222
FXUS65 KRIW 181149
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
449 AM MST WED FEB 18 2026
KEY MESSAGES
- A WEATHER SYSTEM BRINGS LIGHT TO MODERATE SNOW TO MUCH OF THE
AREA FROM TODAY THROUGH THURSDAY MORNING.
- THE COLDEST TEMPERATURES IN SOME TIME BEGIN THURSDAY AND
CONTINUE INTO SATURDAY.
- MAINLY DRY WEATHER RETURNS FRIDAY AND LASTS THROUGH AT LEAST
MONDAY, WITH A GRADUALLY WARMING TREND THROUGH THE PERIOD.
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 /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 437 AM MST WED FEB 18 2026
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
A WINTER STORM WILL CONTINUE TO BRING MVFR TO IFR CONDITIONS TO
TERMINALS FOR MUCH OF THE PERIOD. THIS WILL BE MOST PERSISTENT AT
KJAC, FOLLOWED BY KBPI AND KPNA. KRKS IS LEAST LIKELY TO SEE
PREVAILING IMPACTS AND CURRENTLY HAS A PROB30 IFR GROUP LATE THIS
AFTERNOON INTO THE EVENING. WIND WILL INCREASE THIS AFTERNOON,
BECOMING WESTERLY GUSTING TO 35 KNOTS AT KRKS. SNOW WILL BEGIN TO
DECREASE IN COVERAGE AFTER 06Z THURSDAY.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
A WINTER STORM WILL BRING WIDESPREAD MVFR TO IFR CONDITIONS TO
TERMINALS THIS AFTERNOON AND EVENING. THIS WILL ALSO BRING A WIND
SHIFT FROM SOUTHWESTERLY OR WESTERLY TO NORTHERLY THIS AFTERNOON,
WITH MOST TERMINALS SEEING GUSTS OF 20 TO 30 KNOTS. PLEASE SEE TAFS
FOR TIMING ON SNOW AND WIND IMPACTS.
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
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR
WYZ001-012-014-015-024.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM MST
THURSDAY FOR WYZ005>011-017>020-022.
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR
WYZ013-023.
DISCUSSION...HATTINGS
AVIATION...MYERS
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