Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 262350
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
450 PM MST Wed Nov 26 2014

Updated Aviation Discussion

.DISCUSSION...

Tonight through Thursday night...Moisture will generally move
northeast out of the area overnight as an upper level ridge of
high pressure builds into Montana. Light to moderate snow will
move northeast across North Central Montana, so will keep the
Winter Weather Advisory in effect for the plains. Snow is
decreasing over the mountain areas of Northwest and Central
Montana, so am anticipating that the Warnings for those areas will
gradually be cancelled throughout the evening. Southwest winds
will spread northeast across the area in the wake of a warm
frontal boundary, which will likely allow temperatures to remain
steady or gradually rise overnight most areas. The northeast
plains portion of the forecast area (including Havre) will be a
bit slower to scour the below freezing air out of the area, so the
warmer air aloft may provide a set up for a freezing rain
potential, so have added mention of that in the forecast tonight
into Thursday morning. Otherwise, the westerly winds aloft will
keep a good chance of rain/snow in the mountains, but the
downsloping effect will keep the rest of the area mostly dry
Thursday into Thursday night. The surface pressure gradient will
be strongest right along the Rocky Mountain Front. This will help
mix down the moderately strong mid level winds, so have decided to
upgrade the High Wind Watch to a Warning starting at midnight
tonight and continuing through midnight Friday night. However,
there will be periods when winds will weaken quite a bit during
this period. The bottom line, though is that it should be a mild
but breezy Thanksgiving Day and night.
Coulston

Friday through Wednesday...The upper trough will move over the
Pacific Northwest Friday. An associated cold front will cross the
Canadian border late Friday afternoon with a chance of precip over
Cut Bank by late afternoon. Another period of active weather is
expected to affect the entire region through the holiday weekend.
Expect another major arctic airmass to move southward into the
region...beginning late Friday night over North Central Montana
and during the morning hours on Saturday in Southwest Montana.
Widespread snow will accompany the arctic air. Snow amounts of 3
to 5 inches are expected over the northern Plains late Friday
night through Saturday...with mainly 1 to 3 inches in the valleys
of Southwest MT. Most central mountain ranges will see 6 to 10
inches of snow. However...mountains along the divide could see 2
to 3 feet of snow...mainly from north of Lincoln to the Canadian
border. This includes Marias Pass on Highway 2. Very cold air
moves back into the region on Saturday for a few days as well.
High temperatures on Saturday will likely be early in the day. By
Sunday morning...widespread temperatures of 10 below to 20 below
are expected over much of North Central MT...with temperatures
around zero in the Southwest. These forecasted temperatures are a
blend of the GFS/EC...as the EC is about 8 degrees colder than the
current forecast. Wind chills could be near 40 below from Cut Bank
to Havre on Sunday morning. The GFS13 has the cold air modifying a
bit early next week...but another upper level disturbance moves
southward through the region Monday night into Tuesday. Thus
leaned a bit above climo pops for that period...with below normal
temperates continuing into the mid portion of next week.
Zelzer/Brusda

&&

.AVIATION...
UPDATED 2350Z.
Band of -SN will continue to gradually lift north tonight,
continuing at the KCTB/KLWT/KHVR terminals with IFR/MVFR conditions
into this evening before ending at KLWT and KCTB by 06Z. At KHVR,
warmer air aloft may move into for a mix with -FZRA after 06Z
tonight. Central and SW MT terminals have already begun to see
improvement as precipitation has lifted north, however low levels
are very moist and some patchy fog is possible for a period this
evening before W/SW winds develop at the surface later tonight. W/SW
winds have already increased at 5000 ft MSL and low level wind
shear may be an issue at KGTF and KCTB for a period this evening
before the stronger W/SW wind aloft mix down to the surface later
tonight. Winds increase further for all areas on Thursday with
strongest winds over the North-Central MT Plains. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  33  53  40  50 /  30  10  10  20
CTB  27  46  33  42 /  50  10  20  60
HLN  33  51  35  48 /  20  10  10  20
BZN  29  48  31  47 /  20  10  10  20
WEY  28  38  26  37 /  20  10  30  50
DLN  34  48  35  47 /  10  10  20  20
HVR  25  45  28  39 / 100  30  10  20
LWT  29  52  36  50 /  60  10  10  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until 11 PM MST this evening Blaine...
Chouteau...Eastern Pondera...Eastern Teton...Hill...Liberty...
Toole.

HIGH WIND WARNING from Midnight tonight to Midnight MST Friday
Night Northern Rocky Mountain Front...Southern Rocky Mountain
Front.

WINTER STORM WARNING until 11 PM MST this evening Cascade...
Eastern Glacier...Fergus...Judith Basin...Northern Rocky
Mountain Front...Southern Rocky Mountain Front.

&&

$$

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