Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 232337
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
435 PM MST Sun Nov 23 2014

AVIATION SECTION UPDATED

.DISCUSSION...
Tonight through Tuesday...Unsettled weather conditions will continue
through the short term as an active northwesterly flow remains over
the region. Pacific moisture will bring precipitation to the western
and central Montana mountains this evening and overnight. Models
suggest that Marias Pass and Kings Hill Pass could see a few inches
of snow and thus the Winter Weather Advisory continues. Showers
diminish Monday but another surge of moisture coupled with strong
mid and high level winds develops early Tuesday morning. Strong
westerly winds will develop along the Rocky Mountain Front from
Glacier Park southward to MacDonald Pass. A High Wind Watch
continues for these locations from late Monday evening through
Tuesday afternoon. A low pressure system in southern Alberta will
move southeast through the day on Tuesday bringing northerly winds
to North Central Montana. This will result in a good likelihood of
precipitation that starts off as rain in some locations but changes
to snow across much of the region by late afternoon. Winter weather
highlights could be required with this developing system.
Temperatures will remain fairly seasonal over the next few days.

Tuesday night through Sunday...The ECMWF and GFS models have come
into better agreement with general trends through Thanksgiving. It
looks like a significant snow event will affect at least the Rocky
Mountain Front Tuesday night into Wednesday. Winter weather
highlights will likely be issued for the Rocky Mountain Front and
could be issued elsewhere. The ECMWF has come around to the GFS
solution of pushing this snow mainly into Canada by late Wednesday
and Thanksgiving could end up being a mostly dry day except for
lingering snow over the Rocky Mountain Front. Have lowered the
chances of snow to reflect this trend. The ECMWF and GFS begin to
diverge with their snow forecasts Friday into the weekend so have
continued with the idea of slight chance to chance pops. What the
ECMWF and GFS do agree on is a colder Canadian airmass will invade
the area Friday and continue into the weekend. Forecast lows in the
north are expected to be below zero with highs only in the single
digits to teens over the weekend. Blank

&&

.AVIATION...
UPDATED 2335Z.
VFR conditions will continue this evening, but cloud coverage is
already steadily increasing and ceilings lowering from west-to-east
with the arrival of relatively weak upper-level trof located just
west of the Continental Divide at 00Z.  Trof will make steady
progress through the region tonight and generate some isolated
-SHRASN or -SHSN as the trof axis swings through from 05-12Z.  Have
kept mostly VCSH in local TAFs, with a mention of -SHSN on station
at KLWT owing to slightly better lift and available moisture there
starting around 09Z. Showers should taper off by mid-morning Mon as
the trof heads into eastern MT, with gradually decreasing cloud
cover.
Waranauskas

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  27  41  29  42 /  20  10  20  50
CTB  25  39  28  40 /  10  10  20  60
HLN  28  39  28  41 /  30  20  30  60
BZN  19  33  18  37 /  40  30  30  60
WEY  13  26  12  30 /  70  50  40  70
DLN  17  31  20  40 /  30  10  20  50
HVR  24  40  27  40 /  20  10  20  30
LWT  26  38  26  39 /  40  20  20  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WATCH from Monday evening through Tuesday afternoon
Central and Southern Lewis and Clark...Northern Rocky Mountain
Front...Southern Rocky Mountain Front.

WINTER WEATHER ADVISORY until 6 AM MST Monday For US 89 over
Kings Hill Pass.

WINTER WEATHER ADVISORY until 6 AM MST Monday Northern Rocky
Mountain Front.

&&

$$

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