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000
FXUS65 KTFX 151728
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1128 AM MDT Mon Apr 15 2024

Aviation Section Updated

.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.

&&

.UPDATE...

As of 9 AM MDT, latest radar imagery continues to show a band of
light rainfall moving northwest from Lewistown to Bozeman this
morning that should continue to bring periods of light rain to
these locations through the rest of this afternoon. Adjusted
probability of precipitation for this morning for these locations
to reflect current surface observations and latest trends for
precipitation to continue this morning. Webb

&&

.AVIATION...
1128 AM MDT Mon Apr 15 2024 (15/18Z TAF Period)

VFR conditions are forecasted to continue for KCTB, KGTF, KHVR, and
KHLN through the TAF period. Westerly winds increase for these
locations throughout this afternoon, gusting between 20 and 35
knots that could continue through the TAF period.

For KBZN, KLWT, and KEKS, rain showers continue through 21z,
with potential for thunderstorms to develop for after 21z for KBZN
and 20z for KLWT. These should be quick moving storms with primary
concerns being lightning and gusty erratic winds with any developed
thunderstorms this afternoon and early evening. After 1z, the
probabilities decrease and VFR conditions are favored to return.
Webb


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

&&

.PREV DISCUSSION...
/ISSUED 543 AM MDT Mon Apr 15 2024/
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

&&

.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 /  80  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