY MONDAY MORNING AS ADDITIONAL LOWER DECKS FILTER IN BEHIND THE
COLD FRONT.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE
FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HATTINGS
AVIATION...HENSLEY
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