Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 251730
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1130 AM MDT Wed Mar 25 2015

Aviation Section Updated

.UPDATE...

Today...High pressure is rebuilding over the area and the air
mass is drying and allowed the winter weather advisory to expire.
Some fog remains across the area but also canceled the dense
freezing fog advisory. Also freshened POPs, WX, and snow grids.
Zelzer

&&

.AVIATION...
UPDATED 1730Z.
VFR conditions will prevail over the region thru the period. Gusty
west winds will occur at times thru 00z Thu. Otherwise...expect
mainly some passing mid/high level cloudiness. Brusda

&&

.PREV DISCUSSION...
/ISSUED 600 AM MDT Wed Mar 25 2015/

Today through Friday...The moist northwest flow aloft will
continue scattered snow showers across most of central and
southwest Montana into this morning. Additional snowfall of 1 to 2
inches are expected in the mountains and accumulation of up to 1
inch is possible on mountain passes. Will therefore allow the
Winter Weather Advisory for elevations above 6000 feet to continue
through 9 am. Less than an inch of additional accumulation is
expected along the north facing slopes from Great Falls to
Lewistown. Skies are also clearing out from the northwest over the
plains northwest of a Choteau to Sunburst line. Visibility in
these areas has fallen to less than one mile in freezing fog, so
have put that area under a Freezing Fog Advisory through this
morning. Areas of fog have also developed with the snow farther
south and east of this line, so will need to monitor those areas
for possible further fog advisories when clouds begin to break up
there. Otherwise, the general weather pattern will become warmer
and drier through the remainder of the work week as an upper level
ridge of high pressure moves into the area from the west. The
moist northwest flow aloft will linger into Thursday, keeping a
chance of showers over the mountains, but Friday should be dry. A
surface trough will also develop south out of Alberta through the
period, causing winds to become more southwesterly, especially
over the plains of north central Montana. Winds along the Rocky
Mountain Front may approach high wind criteria, but am expecting
them to remain below criteria at this time. These downsloping winds
will also help warm temperatures to near record levels by Friday.
Temperatures today will mostly warm into the mid 40s to lower 50s,
but highs in the mid 60s to mid 70s will be common on Friday.
Coulston

Friday Night Through Wednesday...High pressure ridge over our
region on Fri will track into eastern MT by Sat morning, followed
closely by a quick-moving, shortwave trof that will cross east of
the Continental Divide around midday. Latest forecast models
suggest that much of the available moisture may get wrung out over
western MT, leaving just spotty showers over central/southwest MT.
This solution is also supported by the drying effects of strong
westerly/downslope winds generated by the trof`s passage. As the
system races into Dakotas by late Sat night, high pressure ridging
will re-establish itself over the Northern Rockies, bringing warm
temperatures and dry conditions for Sun/Mon. On Tues, a second
shortwave that closely matches the look and evolution of
Saturday`s system, is projected to sweep through the state.
Currently, models indicate a bit more moisture and colder air with
the second system, increasing the chances for rain/snow mix and/or
light snow for lower elevations Tues evening. However,
precipitation should end from west-to-east Tues night with dry
conditions returning on Wed. Temperatures will remain above
seasonal averages through this forecast period, with the coolest
temps on Wed after passage of the second system.
Waranauskas

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  53  37  66  41 /  10  10  10   0
CTB  51  35  64  41 /  10  10  10   0
HLN  55  38  64  40 /  10  20  10  10
BZN  53  30  62  33 /  20  20  20  10
WEY  44  18  51  20 /  10  20  20  10
DLN  52  33  61  37 /  10  20  10   0
HVR  49  29  63  35 /  10  10  10  10
LWT  51  33  62  38 /  20  20  10  10

&&

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

&&

$$

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