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000
FXUS65 KTFX 151143
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
543 AM MDT Mon Apr 15 2024

UPDATED AVIATION SECTION

.SYNOPSIS...
Another mild day is expected for most areas today, with showers
and thunderstorms affecting areas mainly east of a line from
Havre to Helena today. On Tuesday, a strong cold front will move
southward from Canada. Rain and snow will develop behind the cold
front, with the rain changing to snow on Tuesday night for all
elevations. Several inches of snow are expected in the mountains,
with lighter snow accumulations along the foothills. It will turn
colder by mid week, but warmer temperatures return by next
weekend.

&&

.DISCUSSION...
Today and tonight...The next upper level trof is approaching
Central MT from the northwest, resulting in a southwesterly flow
currently over Central MT. Thus showers/thunderstorms are moving
from Southwest MT into Central MT this morning. That trend should
continue through the day, with the best chance for precipitation
mainly east of a line from Havre to Helena. The airmass will not
be quite as unstable as yesterday, so the probability of a strong
storm is lower today. However, some gusty winds and small hail is
still possible for a stronger storm this afternoon. Afternoon
temperatures will not be as mild today, with most areas about 5 to
10 degree cooler than yesterday.

Tuesday through Thursday...Little change in the forecast from
yesterday for this time period. A strong cold front is still on
track to move southward through the CWA on Tuesday, with rain/snow
developing. The rain will change to all snow for all elevations
overnight on Tue night. Overall snow amounts look similar to
yesterday. Thus the winter weather advisory was expanded southward
over Central MT, while the winter storm watch was changed to a
winter storm warning for zone 330 where the probability is near 80
percent for warning criteria snowfall in some mountain ranges.
There is a possibility the winter weather advisory could be
expanded to cover a few more lower elevation zones, especially if
later forecasts increase snow amounts a bit. Temperatures will be
colder during this period, about 30 to 40 degrees colder than it
was this past weekend.

Additionally, strong southwest winds over North Central MT will
switch to fairly strong northerly winds behind the front. The
strongest winds should be Tue afternoon through Wed night. Wind
speeds will be just below warning criteria, with the latest
probability of high wind warning gusts in the Cut Bank area
approaching 40 percent. Some blowing snow impacts are also
possible along the front range of the Rockies as well.

Friday through Monday...The upper level trof of mid week will be
exiting the region on Friday, as weak shortwave ridging develops
over MT. Generally dry conditions are expected on Saturday, but
the forecast models start to diverge for Sun/Mon. The EC wants to
continue the dry/mild conditions while the GFS has an upper level
trof moving through, along with scattered showers. Thus the NBM
has the blend of the 2 solutions, but it is favoring the EC model
at this time. Brusda

&&

.AVIATION...
543 AM MDT Mon Apr 15 2024 (15/12Z TAF Period)

VFR conditions are mostly expected to continue through at least
16/06Z across North Central (KCTB KHVR), Central (KLWT KGTF KHLN),
and Southwest Montana.

Scattered showers in a southerly flow aloft will continue over the
portion of North Central, Central, and Southwest Montana along and
east of a KEKS-KHVR line through around 02Z. A few thunderstorms may
move through KLWT through 15Z or so, then again over the entire
showery area between 18Z and 00Z. Brief heavy rain showers, small
hail, erratic wind gusts to 35 kt, and brief periods of MVFR
conditions will be the main threats. The passage of a cold front
from west to east after 21Z will increase prevailing winds and shift
them more westerly, bringing periods of mountain wave turbulence and
low level wind shear. -Coulston

Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  68  39  53  29 /  20  10  10  80
CTB  65  35  47  24 /   0   0  50  60
HLN  68  38  55  30 /  20  10  10  70
BZN  64  32  57  27 /  70  20  30  80
WYS  55  25  48  23 /  60  30  20  80
DLN  60  32  56  28 /  40  10  10  60
HVR  72  40  55  28 /  20  10  20  30
LWT  62  36  52  25 /  70  20  10  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from noon Tuesday to 6 AM MDT Wednesday
for East Glacier Park Region-Northern High Plains.

Winter Weather Advisory from 9 PM Tuesday to noon MDT Wednesday
for Big Belt, Bridger and Castle Mountains-Gates of the
Mountains-Little Belt and Highwood Mountains-Southern High
Plains-Southern Rocky Mountain Front-Upper Blackfoot and
MacDonald Pass.

Winter Storm Warning from 6 PM Tuesday to 6 PM MDT Wednesday for
Gallatin and Madison County Mountains and Centennial Mountains.

&&

$$

http://www.weather.gov/greatfalls