004
FXUS65 KRIW 172316
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
416 PM MST MON FEB 17 2025
KEY MESSAGES
- MODERATE TO HEAVY SNOWFALL WILL CONTINUE ACROSS WESTERN
WYOMING THROUGH TUESDAY. TRAVEL IMPACTS ARE EXPECTED,
ESPECIALLY ACROSS MOUNTAIN PASSES.
- LIGHTER SNOWFALL IS EXPECTED ACROSS NORTHERN WYOMING THROUGH TUESDAY,
WITH THE BEST CHANCES FOR TRAVEL IMPACTS ACROSS THE BIGHORN
BASIN.
- REMAINING AREAS WILL SEE LIGHT SNOW CHANCES ON TUESDAY.
- NEXT SYSTEM ARRIVES WEDNESDAY EVENING TO WESTERN WYOMING.
FURTHER OUT, WARMER THAN NORMAL TEMPERATURES EXPECTED FOR THE
WEEKEND.
DISCUSSION
ISSUED AT 411 PM MST MON FEB 17 2025
SNOW CONTINUES TODAY ACROSS WESTERN WYOMING AS THE MOIST, WESTERLY
FLOW REMAINS IN PLACE. THE HEAVIEST REMAINING SNOW THERE IS EXPECTED
THIS AFTERNOON AND EVENING. RATES WILL TAPER A BIT OVERNIGHT AS
PACIFIC MOISTURE DECREASES. HOWEVER, SNOW WILL NOT END COMPLETELY,
AND INSTEAD CHANCES WILL REMAIN FAIRLY STEADY THROUGH TUESDAY.
ACCORDINGLY, THE WINTER STORM WARNING HAS BEEN EXTENDED THROUGH
TUESDAY EVENING FOR THE WESTERN MOUNTAINS. THAT SAID, THERE IS SOME
ADDED UNCERTAINTY FOR TUESDAY AFTERNOON AS A NORTHWESTERLY, 100 KNOT
UPPER JET STREAK ARRIVES AND SNOW BECOMES MORE BANDED. THIS COULD
RESULT IN SOME AREAS SEEING ENHANCED SNOWFALL RATES; HOWEVER, THE
BEST FORCING WITH THIS IS LIKELY TO BE JUST TO THE EAST. REGARDLESS,
THE WESTERN VALLEYS ARE LESS LIKELY TO SEE ADDITIONAL, IMPACTFUL
SNOW DURING THIS PERIOD, AND WE WILL NOT CONTINUE THOSE HIGHLIGHTS
PAST TUESDAY MORNING.
THE FORECAST CONTINUES TO BE CHALLENGING FOR AREAS EAST OF THE
DIVIDE, AND PARTICULARLY ACROSS THE BIGHORN BASIN. THIS AREA
CONTINUES TO BE INFLUENCED BY A STALLED FRONT THAT HAS SET UP ACROSS
NORTHERN WYOMING AND SOUTHERN MONTANA. LIGHT SNOW IS CURRENTLY
FALLING ACROSS EASTERN PORTIONS OF THE BASIN. THIS ACTIVITY WILL
PICK UP A BIT THIS EVENING AS THE TROUGH DROPS SLIGHTLY FARTHER
SOUTH AND THE JET STREAK APPROACHES. WE WILL ALSO SEE LIGHTER SNOW
FILL IN TO REMAINING PORTIONS OF THE BASIN OVERNIGHT, AS WELL AS
JOHNSON COUNTY. BY LATE TUESDAY MORNING THE JET STREAK WILL BE OVER
THE AREA, WHICH WILL HELP TO ENHANCE LIFT AND LIKELY RESULT HIGHER
SNOWFALL RATES. HOWEVER, SNOW WILL BECOME MORE BANDED IN NATURE, AND
THERE STILL EXISTS A WIDE VARIETY OF SOLUTIONS FOR JUST HOW MUCH
SNOW FALLS ACROSS THE BIGHORN BASIN. GIVEN THE TIMING ON THIS, WE
HAVE EXTENDED THE WINTER WEATHER ADVISORY FOR THE EASTERN BIGHORN
BASIN (AND THE WESTERN BIGHORNS) THROUGH TUESDAY AFTERNOON. WE ARE
STILL SEEING THE POTENTIAL FOR 3 TO 6 INCHES HERE, THOUGH LOCALIZED
HIGHER AMOUNTS ARE POSSIBLE (AROUND A 55 PERCENT CHANCE OF MORE THAN
4 INCHES FOR GREYBULL AND LOVELL, WITH CHANCES INCREASING FARTHER
NORTH AND EAST). THE BIGGER QUESTIONS IS ACROSS WESTERN PORTIONS OF
THE BASIN (CODY FOOTHILLS), WHICH CAN BE FAVORED FOR PERIODS OF
HIGHER SNOWFALL RATES IN THIS TYPE OF SETUP. RIGHT NOW, WE ARE
STILL NOT CONFIDENT THAT WE WILL GET AMOUNTS HIGH ENOUGH TO
JUSTIFY WINTER HIGHLIGHTS, BUT WE WILL BE CLOSELY WATCHING THIS
POTENTIAL; THE BEST CHANCE FOR HEAVIER SNOW HERE WILL BE FROM
MID TUESDAY MORNING THROUGH TUESDAY AFTERNOON.
