874
FXUS65 KMSO 260858
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
258 AM MDT FRI JUN 26 2026
DISCUSSION
KEY MESSAGES:
- DRAMATIC SHIFT TO COLDER AND WET WEATHER TODAY INTO THE WEEKEND,
AS TEMPERATURES FALL 20-30 DEGREES.
- SIGNIFICANT HYPOTHERMIA RISK ACROSS BACKCOUNTRY AND HIGH
ELEVATION AREAS WITH SNOW AND COLD TEMPERATURES ABOVE 6,000
FEET.
A COLD FRONT REMAINS ON TRACK TO SWEEP ACROSS THE AREA THIS
MORNING, BRINGING A DRASTIC CHANGE IN THE WEATHER THROUGH THE
WEEKEND. WIDESPREAD RAIN SHOWERS WILL ACCOMPANY THE FRONTAL
PASSAGE, WITH RAIN FOCUSING ACROSS NORTH-CENTRAL IDAHO THIS
MORNING, BEFORE SPREADING THROUGH WESTERN MONTANA THIS AFTERNOON.
HIGH-RESOLUTION MODELS SUGGEST THUNDERSTORMS WILL DEVELOP ACROSS
CENTRAL IDAHO ALONG THE FRONTAL BOUNDARY, BEFORE SPREADING ACROSS
LEMHI COUNTY AND SOUTHWEST MONTANA DURING THE AFTERNOON AND
EVENING. SNOW LEVELS WILL FALL THROUGH THE WEEKEND AS A CLOSED LOW
SLOWLY MOVES IN SOUTH-CENTRAL IDAHO AND COLD AIR ALOFT MOVES
OVERHEAD. SNOW WILL FOCUS ABOVE 6,500 FEET ACROSS LEMHI COUNTY, ID
MOUNTAIN RANGES, THE BITTEROOT, SAPPHIRE, ANACONDA-PINTLER,
MOUNTAINS AND ALONG CONTINENTAL DIVIDE SATURDAY EVENING INTO
MONDAY MORNING. WINTER STORM WATCHES HAVE BEEN ISSUED FOR THESE
AREAS, GIVEN COLD TEMPERATURES AND WET HEAVY SNOW BRINGING AN
ELEVATED RISK FOR HYPOTHERMIA AND DIFFICULT TRAVEL ACROSS
BACKCOUNTRY AREAS. HEAVY, WET SNOW MAY LEAD TO DOWNED TREES,
POTENTIALLY BLOCKING ACCESS TO BACKCOUNTRY ROADS AND TRAVEL.
LOWER ELEVATIONS WILL EXPERIENCE WIDESPREAD RAIN TOMORROW INTO
SUNDAY MORNING AS THE UPPER LEVEL LOW SPINS ALONG AND SOUTH OF THE
I-90 CORRIDOR. LOCATIONS SOUTH OF A LINE FROM MISSOULA TO HELENA
WILL SEE THE HIGHEST RAIN AMOUNTS DURING THIS PERIOD, HAVING A
70-90 PERCENT CHANCE OF PICKING UP 1 INCH OR MORE OF RAIN BY
SUNDAY MORNING. THOSE PLANNING OUTDOOR RECREATION ON ANY SMALL
STREAMS AND RIVERS, SHOULD BE PREPARED FOR RAPIDLY CHANGING FLOWS
AND MUCH COOLER TEMPERATURES.
LOOKING AHEAD TO SUNDAY, THE CLOSED LOW WILL PICK UP SPEED,
TRACKING THROUGH WESTERN MONTANA, BEFORE SETTLING EAST OF THE
DIVIDE THROUGH MONDAY MORNING. AS THE LOW TRACKS ALONG AND EAST OF
THE DIVIDE, PRECIPITATION SHIFT NORTHWARD IN NORTHWEST MONTANA,
WITH THE HEAVIEST RAIN FOCUSING ACROSS GLACIER PARK AND ALONG THE
DIVIDE. WIDESPREAD RAIN WILL CONTINUE ACROSS NORTHWEST MONTANA FOR
MUCH OF THE DAY MONDAY, BEFORE THE LOW DEPARTS EASTWARD ON
TUESDAY. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON THIS
LOWS TRACK, WITH PRECIPITATION AMOUNTS TRENDING HIGHER. MEDIAN
(MOST-LIKELY) PRECIPITATION AMOUNTS OF 0.50-1.00 INCHES ARE
FORECAST ACROSS NORTHWEST MONTANA NEAR THE IDAHO BORDER, WITH
AMOUNTS INCREASING TO 1.00-2.00 INCHES ALONG THE US-93 CORRIDOR
FROM EUREKA, THROUGH THE FLATHEAD AND MISSION VALLEYS. THE HIGHEST
TOTALS ARE EXPECTED ACROSS GLACIER PARK, AND THE MISSION AND SWAN
MOUNTAINS, WHERE 2.00-3.00 INCHES COULD FALL. THOSE HEADING INTO
GLACIER PARK SUNDAY INTO MONDAY SHOULD PREPARE FOR COLD AND RAW
CONDITIONS, ESPECIALLY AT LOGAN PASS AND THE HIGHER ELEVATIONS.
GLOBAL ENSEMBLE GUIDANCE SUGGESTS UNSETTLED WEATHER WILL CONTINUE
TUESDAY INTO WEDNESDAY AS PACIFIC DISTURBANCES MOVE ACROSS THE
PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES. THESE SYSTEMS WILL
KEEP SHOWERS AND THUNDERSTORMS IN THE FORECAST.
AVIATION
AN UPPER LEVEL LOW APPROACHING THE REGION LAST NIGHT
IS CAUSING RAIN TO SPREAD ACROSS THE REGION. SOME THUNDERSTORMS
ARE POSSIBLE THIS AFTERNOON WITH SOME HIGH RESOLUTION MODELS
SHOWING STORMS INITIATING AROUND 26/18Z. BUT MOST PRECIPITATION
WILL NOT BE FROM THUNDERSTORMS AS A BROAD REGION OF CLOUDS SPREADS
OUT OVER THE REGION. ALSO, THE SHADING FROM THE CLOUDS WILL
INHIBIT CONVECTION KEEPING ANY THUNDERSTORMS FROM GETTING TOO
STRONG TODAY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY MORNING
FOR BITTERROOT/SAPPHIRE MOUNTAINS...BUTTE/BLACKFOOT REGION.
ID...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY MORNING
FOR EASTERN LEMHI COUNTY...WESTERN LEMHI COUNTY.
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