518
FXUS65 KRIW 171755
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1055 AM MST MON FEB 17 2025
KEY MESSAGES
- SNOW CONTINUES ACROSS WESTERN AND NORTHERN WYOMING TODAY AND
TONIGHT.
- SNOW AND COLDER AIR SPREADS INTO CENTRAL WYOMING ON TUESDAY.
- DRIER WEATHER IS EXPECTED FRIDAY INTO THE WEEKEND WITH A SLOW
WARMING TREND.
DISCUSSION
ISSUED AT 242 AM MST MON FEB 17 2025
STILL A LOT GOING ON TONIGHT AS THE ACTIVE PATTERN CONTINUES ACROSS
THE AREA. WITH THE CONTRASTS, WE WILL AGAIN SPLIT THE DISCUSSION
INTO WEST AND EAST OF THE DIVIDE,.
WEST OF THE DIVIDE...AS I WRITE THIS, THE AREA IS IN A BIT OF A LULL
WITH SNOWFALL INTENSITY. RADAR DOES SHOW MORE PRECIPITATION ACROSS
IDAHO THOUGH AND THESE WAVES OF PRECIPITATION WILL CONTINUE TO MAKE
THEIR WAY INTO THE REGION. SNOW WILL CONTINUE AT VARYING RATES
THROUGH THE DAY AND INTO TONIGHT. THE EPICENTER OF THE SNOW
CONTINUES TO BE, GEE WHAT A SURPRISE, THE TETONS WHERE THERE IS
A 4 OUT OF 5 CHANCE OF ANOTHER 12 INCHES OF SNOW OVER THE NEXT
24 HOURS OR SO. THE OTHER MOUNTAIN RANGES HAVE LESS OF A CHANCE,
BUT THE POSSIBILITY OF 6 INCHES OR MORE REMAINS OVER 4 OUT OF 5
IN THESE LOCATIONS. AS A RESULT, WE WILL CONTINUE THE
HIGHLIGHTS FOR THE MOUNTAINS AS IS. AS FOR THE VALLEY LOCATIONS,
MOST LOCATIONS HAVE AT LEAST A 1 IN 2 CHANCE OF 3 INCHES OR
MORE. IT IS LESS THAN THAT AT THE SOUTHERN ENDS OF THE VALLEYS,
ESPECIALLY NEAR THE TOWNS OF JACKSON, AFTON AND PINEDALE. MOST
OF THESE LOCATIONS ONLY HAVE ADVISORIES THOUGH, SO THESE LOOK
FINE FOR NOW. AS FOR SWEETWATER COUNTY, THERE WILL BE SOME SNOW
SHOWERS AROUND BUT NOT A LOT OF ACCUMULATION. THERE WILL BE A
JET STREAK OVER NORTHERN COLORADO THOUGH, AND THIS WILL BE
ENOUGH TO KEEP GUSTY WINDS OVER THE AREA THROUGH TUESDAY BEFORE
SUBSIDING FOR WEDNESDAY.
THE NEXT QUESTION IS THE QUESTION OF EXTENDING THE WARNINGS INTO
TUESDAY. MOST GUIDANCE SHOWS THE DEEPEST MOISTURE MOVING AWAY FROM
THE AREA BY SUNRISE TUESDAY. THE ENSEMBLE PROBABILISTIC
GUIDANCE IS SHOWING AT MOST A 1 IN 4 CHANCE OF 6 INCHES OR MORE
OVER THE 24 HOURS FROM 5 AM TUESDAY TO 5 AM WEDNESDAY WITH THE
MOST LIKELY ACCUMULATIONS IN THE MOUNTAINS OF 2 TO 4 ADDITIONAL
INCHES. THE VALLEYS HAVE LESS THAN 1 IN 7 CHANCE OF 2 INCHES OR
MORE THROUGH THE SAME PERIOD. THERE HAS BEEN SOME INCONSISTENCY
THOUGH IN HOW THIS EVOLVES. WE WILL LET THE DAY SHIFT TAKE
ANOTHER LOOK AT THIS WITH ANY POSSIBLE EXTENSIONS.
