977
FXUS65 KRIW 162303
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
403 PM MST SUN FEB 16 2025
KEY MESSAGES
- MODERATE TO HEAVY SNOWFALL WILL CONTINUE ACROSS WESTERN
WYOMING THROUGH MONDAY NIGHT. TRAVEL IMPACTS ARE EXPECTED,
ESPECIALLY ACROSS MOUNTAIN PASSES.
- LIGHTER SNOWFALL IS EXPECTED ACROSS NORTHERN WYOMING TONIGHT THROUGH
TUESDAY, WITH THE BEST CHANCES FOR TRAVEL IMPACTS ACROSS THE
BIGHORN BASIN.
- REMAINING AREAS WILL SEE LIGHT SNOW CHANCES THROUGH TUESDAY.
- UNCERTAINTY INCREASES FOR A POSSIBLE MIDWEEK SYSTEM. WARMER
TEMPERATURES MAY BE ON THE WAY FOR NEXT WEEKEND.
DISCUSSION
ISSUED AT 359 PM MST SUN FEB 16 2025
THE LATEST WINTER STORM OF THE SEASON ARRIVED EARLY THIS MORNING TO
WESTERN WYOMING WITHIN THE NORTHWESTERLY FLOW. SNOWFALL RATES HAVE
INCREASED OVER THE LAST FEW HOURS OWING TO A PACIFIC MOISTURE SURGE
THROUGH THE SNAKE RIVER PLAIN. THE OVERALL SYNOPTIC SETUP REMAINING
LARGELY UNCHANGED OVER THE NEXT COUPLE OF DAYS WILL MAKE FOR A
FAIRLY STEADY PERIOD OF SNOWFALL ACROSS WESTERN WYOMING. TOTALS HAVE
TRENDED UP AS LATE FOR THE MOUNTAINS, WITH 2+ FEET POSSIBLE FOR THE
TETONS THROUGH MONDAY NIGHT. THE HEAVIEST SNOW IS EXPECTED AFTER
SUNSET THIS EVENING THROUGH MONDAY MORNING AS THE MOIST, UPSLOPING
SOUTHWESTERLY FLOW IS MAXIMIZED. RATES SHOULD THEN DECREASE SLIGHTLY
BY MONDAY NIGHT AS JET ENERGY AND MOISTURE TAPER A BIT. STILL,
MODERATE TO HEAVY SNOW WILL CONTINUE INTO TUESDAY, AND THE CURRENT
WINTER HIGHLIGHTS MAY END UP NEEDING EXTENDED. THE WESTERN VALLEYS
WILL CONTINUE TO SEE LIGHTER SNOW THROUGH THE EVENT, WITH AMOUNTS
GENERALLY IN THE 4 TO 8 INCH RANGE.
SNOW IS ALSO BEING OBSERVED ACROSS SWEETWATER COUNTY, OWING TO THE
INITIAL MOISTURE SURGE WITH THIS SYSTEM. THIS WILL CONTINUE THROUGH
THE EVENING, SUPPORTED IN PART BY THE ARRIVAL OF ADDITIONAL JET
ENERGY. ACCUMULATION WILL BE LIGHT, WITH ONLY A 50 PERCENT CHANCE TO
EXCEED 2 INCHES FOR MOST OF THE AREA. STILL, THIS IS USUALLY ENOUGH
TO CAUSE SOME TRAVEL IMPACTS, ESPECIALLY ALONG THE I-80 CORRIDOR.
AS USUAL WITH WEST OR NORTHWEST FLOW SETUPS WITH NO ACCOMPANYING
LOW, THE REMAINDER OF THE AREA WILL NOT BE AS FAVORED FOR SNOW.
THERE WILL BE PLENTY OF CHANCES FOR AT LEAST LIGHT ACCUMULATION,
THOUGH, ESPECIALLY ACROSS NORTHERN WYOMING. A NEARLY STATIONARY
FRONTAL BOUNDARY HAS SET UP FROM NORTHWEST TO SOUTHEAST ACROSS
SOUTHERN MONTANA TODAY. THIS FEATURE, COMBINED WITH A FAVORABLE
NORTHWESTERLY/WESTERLY UPSLOPING FLOW AND DECENT UPPER JET SUPPORT,
WILL SUPPORT PERIODS OF HEAVIER SNOWFALL FOR NORTHERN AND EASTERN
PORTIONS OF THE BIGHORN BASIN, ESPECIALLY TOWARD THE END OF THE
EVENT ON MONDAY EVENING AS THE FRONT FINALLY STARTS TO DROP SOUTH.
