Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 251758
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1150 AM MDT Sat Oct 25 2014

UPDATED AVIATION SECTION

.DISCUSSION...
Updated forecast is out. The main change was to extend the valley
fog in Southwest MT until about Noon today. Patchy areas of dense
fog continue...especially in the Townsend...Bozeman and Whitehall
areas. Afternoon temperatures look on track.

Looking ahead...strong winds still look possible later tonight and
into Sunday over the Northern Rockies and the Cut Bank area. Brusda

&&

.AVIATION...
UPDATED 1755Z.
High pressure will continue over the area through 00z bringing dry
and stable conditions. An upper level disturbance will approach the
area from the west overnight and showers will develop over the
western mountains after 06z and will spread east through Sunday
morning. Winds will increase after 06z with strong winds possible
along the Rocky Mountain Front and Eastern Glacier County. VFR
conditions prevail with increasing MVFR conditions after 06z due to
lowering of ceilings and precipitation. Mountains obscured at times
after 06z.

&&

.PREV DISCUSSION...
/ISSUED 600 AM MDT Sat Oct 25 2014/
Today through Monday...An upper ridge moving into western Montana
this morning will shift to near the eastern Montana border by late
this afternoon. A Pacific upper trough is expected to move into
western Montana Sunday afternoon then into eastern Montana Sunday
night. Northwest flow aloft will be over the area Monday. As for
weather, with clear skies and light winds and small temperature-dew
point spreads, will mention patchy fog over the southwest valleys
for early this morning. Otherwise for the rest of the day expect
sunny to partly cloudy skies and no precipitation. That changes
beginning tonight as moisture increases ahead of the upper trough.
The associated cold front will move through western Montana tonight
and into central Montana by early Sunday morning. Showers will
develop over the western mountains this evening then spread to
southwest Montana late tonight as snow levels fall to between 7000
and 7500 feet by morning. More precipitation is expected over the
western and southwest mountains Sunday as snow levels continue to
fall. Precipitation should diminish over southwest Montana Sunday
night as snow levels lower to between 4000 and 4500 feet. As for the
plains, gusty downslope winds will limit precipitation chances on
Sunday. That changes Sunday night as northwest flow brings some
moisture down from Canada. Rain showers will turn to mostly snow
showers after midnight. Looking at the forecast area as a whole,
snow amounts should be less than an inch for the plains and valleys
while mountains could see several inches.

High wind situation...A watch has been issued for the Rocky
Mountain Front and eastern Glacier County for tonight through
Sunday. Southwest flow aloft will increase tonight. Unlike the
most recent wind event..conditions look more favorable for high
winds. However there continues be some uncertainty with regard to
the ingredients for high winds so have elected to go the watch
route for now.

Thunderstorms...The airmass could become unstable Sunday afternoon
associated with the upper trough. However am not sure it will be
unstable enough for thunderstorms. It does look like there will be
enough of a threat over far southwest Montana to include its
mention in the forecast. Blank

Monday Night through Saturday...Models remain in good agreement
bringing another low pressure system through the region into Monday.
With generally westerly flow, precipitation chances appear to be
mostly limited to the West and Southwest MT mountains. The system
exits Tuesday with weak transient high pressure briefly moving over
the region. A generally unsettled westerly flow develops Wednesday
and several disturbances embedded in the flow will pass over Montana
Wednesday. High pressure begins to build over the region Thursday as
a low pressure system off the west coast deepens. Warm southwesterly
flow returns to the region by the end of the week. Temperatures
remain cool into Tuesday before warming into the 60s later in the
week. Overall chances of meaningful precipitation for the plains
remain fairly low throughout the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  67  45  52  34 /   0  10  10  40
CTB  59  41  51  28 /   0  10  20  60
HLN  71  43  55  36 /   0  10  20  20
BZN  70  36  54  27 /   0  20  50  20
WEY  60  28  41  20 /   0  30  60  50
DLN  69  39  50  28 /   0  20  40  20
HVR  64  40  58  34 /   0  10  10  70
LWT  71  43  56  34 /   0  10  20  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WATCH from late tonight through Sunday afternoon
Eastern Glacier.

HIGH WIND WATCH from 6 PM MDT this evening through Sunday
evening Northern Rocky Mountain Front...Southern Rocky Mountain
Front.

&&

$$

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