210
FXUS65 KRIW 161047
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
347 AM MST SUN FEB 16 2025
KEY MESSAGES
- MODERATE TO HEAVY SNOW WILL OCCUR IN THE WESTERN MOUNTAINS AND
VALLEYS THROUGH AT LEAST MONDAY NIGHT.
- MAINLY LIGHT SNOW FOR FAR NORTHERN WYOMING TODAY, WITH
SOMEWHAT STEADIER SNOW STARTING MONDAY.
- THE NEXT SYSTEM MOVES INTO WESTERN WYOMING FOR WEDNESDAY OR
THURSDAY.
DISCUSSION
ISSUED AT 234 AM MST SUN FEB 16 2025
THINGS CONTINUE TO BE ACTIVE TONIGHT AND WE CONTINUE TO HAVE A
CONTRAST BETWEEN WEST AND EAST OF THE DIVIDE. SO, WE WILL SPLIT
THE DISCUSSION BETWEEN WEST AND EAST OF THE DIVIDE AGAIN THIS
EARLY SUNDAY MORNING.
WEST OF THE DIVIDE...THE CONCERN HERE IS, ONCE AGAIN, SNOW. RADAR
SHOWS THE FIRST PATCH OF SNOW APPROACHING THE WEST AS I WRITE THIS
AROUND 1:30 AM THIS MORNING. A FEED OF PACIFIC MOISTURE
WILL CONTINUE FEEDING INTO THE AREA OVER AT LEAST THE NEXT 48 HOURS
AND BRING PERIODS OF MODERATE TO HEAVY SNOW THROUGH THE PERIOD. THE
MODELS DO HAVE SOME DIFFERENCES ON TIMING OF THE HEAVIEST PERIODS OF
SNOW THOUGH, SO THIS IS MORE IN FLUX. AT THIS POINT, MOST MODELS ARE
ROUGHLY GIVING THE HEAVIEST SNOW ON MONDAY, BUT THIS IS, TO PUT IN
LEGAL TERMS, A PREPONDERANCE OF THE EVIDENCE AND NOT BEYOND A
REASONABLE DOUBT. SO ALTHOUGH WE HAVE FAIRLY DECENT CONFIDENCE ON
AMOUNTS OF SNOW, THE TIMING OF THE HEAVIEST SNOW REMAINS IN FLUX.
AS FOR TOTAL AMOUNTS THROUGH MONDAY NIGHT, HIGHLIGHTS ARE STILL
LOOKING FAIRLY DECENT AT THIS TIME. MOST OF THE HIGHER
ELEVATION MOUNTAIN LOCATIONS HAVE AT LEAST A 9 OUT OF 10 CHANCE
OF SEEING OVER A FOOT OF SNOW, SO WE WILL CONTINUE THE WARNINGS
THERE FOR NOW. LESSER AMOUNTS ARE LIKELY FOR THE WIND RIVER
MOUNTAINS, SO ADVISORIES LOOK FINE FOR THAT LOCATION. AS FOR
THE VALLEYS, THE CHANCES OF 8 INCHES OR MORE ARE LESS THAN 1
OUT OF 2 FOR THE MOST PART, WITH THE BEST CHANCES IN THE
NORTHERN ENDS OF THE VALLEYS IN LOCATIONS LIKE MORAN AND ALPINE.
EVEN HERE, THIS WOULD FALL OVER A LONGER PERIOD OF TIME AND
IMPACTS WOULD NOT RISE TO THE LEVEL OF A WARNING FOR THE MOST
PART. GUSTY WIND WILL ALSO OCCUR ACROSS THE HIGHER ELEVATIONS.
IN THE VALLEYS, THE WIND DOES NOT LOOK ALL THAT SEVERE.
