164
FXUS65 KRIW 251007
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
407 AM MDT SUN OCT 25 2026
KEY MESSAGES
- ANOTHER COOL DAY TODAY WITH A SCATTERING OF SHOWERS, MAINLY IN
THE SOUTHERN HALF OF WYOMING.
- AN APPROACHING WEATHER SYSTEM WILL BRING SOME MOUNTAIN SNOW
AND STRONG WIND MONDAY NIGHT INTO TUESDAY.
- DRIER WEATHER RETURNS LATER IN THE WEEK WITH NEAR TO ABOVE
NORMAL TEMPERATURES.
DISCUSSION
ISSUED AT 135 AM MDT SUN OCT 25 2026
IT WAS QUITE BRIGHT THIS EVENING WHEN DRIVING TO WORK FROM MY HOUSE
TO THE HUMBLE RIVERTON WEATHER ABODE TO THE WEST OF TOWN. THIS IS
COURTESY OF THE ALMOST FULL HUNTERS MOON, WHICH PEAKS TOMORROW NIGHT
AROUND MIDNIGHT OR SO. MOST AREAS WOULD HAVE A BETTER CHANCE OF
SEEING IT TONIGHT THOUGH, AS THERE WILL BE A COUPLE OF SYSTEMS
IMPACTING THE AREA OVER THE NEXT COUPLE OF DAYS.
THE FIRST SYSTEM IS AN UPPER LEVEL LOW OVER ARIZONA THAT WILL LIFT
NORTHEAST OVER THE NEXT COUPLE OF DAYS. THIS SYSTEM LOOKS MUCH MORE
LIKE A GLANCING BLOW AS IT WILL BE WEAKENING AND THE BEST FORCING
WILL REMAIN TO THE SOUTH AND EAST OF THE AREA. THE BEST CHANCE OF
SHOWERS WILL BE FROM LATER THIS AFTERNOON INTO TONIGHT AND
ESPECIALLY FROM SOUTH OF A ROCK SPRINGS TO CASPER LINE. THIS LOOKS
MORE LIKE A MINOR NUISANCE SYSTEM, ALL AREAS WITH THE EXCEPTION OF
THE HIGHEST ELEVATIONS OF CASPER MOUNTAIN AND THE WIND RIVER RANGE
HAVE LESS THAN A 1 IN 2 CHANCE OF A TENTH OF AN INCH OF
PRECIPITATION. MANY LOCATIONS WILL SEE NOTHING. THE BEST CHANCE OF
SHOWERS WILL BE IN SOUTHERN WYOMING TODAY, SHIFTING TOWARD NATRONA
AS WELL AS EASTERN PORTIONS OF FREMONT AND SWEETWATER COUNTIES
TONIGHT. ALL SHOWERS SHOULD END BY OR SHORTLY AFTER SUNRISE MONDAY.
IT WILL ANOTHER COOL DAY AS WELL, WITH HIGH TEMPERATURES SIMILAR TO
HIGHS ON SATURDAY.
THE SECOND, AND MORE IMPACTFUL SYSTEM IMPACTS THE AREA FROM MONDAY
NIGHT THROUGH TUESDAY. THIS WILL BE A FAST MOVING LOW MOVING INTO
THE PACIFIC NORTHWEST TONIGHT AND MOVING ACROSS THE NORTHERN ROCKIES
MONDAY NIGHT INTO TUESDAY. THIS WILL SET UP THE TYPICAL FALL /
WINTER WESTERLY FLOW SITUATION ACROSS THE AREA, WITH MOST
PRECIPITATION FALLING IN WESTERN WYOMING WITH FAVORABLE OROGRAPHICS
AND WIND BEING THE MAIN IMPACT EAST OF THE DIVIDE. WITH THIS BEING
THE HEART OF FOOTBALL SEASON, WE WILL TACKLE EACH OF THESE THREATS
INDIVIDUALLY, BUT HOPEFULLY NOT BE PENALIZED FOR BEING WRONG.
