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Area forecast discussion 
National Weather Service Great Falls Montana
420 PM MDT sun Sep 25 2016

Updated aviation section


Tonight through upper level high pressure ridge will
bring quiet weather to the forecast area throughout this period.
The ridge axis will gradually shift east from the Pacific coast to
over The Rockies by Tuesday. This will continue the dry and
mostly clear conditions with significant warming. Near normal
temperatures today will warm to 10 degrees above normal for Monday
and around 15 degrees above normal for Tuesday. As a result, highs
mostly in the upper 60s to mid 70s will warm into the mid 70s to
lower 80s on Tuesday. Overnight lows will mostly fall into the
40s, but 30s are possible in the higher mountain valleys. Breezy
westerly winds will continue through the period with the gustiest
winds during the afternoon, especially along the Rocky Mountain
front, where gusts could exceed 35 mph at times. Despite the
winds, patchy fog may develop tonight in some of the more
protected river valleys, though dense fog is unlikely. Warming
temperatures after tonight will likely hinder any further fog
development for the near future.

Tuesday night through Sunday...medium range models are in decent
agreement for Tuesday night through Friday but solutions diverge
for next weekend. The forecast period starts off with remnants of
a flattened shortwave ridge edging eastward from Montana into the
Dakotas. Meanwhile, an upper level low develops off the British
Columbia coast which gradually elongates into a trough along the
Pacific northwest coast with flow aloft over Montana backing to
the south-southwest and becoming increasingly moist. Tuesday
night through Thursday will remain dry for most locations with
seasonable temperatures expected each day. Isolated mountain
showers develop near Glacier park Wednesday then expand across
all the western mountains on Thursday with a few showers or
thunderstorms possibly moving out over the plains Thursday
evening. Showers and possible thunderstorms increase in coverage
across the entire forecast area Friday through Sunday with a
surface cold front expected to move through the region for cooler
temperatures for next weekend.


updated 2220z.

VFR conditions will continue through at least the next 24 hours.
High pressure aloft will keep the area mostly clear through the
period, but some mid level cloudiness will be slower to clear off
(probably by 06z) along and west of the Continental Divide. Breezy
westerly winds will decouple through 03z, but they will mix down
again after 17z. Through 03z and again after 17z, gusts along the
east slopes of The Rockies could reach 20 kt, but gusts in excess of
30 kt will be possible throughout the period closer to the Rocky
Mountain front. Patchy fog may develop between 06z and 17z in the
river valleys, but it will likely not impact the terminals.


Preliminary point temps/pops...
gtf 45 77 49 82 / 0 0 0 0
ctb 42 76 45 79 / 0 0 0 0
hln 42 78 46 82 / 0 0 0 0
bzn 41 77 45 81 / 0 0 0 0
wey 29 70 32 73 / 0 0 0 0
dln 39 75 41 78 / 0 0 0 0
hvr 42 75 46 84 / 0 0 0 0
lwt 42 74 50 81 / 0 0 0 0


Tfx watches/warnings/advisories...



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