851
FXUS65 KMSO 161912
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
112 PM MDT SAT MAY 16 2026
DISCUSSION
KEY MESSAGES:
- UNSETTLED, COOL, AND SHOWERY CONDITIONS PERSIST THROUGH THE
WEEKEND.
- MOUNTAIN SNOW TONIGHT AND ON SUNDAY WILL CREATE DIFFICULT
CONDITIONS FOR BACKCOUNTRY RECREATION, ESPECIALLY ALONG THE
CONTINENTAL DIVIDE.
- WIDESPREAD FROST AND FREEZING TEMPERATURES SUNDAY THROUGH
TUESDAY MORNINGS.
RADAR RETURNS EARLY THIS AFTERNOON ARE REVEALING SCATTERED SHOWERS
ACROSS THE NORTHERN ROCKIES. ISOLATED LIGHTNING STRIKES OVER
NORTH-CENTRAL IDAHO WILL MIGRATE INTO NORTHWEST AND WEST-CENTRAL
MONTANA AS THE AFTERNOON EVOLVES. MARGINAL INSTABILITY/SHEAR WILL
KEEP THUNDERSTORMS ON THE WEAK SIDE, PRODUCING ISOLATED LIGHTNING
AND OUTFLOW WINDS TO ABOUT 30-40 MPH. LOOKING TO THE LARGER SCALE,
SATELLITE IMAGERY IS DEPICTING A TROUGH OF LOW PRESSURE
APPROACHING THE IDAHO PANHANDLE. THIS SYSTEM WILL BRING WIDESPREAD
COOLER TEMPERATURES AND MOISTURE THROUGH SUNDAY MORNING.
TEMPERATURES WILL DROP ENOUGH TO SUPPORT SNOW ABOVE ABOUT 4500
THIS EVENING. THAT NUMBER WILL DROP OVERNIGHT, ALLOWING SNOW TO
REACH VALLEY FLOORS BY SUNDAY MORNING. HIGHER ELEVATION VALLEYS OF
SOUTHWEST MONTANA SUCH AS BUTTE COULD SEE A MODEST ACCUMULATION
BY SUNDAY MORNING. THE PRIMARY IMPACT, HOWEVER, WILL BE THE
HIGHER ELEVATIONS ALONG THE CONTINENTAL DIVIDE, AS WELL AS THE
BITTERROOT, MISSION, AND ANACONDA/PINTLER RANGES WHERE 4-12 INCHES
OF STORM TOTAL SNOW (ENDING MONDAY MORNING) ARE IN THE FORECAST.
THOSE PLANNING ON TRAVELING ABOVE ABOUT 5000 FEET IN ELEVATION
SHOULD BE PREPARED FOR WINTER-LIKE CONDITIONS. WINTER WEATHER
ADVISORIES ARE IN EFFECT FOR SEVERAL FORECAST ZONES IN MONTANA
ABOVE 5000 FEET.
THE COLD AIR ASSOCIATED WITH THE APPROACHING LOW WILL RESULT IN
COLDER THAN NORMAL OVERNIGHT LOW TEMPERATURES. FROST ADVISORIES
ARE IN EFFECT FOR SUNDAY AND MONDAY MORNINGS. CONFIDENCE FOR FROST
IS HIGHER FOR MONDAY MORNING. SKY COVER TONIGHT MAY KEEP
TEMPERATURES ABOVE WHAT IS CONDUCIVE FOR WIDESPREAD FROST.
NEVERTHELESS, IF SENSITIVE VEGETATION IS A CONCERN, IT WOULD BE
WORTHWHILE TO TAKE NECESSARY PRECAUTIONS. ANOTHER FROST ADVISORY
FOR TUESDAY MORNING WILL NOT BE OUT OF THE QUESTION, WE WILL
REASSESS ON SUNDAY.
AVIATION
SCATTERED SHOWERS THIS AFTERNOON WILL CREATE PERIODS
OF DECREASED VISIBILITY DOWN TO ABOUT 4 SM, AND CEILINGS TO ABOUT
2500 FEET. THERE'S ABOUT A 10% CHANCE FOR ISOLATED LIGHTNING
STRIKES IN THE VICINITY OF KGPI AND KMSO THROUGH THIS AFTERNOON.
EXPECT WIDESPREAD PRECIPITATION TO OBSCURE TERRAIN ACROSS THE
ENTIRE NORTHERN ROCKIES AIRSPACE. PRECIPITATION TURNS TO SNOW
TONIGHT ABOVE ABOUT 5000 FT MSL. SNOW LEVELS DESCEND OVERNIGHT,
WITH SNOW POSSIBLE FOR KBTM BY SUNDAY MORNING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT
SUNDAY NIGHT FOR BITTERROOT/SAPPHIRE MOUNTAINS...
BUTTE/BLACKFOOT REGION...POTOMAC/SEELEY LAKE REGION...WEST
GLACIER REGION.
FROST ADVISORY FROM 8 PM THIS EVENING TO 9 AM MDT SUNDAY FOR
FLATHEAD/MISSION VALLEYS...MISSOULA/BITTERROOT VALLEYS.
FROST ADVISORY FROM 8 PM SUNDAY TO 9 AM MDT MONDAY FOR
FLATHEAD/MISSION VALLEYS...MISSOULA/BITTERROOT VALLEYS.
ID...NONE.
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