826
FXUS65 KMSO 260854
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
254 AM MDT SAT SEP 26 2026
DISCUSSION
KEY MESSAGES:
- COLDER TEMPERATURES TODAY, WITH BREEZY WESTERLY WINDS.
- MONITORING THE POTENTIAL FOR WEATHER SYSTEMS TO BRING
SHOWERS/COOLER TEMPERATURES WEDNESDAY AND FRIDAY-SATURDAY.
MANY LOCATIONS ARE WAKING UP TO COLDER TEMPERATURES THIS MORNING,
WITH SNOW LEVELS FALLING NEAR 5,000 FEET. RADAR IMAGERY CONTINUES
TO SHOW SCATTERED SHOWERS, WITH LIGHT SNOW ACCUMULATIONS BEING
OBSERVED ABOVE 7,000 FEET ALONG AND NORTH OF THE I-90 CORRIDOR.
LOOKING AHEAD TO THIS AFTERNOON, DRIER AIR WILL BEGIN TO MOVE INTO
THE AREA UNDER A ZONAL FLOW ALOFT. THIS WILL BRING AN END TO
SHOWER ACTIVITY, WITH STRATUS CLOUDS ERODING AND HIGH CLOUDS
MOVING OVERHEAD. WESTERLY WINDS WILL GRADUALLY WEAKEN THROUGH THE
MID-AFTERNOON TO EVENING HOURS ACROSS WESTERN MONTANA VALLEY
AREAS, WHILE WIND GUSTS OF 20-30+ MPH CONTINUE ACROSS THE HIGHER
TERRAIN.
LOOKING AHEAD TO THIS UPCOMING WEEK, THE NORTHERN ROCKIES WILL
REMAIN UNDER A ZONAL WESTERLY FLOW PATTERN WITH HIGH PRESSURE
CENTERED ACROSS THE DESERT SOUTHWEST AND LOW PRESSURE SYSTEMS
FOCUSED NORTH IN CANADA. A WARMING TREND IS EXPECTED TUESDAY, WITH
TEMPERATURES RETURNING NEAR SEASONAL NORMALS. THERE'S TWO DAYS TO
MONITOR FOR POTENTIAL DISTURBANCES, BRINGING AN INCREASE IN WIND
AND SHOWER ACTIVITY. THE FIRST WINDOW ARRIVES TUESDAY EVENING INTO
WEDNESDAY AS A SHORTWAVE TROUGH MOVES EASTWARD ALONG THE USA/CANADA
BORDER. ENSEMBLE MODEL GUIDANCE HAS A WIDE ARRAY OF SOLUTIONS WITH
HOW FAR SOUTHWARD THIS TROUGH MOVES, WITH CURRENTLY 80% OF
SOLUTIONS SUGGESTING MINIMAL PRECIPITATION WITH SCATTERED SHOWER
ACTIVITY AND AN INCREASE IN WESTERLY WINDS. THE REMAINING 20% OF
SOLUTIONS DIG THE TROUGH FURTHER SOUTHWARD, BRINGING A MODEST COLD
FRONTAL PASSAGE AND WIDESPREAD PRECIPITATION, FOCUSED ALONG AND
NORTH OF THE I-90 CORRIDOR.
FORECAST MODELS CONTINUE TO SHOW LOWER CONFIDENCE IN THE PATTERN
BY FRIDAY INTO SATURDAY, WITH REGARD TO A POTENTIAL LOW PRESSURE
SYSTEM. ENSEMBLE CLUSTER ANALYSIS SHOWS ROUGHLY A 60/40% SPLIT,
WITH AROUND 40 PERCENT OF MODEL SOLUTIONS SHOW A MUCH COLDER AND
DEEPER TROUGH, AND THE REMAINING 60 PERCENT EITHER SHOWING
CONTINUED ZONAL FLOW OR A WEAKER TROUGH PASSAGE. THE MAJORITY
SOLUTION WOULD KEEP SEASONAL TEMPERATURES, BREEZY WINDS, AND
MAINLY DRY CONDITIONS, WHILE THE DEEPER TROUGH PASSAGE WOULD
BRING A STRONGER COLD FRONT, AND WIDESPREAD SHOWER ACTIVITY, WITH
LOWERING SNOW LEVELS DOWN NEAR 5,000-6,000 FEET.
AVIATION
A MODEST PRESSURE GRADIENT THIS MORNING FOLLOWING A
COLD FRONTAL PASSAGE YESTERDAY IS MAINTAINING 15-25KT WINDS ACROSS
BROADER VALLEYS IN NORTHWEST MONTANA AND ACROSS THE HIGHER
TERRAIN. SNOW LEVELS HAVE FALLEN NEAR 6,000 FEET EARLY THIS
MORNING AND WILL REACH NEAR 5,000 FEET BY 26/1200Z AS SCATTERED
SHOWER ACTIVITY CONTINUES ALONG THE ID/MT BORDER AND IN NORTHWEST
MONTANA. DRIER AIR WILL BEGIN TO MOVE INTO THE AREA BY MID-MORNING
THROUGH THE AFTERNOON, ERODING STRATUS CLOUDS AND ENDING SHOWER
ACTIVITY. SURFACE WIND GUSTS WILL BECOME MORE WIDESPREAD BY LATE
MORNING INTO THE AFTERNOON, WITH GUSTS OF 15-20KTS ACROSS WESTERN
MONTANA. GUSTS WILL WEAKEN AFTER 16/2200Z AS THE GRADIENT LESSENS
ACROSS THE REGION.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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