WE WILL START WITH THE PRECIPITATION, WHICH INCLUDES SOME
ACCUMULATING SNOW, MAYBE EVEN FOR THE LOWER ELEVATIONS. MOST OF THE
WESTERN MOUNTAINS HAVE A NEARLY 100 PERCENT CHANCE OF A TENTH OF AN
INCH OF QPF OR MORE FROM MONDAY NIGHT THROUGH TUESDAY. THE AREA WITH
A GREATER THAN 1 IN 2 CHANCE OF A THIRD OF AN INCH OF QPF OR GREATER
IS WHERE YOU WOULD EXPECT IT WITH A WEST TO SOUTHWEST FLOW, MAINLY
FROM THE NORTHERN SALT AND WYOMING RANGE THROUGH THE TETONS AND
SOUTHWESTERN YELLOWSTONE PARK. AMOUNTS HAVE INCREASED SOMEWHAT FROM
YESTERDAY, WITH A DECENT AMOUNT OF THE AFOREMENTIONED AREA HAVING A
GREATER THAN 1 IN 2 CHANCE OF A HALF AN INCH OR MORE. THERE WILL BE
SOME DECENT UPPER LEVEL FORCING WITH THIS SYSTEM, WITH AN 100 TO 110
KNOT JET STREAK MOVING OVER THE AREA, ENHANCING PRECIPITATION RATES.
THE LIMITING FACTOR WILL BE THE SPEED OF THE SYSTEM, WITH MOST OF
THE PRECIPITATION FALLING IN A PERIOD FROM LATER SUNDAY EVENING
THROUGH SUNRISE ON MONDAY.
BUT THE MAIN QUESTION EVERYONE IS WONDERING ABOUT IT THE POTENTIAL
FOR SNOW. ONE FACTOR WILL BE HOW FAST A COLD FRONT CAN MOVE THROUGH
AND LOWER SNOW LEVELS. THROUGH MOST OF MONDAY EVENING, 700 MILLIBAR
TEMPERATURES WOULD LIKELY REMAIN AT 0 CELSIUS OR HIGHER, KEEPING
SNOW LEVELS AT 8500 FEET OR HIGHER. THE MAIN TIME OF SNOW
ACCUMULATION WOULD BE FROM MIDNIGHT SUNDAY NIGHT THROUGH SUNRISE
MONDAY, WHEN 700 MILLIBAR TEMPERATURES FALL AS LOW AS MINUS 5 TO
MINUS 6, WHICH WOULD LOWER SNOW LEVELS TO VALLEY FLOORS. MOST
LOCATIONS, INCLUDING PORTIONS OF THE JACKSON AND STAR VALLEYS HAVE
AT LEAST A 1 IN 2 CHANCE OF AN INCH OF SNOW OR MORE. AS FOR THE
CHANCE OF 3 INCHES, THE 1 IN 2 PROBABILITY IS GENERALLY AROUND 7500
FEET OR HIGHER, WHICH INCLUDES PLACES LIKE TETON AND TOGWOTEE
PASSES. THE MOUNTAIN ADVISORY AMOUNT IS 6 INCHES, AND THE CHANCE OF
THIS IS MAINLY ABOVE 10000 FEET WHERE IMPACTS ARE MINIMAL. HOWEVER,
WITH THE JET OVERHEAD, THERE WILL BE A FAIR AMOUNT OF WIND THAT
COULD BRING SOME BLOWING SNOW. AS FOR POTENTIAL HIGHLIGHTS, THE
CHANCE IS AROUND 2 OUT OF 5 FOR ADVISORIES, PROBABLY FROM SUNDAY
NIGHT INTO MIDDAY MONDAY. WE WON'T ISSUE ANY YET BUT FUTURE SHIFTS
WILL HAVE TO TAKE A CLOSER LOOK. MOST LOWER ELEVATION AREAS WOULD
HAVE FEW IMPACTS, BUT THERE COULD BE A SMALL ACCUMULATION OF SNOW IN
PLACES LIKE BIG PINEY, PINEDALE OR DUBOIS LATER MONDAY NIGHT OR
TUESDAY MORNING.