NOW TO SWEETWATER COUNTY. SNOWFALL AMOUNTS HAVE COME DOWN SOMEWHAT
HERE. THE PREVIOUS DISCUSSION SHOWED AROUND A 1 IN 2 CHANCE OF 2
INCHES OR MORE AT ROCK SPRINGS THROUGH THIS EVENING, FOR EXAMPLE. AT
THIS TIME, IT HAS DROPPED DOWN TO AROUND 1 OUT OF 5 WITH MOST
LOCATIONS HAVING LESS OF A CHANCE THAN THAT. SO, NO WINTER
WEATHER ADVISORY WILL BE ISSUED AT THIS TIME. MOST MODELS
THOUGH, BOTH OF THE SYNOPTIC AND MESOSCALE VARIETY, SHOW A
PERIOD OF SNOW MAINLY BETWEEN AROUND 12 PM AND 4 PM WITH A
SHORTWAVE MOVING THROUGH. IT DOESN'T LOOK LIKE A SNOW SQUALL,
BUT THERE COULD BE A BRIEF PERIOD OF HEAVIER SNOW THIS AFTERNOON
ALONG INTERSTATE 80 FOR A TIME. THINGS LOOK DRIER THERE FOR
MONDAY, ALTHOUGH THE GUSTY WIND WILL CONTINUE WITH A JET STREAK
RIDING CLOSE TO THE AREA.
SNOW WILL CONTINUE INTO TUESDAY, ALTHOUGH MODELS DO HAVE MORE
AGREEMENT OF THE SNOW BECOMING LESS INTENSE AFTER 5 AM TUESDAY. WE
MAY END UP EXTENDING THE WARNINGS SOMEWHAT ON FUTURE SHIFTS, BUT WE
WON'T DO IT NOW. THE NEXT SYSTEM WILL THEN APPROACH THE WEST ON
WEDNESDAY OR THURSDAY. THERE CONTINUES TO BE A LOT OF DIVERGENCE IN
THE DETAILS WITH THIS SYSTEM, SO UNCERTAINTY REMAINS HIGH IN THE
EVOLUTION OF THIS SYSTEM.
EAST OF THE DIVIDE...THINGS ARE MORE UNCERTAIN HERE AND WE
CONTINUE TO HAVE WHAT SOUNDS LIKE THE NAME OF A NOVEL, THE
NORTHERN BORDER CONUNDRUM. IN OTHER WORDS, WHAT WILL OCCUR
ACROSS THE NORTHERN PORTIONS OF OUR AREA, ESPECIALLY ALONG AND
NORTH OF A CODY TO GREYBULL TO BUFFALO LINE. THERE CONTINUES TO
BE SOME SPREAD IN THE MODEL SOLUTIONS. WE DO HAVE SOME LIGHT
SNOW FALLING IN BUFFALO AT THE TIME I AM WRITING THIS (AROUND 2
AM). HOWEVER, ALL OTHER LOCATIONS ARE SNOW FREE. RADAR ALSO
SHOWS MOST OF THE SNOW REMAINING TO THE NORTH AND NOT MAKING A
TON OF PROGRESS TO THE SOUTH RIGHT NOW. ALMOST ALL GUIDANCE
KEEPS ONLY LIGHT SNOW OVER THE FAR NORTH AND SOME AREAS KEEP
THINGS DRY THROUGH THE DAY. FOR NOW, WE HAVE SOME CHANCES ACROSS
THE NORTH BUT AMOUNTS REMAIN ON THE LOW SIDE. MOST GUIDANCE IS
NOW SHOWING MOST OF THE SNOW FALLING MONDAY INTO MONDAY NIGHT
AND EVEN INTO TUESDAY. AS FOR THE TRIGGER, THERE WILL BE A
BOUNDARY OVER THE AREA. HOWEVER, COMPARED TO LAST TIME, JET
FORCING IS NOT AS IMPRESSIVE. AS FOR AMOUNTS, OVER THE NEXT 24
HOURS, PROBABILISTIC GUIDANCE IS NOT THAT IMPRESSIVE. THROUGH 5
AM MONDAY, OTHER THAN THE MOUNTAINS, THERE IS ONLY AT MOST A 1
OUT OF 5 CHANCE OF 1 INCH OR MORE OF SNOW. FOR THE PERIOD FROM 5
AM MONDAY THROUGH 5 AM WEDNESDAY, THE CHANCE OF 3 INCHES OR
MORE OF SNOW INCREASES TO AROUND 1 IN 3 OR GREATER ACROSS THE
AFOREMENTIONED AREA. SO, FOR NOW, WE WILL LIKELY HOLD OFF ON ANY
WINTER WEATHER ADVISORIES SINCE THE MOST IMPACTFUL TIME LOOKS
TO BE MONDAY INTO TUESDAY FOR THE MOST PART. AS FOR THE
BIGHORNS, WINTER WEATHER ADVISORIES LOOK FINE HERE AS THE CHANCE
OF A FOOT OR MORE OF SNOW IS LESS THAN 1 OUT OF 4 EXCEPT FOR
SOME ISOLATED PEAKS IN THE FAR NORTHWESTERN PORTIONS OF THE
RANGE.