LIGHT SNOW WILL PUSH DOWN INTO CENTRAL WYOMING TUESDAY AFTERNOON AS
THE FRONT FINALLY DROPS SOUTH. ACCUMULATIONS HERE WILL BE LIGHT,
GENERALLY UNDER AN INCH THROUGH TUESDAY EVENING. OUT OF THESE AREAS,
CASPER WILL HAVE THE BEST CHANCE OF SEEING TWO INCHES (AROUND A 30
PERCENT CHANCE). OTHERWISE, SOUTHERN WYOMING WILL REMAIN GUSTY AND
WARMER AS THE FRONT STALLS TO THE NORTH. HOWEVER, LIGHT SNOW
WILL STILL BE POSSIBLE HERE TUESDAY NIGHT AS TEMPERATURES DROP
AFTER SUNSET.
SNOW EVERYWHERE WILL MOSTLY COME TO AN END BY THE EARLY MORNING
HOURS OF WEDNESDAY. AFTER A FAIRLY UNEVENTFUL DAY, THE NEXT
SYSTEM WILL PUSH IN BY WEDNESDAY EVENING ACROSS WESTERN WYOMING.
GUIDANCE HAS BEEN ALL OVER THE PLACE WITH THIS SYSTEM, BUT
CURRENT THINKING IS THIS WILL BE A FAIRLY LIGHT AND QUICK SNOW
EVENT FOR THE WEST WITH SUB-ADVISORY AMOUNTS OF SNOW THROUGH
THURSDAY. AS FOR OTHER LOCATIONS, THERE MAY BE A PERIOD OF
UPSLOPING FLOW EAST OF THE DIVIDE FOR THURSDAY, WHICH MAY BRING
AT LEAST LIGHT SNOW TO THESE AREAS. HOWEVER, WITH LOW CONFIDENCE
IN THIS SCENARIO, WE HAVE KEPT ONLY LIGHT POPS IN EAST OF THE
DIVIDE FOR NOW. FURTHER OUT, ENSEMBLE CLUSTER GUIDANCE IS
STRONGLY FAVORING A STRONG RIDGE BUILDING IN AS WE APPROACH THE
WEEKEND. THIS WOULD LEAD TO WIDESPREAD WARMER THAN NORMAL
TEMPERATURES.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 411 PM MST MON FEB 17 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
MAIN SNOW IMPACTS WILL BE AT KJAC THROUGH THE PERIOD. ANOTHER ROUND
OF HEAVIER SNOW LOOKS TO MOVE IN OVERNIGHT AND WILL PERSIST THROUGH
TUESDAY MORNING WITH LIKELY IFR CONDITIONS EXPECTED.
FOR KBPI AND KPNA TERMINALS, MOSTLY VFR CONDITIONS ARE EXPECTED
THROUGH AROUND 06Z TONIGHT. MODELS INDICATE THAT THERE IS A 60-70%
CHANCE OF THE LOW CLOUDS/FOG RETURNING OVERNIGHT, WITH MOST LIKELY
OCCURRENCE AT KBPI, PERSISTING THROUGH MUCH OF TUESDAY MORNING.
AT KRKS, VFR WILL GENERALLY PREVAIL THROUGH THE PERIOD WITH GUSTY
WESTERLY WINDS.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
MVFR CONDITIONS GENERALLY CONTINUE TO PERSIST AT KCOD, KCPR, AND
KWRL TERMINALS THROUGH MUCH OF THE PERIOD. MOST LIKELY SNOW CHANCES
(60-80%) WILL MAINLY BE OVER NORTHERN WYOMING (KCOD/KWRL). KCPR WILL
ALSO START OFF THE PERIOD WITH A 30-40% CHANCE OF SNOW SHOWERS WITH
OCCASIONAL IFR CONDITIONS. ALTHOUGH THERE IS A CHANCE A SNOW SHOWER
COULD IMPACT ANY SITE, FOR KLND AND KRIW THOSE CHANCES ARE 15% OR
LESS. SNOW CHANCES AT KLND AND KRIW WILL INCREASE TO 30-40% LATE IN
THE PERIOD. SNOW WILL BE BANDED AND SHOWERY IN NATURE AND IF A SNOW
BAND MOVES DIRECTLY OVER A TERMINAL, LOCALIZED IFR TO LIFR
CONDITIONS ARE POSSIBLE, OTHERWISE VFR-MVFR WILL PREVAIL. WINDS WILL
MAINLY BE OUT OF THE NORTH/NORTHEAST THROUGH THE PERIOD.
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 11 PM MST TUESDAY FOR WYZ001-002-
012-024.
WINTER WEATHER ADVISORY UNTIL 5 PM MST TUESDAY FOR WYZ004-008-
014.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR WYZ013-023-
025.
DISCUSSION...MYERS
AVIATION...HENSLEY
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