IN AREAS EAST OF THE DIVIDE, THE MAIN CONCERNS SHIFTS TO STRONG TO
POTENTIAL HIGH WIND. THE PRESSURE GRADIENT WILL TIGHTEN AHEAD OF THE
COLD FRONT. AND, WITH A COMBINATION OF THE JET OVERHEAD AND 700
MILLIBAR WINDS CLIMBING AS HIGH AS 55 KNOTS, THINGS WILL GET QUITE
BLUSTERY. A LARGE PORTION OF AREAS EAST OF THE DIVIDE HAVE AT LEAST
A 1 IN 2 CHANCE OF WIND GUSTS OVER 40 MPH. THE CORE OF THE HIGHEST
WIND IS WHERE YOU WOULD EXPECT IT IN THIS PATTERN, FROM MUDDY GAP
THROUGH CASPER, WHERE THERE IS A GREATER THAN 1 IN 2 CHANCE OF WIND
GUSTS PAST 55 MPH. THE CURRENT FORECAST HAS BORDERLINE HIGH WIND,
AND THE NATIONAL BLEND OF MODELS TENDS TO NOT CAPTURE WIND WELL IN
THIS AREA. WE MAY NEED SOME HIGH WIND HIGHLIGHTS, WITH THE CHANCE
AROUND 1 OUT OF 2 AT THIS TIME. WITH THE MAIN THREAT NOT UNTIL
TUESDAY, WE WILL NOT ISSUE RIGHT NOW, BUT WILL CONSIDER FOR FUTURE
SHIFTS.
RIDGING SHOULD THEN BUILD OVER THE AREA THROUGH MOST OF THE
REMAINDER OF THE WORKWEEK, BRINGING LOCALLY BREEZY CONDITIONS AND
NEAR TO ABOVE NORMAL TEMPERATURES. A COUPLE OF WEEK DISTURBANCES MAY
BRING A FEW SHOWERS TO THE WEST, BUT AMOUNTS LOOK SMALL. THE NEXT
MORE WIDESPREAD PRECIPITATION CHANCE MAY MOVE IN NEXT WEEKEND AS A
SYSTEM APPROACHES FROM THE SOUTHWEST BUT DETAILS ARE DIFFICULT TO
HASH OUT THIS FAR OUT.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 402 AM MDT SUN OCT 25 2026
A WEATHER SYSTEM WILL MOVE NORTHEASTWARD TOWARD THE AREA AND
SPREAD THICKENING CLOUDS ACROSS ROUGHLY THE SOUTHERN TWO THIRDS
OF THE AREA. MOST LOCATIONS WILL SEE VFR CONDITIONS THROUGH 12Z
MONDAY. DEEPER MOISTURE WILL BRING AROUND A 30 PERCENT CHANCE OF
A SHOWER IN VICINITY OF KBPI, KPNA AND KRKS THIS AFTERNOON AND
EVENING, SO PROB30 GROUPS HAVE BEEN ADDED TO THOSE SITES. IN
VICINITY OF KCPR, THERE IS A 50 PERCENT CHANCE OF MVFR
CONDITIONS AFTER 04Z TONIGHT WITH AROUND A 40 PERCENT CHANCE OF
SHOWERS AFTER 04Z TONIGHT. A SHOWER CAN'T BE RULED OUT LATER
THIS AFTERNOON IN VICINITY OF KRIW AND KLND, BUT WITH THE CHANCE
LESS THAN 20 PERCENT WE LEFT IT OUT OF THE TAFS FOR NOW.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HATTINGS
AVIATION...HATTINGS
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