424
FXUS65 KMSO 232010
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
210 PM MDT MON MAR 23 2026
DISCUSSION
KEY MESSAGES:
- ATMOSPHERIC RIVER TO BRING WIDESPREAD PRECIPITATION, HIGH
ELEVATION SNOW, AND GUSTY WINDS TUESDAY INTO WEDNESDAY
- MOUNTAIN SNOW SHOWERS WEDNESDAY NIGHT INTO THURSDAY, WITH MINOR
ACCUMULATIONS.
- WARMING TREND FRIDAY INTO THE WEEKEND, WITH ABOVE NORMAL
TEMPERATURES.
A RIDGE OF HIGH PRESSURE WILL MOVE OUT OF THE REGION LATER
TONIGHT INTO TUESDAY, SHIFTING THE UPPER-LEVEL FLOW TO THE
SOUTHWEST. A QUICK SHOT OF SUBTROPICAL MOISTURE (A SHORT-LIVED
ATMOSPHERIC RIVER) WILL MOVE INTO THE REGION TUESDAY AFTERNOON AND
OVERNIGHT, PRIMARILY TARGETING NORTH-CENTRAL IDAHO AND NORTHWEST
MONTANA. THIS SYSTEM WILL BRING 0.5 TO 1.5 INCHES OF PRECIPITATION
TO THE HIGHER TERRAIN ALONG THE MONTANA/IDAHO BORDER,
PARTICULARLY IN NORTHWEST MONTANA.
A COLD FRONT WILL PUSH THROUGH THE AREA TUESDAY NIGHT INTO WEDNESDAY. AS
THIS FRONT MOVES IN, SNOW LEVELS WILL DROP TO AROUND 3,000 FEET ACROSS
NORTHWEST MONTANA. FURTHER SOUTH, AHEAD OF THE MAIN COOLING, SNOW LEVELS
WILL STEADILY RISE TO AROUND 7,000 FEET ACROSS LEMHI COUNTY AND SOUTHWEST
MONTANA BY WEDNESDAY AFTERNOON. SNOW LEVELS WILL THEN FALL REGION-WIDE
OVERNIGHT WEDNESDAY INTO THURSDAY MORNING, MEANING ANY LINGERING SHOWERS
DURING THIS PERIOD WILL TRANSITION TO MAINLY SNOW. MOUNTAIN PASSES,
ESPECIALLY LOOKOUT AND MARIAS PASSES, COULD SEE A FEW INCHES OF NEW SNOW
THROUGHOUT THE EVENT, THOUGH TRAVEL IMPACTS ARE EXPECTED TO BE MINIMAL.
THE BIGGEST CONCERN WITH THIS MID-WEEK SYSTEM WILL BE THE WINDS ON
WEDNESDAY. A 40 TO 60 KNOT LOW-LEVEL JET WILL SET UP OVER THE NORTHERN
ROCKIES, BRINGING A BROAD AREA OF BREEZY TO WINDY CONDITIONS. THE
STRONGEST WINDS ARE EXPECTED ACROSS LEMHI COUNTY INTO SOUTHWEST
MONTANA ON WEDNESDAY AFTERNOON. WHILE THERE IS A 25 TO 50% CHANCE
FOR VALLEYS OF WESTERN MONTANA MAY SEE WIND GUSTS OF 30 TO 40
MPH, THE HIGHER TERRAIN ALONG THE CONTINENTAL DIVIDE COULD
EXPERIENCE GUSTS UP TO 60 MPH. LEMHI COUNTY AND THE BUTTE/ANACONDA
AREA CURRENTLY HAVE A 40% TO 60% CHANCE OF SEEING GUSTS IN EXCESS
OF 40 MPH.
ADDITIONALLY, PARTS OF SOUTHWEST MONTANA WILL BECOME VERY DRY WEDNESDAY
AFTERNOON, WITH RELATIVE HUMIDITY VALUES DROPPING INTO THE TEENS. THE
COMBINATION OF LOW HUMIDITY AND STRONG WINDS WILL LEAD TO CRITICAL FIRE
WEATHER CONDITIONS, PROMPTING THE ISSUANCE OF A FIRE WEATHER WATCH.
FOLLOWING THE FRONTAL PASSAGE ON WEDNESDAY, TEMPERATURES WILL DIP BELOW
NORMAL FOR THIS TIME OF YEAR ON THURSDAY, ACCOMPANIED BY A FEW LINGERING
SHOWERS. A RIDGE OF HIGH PRESSURE WILL THEN REBOUND OVER THE REGION BY THE
END OF THE WEEK AND INTO THE WEEKEND, INITIATING A WARMING AND DRYING
TREND. TEMPERATURES WILL CLIMB BACK ABOVE NORMAL BY SATURDAY.
AVIATION
A LOW AMPLITUDE RIDGE WILL KEEP VFR FLYING CONDITIONS
OVER THE REGION THROUGH TODAY. AREAS OF HIGH CLOUDS WILL CONTINUE
TO STREAM OVERHEAD. WESTERLY BREEZES WILL DEVELOP BY EARLY
AFTERNOON, WITH PERIODIC GUSTS OF 10-15KTS FOR AREA TERMINALS.
CLOUD CEILINGS WILL GRADUALLY LOWER WITH TIME INTO TUESDAY AS A
FRONTAL SYSTEM NEARS THE NORTHERN ROCKIES. AN ATMOSPHERIC RIVER IS
EXPECTED TO BRING PRECIPITATION ACROSS NORTHWEST MONTANA STARTING
BY 1800Z TUESDAY (12 PM MDT) WITH MOUNTAIN OBSCURATION LIKELY BY
THE AFTERNOON AND EVENING HOURS. THIS AREA OF PRECIPITATION WILL
SHIFT SOUTHWARDS ACROSS NORTH-CENTRAL IDAHO AND WESTERN MONTANA BY
TUESDAY NIGHT. ALSO MID-LEVEL WESTERLY WINDS WILL RANGE BETWEEN 50
AND 60+ KNOTS TUESDAY EVENING THROUGH WEDNESDAY, SO MOUNTAIN WAVE
ACTIVITY IS EXPECTED OVER AND NEAR THE CONTINENTAL DIVIDE. ON
TUESDAY AFTERNOON MANY TERMINALS MAY SEE BREEZY SOUTHWEST WIND
GUSTS GENERALLY UNDER 25 KNOTS, EXCEPT THE MORE STABLE CONDITIONS
FROM THE RAIN IN NORTHWEST MONTANA(KGPI) WILL LIMIT MUCH WIND.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR EAST BEAVERHEAD.
ID...NONE.
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