616
FXUS65 KRIW 300514
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1114 PM MDT FRI MAY 29 2026
KEY MESSAGES
- SCATTERED RAIN SHOWERS AND ISOLATED THUNDERSTORMS LINGER THIS
EVENING, WITH RAIN CHANCES INCREASING TONIGHT OVERSPREADING
THE AREA FROM SOUTHWEST TO NORTHEAST.
- AN APPROACHING WEATHER SYSTEM WILL BRING A GOOD CHANCE OF
SHOWERS TO MUCH OF THE AREA FROM LATER TONIGHT INTO THE
WEEKEND, WITH MOST RAIN ACROSS NORTHERN AND WESTERN WYOMING.
- ACCUMULATING SNOW IS LIKELY THIS WEEKEND IN THE MOUNTAINS,
ESPECIALLY ABOVE 9500 FEET.
- TEMPERATURES WILL BE MUCH COOLER THIS WEEKEND REBOUNDING NEXT
WEEK.
UPDATE
ISSUED AT 1230 PM MDT FRI MAY 29 2026
SEEING MOISTURE ON IR STREAM UP FROM THE SOUTHEAST ACROSS AREAS
EAST OF THE DIVIDE. THESE MID TO UPPER LEVEL CLOUDS SEEM TO BE
THIN ENOUGH NOT TO HINDER FORECASTED HIGH TEMPERATURES THIS
AFTERNOON IN THE WIND RIVER/BIGHORN BASINS. OTHERWISE, THE MAIN
UPPER LEVEL LOW CONTINUES TO SPIN IN A STILL PATTERN OVER NEVADA
THAT SHOULD START TO PROGRESS NORTHEASTWARD FINALLY IN THE NEXT
6 TO 12 HOURS. THIS WILL START TO BRING IN THE MORE WIDESPREAD
PRECIPITATION AFTER MIDNIGHT AND MUCH OF SATURDAY AND INTO
SUNDAY. QPF AMOUNTS HAVE DIMINISHED SOME, ESPECIALLY EAST OF
THE DIVIDE BUT MOST SHOULD STILL SEE AT LEAST THE .1" WETTING
RAIN. THE HIGHEST AMOUNTS CONTINUE TO PING FOR YELLOWSTONE AND
FAR NORTHERN PARTS OF THE BIGHORN BASIN. HREF MODELS INDICATE
THE LOW BECOMING MORE PROGRESSIVE WITH EACH MODEL RUN, AND THUS,
SHOULD PUSH OUT SOONER SUNDAY LATE MORNING TO EARLY AFTERNOON
WITH ONLY LINGERING LIGHT SHOWERS IN ITS WAKE BEFORE WEEKEND'S
END. OTHERWISE, COOLER TEMPERATURES TO MORE SEASONABLE FOR THIS
TIME OF YEAR STILL ON TRACK OVER THE WEEKEND AND INTO EARLY NEXT
WEEK.
DISCUSSION
ISSUED AT 230 AM MDT FRI MAY 29 2026
METEOROLOGY IS ONE OF THE PHYSICAL AND MATHEMATICAL SCIENCES. AND
THE WEATHER IS BASICALLY GOVERNED BY COMPLEX MATHEMATICAL EQUATIONS
(SOME I WOULD LIKE TO FORGET, I STILL HAVE NIGHTMARES ABOUT DYNAMICS
CLASS 28 YEARS AFTER I FINALLY PASSED IT). ONE OF THE MOST COMMON IS
THE SINE WAVE, MOST OFTEN USED WITH ROSSBY WAVES. THE WEATHER OFTEN
RUNS LIKE A WAVE PATTERN WITH CRESTS AND TROUGHS OF DIFFERENT
PARAMETERS. AND WE ARE CURRENTLY IN A CREST AND TROUGH OF ONE RIGHT
NOW. ON THURSDAY, WE HAD THE CREST IN TEMPERATURES, WITH A TROUGH IN
COVERAGE OF PRECIPITATION. STARTING TODAY AND ESPECIALLY GOING INTO
THIS WEEKEND, THIS IS GOING TO BEGIN FLIPPING.
