677
FXUS65 KMSO 221848
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1248 PM MDT THU OCT 22 2026
DISCUSSION
KEY MESSAGES:
- CHANGE TO MORE TYPICAL FALL WEATHER COMING FRIDAY.
TEMPERATURES WARM YET AGAIN TOWARDS LATE SUMMER LEVELS, HOWEVER
SATELLITE CLEARLY SHOWS CLOUDS MOVING UP FROM THE SOUTH.
SHOWERS DEVELOP THIS EVENING FROM SOUTH TO NORTH. A FEW
THUNDERSTORMS WILL ALSO BE POSSIBLE IN IDAHO AND LEMHI COUNTIES.
FOR MOST LOCATIONS AT LEAST A TENTH OF AN INCH OF RAIN IS LIKELY,
IN NORTHWEST MT PRECIPITATION WILL BE SHOWERY ALONG THE FRONT AND
THERE IS A 40 TO 60% CHANCE OF RECEIVING UP TO A TENTH. AFTER A
FAIRLY DRY START TO OCTOBER, FROM LOST TRAIL PASS THROUGH
SOUTHWEST MT THERE IS A 70 TO 90% CHANCE OF RECEIVING UP TO 1/2 OF
AN INCH OF TOTAL PRECIPITATION BY FRIDAY EVENING. ABOVE 6000 FEET,
AS PRECIPITATION IS ENDING A CHANGE OVER TO SNOW IS POSSIBLE WITH
A SLUSHY TRACE TO 3 INCHES IN ACCUMULATIONS AT LOCATIONS LIKE
GEORGETOWN LAKE AND HOMESTAKE AND MACDONALD PASSES. DUE TO THE
TIMING OF SNOW AROUND RUSH HOUR FRIDAY EVENING A WINTER WEATHER
ADVISORY HAS BEEN ISSUED FOR THE POTENTIAL OF SLICK DRIVING
CONDITIONS.
THE MODELS CONTINUE TO HAVE SIGNIFICANT UNCERTAINTY AFTER DAY 3
(SUNDAY). WHAT IS CLEAR IS TEMPERATURES WILL CATCH UP TO THE
CALENDAR AND OCTOBER TEMPERATURES ARRIVE. HIGH TEMPERATURES ARE
EXPECTED TO BE IN THE 50S FOR WESTERN MT AND 60S FOR NORTH-CENTRAL
ID, WHILE LOW TEMPERATURES ROUTINELY FALL INTO THE TEENS AND 20S
IN MT. WEATHER SYSTEMS ARE LESS CLEAR BUT THERE ARE MORE SOLUTIONS
DEPICTING A SYSTEM BY MID-WEEK. MORE DETAILS TO COME.
AVIATION
A LOW PRESSURE SYSTEM WILL MOVE NORTHWARD INTO THE
GREAT BASIN THIS AFTERNOON, SENDING ATMOSPHERIC MOISTURE AND
INSTABILITY NORTHWARD. THIS WILL SET THE STAGE FOR NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS NORTH-CENTRAL IDAHO AND
SOUTHWEST MONTANA BY MID-AFTERNOON THROUGH THE EVENING HOURS.
PRECIPITATION BECOMES MORE WIDESPREAD AFTER 23/0600Z, WITH PERIODS
OF LOWERED VISIBILITY AND CEILINGS EXPECTED THROUGH 23/1800Z.
FREEZING LEVELS WILL LOWER TO AROUND 5000 FEET FRIDAY EVENING, AND
WHILE NO IMPACTS ARE EXPECTED, PRECIPITATION MAY END AS WET SNOW
AT KBTM.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY FROM 3 PM FRIDAY TO MIDNIGHT MDT FRIDAY
NIGHT FOR BUTTE/BLACKFOOT REGION.
ID...NONE.
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