349
FXUS65 KRIW 190430
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
930 PM MST WED FEB 18 2026
KEY MESSAGES
- WINTER WEATHER FOR MANY LOWER ELEVATION LOCATIONS THIS
OVERNIGHT THROUGH THURSDAY MORNING. PERIODS OF MODERATE TO
HEAVY SNOW WILL BE POSSIBLE INTO THE EARLY MORNING HOURS
THURSDAY.
- FRESHLY FALLEN SNOW WILL AID IN USHERING SOME OF THE COLDEST
TEMPERATURES IN QUITE SOMETIME. LOWS MAY GET NEAR TO EVEN
BELOW ZERO OVER THE NEXT FEW DAYS.
- QUIET AND WARMER CONDITIONS RETURN TO THE AREA FOR THE
UPCOMING WEEKEND, LIKELY PERSISTING INTO THE START OF NEXT
WEEK.
UPDATE
ISSUED AT 1214 PM MST WED FEB 18 2026
FOR THE FIRST TIME IN QUIET A LONG WHILE, WEATHER CONCERNS
SHIFT EAST OF THE DIVIDE AND THEY ARE NOT RELATED TO STRONG
WINDS, WARM TEMPERATURES, OR OVERLY DRY CONDITIONS. WINTER
LOOKS TO RISE FROM ITS LONG DORMANT SLUMBER IN THE FORM OF
ACCUMULATING SNOW AND COLD TEMPERATURES. THE OVERALL FORECAST
REMAINS MOSTLY ON TRACK COMPARED TO THE PREVIOUS DISCUSSION.
THERE IS STILL SOME UNCERTAINTY MAINLY IN REGARDS TO THE TRACK
OF THE 700 MB LOW THAT IS EXPECTED TO DEVELOP. HI-RES MODELS
CONTINUE TO HAVE SLIGHT DEVIATIONS REGARDING ITS TRACK WHICH IS
ENOUGH TO SHIFT IMPACTS. HOWEVER, AS OF THIS AFTERNOON THERE IS
A GOOD IDEA OF WHAT TO EXPECT ACROSS THE CWA. SNOWFALL AMOUNTS
HAVE GONE UP SLIGHTLY COMPARED TO THE PREVIOUS FORECAST. AS A
RESULT OF THIS, WINTER WEATHER ADVISORIES HAVE BEEN ISSUED FOR
THE REMAINDER OF THE BIGHORN BASIN. THE MAIN AREAS OF CONCERN
ARE ACROSS PORTIONS OF NATRONA INTO SOUTHERN JOHNSON COUNTIES.
LOCATIONS NORTH OF CASPER MAY SEE A PERIOD OF FAVORABLE
OROGRAPHICALLY DRIVEN SNOWFALL CREATING SNOWFALL RATES UP TO 1
INCH AN HOUR, WHICH HAS LEAD TO FORECAST SNOWFALL AMOUNTS OF 4
TO 8 INCHES. AT THE SAME TIME THIS SNOW IS FALLING WINDS,
INCREASE TO AROUND 20 MPH WITH GUSTS NEARING 40 MPH AT TIMES.
THE MODERATE TO HEAVY SNOWFALL AND GUSTY WINDS WILL LIKELY
CREATE BLOWING SNOW AS WELL AS REDUCED VISIBILITIES ALONG THE
I-25 CORRIDOR. HIGHER SNOWFALL AMOUNTS AND A PERIOD OF GUSTY
WINDS HAVE LED TO THE UPGRADE FROM ADVISORIES TO WINTER STORM
WARNINGS FOR THESE LOCATIONS. OTHER AREAS OF NOTE ARE THE WIND
RIVER BASIN AND LANDER FOOTHILLS, WHERE ANY SLIGHT SHIFT IN THE
700 MB LOW COULD ALTER IMPACTS. THE THOUGHT PROCESS CURRENTLY,
IS THAT THERE SHOULD BE A LONG ENOUGH WINDOW OF UPSLOPING TO
ALLOW FOR MEASURABLE SNOWFALL TO OCCUR. THIS SHOULD ALLOW FOR
ANYWHERE FROM 3 TO 6 INCHES TO FALL FROM LANDER TO RIVERTON.
PROBABILISTIC GUIDANCE IS SUPPORTIVE OF THIS WITH THERE BEING A
SOLID 60-80% OF 4 OR MORE INCHES ACROSS MUCH OF THE BASIN.
