168  
FXUS65 KMSO 261152 CCA  
AFDMSO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MISSOULA MT  
319 AM MST FRI FEB 26 2021  
   
DISCUSSION
 
REGIONAL RADAR AND SATELLITE ANALYSIS DEPICT THE  
NEXT SURGE OF PACIFIC MOISTURE HAS MOVED ONSHORE INTO WESTERN OREGON  
AND WASHINGTON EARLY THIS MORNING. WIDESPREAD SNOWFALL IS EXPECTED  
BY THE MORNING COMMUTE ACROSS NORTH CENTRAL IDAHO AS THIS SURGE OF  
MOISTURE MOVES ACROSS EASTERN WASHINGTON. HIGH CONFIDENCE EXISTS FOR  
A PERIOD OF HEAVY SNOWFALL ACROSS THE CLEARWATER MOUNTAINS THIS  
MORNING THROUGH THE LATE AFTERNOON HOURS, WHERE A WINTER STORM  
WARNING REMAINS IN EFFECT. FORECAST SOUNDINGS AND CROSS- SECTIONS  
DEPICT A FAVORABLE SCENARIO FOR SNOWFALL RATES EXCEEDING ONE INCH  
PER HOUR, PARTICULARLY ACROSS MOUNTAIN LOCALES IN IDAHO COUNTY.  
 
A SHORTWAVE TROUGH AND ASSOCIATED SURFACE COLD FRONT WILL PUSH  
ACROSS WESTERN MONTANA BY THE EARLY AFTERNOON. MODEST CONFIDENCE  
EXISTS FOR A PERIOD OF ACCUMULATING SNOWFALL ACROSS THE CAMAS  
PRAIRIE FRIDAY AFTERNOON AS THE UPPER LEVEL FLOW BECOMES  
NORTHWESTERLY. HIGH RESOLUTION MODEL GUIDANCE CONTINUES TO ADVERTISE  
THE POTENTIAL FOR INTENSE SNOW SHOWERS ALONG AND SOUTH OF THE I-90  
CORRIDOR IN WESTERN MONTANA THIS AFTERNOON AND EARLY EVENING. GIVEN  
RELATIVELY WARM SURFACE TEMPERATURES AND A LATE FEBRUARY SUN ANGLE,  
ROAD IMPACTS WILL BE HIGHLY VARIABLE. NONETHELESS, THE AFTERNOON  
COMMUTE WILL LIKELY BE IMPACTED BY THESE SNOW SHOWERS. MODEL  
GUIDANCE HAS TRENDED HIGHER ON SNOWFALL ACCUMULATIONS THIS AFTERNOON  
AND EARLY EVENING ACROSS THE MISSOULA AND BITTERROOT VALLEYS,  
SUGGESTING A 50/50 CHANCE FOR 2 INCHES OR MORE OF SNOWFALL BY LATE  
THIS EVENING. FURTHER WINTER WEATHER HIGHLIGHTS MAY BE WARRANTED FOR  
THE BITTERROOT AND MISSOULA VALLEY AS THESE SHOWERS BEGIN TO COME  
TOGETHER. SNOW SHOWER ACTIVITY WILL GRADUALLY RETREAT TO THE HIGHER  
TERRAIN FRIDAY NIGHT INTO SATURDAY MORNING.  
 
A RELATIVELY UNSTABLE NORTHWESTERLY FLOW WILL PROMOTE SNOW SHOWER  
ACTIVITY SATURDAY ACROSS THE NORTHERN ROCKIES. PERIODIC VISIBILITY  
REDUCTIONS WILL BE THE PRIMARY IMPACT TO VALLEY LOCATIONS, WITH  
LITTLE TO ANY ACCUMULATION EXPECTED. THE CLEARWATER, BITTERROOT, AND  
MISSION MOUNTAINS WILL CONTINUE TO SEE ACCUMULATING SNOW, ALBEIT,  
LIGHT AMOUNTS.  
 
A DRYING AND WARMING TREND IS EXPECTED SUNDAY AND MONDAY AS HIGH  
PRESSURE BUILDS ACROSS THE NORTHERN ROCKIES. MODEL GUIDANCE  
CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE WEATHER PATTERN  
TUESDAY THROUGH THURSDAY THIS UPCOMING WEEK. GUIDANCE DOES AGREE  
WITH A SPLITTING UPPER TROUGH APPROACHING THE PACIFIC NORTHWEST  
COASTLINE MONDAY. MODEL SOLUTIONS QUICKLY DIVERGE AS THIS SYSTEM  
APPROACHES THE NORTHERN ROCKIES. THE BOTTOM LINE IS TEMPERATURES  
WILL REMAIN NEAR SEASONAL AVERAGES WITH HIGHS IN THE UPPER 30S TO  
LOW 40S ACROSS VALLEY LOCATIONS. PERIODS OF LIGHT TO MODERATE  
MOUNTAIN SNOWFALL ARE POSSIBLE DURING THIS PERIOD, PARTICULARLY  
ALONG THE IDAHO AND MONTANA BORDER. /LUKINBEAL  
 

 
   
AVIATION
 
HIGH CONFIDENCE EXISTS FOR WIDESPREAD SNOWFALL  
ACROSS NORTH CENTRAL IDAHO THROUGH 27/0000Z AS A PACIFIC STORM  
SYSTEM MOVES INTO THE AREA. PERIODIC REDUCTIONS IN VISIBILITY WILL  
CONTINUE ACROSS WEST CENTRAL MONTANA THIS MORNING AS SNOW SHOWERS  
TRAVERSE ACROSS THE CLEARWATER AND BITTERROOT MOUNTAINS. CONVECTIVE  
SNOW SHOWERS AND BANDS WILL DEVELOP FOR AREAS ALONG AND SOUTH OF THE  
I-90 CORRIDOR IN WESTERN MONTANA THIS AFTERNOON. SUDDEN VISIBILITY  
REDUCTIONS WILL BE COMMON AS SNOW SHOWERS WILL BE CAPABLE OF  
PRODUCING SNOWFALL RATES OF UP TO ONE INCH PER HOUR.  
BRIEF IFR TO LIFR VISIBILITY REDUCTIONS ARE POSSIBLE AT KMSO FROM  
26/1800Z TO 27/0300Z. SNOW SHOWER ACTIVITY WILL GRADUALLY DIMINISH  
FOLLOWING 27/0600Z, WITH THE MAJORITY OF ACCUMULATING SNOW BEING  
CONFINED THE HIGHER TERRAIN. /LUKINBEAL  
 

 
   
MSO WATCHES/WARNINGS/ADVISORIES
 
 
MT... WINTER WEATHER ADVISORY UNTIL 8 AM MST THIS MORNING WEST  
GLACIER REGION.  
 
WINTER WEATHER ADVISORY UNTIL 8 AM MST THIS MORNING  
KOOTENAI/CABINET REGION.  
 
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON  
BITTERROOT/SAPPHIRE MOUNTAINS.  
 
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON  
POTOMAC/SEELEY LAKE REGION.  
 
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON LOWER  
CLARK FORK REGION.  
 
ID...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON LOWER  
HELLS CANYON/SALMON RIVER REGION.  
 
WINTER STORM WARNING UNTIL 4 PM PST THIS AFTERNOON NORTHERN  
CLEARWATER MOUNTAINS.  
 
WINTER STORM WARNING UNTIL 4 PM PST THIS AFTERNOON SOUTHERN  
CLEARWATER MOUNTAINS.  
 
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON  
OROFINO/GRANGEVILLE REGION.  
 

 
 

 
 
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