958
FXUS65 KMSO 280843
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
143 AM MST SUN DEC 28 2025
DISCUSSION
KEY MESSAGES:
-MUCH COLDER TEMPERATURES SUNDAY MORNING, WITH MANY VALLEY
LOCATIONS DROPPING INTO THE SINGLE DIGITS TO LOW TEENS.
-BUILDING RIDGE (EARLY NEXT WEEK): COLD AND MUCH DRIER CONDITIONS
STARTING SUNDAY. POTENTIAL FOR FOG AND LOW STRATUS TO DEVELOP.
SOME OF THE COLDEST AIR HAS SETTLED OVER THE NORTHERN ROCKIES.
BOTH TODAY AND MONDAY MAY HAVE SIMILAR TEMPERATURES TO START THE
DAY. THE OTHER KEY COMPONENT TO THE FORECAST IS RISING HEIGHTS,
VIA AN UPPER LEVEL HIGH PRESSURE RIDGE. IN ESSENCE, THOSE RISING
HEIGHTS WARMS THE UPPER ATMOSPHERE PRODUCING STRONG INVERSIONS.
WHILE NO CHANGES HAVE BEEN MADE TO TEMPERATURES BY MID-WEEK,
SUBSEQUENT FORECASTS WILL LIKELY NEED TO MAKE ADJUSTMENTS AS THE
NBM TRIES TO WARM THE VALLEYS TO FAST.
THE INDICATORS THAT WILL BE WATCHED FOR THE DEVELOPMENT OF STRONG
COLD POOLS ARE THE DEVELOPMENT AND EXPANSION OF VALLEY FOG AND
STRATUS, HIGH TEMPERATURES THAT COOL SLIGHTLY EACH DAY UNDER THE
RIDGE, AND A SMALL RANGE OF TEMPERATURES FROM LOW TO HIGH
TEMPERATURE. THE RIDGE IS EXPECTED TO REMAIN IN PLACE THROUGH AT
LEAST THURSDAY, THIS MAY KEEP IMPACTS FROM STAGNANT VALLEY AIR TO
A MINIMUM BUT WILL BE WATCHED CLOSELY AS THIS PERIOD EVOLVES.
HOW THE RIDGE BREAKS DOWN CURRENTLY IS UNCERTAIN AS LONG RANGE
MODELS HAVE MULTIPLE EQUALLY PLAUSIBLE SOLUTIONS. MORE TO COME IN
FUTURE FORECASTS.
AVIATION
THE COLDEST MORNINGS OF THE SEASON AND DEVELOPMENT OF
HIGH PRESSURE WILL RULE THE FORECAST THROUGH MONDAY. INITIALLY,
FOG AND LOW STRATUS WILL BE LOW PROBABILITY AT AREA TERMINALS.
EACH DAY THROUGH WEDNESDAY IT IS EXPECTED THIS IMPACT WILL
INCREASE IN BOTH AREA AND LONGEVITY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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