059
FXUS65 KRIW 161752
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1052 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 /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1049 AM MST SUN FEB 16 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
A WEATHER SYSTEM WITH SNOW AND WIND IS BRINGING LIFR TO MVFR FLIGHT
CONDITIONS THIS TAF PERIOD TO ALL WEST OF THE DIVIDE TERMINALS. KJAC
IS FORECAST TO HAVE LIFR TO IFR CEILINGS OR VISIBILITIES THROUGH A
MAJORITY OF THIS TAF PERIOD WITH PERIODS OF VISIBILITY IMPROVEMENTS
WITH LIGHTER SNOW BETWEEN 01-10Z. SNOW AND REDUCED FLIGHT CONDITIONS
HAS ALREADY BEGUN AT KPNA BUT HAS TAKEN LONGER TO REACH KBPI. KBPI
SHOULD BEGIN SEEING IMPACTS BETWEEN 20-00Z. ANTICIPATE FREQUENT
MOUNTAIN OBSCURATION WITH SNOW, LOW VISIBILITIES AND LOW CEILINGS.
GUSTY WINDS AT KRKS WILL CONTINUE THIS TAF PERIOD WITH SNOW ALREADY
IMPACTING THE TERMINAL. WIND COMBINED WITH SNOW WILL CREATE IFR
VISIBILITIES WITH HEAVIER BANDS OF SNOW. THERE IS A LOW CHANCE (30%)
OF SNOW AND REDUCED FLIGHT CONDITIONS THROUGH 07Z AND IS REFLECTED
IN THE PROB30 GROUP. KRKS IS LIKELY (GREATER THAN 90% CHANCE) TO BE
THE ONLY WEST OF DIVIDE TERMINAL THAT WILL SEE VFR FLIGHT CONDITIONS
THE SECOND HALF OF THIS TAF PERIOD.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
A WEATHER SYSTEM WILL BRING SNOW AND REDUCED FLIGHT CONDITIONS TO
KCOD AND KCPR THIS TAF PERIOD. LIGHT SNOW AND IFR/MVFR CONDITIONS AT
KBPI IS EXPECTED TO BEGIN BETWEEN 20-00Z BUT COULD (30% CHANCE)
BEGIN AS EARLY AS 18Z. CONFIDENCE IS MUCH LOWER IN DIRECT IMPACTS
AND EXACT TIMING OF MVFR VISIBILITIES WITH SNOW AT KCPR WITH A COLD
FRONT PASSAGE. HOWEVER, NORTH/NORTHEASTERLY FLOW BEHIND THE FRONT
WILL ALLOW FOR THE DEVELOPMENT OF MVFR CEILINGS AFTER 04Z.
KRIW, KLND AND KWRL SHOULD REMAIN SNOW FREE WITH MOSTLY VFR FLIGHT
CONDITIONS THIS TAF PERIOD, EXPECT AT KWRL WHERE MVFR CEILINGS ARE
FORECAST AROUND 14Z.
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 WYZ008-013-
014-023-025.
DISCUSSION...HATTINGS
AVIATION...GERHARDT
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