Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 171744
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
945 AM MST Tue Jan 17 2017

Updated Aviation Discussion.

.UPDATE...

Raised max temperatures up to a few degrees across parts of
north-central MT given latest model guidance. Also lowered max
temperatures a few degrees across the southwest valleys (Wisdom
and West Yellowstone especially). No changes otherwise. Cassell


&&

.AVIATION...
Updated 1745Z.
Overall VFR conditions should prevail at most terminals through the
period. However...some haze could reduce visibility at times in
Helena...mostly this morning and again Wednesday morning. A Chinook
arch over the region this morning will give way to more widespread
clouds over the Rocky Mountain Front with some passes obscured by
12z Wed. Expect gusty winds as well...mostly over the northern
Plains...with some low level wind shear possible towards 06z this
evening. Cassell

&&

.PREV DISCUSSION...
/ISSUED 505 AM MST Tue Jan 17 2017/
Today through Thursday...An upper level ridge of high pressure
over the region this morning will become more westerly by this
afternoon. As a result, expect gusty west winds along the front
range of the Rockies and the adjacent Plains today through
Wednesday. Wind speeds are expected to be just below warning
criteria. Additionally, mild temperatures are expected over the
north because of the gusty winds today and Wed. However, cold air
continues to be trapped in some of the valleys of Southwest MT
and another cold day is likely. Some mixing might occur on
Wednesday, and temperatures are forecasted to be near freezing in
the valleys of the Southwest. Expect a chance for showers along
the divide later today and through Thursday, but any
precipitation on our side of the divide should remain quite light
through the short term. Brusda

Thursday night through Tuesday...Medium range models continue to be
in good agreement for much of the forecast period but solutions
gradually diverge early next week. Period starts off with a closed
low off the Washington coast merging with a weak trough over the
Great Basin to form a broad upper level trough over the entire
western USA with above normal temperatures across north central
portions of the state returning to more seasonable averages. Core of
energy associated with the upper trough should remain well south of
Montana but occasional disturbances being ejected from the main
trough will bring some chance for precipitation to southwest Montana
and the western mountains. However, expect only a slight chance for
light rain and snow showers across the north central plains. Main
portion of the upper trough drops into the Desert Southwest and
progresses into the southern Great Plains over the weekend.
Shortwave ridging behind this trough will probably remain too weak
to significantly affect temperatures and weather in Montana but
another broad upper trough is expected to develop over the west
coast by early next week. GFS progresses this feature steadily
eastward but the ECMWF holds the trough axis back along the
California coast for an extra 24 hours before beginning eastward
progression. As a result, the ECMWF puts additional precipitation in
southwest Montana on Tuesday while the GFS remains generally dry.
mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  47  36  47  35 /   0   0   0  10
CTB  45  29  45  32 /   0  10  10  10
HLN  22  16  36  19 /   0  10  10  10
BZN  25  13  38  17 /   0  10   0  10
WEY  14  -7  25  12 /   0  10  10  20
DLN  33  12  36  22 /   0  10  10  10
HVR  43  31  46  30 /   0  10   0   0
LWT  47  34  48  31 /   0  10   0   0

&&

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

$$

weather.gov/greatfalls



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