693
FXUS65 KMSO 160927
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
327 AM MDT MON MAR 16 2026
DISCUSSION
KEY MESSAGES:
- A WARM FRONT WILL BRING ACCUMULATING SNOW THROUGH THIS MORNING.
EXPECT GENERALLY ONE HALF TO 3 INCHES IN THE VALLEYS, BUT IT IS
COMMON FOR THESE TYPES OF WEATHER SYSTEMS TO PRODUCE HIGHER
AMOUNTS IN FAVORED LOCATIONS. A WINTRY MIX IS ALSO POSSIBLE.
- A STRONG RIDGE OF HIGH PRESSURE WILL BUILD LATER THIS WEEK,
SENDING TEMPERATURES SOARING 15 TO 20 DEGREES ABOVE NORMAL BY
FRIDAY.
- THE RAPID LATE-WEEK WARMING WILL QUICKLY MELT THE FRESH VALLEY
SNOW, WHICH MAY LEAD TO URBAN RUNOFF ISSUES AND PONDING OF
WATER IN LOW-LYING AREAS AND POORLY DRAINED STREETS.
AS A WARM FRONT CONTINUES TO PUSH INTO THE REGION THIS MORNING, IT
IS LIFTING ABUNDANT MOISTURE UP AND OVER OUR EXISTING COLD, DRY
AIR MASS. AS PRECIPITATION BEGINS, EVAPORATIVE COOLING IS QUICKLY
LOCKING IN FREEZING TEMPERATURES FOR THE VALLEYS THIS MORNING.
COMBINED WITH NORTHWESTERLY FLOW ALOFT, THIS CREATES A CLASSIC
SETUP FOR ACCUMULATING SNOW IN THE NARROW VALLEYS OF NORTH-CENTRAL
IDAHO AND WEST-CENTRAL MONTANA, INCLUDING MISSOULA.
STANDARD MODEL GUIDANCE TENDS TO UNDER-FORECAST SNOW AMOUNTS IN
THESE SETUPS, GENERALLY SHOWING LESS THAN AN INCH. HOWEVER, GIVEN
THE ENVIRONMENT, HIGHER AMOUNTS OF 2 TO 4 INCHES ARE ENTIRELY
POSSIBLE. COMMUTERS SHOULD PLAN FOR WINTER DRIVING CONDITIONS AND
EXTRA TRAVEL TIME MONDAY MORNING, AS ROADS WILL LIKELY BE SNOW-
COVERED AND SLICK. ADDITIONALLY, AS SNOW LEVELS RAPIDLY RISE ON
MONDAY, POCKETS OF FREEZING RAIN ARE POSSIBLE, WHICH WOULD FURTHER
COMPLICATE TRAVEL.
FURTHER NORTH TOWARD KALISPELL, THE FORECAST IS TRICKIER. THE
DEEPEST MOISTURE IS EXPECTED TO REMAIN FURTHER SOUTH. WHILE THE
FLATHEAD VALLEY WILL LIKELY SEE SOME SNOW, AMOUNTS SHOULD BE
LIGHT, GENERALLY AN INCH OR LESS, UNLESS THE MOISTURE SHIELD
DRIFTS FURTHER NORTH THAN ANTICIPATED.
BEHIND TODAY'S SYSTEM, A SIGNIFICANT PATTERN CHANGE TAKES HOLD AS
A STRONG RIDGE OF HIGH PRESSURE BUILDS ACROSS THE WESTERN US.
WHILE THE NORTHERN ROCKIES WILL SIT ON THE NORTHERN PERIPHERY OF
THIS RIDGE, ATMOSPHERIC HEIGHTS WILL CLIMB WELL ABOVE AVERAGE,
DRIVING A MAJOR WARMING TREND.
BY THURSDAY AND FRIDAY, TEMPERATURES WILL RUN 15 TO 20 DEGREES
ABOVE NORMAL, PUSHING AFTERNOON HIGHS INTO THE UPPER 50S TO UPPER
60S FOR MANY VALLEY LOCATIONS. DESPITE THE WARMTH, PACIFIC
MOISTURE WILL CONTINUE TO STREAM INTO NORTHWEST MONTANA. THIS WILL
KEEP SHOWERS IN THE FORECAST FOR THE ENTIRE WEEK, PRIMARILY IN THE
MOUNTAINS, WITH SNOW LEVELS RISING REMARKABLY HIGH TO BETWEEN
7,000 AND 8,000 FEET.
URBAN RUNOFF POTENTIAL: WITH THIS RAPID TRANSITION FROM FREEZING
TEMPERATURES AND FRESH SNOW TO WELL- ABOVE-AVERAGE WARMTH, THE
NEWLY DEPOSITED VALLEY SNOWPACK WILL MELT RAPIDLY. EXPECT
LOCALIZED PONDING OF WATER IN LOW-LYING AREAS, POOR DRAINAGE
ZONES, AND URBAN ROADWAYS FROM TUESDAY INTO THE WEEKEND.
NEXT WEEKEND:
THE RIDGE AXIS IS EXPECTED TO SHIFT EASTWARD BY SUNDAY, OPENING
THE DOOR FOR THE NEXT PACIFIC TROUGH TO APPROACH FROM THE
NORTHWEST. THIS WILL LIKELY BRING OUR NEXT CHANCE FOR WIDESPREAD
PRECIPITATION AND COOLER TEMPERATURES, THOUGH THE EXACT TIMING
REMAINS UNCERTAIN.
AVIATION
A WARM FRONT OVER THE REGION IS CAUSING LOW TO
MODERATE CEILINGS AND MINOR VISIBILITY REDUCTIONS WITH LIGHT
PRECIPITATION. PRECIPITATION WILL BE SNOW THIS MORNING, BUT AS THE
WARM FRONT PROGRESSES SNOW LEVELS WILL RAPIDLY RISE, AND
PRECIPITATION WILL CHANGE OVER TO RAIN DURING THE DAY TODAY. THE
REGION WILL REMAIN ON THE PERIPHERY OF A BUILDING RIDGE ACROSS THE
REGION FOR THE REST OF THE WEEK. MOISTURE STREAMING OVER THE RIDGE
WILL CAUSE INTERMITTENT SHOWERS, BUT THE MUCH ABOVE AVERAGE
TEMPERATURES MEAN IT WILL GENERALLY FALL AS RAIN AT AREA
TERMINALS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY FOR
BITTERROOT/SAPPHIRE MOUNTAINS...LOWER CLARK FORK REGION...
MISSOULA/BITTERROOT VALLEYS...POTOMAC/SEELEY LAKE REGION.
ID...WINTER WEATHER ADVISORY UNTIL 11 AM PDT THIS MORNING FOR
SOUTHERN CLEARWATER MOUNTAINS.
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