924
FXUS65 KRIW 011003
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
403 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 ARE TONIGHT AND BRING AN END TO THE
WELL ABOVE NORMAL TEMPERATURES. THE CHANCE 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 REMAIN 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 /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 401 AM MDT SUN JUN 1 2025
VFR CONDITIONS ALONG WILL PREVAIL ACROSS ALL TERMINALS THROUGH
MUCH OF THE TAF PERIOD. WINDS ARE EXPECTED TO REMAIN LIGHT
THROUGH THE PERIOD AS WELL WITH ONLY A FEW SLIGHT WIND DIRECTION
SHIFTS. A COLD FRONT WILL BEGIN TO NEAR THE AREA BY THE LATE
SUNDAY MORNING. THE NEARING FRONT WILL BEGIN TO PRODUCE
SCATTERED SHOWERS AND THUNDERSTORMS. NEARLY ALL TERMINALS WILL
HAVE CHANCES TO SEE SHOWERS AND THUNDERSTORMS WITH THE BEST
LIKELIHOOD 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 20Z SUNDAY THROUGH 06Z MONDAY. THE FRONT WILL ALSO BRING IN
MIDLEVEL SCT TO BKN CLOUD DECKS THROUGH THE END OF THE TAF
PERIOD.
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...DZIEWALTOWSKI/HATTINGS
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