977
FXUS65 KMSO 181026
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
326 AM MST WED FEB 18 2026
DISCUSSION
KEY MESSAGES:
- RELATIVELY DRY, WESTERLY PUSH OF ARCTIC AIR THIS MORNING WILL
DROP WIND CHILLS TO BELOW ZERO ALONG AND WEST OF THE DIVIDE.
- ACCUMULATING SNOW ACROSS NORTH-CENTRAL IDAHO, SPREADING INTO
WESTERN MONTANA TODAY.
- HIGHEST PROBABILITIES FOR BELOW ZERO TEMPERATURES EXIST ALONG
AND WEST OF DIVIDE THURSDAY AND FRIDAY MORNINGS.
- QUIET WEEKEND FOLLOWED BY UNSETTLED PATTERN NEXT WEEK THAT
COULD HELP TO BUILD MORE MOUNTAIN SNOWPACK.
ARCTIC AIR IS CURRENTLY MOVING WESTWARD ACROSS THE CONTINENTAL
DIVIDE INTO THE FLATHEAD VALLEY AND THE BLACKFOOT/BUTTE REGION.
PRESSURE GRADIENTS WILL SUPPORT GAP WINDS WITH GUSTS EXCEEDING 35
MPH THROUGH BADROCK CANYON TO GLACIER PARK INTERNATIONAL AIRPORT,
AS WELL AS THE HELMVILLE AREA THROUGH MIDDAY. THE COMBINATION OF
SINGLE-DIGIT TEMPERATURES AND BREEZY CONDITIONS WILL PRODUCE SUB-
ZERO WIND CHILLS THIS MORNING, POSING A RISK TO NEWBORN LIVESTOCK
AND NECESSITATING WINTER SURVIVAL KITS FOR TRAVELERS ALONG THE
US-2 AND MT-200 CORRIDORS EAST OF BONNER.
FURTHER WEST, A WELL-DEFINED SURFACE LOW IS CENTERED OVER THE
INTERSECTION OF NE OREGON AND SE WASHINGTON. AN ASSOCIATED
DEFORMATION BAND OF MODERATE PRECIPITATION IS PROJECTED TO PIVOT
NORTHWARD INTO THE IDAHO PANHANDLE AND THE MONTANA/IDAHO BORDER
REGION THIS MORNING. WINTER WEATHER ADVISORIES REMAIN IN EFFECT
FOR THESE AREAS DUE TO HIGH CONFIDENCE IN SLICK TRAVEL CONDITIONS.
HOWEVER, HAVE OPTED TO WITHHOLD ADVISORIES FOR THE
MISSOULA/BITTERROOT VALLEYS AND THE SEELEY LAKE REGION. WHILE
LIGHT ACCUMULATIONS ARE POSSIBLE, THE ENCROACHING ARCTIC AIRMASS
FEATURES SIGNIFICANTLY DRIER AIR THAT SHOULD LIMIT SNOWFALL
EFFICIENCY AND OVERALL TOTALS IN THESE EASTERN VALLEYS.
MODEL GUIDANCE REMAINS INCONSISTENT REGARDING THE PRECISE PLACEMENT
OF FORCING ASSOCIATED WITH TODAY'S SHORTWAVE. HOWEVER, HI-RES
MODELS HIGHLIGHT A CORRIDOR OF CONVECTIVE ENHANCEMENT ACROSS
SANDERS AND MINERAL COUNTIES THIS AFTERNOON. GIVEN THE POTENTIAL
FOR LOCALIZED INSTABILITY, THESE AREAS MAY SEE BRIEF PERIODS OF
HIGHER SNOWFALL RATES COMPARED TO THE BROADER REGION.
AS THE ARCTIC AIRMASS SETTLES IN TONIGHT, TEMPERATURES WILL PLUMMET.
PROBABILITIES FOR SUB-ZERO LOWS ARE ROUGHLY 30 TO 40% FOR THE
FLATHEAD VALLEY/EUREKA, BUT EXCEED 90% FOR HIGH-VALLEY LOCATIONS
LIKE POLEBRIDGE, MARIAS PASS, AND WESTERN POWELL COUNTY. LIGHT,
TERRAIN-DRIVEN SNOW SHOWERS MAY PERSIST THROUGH FRIDAY AS THE COLD
AIR LINGERS.
SHORTWAVE RIDGING BUILDS OVER THE WEEKEND, LEADING TO A DRYING
TREND AND A GRADUAL MODERATION OF THE AIRMASS. BY EARLY NEXT
WEEK, ENSEMBLE CLUSTERS STRONGLY AGREE ON A DEEP LONGWAVE TROUGH
IMPACTING THE WESTERN U.S. NBM GUIDANCE CURRENTLY REFLECTS HIGH
PRECIPITATION PROBABILITIES (60 TO 80%) FOR MONDAY AND TUESDAY.
NOTABLY, RISING 700MB TEMPERATURES WILL PUSH SNOW LEVELS INTO THE
3500 TO 4500 FT RANGE. THIS SUGGESTS A TRANSITION TOWARD MIXED
PRECIPITATION OR RAIN FOR THE LOWER VALLEYS, WHILE SNOW
ACCUMULATIONS REMAIN LIKELY FOR THE MOUNTAINS.
AVIATION
A COMPLEX TERMINAL ENVIRONMENT PERSISTS TODAY AS AN
ARCTIC FRONT BLEEDS WESTWARD ACROSS THE CONTINENTAL DIVIDE. AT
KGPI, EXPECT GUSTY NORTHEAST WINDS EXCEEDING 30 KNOTS THROUGH 18Z
DUE TO TIGHT GRADIENTS NEAR BADROCK CANYON, RESULTING IN LOW-LEVEL
WIND SHEAR AND MECHANICAL TURBULENCE. CEILINGS WILL FLUCTUATE
BETWEEN MVFR AND IFR AS A DEFORMATION BAND PIVOTS ACROSS THE
REGION. HOWEVER, THE ENCROACHING ARCTIC AIRMASS IS NOTABLY DRY,
WHICH MAY LIMIT SNOW ACCUMULATION EFFICIENCY AT KMSO AND KBTM.
FURTHER WEST, HIGHER CONFIDENCE IN PERSISTENT IFR/LIFR CONDITIONS
EXISTS FOR NORTH-CENTRAL IDAHO AND THE MONTANA/IDAHO BORDER
(INCLUDING LOOKOUT PASS) WHERE DEEPER MOISTURE RESIDES.
ADDITIONALLY, HI-RES GUIDANCE SUGGESTS POTENTIAL FOR CONVECTIVE
SNOW SHOWERS ACROSS SANDERS AND MINERAL COUNTIES THIS AFTERNOON,
WHICH COULD LEAD TO RAPID, LOCALIZED REDUCTIONS IN VISIBILITY AND
SUDDEN CEILING DROPS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR
FLATHEAD/MISSION VALLEYS...KOOTENAI/CABINET REGION.
WINTER WEATHER ADVISORY UNTIL 8 AM MST THURSDAY FOR WEST GLACIER
REGION.
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR LOWER
CLARK FORK REGION.
WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR
BITTERROOT/SAPPHIRE MOUNTAINS.
ID...WINTER WEATHER ADVISORY UNTIL 1 PM PST THIS AFTERNOON FOR
NORTHERN CLEARWATER MOUNTAINS...SOUTHERN CLEARWATER
MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR
OROFINO/GRANGEVILLE REGION.
WINTER WEATHER ADVISORY UNTIL 8 AM PST THURSDAY FOR LOWER HELLS
CANYON/SALMON RIVER REGION.
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