THE MAIN REASON IS THE CUT OFF LOW THAT HAS BEEN SPINNING ACROSS
CALIFORNIA AND NEVADA FOR THE PAST FEW DAYS. IT WILL FINALLY
GET A NUDGE AND WILL BEGIN HEADING NORTHEASTWARD TOWARD WYOMING
TODAY. MOISTURE WILL BEGIN TO HEAD BACK INTO THE AREA, ALTHOUGH
IT WILL TAKE A WHILE TO DEEPEN. THERE WILL BE A FEW MORE SHOWERS
AND STORMS AROUND TODAY. HOWEVER, MOST GUIDANCE SHOWS IT WILL
BE A LATER SHOW WITH SOME STICKING AROUND INTO THE EVENING.
WITH THE FLOW TURNING SOUTHEAST, THE MOST IMPACTED AREAS WILL BE
SIMILAR TO YESTERDAY, THE FAVORED UPSLOPE AREAS LIKE AROUND THE
EAST SLOPES OF THE ABSAROKAS AND THE BIGHORNS AS WELL AS
NATRONA AND JOHNSON COUNTY WHERE MOISTURE WILL BUILD THE
FASTEST. EVEN HERE, THE CHANCE OF A SHOWER OR STORM IS PROBABLY
NO MORE THAN 1 OUT OF 3. IT WILL BE ANOTHER VERY WARM DAY, BUT
WITH INCREASING CLOUD COVER PROBABLY A FEW DEGREES COOLER THAN
YESTERDAY. AND THERE WILL AGAIN BE A BIT OF A GUSTY BREEZE,
ESPECIALLY IN SOUTHWEST WYOMING, WHERE, COMBINED WITH STILL LOW
HUMIDITY, MAY BRING ELEVATED FIRE WEATHER CONDITIONS THIS
AFTERNOON.
PRECIPITATION WILL REALLY INCREASE LATER TONIGHT AND INTO SATURDAY
AS THE UPPER LEVEL LOW FINALLY MOVES INTO WYOMING. MOST GUIDANCE
SHOWS THE SAME GENERAL PATTERN AS YESTERDAY, WITH A NORTHWEST TO
SOUTHEAST GRADIENT OF QPF WITH THE HIGHEST AMOUNTS IN THE WEST AND
NORTH. AREAS FURTHER TO THE EAST WILL LIKELY HAVE MORE OF A
SOUTHWEST DOWNSLOPING FLOW THAT WILL KEEP THE PRECIPITATION MORE
SHOWERY. EVERY LOCATION WILL HAVE A CHANCE OF RAIN THOUGH. AS
FOR HOW MUCH, WE WILL TAKE A LOOK AT THE NBM ENSEMBLES FOR
THIS. AT THIS POINT, IT IS FAIRLY SIMILAR TO YESTERDAY, WITH A
GREATER THAN 1 IN 2 CHANCE OF A QUARTER OF AN INCH OF QPF OR
MORE MAINLY NORTH AND WEST OF A EVANSTON TO RIVERTON TO KAYCEE
LINE. THE HIGHEST AMOUNTS STILL LOOK TO BE IN NORTHWESTERN
WYOMING AND NEAR THE BIGHORNS THOUGH, WITH A GREATER THAN 1 IN 2
CHANCE OF AN INCH OF QPF OR MORE. THE WEATHER PREDICTION CENTER
CONTINUES TO HAVE A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS
NORTHERN WYOMING ON BOTH SATURDAY AND SUNDAY. IT HAS BEEN FAIRLY
DRY SO THERE IS ROOM IN THE SOIL, BUT IT IS SOMETHING TO KEEP
IN MIND. SATURDAY CONTINUES TO LOOK LIKE THE WETTEST DAY.
HOWEVER, THE LOW WILL LIKELY SLOW DOWN SOMEWHAT AND STALL OVER
MONTANA. THIS WILL KEEP UNSETTLED WEATHER OVER PARTS OF THE
AREA, WITH NORTHERN WYOMING THE MOST IMPACTED. HOW FAR SOUTH IT
CAN STAY THIS WAY IS IN QUESTION, SINCE THERE ARE DIFFERENCES IN
GUIDANCE AS TO WHEN THE LOW WILL LIFT OUT OF THE AREA.
