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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