500
FXUS65 KRIW 160935
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
235 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 IN WEST AND EAST OF THE DIVIDE. SO, AS LOGIC WOULD AGREE
WITH, 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.
AND 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 RANGE, SO ADVISORIES
LOOK FINE FOR THAT LOCATION. AS FOR THE VALLEYS, THE CHANCES OF 8
INCHES OR MORE IN THE WESTERN VALLEYS 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 WARNING FOR THE MOST PART. GUSTY WIND WILL ALSO OCCUR
ACROSS THE HIGHER ELEVATIONS. IN THE VALLEYS, THE WIND DOES NOT
LOOKS 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 THAT THAT. SO, NO WINTER WEATHER
ADVISORY WILL BE ISSUED AT 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 LOOKS 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
THOUGH. 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 /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 950 PM MST SAT FEB 15 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
THE NEXT WINTER STORM BEGINS TO MOVE IN TO START THE TAF PERIOD. AT
JAC, HI-RES MODELS START TO PUSH IN IMPACTFUL (LOWERING FLIGHT
CATEGORIES CHANCES) AROUND 07Z, WITH THE MAIN PUSH OF SNOW COMING IN
BETWEEN 09Z AND 11Z. VISIBILITIES WILL LARGELY BE HALF A MILE TO A
MILE THROUGH MUCH OF THE PERIOD STARTING BETWEEN 12Z AND 14Z; HAVE
OPTED FOR 1 MILE IN THE TAF, WITH ABOUT A 60% CHANCE OF PREVAILING
CONDITIONS AROUND HALF A MILE. CONDITIONS MAY BEGIN TO IMPROVE AFTER
01Z/MON, BUT CONFIDENCE IS LOW AT THIS RANGE.
AT RKS, THE BEST SNOW CHANCES HOLD OFF UNTIL ABOUT 17Z. THERE ARE
INDICATIONS THAT SOME SNOW SHOWERS MAY BRING RAPID DECREASES IN
VISIBILITIES ALONG WITH GUSTY WINDS. THESE CHANCES ARE THROUGH THE
ENTIRE AFTERNOON. HAVE INCLUDED A PREVAILING SNOW GROUP, BUT THERE
COULD BE PERIODS WHERE SNOW IS NOT FALLING.
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 COD, 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 AT THE VERY END OF THE PERIOD, BUT MAY NEED TO BE PUSHED
BACK INTO THE NEXT PERIOD. CPR MAY ALSO SEE AN OCCASIONAL SNOW
SHOWER THIS AFTERNOON, INDICATED WITH A PROB30 GROUP.
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...WITTMANN
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