Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 150332
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
832 PM MST Tue Nov 14 2017

.UPDATE...
Updated forecast is out. Just a few minor adjustments this
evening. A cold front continues to push southward into North
Central MT this evening. However, it should not go to much further
south, possibly as far south as the Highway 200 corridor and as
far west as Highway 89. Thus small adjustments to temperatures
north of this front. In Southwest MT fresh snow and some clearing
skies should allow valley temperatures to fall a bit. Otherwise
other than a passing shower over the northern Rockies and patchy
freezing fog mainly after Midnight, the rest of the forecast is on
track for tonight. Brusda

&&

.SYNOPSIS...
Mostly clear skies and near normal temperatures prevail tonight.
Freezing fog is possible along the Milk River Valley near Havre
and in the valleys of Southwest MT. Expect generally good weather
continues during the day on Wednesday. The next round of Pacific
moisture brings snow to the mountains along and west of the
Continental Divide Wednesday night into Thursday.

&&

.AVIATION...
Updated 2345Z.
Partly cloudy skies with VFR conditions expected over the region
this evening. A wind shift to the north is trying to slowly move
southward into N Central MT but it should generally stall out near a
Cut Bank/Great Falls/Lewistown line. Some patchy freezing fog could
develop around Bozeman/Havre toward 12z. Otherwise VFR conditions
are expected across the region during the day on Wednesday. Brusda

&&

.PREV DISCUSSION...
/ISSUED 445 PM MST Tue Nov 14 2017/

Tonight through Thursday...Shortwave ridging aloft will support
fair weather across the forecast area tonight. Temperatures in the
southwest valleys may drop below guidance due to net radiative
cooling under mostly clear skies. Remnants of a colder air mass
are expected to support an area of freezing fog along the Milk
River Valley to the east of Havre. Temperatures remain near
average on Wednesday under mostly clear skies and generally light
winds. Clouds increase later Wednesday afternoon as moisture
increases on the southwest flow aloft. Snow develops on Thursday
up to the Continental Divide and spreads across southwest Montana.
A lee-side trough moves off the Rocky Mountain Front Thursday
afternoon, producing a period of strong gusty winds across North-
central Montana. Wind gusts could range from around 30 to 50 mph
Thursday afternoon. The pressure gradient will also be rather
strong across southwest Montana due to a surface high pressure
centered over southern Idaho. Thus, strong southerly winds will
also be expected through the Madison River valley. PN

Thursday night through Tuesday...Progressive pattern aloft will
continue through the end of the work week. Models bring another
upper level trough and associated surface cold front through the
region Thursday evening. This system is expected to be quite similar
to that of yesterday with the main impacts expected to be mountain
snows in Western/Southwest Montana with strong and gusty winds east
of the divide. Snowfall amounts through Friday could reach 4-6
inches for Marias Pass, and 2-5 inches for Monida and Raynolds
passes and the West Yellowstone area. High temperatures behind
the front on Friday are expected to be mainly in the 30s with
temperatures slowly rebounding to near or slightly above seasonal
averages by Sunday. Unfortunately, model solutions diverge
significantly over the weekend to such an extent that, by early
next week, the upper level trough/ridge pattern between the two
models is shifted nearly 180 degrees. Have trended the forecast
closer to the wetter GFS pattern but confidence beyond Saturday is
quite low at this time. mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  29  43  37  45 /   0   0   0  10
CTB  21  33  26  37 /   0   0  10  20
HLN  24  40  31  43 /   0   0  10  30
BZN  15  39  31  47 /   0   0  10  40
WEY  13  37  27  38 /   0   0  90  90
DLN  18  43  35  45 /   0   0  20  30
HVR  15  37  26  42 /   0   0   0  10
LWT  26  41  34  48 /   0   0   0  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

http://www.weather.gov/greatfalls



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