786
FXUS65 KMSO 240702
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
102 AM MDT TUE MAR 24 2026
DISCUSSION
KEY MESSAGES:
- ATMOSPHERIC RIVER: WIDESPREAD PRECIPITATION, HIGH ELEVATION
SNOW, AND GUSTY WINDS THROUGH WEDNESDAY.
- MOUNTAIN SNOW: SNOW ACCUMULATIONS WILL PRIMARILY IMPACT HIGH
ELEVATIONS ABOVE 6,000 FEET, WITH MINOR TRAVEL IMPACTS ON
MOUNTAIN PASSES.
- WIND AND FIRE RISK: STRONG WINDS ARRIVE WEDNESDAY. COMBINED
WITH LOW HUMIDITY, CONFIDENCE IS GROWING FOR CRITICAL FIRE
WEATHER CONDITIONS EAST OF THE DIVIDE IN SOUTHWEST MONTANA.
- MILD WEEKEND: A WARMING TREND BEGINS FRIDAY, BRINGING ABOVE-
NORMAL TEMPERATURES BY SATURDAY.
A QUICK SHOT OF SUBTROPICAL MOISTURE-A SHORT-LIVED ATMOSPHERIC
RIVER (AR) WILL ARRIVE ACROSS NORTH-CENTRAL IDAHO AND NORTHWEST
MONTANA BY MIDAFTERNOON TODAY. THIS SYSTEM IS EXPECTED TO DELIVER
0.5 TO 1.5 INCHES OF LIQUID PRECIPITATION ACROSS THE HIGHER
TERRAIN AND ALONG THE MONTANA/IDAHO BORDER, WITH THE HEAVIEST
TOTALS IN NORTHWEST MONTANA. SNOW LEVELS WILL RISE SHARPLY THIS
AFTERNOON, WITH RAIN FALLING ABOVE 7,000 FEET THROUGH TONIGHT.
A POTENT COLD FRONT REMAINS ON TRACK TO ARRIVE WEDNESDAY MORNING,
WITH SNOW LEVELS FALLING QUICKLY ACROSS NORTHWEST MONTANA,
FALLING NEAR 3,500 BY WEDNESDAY AFTERNOON. CONVERSELY, AHEAD OF
THE FRONT IN SOUTHWEST MONTANA AND LEMHI COUNTY, SNOW LEVELS WILL
STEADILY RISE TO NEAR 7,000 FEET THROUGH WEDNESDAY AFTERNOON. BY
WEDNESDAY NIGHT AND INTO THURSDAY MORNING, SNOW LEVELS WILL FALL
REGION-WIDE, TRANSITIONING ANY LINGERING SHOWERS TO SNOW. WHILE
LOOKOUT AND MARIAS PASSES COULD SEE A FEW INCHES OF NEW
ACCUMULATION, TRAVEL IMPACTS ARE EXPECTED TO REMAIN MINIMAL.
THE PRIMARY CONCERN WITH THIS MID-WEEK SYSTEM REMAINS THE WIND ON
WEDNESDAY. A 40 TO 60 KNOT LOW-LEVEL JET WILL SET UP OVER THE
NORTHERN ROCKIES, CREATING WIDESPREAD BREEZY TO WINDY CONDITIONS.
THE STRONGEST WINDS ARE ANTICIPATED ACROSS LEMHI COUNTY AND INTO
SOUTHWEST MONTANA WEDNESDAY AFTERNOON, WHERE THERE IS A 50% TO 70%
CHANCE OF GUSTS EXCEEDING 40 MPH. WHILE THE HIGHER TERRAIN ALONG
THE CONTINENTAL DIVIDE COULD SEE GUSTS UP TO 60 MPH, WESTERN
MONTANA VALLEYS CARRY A 25% TO 50% CHANCE FOR GUSTS IN THE 30 TO
40 MPH RANGE.
CRITICAL FIRE WEATHER CONDITIONS ARE A MAJOR CONCERN FOR
SOUTHWEST MONTANA, EAST OF THE DIVIDE WITHIN THE EAST BEAVERHEAD
ON WEDNESDAY AFTERNOON. AS THE WINDS PEAK, RELATIVE HUMIDITY
VALUES ARE FORECAST TO DROP INTO THE TEENS. THIS COMBINATION OF
HIGH WIND AND LOW HUMIDITY HAS PROMPTED THE ISSUANCE OF A FIRE
WEATHER WATCH.
FOLLOWING THE FRONTAL PASSAGE, TEMPERATURES WILL DIP BELOW
SEASONAL NORMALS ON THURSDAY BEFORE A RIDGE OF HIGH PRESSURE
REBOUNDS LATE IN THE WEEK. THIS WILL INITIATE A NOTABLE WARMING
AND DRYING TREND, WITH TEMPERATURES RETURNING TO ABOVE NORMAL BY
SATURDAY.
AVIATION
A FAST-MOVING ATMOSPHERIC RIVER (AR) ARRIVES THIS AFTERNOON,
BRINGING WIDESPREAD RAIN AND TERRAIN-OBSCURING CLOUDS TO NORTH-
CENTRAL IDAHO AND NORTHWEST MONTANA. CEILINGS AND VISIBILITY
REDUCTIONS WILL BECOME MORE COMMON AFTER 23/2100Z.
CEILINGS/VISIBILITY: VFR CONDITIONS WILL DETERIORATE TO AREAS OF
MVFR BY MID-AFTERNOON (APPROX. 21Z-00Z) ACROSS NORTH-CENTRAL IDAHO
AND NORTHWEST MONTANA AS WIDESPREAD PRECIPITATION BEGINS. EXPECT
PERSISTENT MOUNTAIN OBSCURATION ALONG THE MONTANA/IDAHO BORDER AND
THE CONTINENTAL DIVIDE THROUGH THE PERIOD.
WIND/TURBULENCE: LOW-LEVEL WIND SHEAR (LLWS) AND MECHANICAL
TURBULENCE WILL BECOME THE PRIMARY HAZARDS TOWARD THE END OF THE
24-HOUR PERIOD (APPROX 21-06Z). SURFACE GUSTS OF 25-40 KT ARE
EXPECTED IN WESTERN MONTANA VALLEYS BY LATE WEDNESDAY MORNING AS A
COLD FRONT PASSES, WITH GUSTS EXCEEDING 40 KT OVER RIDGES AND
THROUGH WIND-PRONE CANYONS IN SOUTHWEST MONTANA AND LEMHI COUNTY
(NEAR KTBM AND KSMN) BY WEDNESDAY AFTERNOON.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH
WEDNESDAY EVENING FOR EAST BEAVERHEAD.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page