934
FXUS65 KTFX 140514
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1114 PM MDT Sun Jul 13 2025

Aviation Section Updated.

.KEY MESSAGES...

- Isolated storms possible tonight, mainly near the Canadian
  border over the north and near the Idaho border over the south.

- A strong July cold front moves southward through the area on
  Monday afternoon.

- Unseasonably cool Tue and Wed, with a good chance for rain Tue.

- A return to summer like temperatures and mostly dry conditions
  by the weekend.

&&

.UPDATE...
/Issued 827 PM MDT Sun Jul 13 2025/

Thunderstorms tracking east across southern Alberta this evening
may graze areas near the border in far northern Liberty, Hill and
Blaine counties between 10pm and 2am. While the bulk of any
lightning and precipitation is likely to be limited to areas near
the border, thunderstorm outflow could push gusty north winds to
areas as far south as US-2. A few showers and thunderstorms also
track east along the ID border through the next several hours with
the drier environment there bringing mainly a risk for gusty
winds from Monida pass east to West Yellowstone. Otherwise, the
majority of the forecast area will continue to see mainly clear,
dry and mild conditions through the overnight period. Hoenisch

&&

.DISCUSSION...
/Issued 827 PM MDT Sun Jul 13 2025/

 - Meteorological Overview:
A few weak upper level disturbances will move eastward across MT
this evening. There is just enough instability and moisture for a
few thunderstorms to develop near the Canadian border over the
north and near the Idaho border over the South. Any storms should
be short lived.

On Monday, a strong July cold front will move southward through
the CWA. Right now, the front should mostly move southward during
the afternoon hours. If the front is a little faster, afternoon
highs might not be quite as warm as currently forecasted. A few
storms could be on the strong side as well, with the main impact
being strong wind gusts.

For Monday night through Wednesday, expect periods of rain to
develop Monday night over North Central MT and then continue
through Tuesday, before diminishing on Wed. The heaviest precip is
expected to fall north of I-90 from Butte to Bozeman. The forecast
models are agreeing on the wetter solutions, with much of North
Central MT now having a 70 percent chance or higher of 1 inch of
qpf. Temperatures on Tuesday will not rise much, especially over
the north, with afternoon highs in the 50s and 60s. The upper
level trof begins to push east of the CWA by Wednesday, with
precip slowly ending from west to east.

Thursday through Sunday...A northwest flow develops on Thursday,
as warmer air starts to move back into the CWA. There is a chance
for a passing shower/thunderstorm on Thu, mostly over the northern
portions of the CWA. Generally dry conditions expected Friday thru
Sunday, along with a nice warming trend. Any chance for
thunderstorms is generally less than 20 percent for next weekend.

 - Forecast Confidence & Scenarios:
The main concern with the frontal passage on Monday is the timing,
as a faster frontal passage will keep daytime temperatures lower
than currently forecast. Additionally, a faster frontal passage
means less chance for severe storms on Monday.

Again, most of North Central MT now has a 90 percent chance for
0.50 inches of precip and a 70 percent chance to get over 1 inch.
There will be some snow in Glacier Park, mainly above 9000 feet,
thus snowfall impacts should be confined mostly to ridge top
areas.

Do expect a windy period, from Monday night into Tuesday,
especially along the Rocky Mountain Front. This will be a north
to east wind, which is a opposite our normal stronger westerly
wind flows. Brusda

&&

.AVIATION...
14/06Z TAF Period

The initial concern this TAF period will be for gusty showers and
thunderstorms across the Hi-Line through 10Z or so. Thereafter
attention turns to a southward advancing cold front over the plains
Monday afternoon, making it into Central and Southwest Montana
valleys by the evening. A shift to gusty north winds is forecast
behind the front.

Showers and thunderstorms capable of producing gusty winds will be
a concern across SW MT Monday afternoon, with a mix of showers,
thunderstorms, and stratiform rain and associated low clouds behind
the front further north over the plains. -AM

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  60  91  52  56 /  10  20  90  90
CTB  55  76  47  52 /  10  40  90  90
HLN  61  93  55  62 /   0  10  50  80
BZN  55  95  53  69 /   0  10  40  80
WYS  44  84  43  76 /  10  20  20  70
DLN  54  90  50  72 /   0  10  20  70
HVR  58  89  52  62 /  20  20  90  80
LWT  57  88  49  57 /  10  20  70  80

&&

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

$$
http://www.weather.gov/greatfalls