Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 301134
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
434 AM MST Fri Jan 30 2015

...UPDATE TO AVIATION...

.DISCUSSION...
Today through Sunday...Today will be the last widespread nice day
for awhile across all of North Central and Southwest MT...as a
more unsettled weather pattern sets up over the region. For
today...afternoon highs will mostly be in the 40s...with sunny
skies in the north and partly cloudy skies in the south. Patchy
freezing fog will affect areas mainly north of Highway 2 from
Shelby to Harlem through mid morning today. For tonight...a
Canadian cold front will move southward through the region. The
cold front should arrive in the Cut Bank area around Midnight...in
Great Falls/Havre areas around 3 AM...Lewistown around
5 AM...Helena around 8 AM and Bozeman by mid day Saturday. Snow
will develop behind the cold front...but the majority of the
accumulating snowfall will affect areas mainly north of a Helena
to White Sulphur Springs line. South of that line...any snow
accumulations should be minor...with most areas seeing less than a
half inch. North of the Helena/White Sulphur Springs line...about
1 to 2 inches of snow is expected in the Lewistown/Great Falls/Cut
Bank areas...with 2 to 3 inches in the Fort Benton/Havre/Harlem
areas. Most of the accumulating snow will occur from 3 AM Saturday
until about 8 PM Saturday evening. Thus pops have been raised
quite a bit during the day on Saturday...but this is more for the
event/confidence of snowfall on Saturday. On Saturday...high
temperatures will be in the morning...with slowly falling
temperatures the remainder of the day. It will be a cold start on
Sunday morning...with areas east of I-15 not warming up much on
Sunday. For areas west of I-15 on Sunday...a fast moving warm
front is expected to develop and start to push eastward through
the region during the afternoon hours. Thus temperatures will be a
bit warmer...especially over Southwest MT. Additionally...there is
a chance for snow over the Rocky Mountain Front and adjacent
Plains by late Sunday afternoon...although confidence is low for
location/amounts of snow on Sunday. Brusda

Sunday night through Friday...Shortwave energy in a moist
northwesterly flow aloft will bring a continuing chance for light
rain and snow across the forecast area Sunday night and Monday. More
widespread snow is expected over the western mountains but
accumulations amounts do not look overly impressive at this time. By
Monday night, however, models are in good agreement pushing another
batch of cold Canadian air into central Montana along with periods
of snow. This system will continue to move southward through the
state with a band of precipitation gradually moving into southwest
Montana by Tuesday night. For the remainder of the week, models are
in relatively good agreement in building an upper level ridge over
the northern Rocky Mountains. Temperatures are expected to warm back
toward seasonal averages by Thursday with highs possibly climbing
well above average by Friday. Breezy and mostly dry conditions will
likely prevail at lower elevations with a chance for precipitation
expected to persist over the western mountains as flow aloft
squeezes out any moisture due to orographic lift. mpj

&&

.AVIATION...
UPDATED 1134Z.
Generally dry northwest flow aloft will prevail over Montana today
through this evening for widespread VFR conditions. However, patch
fog has developed along the Hi-line and should persist until about
15Z but I have removed mention of fog from the KHVR terminal due to
patchy nature. Upper level disturbance will approach the region
early Saturday morning with increasing low and mid level clouds over
the northern third of the forecast area. An associated surface cold
front will push south out of Canada with light snow expected to
develop along the Hi-Line after 09Z. mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  46  24  27  11 /   0   0  90  30
CTB  44  22  22   7 /   0  20  90  20
HLN  42  20  35  16 /   0   0  30  20
BZN  40  17  37  16 /   0   0  20  20
WEY  37   8  34   9 /   0   0  10  10
DLN  43  20  44  19 /   0   0  10  10
HVR  40  21  23   5 /   0  20  90  30
LWT  44  23  26   9 /   0   0  80  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

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