NEEDLESS TO SAY, IT WILL BE MUCH COOLER WITH THE CLOUD COVER AND
SHOWERS. THIS IS ESPECIALLY SO ON THE WESTERN SIDE OF THE LOW WHERE
FLOW WILL BE NORTHERLY. A PLACE LIKE JACKSON MAY STAY BELOW 55 ALL
WEEKEND. AND THIS BRINGS US TO ANOTHER PART OF THE SYSTEM, THE
CHANCE OF SNOW. YES, ANY VISITORS TO THE COWBOY STATE, IT CAN
SNOW HERE ANY MONTH OF THE YEAR. NOW, IT WILL NOT ACCUMULATE IN
THE LOWER ELEVATIONS, AND TRAVEL SHOULD NOT BE IMPACTED MUCH AS
IT HAS BEEN VERY WARM AND THE HIGH SUN ANGLE WOULD MELT SNOW ON
ROADS. HOWEVER, WE DO HAVE A DECENT CHANCE OF SOME ACCUMULATING
SNOW IN THE MOUNTAINS. SOME MODELS DROP THE 700 MILLIBAR
TEMPERATURES AS LOW AS MINUS 1C, WHICH WOULD LOWER SNOW LEVELS
TO 8000 FEET. WE STILL THINK THIS IS TOO LOW, IT WOULD LIKELY BE
CLOSER TO 9000 FEET. AREAS ABOVE 9500 FEET IN THE WESTERN
MOUNTAINS HAVE A GREATER THAN 1 IN 2 CHANCE OF AN INCH OR SNOW,
AND THIS INCLUDES TOGWOTEE PASS. SOME OF THE HIGHER ELEVATIONS
OF THE TETONS AND WIND RIVERS COULD SEE 6 INCHES OR MORE OF SNOW
THIS WEEKEND. SO IF YOU ARE RECREATING IN THE MOUNTAINS,
PREPARE FOR A COLD AND WET WEEKEND. YOU WILL ALSO LIKELY SEE
SOME SNOW IF YOU ARE DRIVING OVER TOGWOTEE PASS.
EARLY NEXT WEEK IS IN QUESTION AS WELL. SOME GUIDANCE LINGERS
THE LOW CLOSE ENOUGH FOR SOME SHOWERS TO LINGER INTO MONDAY,
OTHERS FAVOR FLOW TURNING MORE TO THE WEST-SOUTHWEST FOR A
WARMER AND DRIER PATTERN. FOR MOST OF THE NEXT WEEK, THE
CONSENSUS SEEMS TO BE FOR WARM BUT NOT HOT WEATHER AND A COUPLE
OF CHANCES OF MAINLY DIURNAL SHOWERS AND THUNDERSTORM AS
SHORTWAVES MOVING THROUGH THE LARGELY ZONAL FLOW.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1112 PM MDT FRI MAY 29 2026
THE WEATHER SYSTEM PUSHES THROUGH THE AREA OVER THE NEXT 24 HOURS,
WITH WIDESPREAD RAIN AND THUNDERSTORM CHANCES. CONDITIONS WILL
FREQUENTLY CHANGE BETWEEN VFR AND IFR AT MOST TERMINALS THROUGH THE
TAF PERIOD. TERMINALS WITH THE LEAST IMPACTS WILL BE KCPR, KRIW, AND
KLND. WIND WILL BE GUSTY, ESPECIALLY WITH CONVECTION SATURDAY
MORNING THROUGH SATURDAY EVENING. AS THE AREA OF LOW PRESSURE TRACKS
THROUGH CENTRAL WYOMING, WIND WILL BE SHIFTING DIRECTIONS WITH
IT, WHICH IS ILLUSTRATED IN THE MANY CHANGES IN WIND DIRECTION
IN THE TAFS. MOUNTAIN OBSCURATION WILL BECOME PREVALENT TONIGHT,
ESPECIALLY AROUND WESTERN TERMINALS, AND PERSIST THROUGH 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...LOWE
DISCUSSION...HATTINGS
AVIATION...LAVOIE/ROWE
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