761
FXUS65 KMSO 280929
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
329 AM MDT THU MAY 28 2026
DISCUSSION
KEY MESSAGES:
- WARM TEMPERATURES AND ISOLATED STRONG STORMS TODAY, ESPECIALLY
ACROSS NORTHWEST MONTANA AND THROUGH NORTH CENTRAL IDAHO
- PROLONGED HEAVY RAINFALL THIS WEEKEND IN WESTERN MONTANA,
ELEVATING RISKS FOR HYDROLOGIC RESPONSES AND ROCKFALLS
ESPECIALLY NEAR AND ALONG THE CONTINENTAL DIVIDE.
HIGH PRESSURE BUILDING OVER THE REGION WILL BRING THE WARMEST
TEMPERATURES OF THE WEEK TODAY, WITH AFTERNOON VALLEY HIGHS
REACHING THE UPPER 80S TO NEAR 90 DEGREES ACROSS WESTERN MONTANA
AND NORTH-CENTRAL IDAHO. WHILE THUNDERSTORM COVERAGE WILL BE LESS
WIDESPREAD THAN YESTERDAY, SIGNIFICANT MOISTURE REMAINS IN PLACE.
SHOWERS AND STORMS WILL FOCUS PRIMARILY NORTH OF INTERSTATE 90 AND
ACROSS NORTH-CENTRAL IDAHO, INCLUDING THE CAMAS PRAIRIE, WHERE A
FEW STRONGER STORMS COULD PRODUCE GUSTY WINDS, HEAVY RAIN, AND
HAIL. MEANWHILE, ACROSS SOUTHWEST MONTANA, PARTICULARLY SOUTH OF
DILLON, ELEVATED FIRE WEATHER CONCERNS REMAIN THIS AFTERNOON DUE
TO GUSTY WINDS COMBINED WITH LOW HUMIDITY DROPPING INTO THE TEENS.
THE WEATHER PATTERN CHANGES ON FRIDAY AS A LOW-PRESSURE SYSTEM
TRACKS TOWARD THE REGION, BRINGING A WIDESPREAD BAND OF HEAVY
RAIN TO NORTH-CENTRAL IDAHO AND WESTERN MONTANA. THE HEAVIEST
INITIAL RAINFALL IS EXPECTED ALONG THE US-12 AND US-95 CORRIDORS
IN IDAHO BEFORE SPREADING INTO WESTERN MONTANA. THUNDERSTORMS
DEVELOPING IN THE AFTERNOON AND EVENING WILL ENHANCE THESE
HAZARDS, BRINGING THE POTENTIAL FOR INTENSE DOWNPOURS, GUSTY
WINDS, AND HAIL.
THIS SYSTEM WILL SETTLE NEAR THE YELLOWSTONE REGION BY SATURDAY,
TRIGGERING PROLONGED AND EFFICIENT RAINFALL ACROSS WESTERN
MONTANA FROM SATURDAY MORNING THROUGH SUNDAY. BECAUSE RECENT RAINS
HAVE ALREADY SATURATED SOILS AND HIGH-ELEVATION SNOWMELT IS
ONGOING, THIS WEEKEND'S RAINFALL INTRODUCES A RISK FOR SIGNIFICANT
RISES ON LOCAL STREAMS AND RIVERS, ALONGSIDE AN INCREASED
POTENTIAL FOR ROCKFALLS IN STEEP TERRAIN. THE HEAVIEST
PRECIPITATION TOTALS ARE EXPECTED NEAR THE CONTINENTAL DIVIDE,
WHERE THERE IS A 70 TO 90 PERCENT CHANCE OF EXCEEDING 1 INCH OF
RAIN, WITH LOCALIZED AMOUNTS OF 2 TO 3 INCHES POSSIBLE.
ADDITIONALLY, MUCH COOLER AIR ARRIVING WITH THIS SYSTEM WILL CAUSE
SNOW LEVELS TO DROP TO AROUND 6,000 FEET ALONG THE CONTINENTAL
DIVIDE BY SUNDAY MORNING.
AVIATION
AREAS OF FOG AND LOW STRATUS HAVE DEVELOPED THIS
MORNING, PRIMARILY THROUGH NORTH-CENTRAL IDAHO, AND MAY CAUSE
LOCALLY LOWERED CEILINGS AND VISIBILITY THROUGH 28/1400Z.
OTHERWISE, VFR CONDITIONS WILL PREVAIL ACROSS WESTERN MONTANA AND
NORTH-CENTRAL IDAHO TERMINALS TODAY, THOUGH HIGH VALLEY
TEMPERATURES APPROACHING 90 DEGREES WILL CONTRIBUTE TO ELEVATED
DENSITY ALTITUDE. SCATTERED AFTERNOON AND EVENING THUNDERSTORMS
ARE EXPECTED TO DEVELOP, FOCUSING PRIMARILY NORTH OF INTERSTATE 90
AND ACROSS NORTH-CENTRAL IDAHO. WHILE OVERALL CONVECTIVE COVERAGE
IS ANTICIPATED TO BE LOWER THAN YESTERDAY, ANY STORMS THAT FORM
COULD PRODUCE LOCALIZED MVFR/IFR CONDITIONS DUE TO HEAVY DOWNPOURS
AND LOWERED CEILINGS, ALONGSIDE ERRATIC OUTFLOW WIND GUSTS AND
HAIL. AIRFIELDS IN SOUTHWEST MONTANA AND LEMHI COUNTY, INCLUDING
KBTM AND KSMN, WILL EXPERIENCE BREEZY SOUTHEASTERLY SURFACE WINDS
THIS AFTERNOON OUTSIDE OF CONVECTIVE ACTIVITY. TERMINAL IMPACTS
WILL BE SHORT-LIVED, BUT SUDDEN WIND SHIFTS AND LOCALIZED MOUNTAIN
OBSCURATIONS REMAIN A RISK NEAR ANY DEVELOPING CONVECTIVE CELLS
THROUGH THE EVENING HOURS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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