WITH 3 TO 6 INCHES NOW FORECAST FOR EASTERN PORTIONS OF THE BIGHORN
BASIN, WE HAVE ISSUED A WINTER WEATHER ADVISORY THERE VALID
TONIGHT THROUGH MONDAY NIGHT. NOTABLY, THERE IS SOME GUIDANCE
THAT IS EVEN MORE BULLISH THERE, WITH THE POTENTIAL FOR HIGHER
AMOUNTS IN THE GREYBULL TO LOVELL VICINITY (AROUND A 40% CHANCE
FOR AT LEAST 6 INCHES). OTHERWISE, THIS WILL NOT BE A
PARTICULARLY COLD SYSTEM, AND HIGHS ACROSS CENTRAL AND SOUTHERN
WYOMING WILL REACH THE MID 30S ON MONDAY. HOWEVER, AREAS NORTH
OF A SHOSHONI TO CASPER LINE WILL REMAIN UNDER A COLD POOL
MONDAY AND WILL NOT GET MUCH WARMER THAN THE LOW 20S (AND NEAR
THE MONTANA BORDER ON MONDAY - SINGLE DIGITS). THE SOUTHERN HALF
OF THE AREA WILL SEE A GUSTY WEST WIND ON MONDAY, THOUGH GUSTS
WILL NOT BE TOO IMPRESSIVE, GENERALLY REMAINING UNDER 35 MPH.
THE FRONT WILL DROP SOUTH ON TUESDAY, MAKING FOR A COLDER DAY EAST
OF THE DIVIDE WITH CONTINUED LIGHT SNOW ACROSS WESTERN AND NORTHERN
WYOMING. GUIDANCE IS HINTING AT THE NEXT SYSTEM ARRIVING SOMETIME IN
THE WEDNESDAY TO FRIDAY TIMEFRAME. HOWEVER, THERE IS STILL QUITE A
LOT OF SPREAD IN SOLUTIONS FOR THIS. IN FACT, ENSEMBLE GUIDANCE IS
NOW 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 354 PM MST SUN FEB 16 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
A WINTER SYSTEM CONTINUES BRINGING SNOW AND REDUCED FLIGHT
CONDITIONS TO MOST WEST OF THE DIVIDE TERMINALS. KJAC IS EXPECTED TO
HAVE LOW MVFR TO IFR FLIGHT CONDITIONS MOST OF THIS TAF PERIOD.
LIGHTER SNOW AND MORE PERSISTENT MVFR CONDITIONS ARE FORECAST AFTER
17Z, HOWEVER IFR CONDITIONS BEYOND 17Z CANNOT BE RULED OUT.
ANTICIPATE FREQUENT MOUNTAIN OBSCURATION WITH SNOW, LOW VISIBILITIES
AND LOW CEILINGS.
KPNA AND KBPI HAVE STRUGGLED TO HAVE CONSISTENT SNOW AND ASSOCIATED
REDUCED FLIGHT CONDITIONS TODAY; THUS, CONFIDENCE IN PERSISTENT SNOW
IS MUCH LESS COMPARED TO THE PRIOR FORECAST. THAT BEING SAID,
CONFIDENCE IS HIGHER THAT KPNA WILL SEE DIRECT IMPACTS WITH SNOW AT
VARIOUS TIMES THROUGH 18Z COMPARED TO KBPI DUE TO A MORE FAVORABLE
FLOW. SKIES HAVE BEGUN TO CLEAR MORE THAN EXPECTED AND THIS TREND
SHOULD CONTINUE. WITH MORE CLEAR SKIES IN COMBINATION WITH SNOW
ALREADY ON THE GROUND AND LIGHT WINDS, CONFIDENCE IS INCREASING IN
AN OVERNIGHT IFR CLOUD DECK AT KBPI AND KPNA ONCE SNOW CHANCES
DIMINISH AFTER 04Z. THIS CLOUD DECK IS FORECAST TO BREAK UP BY
MIDDAY ON MONDAY LEAVING VFR FLIGHT CONDITIONS FOR THE REST OF THE
TAF PERIOD.
AS OF 23Z, A BAND OF SNOW CREATING IFR FLIGHT CONDITIONS IS DIRECTLY
IMPACTING KRKS. THIS WILL CONTINUE THROUGH 04Z WITH A LOW
PROBABILITY (30%) OF MVFR VISIBILITIES WITH LINGERING LIGHT SNOW AND
WIND LASTING UNTIL 07Z. GUSTY WINDS WILL RETURN ON MONDAY WITH VFR
FLIGHT CONDITIONS.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
A WEATHER SYSTEM WILL BRING SNOW CHANCES AND ASSOCIATED REDUCED
FLIGHT CONDITIONS TO KCOD THIS TAF PERIOD. LOW VFR VISIBILITIES AND
IFR CEILINGS WITH LIGHT SNOW ARE FORECAST BETWEEN 05-13Z. AT KCPR
NORTH/NORTHEASTERLY FLOW BEHIND A COLD FRONT WILL ALLOW FOR THE
DEVELOPMENT OF MVFR TO IFR CEILINGS AROUND 04Z. THESE LOW CEILINGS
COULD LINGER THROUGH THE REMAINDER OF THE TAF PERIOD BUT CONFIDENCE
AT THIS TIME IS TOO LOW TO PUT AS A PREVAILING GROUP BEYOND 20Z.
KRIW, KLND AND KWRL SHOULD REMAIN SNOW FREE WITH MOSTLY VFR FLIGHT
CONDITIONS THIS TAF PERIOD, EXCEPT AT KWRL WHERE MVFR CEILINGS ARE
FORECAST AROUND 17Z.
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 FROM 11 PM THIS EVENING TO 5 AM MST
TUESDAY FOR WYZ004.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR WYZ008-013-
014-023-025.
DISCUSSION...MYERS
AVIATION...GERHARDT
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