269
FXUS65 KMSO 080644
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1244 AM MDT MON JUN 8 2026
DISCUSSION
KEY MESSAGES:
- WIDESPREAD FROST THIS MORNING
- COOL AND WET CONDITIONS TUESDAY THROUGH WEDNESDAY
TODAY THROUGH WEDNESDAY:
A CHILLY START TO THE WORKWEEK IS UNDERWAY UNDER MOSTLY CLEAR
SKIES AS HIGH PRESSURE SETTLES OVER THE REGION. FROST ADVISORIES
REMAIN IN EFFECT THROUGH MID-MORNING, AS MORNING LOWS ARE EXPECTED
TO DROP INTO THE LOW TO MID-30S ACROSS MANY VALLEY LOCATIONS;
SENSITIVE VEGETATION SHOULD BE PROTECTED. AN UPPER-LEVEL TROUGH
MOVING ONTO THE PACIFIC NORTHWEST COAST THIS AFTERNOON WILL
STRENGTHEN SOUTHWESTERLY FLOW ALOFT, CAUSING HIGH- AND MID-LEVEL
CLOUDS TO GRADUALLY LOWER AND THICKEN.
VIRGA SHOWERS WILL BECOME COMMON BY THIS EVENING AS THE MID-
LEVELS SATURATE. RAIN WILL EVENTUALLY REACH THE GROUND AND BECOME
WIDESPREAD OVERNIGHT INTO TUESDAY MORNING, WITH PERIODS OF SHOWERS
CONTINUING THROUGH WEDNESDAY. ADDITIONALLY SCATTERED
THUNDERSTORMS ARE EXPECTED TUESDAY AFTERNOON AND EVENING. THE
HEAVIEST RAINFALL IS FORECAST ACROSS NORTH-CENTRAL IDAHO AND ALONG
THE CONTINENTAL DIVIDE IN NORTHWEST MONTANA, WHERE A HALF-INCH OR
MORE IS LIKELY (70 TO 90 PERCENT CHANCE). BROAD WESTERN MONTANA
VALLEYS WILL SEE LIGHTER RAINFALL AMOUNTS DUE TO DOWNSLOPING
EFFECTS. IN ADDITION TO THE RAIN, BREEZY WINDS OF 25 TO 35 MPH AND
NOTICEABLY COOLER TEMPERATURES WILL CREATE RAW, COLD CONDITIONS
IN THE HIGH COUNTRY. BACKCOUNTRY RECREATIONISTS SHOULD PREPARE FOR
WINTER-LIKE WEATHER, AS SNOW LEVELS WILL DROP TO ROUGHLY 6,000 TO
6,500 FEET BY WEDNESDAY MORNING, WITH LIGHT ACCUMULATIONS OF 1 TO
2 INCHES POSSIBLE.
THURSDAY THROUGH SUNDAY:
MOST ENSEMBLE CLUSTERS CONTINUE TO INDICATE A DRIER TREND FOR
THURSDAY. ANOTHER ROUND OF FROST IS POSSIBLE THURSDAY MORNING,
THOUGH IT CURRENTLY APPEARS LESS WIDESPREAD THAN THIS MORNING'S
EVENT.
MOST GUIDANCE POINTS TOWARD A LINGERING TROUGH ACROSS THE
NORTHERN ROCKIES FROM FRIDAY THROUGH THIS COMING WEEKEND AS HIGH
PRESSURE BUILDS ALONG THE WEST COAST. WHILE SPECIFIC DETAILS
REMAIN SPARSE DUE TO A LACK OF MODEL CONTINUITY REGARDING THE
DEPTH AND TIMING OF POTENTIAL DISTURBANCES, TWO MAIN TRENDS STAND
OUT: A WEAK COLD FRONT WILL DROP DOWN FROM THE NORTH, KEEPING
TEMPERATURES NEAR SEASONAL VALUES, AND PERIODIC SHOWER CHANCES
WILL PERSIST, PRIMARILY ACROSS WESTERN MONTANA, AND LESS SO FOR
NORTH- CENTRAL IDAHO.
AVIATION
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE DAYTIME
HOURS AS MID- AND HIGH-LEVEL CLOUDS GRADUALLY OVERSPREAD THE
REGION UNDER STRENGTHENING SOUTHWESTERLY FLOW ALOFT. THE PRIMARY
EXCEPTION WILL BE LOCALIZED, SHALLOW VALLEY FOG EARLY THIS MORNING
IN AREAS THAT RECEIVED RAINFALL YESTERDAY EVENING. WHILE SURFACE
WINDS WILL REMAIN GENERALLY LIGHT ACROSS MOST TERMINALS, DEEPER
DIURNAL MIXING WILL SUPPORT AFTERNOON SOUTHERLY WIND GUSTS OF 20
TO 25 KNOTS AT KBTM, KHRF, AND KSMN.
VIRGA SHOWERS WILL BECOME COMMON THIS EVENING AS MID-LEVELS
SATURATE. PRECIPITATION IS FORECAST TO STEADILY REACH THE GROUND
AND EXPAND IN COVERAGE FROM SOUTHWEST TO NORTHEAST OVERNIGHT INTO
TUESDAY MORNING. THIS WIDESPREAD RAIN WILL LEAD TO GRADUALLY
LOWERING CEILINGS AND VISIBILITIES, WITH A TRANSITION TO
OCCASIONAL MVFR CONDITIONS EXPECTED BY TUESDAY MORNING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FROST ADVISORY UNTIL 9 AM MDT THIS MORNING FOR FLATHEAD/MISSION
VALLEYS...KOOTENAI/CABINET REGION...LOWER CLARK FORK
REGION...MISSOULA/BITTERROOT VALLEYS.
ID...FROST ADVISORY UNTIL 9 AM MDT /8 AM PDT/ THIS MORNING FOR
EASTERN LEMHI COUNTY...NORTHERN CLEARWATER MOUNTAINS...
OROFINO/GRANGEVILLE REGION...SOUTHERN CLEARWATER MOUNTAINS.
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