THE NEXT SYSTEM THEN APPROACHES FOR WEDNESDAY NIGHT INTO THURSDAY.
THIS SYSTEM HAS BEEN TRENDING WEAKER THOUGH. RIGHT NOW, ENSEMBLE
GUIDANCE ONLY GIVES AT MOST A 1 IN 3 CHANCE OF 6 INCHES OF SNOW OR
MORE ACROSS THE HIGHER ELEVATIONS OF THE TETONS AND SALT AND WYOMING
RANGES WITH AT MOST A 1 IN 5 CHANCE OF 4 INCHES OR MORE IN THE
VALLEYS. IF THIS WORKS OUT, NO HIGHLIGHTS WOULD BE NEEDED OR AT MOST
SOME WINTER WEATHER ADVISORIES FOR THE MOUNTAINS. THIS DEFINITELY
DOES NOT LOOK AS POTENT AS THE CURRENT SYSTEM.
QUIETER WEATHER SHOULD FOLLOW THIS AS MOST GUIDANCE SHOWS RIDGING
BUILDING INTO THE STATE FOR FRIDAY AND THE WEEKEND. THERE COULD BE A
FEW MOUNTAIN SNOW SHOWERS, BUT IMPACTS WOULD BE MINIMAL TO NONE.
EAST OF THE DIVIDE...THINGS REMAIN IN FLUX HERE. THE MILLION DOLLAR
QUESTION REMAINS THE EXTENT OF THE SNOW ACROSS NORTHERN WYOMING WITH
A STALLED FRONTAL BOUNDARY ACROSS NORTHERN WYOMING. THERE IS NOT A
TON OF JET SUPPORT AT THIS TIME, AND AS A RESULT, MOST OF THE
SNOWFALL RATES HAVE BEEN ON THE LIGHT SIDE. ENSEMBLE GUIDANCE
REMAINS SIMILAR TO YESTERDAY WITH THE MAXIMUM SNOWFALL AMOUNTS IN
THE LOWER ELEVATIONS LARGELY EAST OF A POWELL TO LOVELL LINE, WITH A
GREATER THAN 3 IN 4 CHANCE OF 2 INCHES OR MORE THROUGH TUESDAY
MORNING. OTHER LOCATIONS LIKE CODY AND BUFFALO HAVE AROUND A 1 IN 5
CHANCE AT THIS TIME. FURTHER SOUTH ACROSS CENTRAL WYOMING, THINGS
LOOK LARGELY QUIET. WE WILL ONCE AGAIN HAVE A CONTRAST IN
TEMPERATURES ACROSS THE AREA LIKE THE PAST COUPLE OF DAYS. THE
NORTHERN THIRD OF THE AREA WILL HAVE WELL BELOW NORMAL TEMPERATURES,
WITH SOME AREAS LIKELY STAYING AROUND 10 DEGREES. IN CENTRAL
WYOMING, BEING SOUTH OF THE FRONT AND HAVING LITTLE SNOW COVER,
TEMPERATURES WILL RISE INTO THE 30S FOR SOME LOCATIONS.
THIS AREA MAY NEED AN EXTENSION OF THE ADVISORY. A JET STREAK
WILL BE APPROACHING THE AREA ON TUESDAY AS THE BOUNDARY MOVES
SOUTHWARD, ENHANCING FORCING. HERE, I AM BECOMING INCREASINGLY
CONCERNED ABOUT CODY, AS THIS IS A GOOD PATTERN FOR THEM,
ESPECIALLY WITH THE LOW LEVEL NORTHEASTERLY FLOW PROVIDING THE
UPSLOPE. THE DEEPER MOISTURE WILL BE DEPARTING THOUGH. THE
CHANCE OF 2 INCHES OF SNOW IN CODY FROM TUESDAY MORNING TO
WEDNESDAY MORNING IS NOW UP TO 2 OUT OF 5 AND THIS COULD BE
UNDERDONE. THE JET STREAK WILL ALSO KICK THE FRONTAL BOUNDARY
SOUTH, SPREADING ARCTIC AIR ACROSS THE ENTIRE REGION TUESDAY
INTO TUESDAY NIGHT. THIS WILL ALSO SPREAD SOME SNOW SOUTHWARD
INTO CENTRAL WYOMING. MOISTURE IS LIMITED BUT WITH THE JET
ENERGY THERE COULD BE SOME CONVECTIVE SHOWERS THAT OVERPERFORM.
