554
FXUS65 KMSO 182004
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
204 PM MDT THU OCT 18 2018
DISCUSSION
HIGH PRESSURE CONTINUES THROUGH THE WEEKEND FOR
CENTRAL IDAHO AND WESTERN MONTANA. VALLEY FOG IN THE MORNINGS AND
HAZE UNDER A VERY STABLE AIR MASS WILL CONTINUE THROUGH EARLY NEXT
WEEK.
MODELS AGREE ON A BREAK DOWN IN THE RIDGE AND A RETURN TO ACTIVE
WEATHER SOMETIME NEXT WEEK. HOWEVER, THE OVERALL AGREEMENT IS POOR
AND THE TIMING REMAINS VARIABLE FROM MODEL RUN TO MODEL RUN.
CHANGES TO THE CURRENT PREVIOUS FORECAST INCLUDE LOWERING THE
CHANCES OF RAIN EARLY NEXT WEEK AND PUSHING THEM BACK TO THE
MIDDLE OR END OF NEXT WEEK. THIS IS CONSISTENT WITH MODELS HAVING
DIFFICULTY HANDLING THE UNUSUALLY WARM WATERS IN THE GULF OF
ALASKA, WHICH WILL HELP THE RIDGE PERSIST LONGER THAN MODELS
INITIALLY FORECAST. ALSO, ONCE THE BREAK DOWN OF THE RIDGE STARTS
IT LOOKS TEMPORARY AND WITH RATHER HIGH SNOW LEVELS, SO MOUNTAIN
SNOW WILL ONLY BE AN ISSUE AROUND 7,000 FEET AND ABOVE.
AVIATION
A RIDGE CONTINUES TO DOMINATE THE WEATHER ACROSS THE
NORTHERN ROCKIES. STABLE CONDITIONS ARE CAUSING HAZE AND ALLOWING
SOME PATCHY FOG IN THE MORNINGS. FOG WILL MAINLY AFFECT THE NARROW
VALLEYS AND REMAIN ALONG THE RIVERS IN THE LARGER VALLEYS OF
WESTERN MONTANA. AT THIS TIME IT IS NOT EXPECTED TO AFFECT ANY
TERMINALS, HOWEVER, DEW POINTS HAVE BEEN CREEPING UP THE LAST
SEVERAL DAYS SO THE FOGGY AREAS ARE INCREASING. TERMINAL KGPI AND
KMSO ARE THE MOST LIKELY TO HAVE VICINITY FOG FROM 10 TO 16Z IN
THE MORNING. HOWEVER, THE CHANCES ARE LOW ENOUGH THAT FOG WAS NOT
PUT INTO THE TAFS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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