HOWEVER, IT SHOULD BE NOTED THAT THIS AMOUNT CAN EASILY SHIFT
SLIGHTLY HIGHER OR EVEN LOWER, ALL DEPENDING ON THE TRACK AND
TIMING OF THE 700 MB LOW. ANOTHER LOCATION TO MONITOR IS THE
SOUTHERN BIGHORN BASIN INCLUDING WORLAND AND THERMOPOLIS. THERE
ARE SOME SIGNALS FOR A PERIOD OF FAVORABLE FLOW TO OCCUR HERE AS
WELL. THE CURRENT FORECAST CALLS FOR 3 TO 6 INCHES AS WELL BUT
PROBABILISTIC GUIDANCE IS SUGGESTING A 40-70% CHANCE FOR 6 OR
MORE INCHES. AT THIS TIME ADVISORIES REMAIN IN PLACE BUT IT IS
NOT OUT OF THE REALM OF POSSIBILITY FOR SOME LOCALIZED AREAS
SEEING WARNING AMOUNTS.
SNOW SHOWERS LINGER THROUGH THE MORNING INTO THE AFTERNOON ON
THURSDAY. TEMPERATURES WILL BE ON THE COLDER SIDE FOR THE NEXT
FEW DAYS, AS A RESULT OF THE COLDER AIR ASSOCIATED WITH THIS
SYSTEM ALONG WITH FRESH SNOW COVER. THIS COULD LEAD TO SOME
INVERSIONS DEVELOPING WHICH COULD GREATLY TANK CURRENT
FORECASTED HIGHS. LOW TEMPERATURES WILL ALSO SEE AN IMPACT FROM
THE FRESH SNOW. STARTING THURSDAY NIGHT THROUGH SATURDAY NIGHT
LOW TEMPERATURES LOOK TO FLIRT WITH THE ZERO DEGREE MARK ACROSS
MUCH OF THE STATE. IT IS CERTAINLY POSSIBLE THAT MANY LOCATIONS
HIT SUB-ZERO TEMPERATURES IF SKIES CAN CLEAR AND ENOUGH SNOW HAS
ACCUMULATED ON THE SURFACE. OTHERWISE, THE REST OF THE FORECAST
REMAINS UNCHANGED WITH QUIET WEATHER EXPECTED FOR THE WEEKEND.
DISCUSSION
ISSUED AT 210 AM MST WED FEB 18 2026
MUCH OF THE AREA EAST OF THE CONTINENTAL DIVIDE IS ABOUT TO GET
SLAPPED BACK INTO REALITY OF WINTER. IT WON'T BE A HUGE PUNCH,
LIKE A MIKE TYSON UPPERCUT. IT WILL BE MORE LIKE A GOOD JAB,
LIKE ONE FROM LARRY HOLMES OR FLOYD MAYWEATHER JR. IN OTHER
WORDS, IT WILL TURN MUCH COLDER, BUT NOT BITTERLY COLD. AND
THERE WILL BE ACCUMULATING SNOW, BUT NOT A REAL BIG STORM.
BACK TO THE FORECAST NOW. RADAR IS SHOWING A GOOD BAND OF SNOW AT
THIS TIME EXTENDING FROM IDAHO INTO NORTHWESTERN WYOMING, LARGELY
NORTH OF JACKSON. THIS IS IN ASSOCIATION WITH THE RIGHT REAR
QUADRANT OF A JET STREAM MOVING ACROSS THE AREA. THE MAIN CULPRIT
FOR THIS SYSTEM IS AN UPPER LEVEL LOW THAT IS OPENING UP ACROSS THE
PACIFIC NORTHWEST AND WILL BECOME A NEGATIVELY TILTED TROUGH AS IT
MOVES ACROSS WYOMING. WE HAVE SOME THINGS GUIDANCE THAT ARE IN
FAIRLY GOOD AGREEMENT AND A FEW THINGS THAT DON'T LINE UP VERY WELL
EVEN NOW.
