510  
FXUS65 KRIW 171049  
AFDRIW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RIVERTON WY  
349 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 /12Z TAFS THROUGH 12Z TUESDAY/
 
 
ISSUED AT 347 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. CONFIDENCE  
REMAINS LOW AS GUIDANCE IS A BIT ALL OVER THE PLACE, HOWEVER  
WILL KEEP IFR VIS/MVFR CIG TO START THE FORECAST. VISIBILITY  
LOOKS TO DROP TO LIFR AFTER 14Z AS THE NEXT ROUND OF HEAVIER  
SNOW MOVES IN. IFR/MVFR CONDITIONS WILL REMAIN IN PLACE THROUGH  
THE TAF PERIOD AS SNOW CONTINUES.  
 
VLIFR/LIFR CONDITIONS FROM LOW CLOUDS WILL CONTINUE AT KBPI/KPNA  
THROUGH 16Z-18Z. VFR CONDITIONS ARE THEN EXPECTED THROUGH THE  
REST OF THE DAY, WITH MVFR CEILINGS RETURNING TO KPNA AFTER 06Z.  
 
THE OTHER PLACE OF NOTE IS KRKS, WHERE SOME AFTERNOON/EARLY EVENING  
SNOW SHOWERS COULD IMPACT THE SITE, BRINGING BRIEF SNOW AND  
VISIBILITY IMPACTS. LOW CONFIDENCE IN WHEN SNOW WILL END AT KPNA.  
 
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.  
 
VLIFR/LIFR CONDITIONS HAVE ALSO DEVELOPED AT KCPR AND ARE  
EXPECTED THROUGH MUCH OF THE MORNING. SNOW CHANCES WILL MAINLY  
BE OVER NORTHERN WYOMING (KCOD/KWRL) FOR MONDAY 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.  
 
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...LAVOIE/WITTMANN  
 
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