AMOUNTS SOUTH OF THE OWL CREEK RANGE LOOK SMALL THOUGH,
GENERALLY AN INCH OR LESS UNLESS BANDING DEVELOPS.
QUIETER WEATHER THEN RETURNS AS RIDGING BUILDS INTO THE AREA FOR
WEDNESDAY. THIS WILL BE A VERY COLD DAY THOUGH WITH HIGH
TEMPERATURES AVERAGING 20 TO 25 DEGREES BELOW SEASONAL NORMALS.
A PACIFIC SYSTEM MAY THEN MOVE IN FOR THURSDAY. IT HAS A SMALL
CHANCE OF BRINGING SOME SHOWERS, BUT THE PATTERN IS NOT
FAVORABLE FOR A HEAVY SNOW. QUIETER WEATHER IS THEN EXPECTED FOR
FRIDAY AND INTO THE WEEKEND AS RIDGING MOVES OVER THE AREA.
TEMPERATURES SHOULD GRADUALLY WARM THROUGH THE PERIOD, WITH THE
SLOWEST WARM UP ACROSS NORTHERN AREAS WITH THE DEEPEST SNOWPACK.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1054 AM MST MON FEB 17 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
MAIN SNOW IMPACTS WILL BE AT KJAC THROUGH THE PERIOD. A HEAVIER BAND
OF SNOW TO START THE PERIOD WILL BRING OCCASIONAL IFR/LIFR
CONDITIONS THROUGH 19Z TO 20Z, BUT MVFR/IFR CONDITIONS WILL PERSIST
THROUGH THE AFTERNOON. ANOTHER ROUND OF HEAVIER SNOW LOOKS TO MOVE
IN OVERNIGHT, AND WILL PERSIST THROUGH TUESDAY MORNING. MODELS
REMAIN IN DISAGREEMENT ABOUT EXACT TIMING OF HEAVIEST SNOW AND
LOWEST CIG/VSBY READINGS FOR THE ENTIRE PERIOD.
VLIFR/LIFR CONDITIONS FROM LOW CLOUDS AT KBPI/KPNA WILL IMPROVE AT
THE START OF THE PERIOD. THERE IS LOW CONFIDENCE IN TIMING, BUT
THERE IS A 20-30% CHANCE OF SNOW SHOWERS THIS AFTERNOON AT KPNA, BUT
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, PERSISTING THROUGH MUCH OF TUESDAY MORNING.
THE OTHER PLACE OF NOTE IS KRKS, WHERE SOME AFTERNOON/EARLY EVENING
SNOW SHOWERS COULD IMPACT THE SITE, BRINGING BRIEF SNOW AND
VISIBILITY IMPACTS, BUT VFR WILL GENERALLY PREVAIL THROUGH THE
PERIOD.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
A BAND OF SNOW WILL IMPACT KCPR TO START THE PERIOD, WITH MVFR
CONDITIONS GENERALLY PERSISTING AT KCOD, KCPR, AND KWRL TERMINALS
THROUGH MUCH OF THE PERIOD. SNOW CHANCES WILL MAINLY BE OVER
NORTHERN WYOMING (KCOD/KWRL) THIS AFTERNOON. THERE IS A CHANCE A
SNOW SHOWER COULD IMPACT ANY SITE, BUT FOR KLND AND KRIW THOSE
CHANCES ARE 15% OR LESS. WINDS WILL MAINLY BE OUT OF THE
NORTH/NORTHEAST THROUGH THE PERIOD. STEADIER SNOW WILL MOVE INTO
KCOD AND KWRL LATE IN THE PERIOD, WITH IFR CONDITIONS LIKELY (80%
CHANCE).
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 WYZ004-008-
013-014-023-025.
DISCUSSION...HATTINGS
AVIATION...HENSLEY
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