THERE IS GOOD AGREEMENT ON TIMING OF THE SYSTEM. MOST PRECIPITATION
SHOULD REMAIN WEST OF THE DIVIDE THROUGH THIS AFTERNOON, THE SPREAD
TO THE EAST AFTER SUNSET AS THE TROUGH MOVES THROUGH THE AREA. THERE
IS DECENT AGREEMENT IN HAVING THE HEAVIEST SNOW IN THE AFTERNOON
ACROSS WESTERN WYOMING AND THEN PROGRESSING EASTWARD, WITH THE
HEAVIEST SNOW EAST OF THE DIVIDE FALLING THIS EVENING FROM 6 PM
UNTIL AROUND 2 AM OR SO. AMOUNTS LOOK FAIRLY CONSISTENT WEST OF
THE DIVIDE AS WELL. THERE COULD SOME LOCATIONS ON THE PEAKS
THAT GET GREATER THAN 12 INCHES, BUT THESE ARE PLACES WITH
LITTLE IMPACT OR PLACES THAT WANT TO SNOW, LIKE THE SKI RESORTS.
MOST OF THE WESTERN MOUNTAINS STILL HAVE A GREATER THAN 5 IN 6
CHANCE OF 6 INCHES OR MORE, BUT ONLY AROUND 1 IN 4 CHANCE OVER
12 INCHES. SO, WE WILL LET THE ADVISORY RIDE HERE FOR NOW. IN
THE VALLEYS, THE CHANCE OF 6 INCHES IS LESS THAN 1 OUT 4 FOR THE
MOST PART. ONE AREA OF CONCERN HERE IS ALPINE, WHERE A PERIOD
OF FAVORABLE NORTHWEST FLOW WITH THE TROUGH AXIS MAY BRING
SOMEWHAT HIGHER AMOUNTS, WITH AROUND A 2 IN 5 CHANCE OF 6 INCHES
OR MORE. WE WILL LET THINGS GO FOR NOW THOUGH. SNOW WILL
CONTINUE IN THE WEST, BUT SHOULD GRADUALLY TAPER OFF THROUGH THE
NIGHT.
NOW WE MOVE TO WHERE THINGS ARE A BIT MORE UNCERTAIN, MAINLY EAST OF
THE DIVIDE WITH SNOWFALL AMOUNTS. THE MAIN CONCERN IS THE SAME AS
YESTERDAY, THE POSITION OF THE 700 MILLIBAR LOW AND IT'S IMPACTS ON
THINGS LIKE EASTERLY FLOW TO BRING IN MOISTURE AND FLOW TURNING
UPSLOPE TO ENHANCE AREAS OF SNOW. SO, WE WENT WITH A BLEND OF MODELS
WITH A GOOD AREA OF ADVISORY LEVEL SNOW. FOR THE ADVISORY, WE
DECIDED TO GO CLOSE TO THE 1 OUT OF 2 CHANCE OF 3 INCHES OR MORE ON
THE NATIONAL BLEND OF MODEL ENSEMBLE. THIS IS GENERALLY EAST OF A
SHELL TO THERMOPOLIS TO RIVERTON LINE. ALL THESE AREAS HAVE HAD
WINTER WEATHER ADVISORIES STARTING AT 00Z THURSDAY AND RUNNING
THROUGH 18Z THURSDAY. THE HEAVIEST SNOW WOULD LIKELY FALL IN
PERIOD FROM AROUND 6 PM TO 2 AM THOUGH. AS FAR AS AN AREA OF 6
INCHES OR MORE, THE NBM ENSEMBLE IS GIVING AROUND A 2 IN 5
CHANCE FORM ROUGHLY THE FREMONT-NATRONA COUNTY LINE TO CASPER
AS WELL AS FROM EAST TO THERMOPOLIS TO THE SOUTH OF WORLAND,
PROBABLY INDICATING THAT MORE ENSEMBLE MEMBERS ARE PICKING UP ON
AN ENHANCED PERIOD OF NORTHERLY UPSLOPE IN THIS LOCATION. OUR
IN-HOUSE MODEL ALSO SHOWS LESS THAN 1 IN 4 CHANCE OF 6 INCHES OR
MORE IN ALL LOCATIONS. SO, WE KEPT THINGS WITH ADVISORIES. THE
DAY SHIFT CAN SEE IF ANY LOCATIONS NEED AN UPGRADE TO A WARNING.
MOST OF THE SNOW SHOULD END THURSDAY MORNING WITH DRY
CONDITIONS BY SUNSET.
OUR ATTENTION THEN TURNS TO TEMPERATURES. THURSDAY WILL BE A MUCH
COLDER DAY, 20 TO 25 DEGREES COOLER THAN TODAY EAST OF THE DIVIDE.
