442
FXUS65 KMSO 221925
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
125 PM MDT WED APR 22 2026
DISCUSSION
KEY MESSAGES:
- WIDESPREAD RAIN CONTINUES TODAY, FOLLOWED BY MUCH COOLER
TEMPERATURES AND A RETURN TO WINTER DRIVING CONDITIONS OVER
MOUNTAIN PASSES BY THURSDAY.
- A POTENTIALLY IMPACTFUL BAND OF HEAVY, WET SNOW COULD DISRUPT
THE THURSDAY AND FRIDAY MORNING COMMUTES ACROSS WESTERN MONTANA
VALLEYS.
- COLD OVERNIGHT LOWS ON FRIDAY AND SATURDAY MORNINGS COULD IMPACT
SENSITIVE VEGETATION.
SATELLITE IMAGERY AND RADAR RETURNS THIS AFTERNOON INDICATE
WIDESPREAD RAINFALL MOVING SOUTH TO NORTH OVER THE NORTHERN
ROCKIES, WITH THE MAIN LOW PRESSURE CIRCULATION OVER SOUTHWEST
MONTANA AND LEMHI COUNTY. THE LEADING EDGE OF THE PRECIPITATION IS
PROVIDING THE MOST INTENSE RAINFALL RATES. SOME MEASURING SITES
IN CLEARWATER COUNTY AND WEST-CENTRAL MONTANA ALREADY PICKED UP
ABOUT ONE-HALF INCH OF RAIN AS OF NOON TODAY. THIS SYSTEM IS ALSO
SPAWNING ISOLATED WEAK THUNDERSTORMS, WHICH WILL CONTINUE
THROUGHOUT THIS AFTERNOON AND EVENING. GUSTY WEST OR SOUTHWEST
WINDS ALONG A COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL ALSO
PERSIST TODAY.
WIDESPREAD PRECIPITATION WILL CONTINUE INTO FRIDAY AS THE MONTANA
LOW MOVES EAST AND ANOTHER DISTURBANCE MOVES OVER THE NORTHERN
ROCKIES FROM THE NORTH. COLDER AIR ASSOCIATED WITH THIS SYSTEM
WILL BRING SNOW LEVELS DOWN TO MOUNTAIN PASSES AND SOME VALLEYS.
EXPECT WET, HEAVY SNOW OVER PASSES AND HIGHER VALLEYS FOR THURSDAY
MORNING. MOTORISTS SHOULD EXPECT WINTER DRIVING CONDITIONS OVER
HOMESTAKE, MACDONALD, LOLO, MARIAS, AND LOOKOUT PASSES.
ALTHOUGH CONFIDENCE IN MOUNTAIN AND MOUNTAIN PASS SNOW IS HIGH,
THERE IS STILL SOME UNCERTAINTY INVOLVING WINTER IMPACTS IN THE
VALLEYS OF WESTERN MONTANA. HIGH RESOLUTION MODELS ARE INDICATING
A BAND OF SNOW SHOWERS DROPPING NORTH TO SOUTH ON THURSDAY
MORNING. IF THIS BAND DEVELOPS OVER THE VALLEYS, HEAVY WET SNOW
WILL CAUSE LOW VISIBILITY, SLUSHY ROADS, SNAPPED TREE BRANCHES,
AND ISOLATED POWER OUTAGES. A SECOND BAND OF SNOW MAY DEVELOP OVER
WEST-CENTRAL MONTANA THURSDAY NIGHT, IMPACTING THE FRIDAY MORNING
COMMUTE. COLDER AIR FROM THE NORTHEAST WILL HELP TO ENHANCE SNOW
PRODUCTION ON FRIDAY MORNING. REGARDLESS OF PRECIPITATION AMOUNT
AND TYPE, SUB-FREEZING TEMPERATURES WILL BE HERE FOR FRIDAY AND
SATURDAY MORNINGS, 20S IN MANY LOCATIONS (INCLUDING GRANGEVILLE
AND PIERCE IDAHO). SOME VALLEYS (BUTTE, STEVENSVILLE, SEELEY
LAKE, OVANDO, PHILIPSBURG,ETC.) WILL GET TO THE TEENS ON SATURDAY
MORNING. COOL, UNSETTLED WEATHER WILL STICK AROUND THROUGH THE
WEEKEND AND INTO NEXT WEEK WHILE TEMPERATURES MODERATE BACK
TOWARDS SEASONABLE VALUES.
AVIATION
AN UPPER LEVEL TROUGH WILL TRACK OVER SOUTH-CENTRAL
MONTANA BY 0000Z(6 PM MDT), THEN INTO EASTERN MONTANA BY 0600Z(12
AM THURSDAY). WRAP-AROUND RAIN AND SNOW WILL PERSIST THROUGH
THURSDAY MORNING BY 1200Z(6 AM MDT). GENERAL IFR FLYING IS
EXPECTED WITH MOUNTAIN OBSCURATION FROM FOG AND LOW CLOUDS. BREEZY
WESTERLY WINDS ARE MORE LIKELY AT KSMN AND KBTM AT TIMES THROUGH
THIS EVENING. A COLD FRONT MOVING SOUTH OUT OF CANADA WILL BRING
SNOW TO VALLEY FLOORS ACROSS NORTHWEST MONTANA BETWEEN 1000Z(4 AM
MDT) AND 1700Z(11 AM MDT) THURSDAY. BRIEF PERIODS OF LIFR FLYING
IS POSSIBLE UNDER THE STRONGER SNOW SHOWERS, POSSIBLY IMPACTING
KGPI. BY THURSDAY AFTERNOON, SNOW OR GRAUPEL SHOWERS ABOVE 3000
FEET ALONG WITH LOWER VISIBILITY AND CEILING ARE POSSIBLE ACROSS
WESTERN MONTANA AND HIGHER TERRAIN OF NORTH-CENTRAL IDAHO.
ADDITIONAL SNOW SHOWERS ARE POSSIBLE THURSDAY NIGHT WHICH COULD
IMPACT ALL THE TERMINALS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON MDT
FRIDAY FOR BITTERROOT/SAPPHIRE MOUNTAINS...BUTTE/BLACKFOOT
REGION...POTOMAC/SEELEY LAKE REGION.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM MDT
THURSDAY FOR WEST GLACIER REGION.
ID...WINTER WEATHER ADVISORY FROM 6 PM MDT /5 PM PDT/ THIS EVENING TO
NOON MDT /11 AM PDT/ FRIDAY FOR EASTERN LEMHI COUNTY...
SOUTHERN CLEARWATER MOUNTAINS...WESTERN LEMHI COUNTY.
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