FURTHER SOUTH, THINGS LOOK MAINLY DRY THROUGH MONDAY NIGHT. WE
WILL ALSO CONTINUE TO HAVE THE CONTRAST IN TEMPERATURES, WITH
HIGHS IN THE TEENS ACROSS NORTHERN WYOMING AND HIGHS IN THE 20S
AND 30S ACROSS CENTRAL WYOMING WHERE SNOW COVER IS LIMITED. THE
BOUNDARY WILL SLIDE SOUTHWARD ON TUESDAY THOUGH AND THIS MAY
SPREAD SOME LIGHT SNOW INTO CENTRAL WYOMING. AMOUNTS LOOK SMALL
AT THIS POINT. IT WILL BRING COLDER TEMPERATURES FOR TUESDAY,
WITH TEMPERATURES AVERAGING 10 TO 15 DEGREES COOLER THAN ON
SUNDAY AND MONDAY. AS FOR THE MIDWEEK SYSTEM, GUIDANCE IS SPLIT
ON ANY POTENTIAL SNOW. BUT EVEN THE MODELS THAT HAVE IT SHOW
ONLY LIGHT AMOUNTS OF PRECIPITATION. TEMPERATURES SHOULD THEN
WARM INTO NEXT WEEKEND AS RIDGING TRIES TO BUILD IN FROM THE
SOUTH.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 340 AM MST SUN FEB 16 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
SNOW HAS RETURNED TO KJAC THIS MORNING, WITH MOST OF WESTERN
PORTIONS OF THE FORECAST AREA BEING IMPACTED BY SUNRISE. IMPACTS
WILL BE MAINLY LIFR/IFR VISIBILITY/MVFR CEILINGS THROUGH THE TAF
PERIOD. KPNA WILL HAVE SIMILAR IMPACTS AFTER 14Z AND AFTER 17Z
AT KBPI. SNOW WILL CONTINUE AT ALL THESE THREE SITES THROUGH
THE REST OF THE TAF PERIOD.
AT KRKS, THE BEST SNOW CHANCES HOLD OFF UNTIL ABOUT 19Z. THERE
ARE INDICATIONS THAT SOME SNOW SHOWERS MAY BRING RAPID DECREASES
IN VISIBILITIES. THESE SHOWERS WILL GENERALLY END BY 02Z, BUT
THERE IS A CHANCE FOR THEM TO LINGER BETWEEN 02Z AND 06Z.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
EXPECTING DRY AND VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD.
THERE COULD BE A COUPLE EXCEPTIONS, THOUGH. AT KCOD, SNOW WILL
BE OCCURRING OVER THE NEARBY MOUNTAINS, AND AN OCCASIONAL SHOWER
MAY IMPACT THE SITE THROUGH THE AFTERNOON. BETTER SNOW CHANCES
COME FROM THE NORTH AROUND 05Z AND CONTINUE THROUGH THE REST OF
THE PERIOD. KCPR MAY ALSO SEE AN OCCASIONAL SNOW SHOWER THIS
AFTERNOON, INDICATED WITH A PROB30 GROUP. WINDS WILL TURN
NORTHERLY BY 00Z AS WELL.
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 STORM WARNING UNTIL 5 AM MST TUESDAY FOR WYZ001-002-012-
024.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR WYZ008-014.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR WYZ013-023-
025.
DISCUSSION...HATTINGS
AVIATION...LAVOIE/WITTMANN
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