MANY LOCATIONS HAVE AROUND A 1 IN 2 CHANCE OF SEEING BELOW ZERO LOWS
ON THURSDAY NIGHT. THE X FACTOR WILL BE HOW MUCH CLEARING OCCURS. IF
IT STAYS CLOUDY, TEMPERATURES COULD REMAIN A BIT WARMER. FOR NOW, WE
WENT WITH LOW TEMPERATURES AROUND ZERO. NOT BITTERLY COLD FOR
WYOMING, BUT IT WILL FEEL COLD GIVEN THE RECENT MILD WEATHER WE HAVE
HAD.
QUIETER WEATHER SHOULD THEN DOMINATE FOR THE MOST OF THE
REMAINDER OF THE PERIOD. ON FRIDAY, A WEAK SHORTWAVE MAY BRING
A FEW SHOWERS TO NORTHWESTERN WYOMING BUT NOTHING HEAVY. ANOTHER
SYSTEM PASSING OVER COLORADO MAY SPREAD A FEW SHOWERS TO
SOUTHERN WYOMING, BUT NOTHING HEAVY IS EXPECTED. TEMPERATURES
SHOULD MODERATE A BIT BUT REMAIN BELOW NORMAL. RIDGING THEN
BUILDS INTO THE AREA SATURDAY INTO MONDAY AND BRINGS DRY
CONDITIONS ALONG WITH MODERATING TEMPERATURES. BASINS MAY BE A
BIT LONGER TO WARM AS THERE MAY BE INVERSIONS, BUT THESE SHOULD
GRADUALLY SHRINK AS THE STRONGER LATE FEBRUARY SUN MELTS TO THE
SNOW OFF AND DECREASES THE ALBEDO. THE NEXT SYSTEM SHOULD
APPROACH EARLY NEXT WEEK AND BRING SOME SHOWERS TO WESTERN
WYOMING, BUT DETAILS THIS FAR OUT ARE DIFFICULT TO HASH OUT.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 930 PM MST WED FEB 18 2026
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
SNOW HAS TAPERED OFF WITH SOME LIGHT SNOW LINGERING AROUND
JAC/RKS. VFR CONDITIONS EXPECTED STILL WITH LOW CEILINGS FOR
MUCH OF THE PERIOD BEFORE LIFTING TO THE MID LEVELS BY 00Z
THURSDAY EVENING. WINDS ARE ON THE DECLINE OVERNIGHT FOR ALL BUT
RKS, THAT WILL SEE 25KT GUSTS THROUGH MUCH OF THE NIGHT AND DAY
THURSDAY BEFORE DIMINISHING TOWARDS SUNSET AROUND 00Z. ALL
OTHER TAF SITES EXPECTED TO BE 10KTS OR LESS. LOW STRATUS/FOG
POSSIBLE INTO THE NEXT TAF CYCLE FOR FRIDAY MORNING WITH THE
RECENT SNOWFALL.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
SNOW CONTINUES FOR ALL LOCATIONS WITH MVFR TO IFR CONDITIONS.
THIS IS EXPECTED TO PUSH THROUGH EARLY THURSDAY MORNING BEFORE
TAPERING OFF BY 12-14Z, LINGERING A BIT LATER AT CPR AROUND
15Z. OTHERWISE, WINDS REMAIN GUSTY UP TO 25KTS AT ALL LOCATIONS
BUT WILL BE DIMINISHING BY EARLY MORNING AROUND THAT SAME 12-14Z
TIME FRAME AS THE SNOW TAPERS OFF. LOW BUT VFR CONDITIONS FOR
THE REMAINDER OF THE PERIOD NOT LIFTING TO THE MID LEVELS UNTIL
AFTER 00Z THURSDAY EVENING. AGAIN, FOG/LOW STRATUS POSSIBLE COME
FRIDAY MORNING WITH THE RECENT SNOWFALL INTO THE NEXT TAF
CYCLE.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZLC AND ZDV FOR THE
LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR
WYZ001-012-014-015-024.
WINTER WEATHER ADVISORY UNTIL 11 AM MST THURSDAY FOR
WYZ003>010-017>019-022.
WINTER STORM WARNING UNTIL 11 AM MST THURSDAY FOR WYZ011-020.
UPDATE...DZIEWALTOWSKI
DISCUSSION...HATTINGS
AVIATION...LOWE
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