368
FXUS65 KMSO 061929
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
129 PM MDT SAT JUN 6 2026
DISCUSSION
KEY MESSAGES:
- SCATTERED SHOWERS, ISOLATED THUNDERSTORMS, AND COOLER
TEMPERATURES THIS WEEKEND.
- FROST POTENTIAL IN NORTHWEST MONTANA SUNDAY MORNING, BECOMING MORE
WIDESPREAD ON MONDAY MORNING.
- COOL AND WET CONDITIONS TUESDAY THROUGH THURSDAY
A COLD FRONT MOVING THROUGH THE NORTHERN ROCKIES TODAY WILL
MAINTAIN MOSTLY DRY AND BREEZY CONDITIONS, THOUGH ISOLATED
THUNDERSTORMS ARE POSSIBLE IN SOUTHWEST MONTANA NEAR BUTTE. DUE TO
DRY AIR NEAR THE SURFACE, THESE STORMS MAY PRODUCE STRONG WIND
GUSTS UP TO 50 MPH. TONIGHT, LINGERING CLOUD COVER WILL PERSIST
FOR MOST LOCATIONS, BUT CLEARING SKIES IN FAR NORTHWEST MONTANA
WILL ALLOW TEMPERATURES TO DROP INTO THE LOW TO MID 30S. THIS HAS
PROMPTED A FROST ADVISORY FOR LINCOLN COUNTY, WHERE VALLEY FROST
IS EXPECTED.
ON SUNDAY, A LOW-PRESSURE SYSTEM MOVING DIRECTLY OVER WESTERN
MONTANA AND NORTH-CENTRAL IDAHO WILL GENERATE WIDESPREAD SHOWERS,
PRIMARILY SOUTH OF INTERSTATE 90 FROM LATE TONIGHT THROUGH SUNDAY
MORNING. SNOW LEVELS WILL DROP TO AROUND 6,000 FEET, RESULTING IN
1 TO 2 INCHES OF LIGHT ACCUMULATION IN THE BACKCOUNTRY. BY SUNDAY
AFTERNOON, SCATTERED RAIN SHOWERS WILL DEVELOP ACROSS THE REST OF
THE REGION. AS SKIES CLEAR AND DRIER AIR SETTLES IN SUNDAY NIGHT
INTO MONDAY MORNING, WIDESPREAD FROST WILL THREATEN SENSITIVE
VEGETATION IN THE VALLEYS OF WESTERN MONTANA AND THE HIGH VALLEYS
OF NORTH-CENTRAL IDAHO, WHICH MAY REQUIRE ADDITIONAL FROST
ADVISORIES.
MONDAY WILL PROVIDE A BRIEF PERIOD OF CALM WEATHER BEFORE ANOTHER
SYSTEM APPROACHES ON TUESDAY, INCREASING THUNDERSTORM ACTIVITY
ACROSS ALL OF WESTERN MONTANA AND NORTH-CENTRAL IDAHO. BY
WEDNESDAY AND THURSDAY, WEATHER MODELS SUGGEST THIS SYSTEM WILL
MOVE PROGRESSIVELY THROUGH THE REGION, UNLIKE PREVIOUS MODEL RUNS
WHICH SHOWED A SLOWER MOVING SYSTEM. THERE REMAINS A HIGH
PROBABILITY (70 TO 90 PERCENT) OF AT LEAST HALF AN INCH OF RAIN
ACROSS PORTIONS OF NORTH-CENTRAL IDAHO AND NORTHWEST MONTANA ALONG
THE CONTINENTAL DIVIDE, WITH LIGHTER PRECIPITATION EXPECTED IN
THE BROADER VALLEYS OF WESTERN MONTANA. THERE REMAINS A LOWER 10
TO 20 PERCENT CHANCE OF HEAVIER RAINFALL TOTALING 1 TO 2 INCHES OR
MORE ALONG THE DIVIDE. IF THIS WETTER SCENARIO DEVELOPS,
LOCALIZED FLOODING COULD BECOME A CONCERN FOR RECENTLY SATURATED
AREAS, INCLUDING THE MISSION MOUNTAINS AND SURROUNDING VALLEYS.
AVIATION
AN UPPER-LEVEL TROUGH WILL SETTLE OVER THE PACIFIC
NORTHWEST TODAY, GRADUALLY PUSHING A COLD FRONT THROUGH THE
NORTHERN ROCKIES. WHILE MID-LEVEL MOISTURE STREAMS OVERHEAD,
LIMITED DYNAMIC FORCING AND WEAK INSTABILITY WILL KEEP THE
MAJORITY OF REGIONAL PRECIPITATION RESTRICTED TO SCATTERED LIGHT
SHOWERS. VFR CONDITIONS WILL GENERALLY PREVAIL AT TERMINALS,
THOUGH OCCASIONAL MOUNTAIN OBSCURATIONS CAN BE EXPECTED DUE TO
LOWERING CLOUD BASES, PARTICULARLY ACROSS NORTHWEST MONTANA AND
ALONG THE CONTINENTAL DIVIDE. HIGH- RESOLUTION GUIDANCE SUPPORTS A
20% TO 30% CHANCE OF THUNDERSTORM DEVELOPMENT IN SOUTHWEST
MONTANA THIS AFTERNOON, PRIMARILY BETWEEN 20Z AND 02Z, WHICH COULD
BRIEFLY IMPACT KBTM.
A TIGHTENING WESTERLY GRADIENT WILL SUPPORT SUSTAINED SURFACE
WINDS OF 10 TO 15 KNOTS WITH AFTERNOON GUSTS REACHING 15 TO 25
KNOTS. LOCALIZED, ERRATIC GUSTS UP TO 35 KNOTS WILL BE POSSIBLE IN
THE VICINITY OF ANY AFTERNOON THUNDERSTORMS IN SOUTHWEST MONTANA.
SURFACE WINDS ARE FORECAST TO DIMINISH AND DECOUPLE WITHIN THE
VALLEYS BY LATE EVENING, BUT THEY WILL REMAIN ELEVATED ALONG
REGIONAL RIDGETOPS OVERNIGHT. THIS WILL MAINTAIN A RISK FOR
LOCALIZED MECHANICAL TURBULENCE OVER HIGH TERRAIN THROUGH SUNDAY
MORNING. MEANWHILE, ONGOING LIGHT SHOWER ACTIVITY WILL TRANSITION
TO AREAS PRIMARILY ALONG AND SOUTH OF THE I-90 CORRIDOR OVERNIGHT
INTO SUNDAY MORNING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM MDT SUNDAY FOR
KOOTENAI/CABINET REGION.
ID...NONE.
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