007
FXUS65 KMSO 281031
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
431 AM MDT THU SEP 28 2023
DISCUSSION
A COUPLE OF WEAK WEATHER DISTURBANCES WILL MOVE
ACROSS NORTHWEST MONTANA TODAY AND FRIDAY. SCATTERED SHOWERS WILL
OCCUR EACH DAY AND BE STRONGEST DURING THE AFTERNOON HOURS. A
COOLER AIR MASS WILL SETTLE OVER THE REGION LOWERING SNOW LEVELS
TO 6000-6500 FEET. SO IF ONE IS IN THE BACKCOUNTRY TODAY OR
FRIDAY BE WARY OF SNOW SHOWERS IN THE VICINITY AS THEY WILL
CONTAIN GUSTY WINDS WITH COOL RAW CONDITIONS.
FRIDAY NIGHT INTO SATURDAY, THE ENSEMBLE MODELS HAVE TRENDED FOR
INCOMING UPPER LEVEL TROUGH TO DIG FURTHER SOUTH TOWARDS
CALIFORNIA AND NEVADA. BECAUSE OF THIS, THE PROBABILITY FOR SNOW
LEVELS LESS THAN 6000 FEET HAS FALLEN SIGNIFICANTLY. THOUGH THE
MAIN TROUGH IS OUT OF OUR REGION, THERE WILL BE A NORTHERLY BREEZE
THAT DEVELOPS WITH HIGH PRESSURE TO THE NORTH AND LOWER PRESSURE
TO THE SOUTH. THE SOUTHERLY FLOW ALOFT WILL BRING IN SLIGHTLY
MILDER AND MOISTER AIR AND SET UP AN OVERRUNNING SCENARIO. THIS
COULD BRING AREAS OF RAIN, CLOUDS AND CONTINUED COOL CONDITIONS AS
EARLY AS FRIDAY NIGHT OVER THE NORTHERN CLEARWATER MOUNTAINS INTO
NORTHWEST MONTANA. THEN RAIN COULD DEVELOP IN PORTIONS OF THE
REGION LATER SATURDAY...50 PERCENT PROBABILITY OF OCCURRENCE. SNOW
LEVELS GENERALLY WILL BE 6000 TO 7000 FEET TO THE NORTH AND UP TO
8500 FEET TO THE SOUTH. AGAIN, BACKCOUNTRY CONDITIONS WILL
CONTINUE TO BE RAW AND WET.
ON SUNDAY THROUGH MONDAY ENSEMBLE MODELS INDICATE THAT A FEW
LOBES OF ENERGY MAY ROTATED AROUND THE UPPER LEVEL LOW INTO OUR
REGION, MAINLY SOUTH OF MISSOULA. SNOW LEVELS ARE PRETTY HIGH,
GENERALLY AROUND 8000 FEET DURING THIS PERIOD.
AFTER MONDAY, ZONAL FLOW IS POSSIBLE THROUGH WEDNESDAY. THAT COULD
MEAN MILDER TEMPERATURES BUT WITH POSSIBLE SHOWERS AND CLOUD COVER
AT TIMES.
THERE IS INCREASING CONFIDENCE, AROUND 65 PERCENT PROBABILITY THAT
A COLDER SYSTEM COULD INFLUENCE OUR WEATHER BY NEXT THURSDAY OR
FRIDAY. TYPICALLY WITH A AMPLIFIED UPPER RIDGE OVER THE NORTHEAST
PACIFIC INTO ALASKA, THIS COULD BRING MUCH COLDER AIR SOUTHWARDS
OUT OF CANADA. RIGHT NOW, THE NBM FORECAST SNOW LEVELS DEPICT DOWN
TO 5000 FEET, BUT THEY COULD BE MUCH LOWER. THE HIGHEST
PROBABILITIES FOR GREATER THAN AN INCH OF SNOW INCLUDE MUCH OF THE
DIVIDE NORTH OF OVANDO...AROUND 56 PERCENT FOR MARIAS PASS. ALSO
THIS MAP TYPE WOULD SUGGEST THE POTENTIAL FOR STIFF NORTHEAST
WINDS. IF YOU HAVE BOATS THAT COULD GET DAMAGED ON THE WESTERN
SIDE OF FLATHEAD LAKE, YOU MIGHT WANT TO TAKE PRECAUTIONS AHEAD OF
TIME, AND CONTINUE TO MONITOR THE FORECAST.
AVIATION
EXPECT ISOLATED SHOWERS AT KMSO AND KGPI THIS MORNING.
SCATTERED SHOWER ACTIVITY WILL BE LIMITED TO KGPI THIS AFTERNOON
AND EVENING. SOME SHOWERS WILL BE STRONG ENOUGH TO PRODUCE OUTFLOW
WINDS BRIEFLY TO 30 MPH. SHOWERS WILL DIMINISH LATER THIS EVENING
AND OVERNIGHT AS WE LOSE THAT DAYTIME HEATING
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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