498
FXUS65 KTFX 150231
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
831 PM MDT Mon Jul 14 2025

.KEY MESSAGES...

- Widespread rain and isolated thunderstorms develop tonight over
  North Central MT.

- Scattered thunderstorms this evening over Southwest MT.

- Cool and rainy day over North Central MT on Tue.

- Scattered afternoon thunderstorms on Thursday.

- Mostly dry and warm this weekend.


&&

.UPDATE...

A few thunderstorms continue to track across southwest MT this
evening, mainly south of a Dillon to Bozeman line where a very
warm and dry airmass is still in place, maintaining a risk for
gusty winds. A much cooler airmass is surging south into central
MT this evening as precipitation intensifies ahead the of the
incoming upper level trough, currently rotating through far
southern BC. Shower and thunderstorm coverage has begun to
increase across north- central MT over the last hour with
sufficient elevated CAPE and wind shear to support the risk for
isolated strong to severe thunderstorms over mainly eastern
portions of central MT through midnight. Large scale lift ahead of
the trough will increase overnight with an area of widespread
precipitation sagging south from Alberta into north-central MT
later in the overnight period. Pops and winds were updated to
reflect latest observed trends and incorporate incoming hi-
resolution model data, but overall forecast remains on track.
Hoenisch

&&

.DISCUSSION...
/Issued 438 PM MDT Mon Jul 14 2025/

 - Meteorological Overview:
The summer storm is on track to affect much of CWA starting
tonight. Ahead of the storm, showers/thunderstorms are developing
over Southwest MT. These storms could produce some strong wind
gusts. As of 130 PM, the cold front is generally along a line from
Lincoln to Lewistown, and slowly moving southward. This front
should move down to the I-90 corridor from Butte to Bozeman this
evening, before stalling out once again. The precip develops this
evening near the Canadian border and gradually moves southward
overnight. Expect a rainy/cool day over North Central MT on Tue.
Temperatures will not rise much from the overnight lows on Tue
over North Central MT.

Wednesday and Thursday...much of the precipitation will exit the
area by Wednesday morning, with just a few showers left over the
eastern portions of the CWA by Wednesday afternoon. On Thursday,
warmer air pushes back into the CWA, but a weak upper level
disturbance also moves southeast through the CWA as well. This
will result in a few afternoon showers/thunderstorms.

Friday through Monday...Generally warm and mostly dry conditions
are expected through the weekend and into early next week. The GFS
model does have a few isolated thunderstorms during the evening
hours Sat thru Mon over the eastern portions of the CWA though.

 - Forecast Confidence & Scenarios:

The main concern is rainfall potential tonight through Tuesday.
Widespread rainfall of about 1/2 to 1 inch is expected over North
Central MT with this summer storm. Areas in Glacier Park could get
a bit more, generally in the 1 to 3 inch range. Snowfall looks to
mainly affect areas above 8500 feet in Glacier Park, with an inch
or two possible at ridge tops above 9000 feet. The total rainfall
over Southwest MT still looks to be on the light side with most
areas just averaging about 1/4 to 1/2 inch over the next few
days.

Confidence is low for thunderstorm activity Saturday thru Monday
over the eastern portions of the CWA. The upper level support for
the storms is low, thus confidence in timing for any storms is
also low. Brusda

&&

.AVIATION...
15/00Z TAF Period

A cold front continues to push southward into Southwest MT as of
late this afternoon. Low ceilings are developing on the north
side of the front. Expect showers/thunderstorms to develop this
evening along the Canadian border, and transition to more of a
stratiform rain by Tuesday morning over North Central MT. Isolated
thunderstorms will also affect far Southwest MT through the early
evening hours as well. Expect the precipitation to become more
scattered by Tuesday evening. Low level wind shear in Helena
should diminish early this evening as winds become more northerly
behind the cold front. Mountains/passes will become obscured this
evening, and remain obscured through Tuesday across the CWA.
Brusda

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  53  56  49  69 /  80 100  60  20
CTB  50  54  43  66 / 100  90  30  10
HLN  56  62  49  76 /  30  90  70  20
BZN  53  72  48  75 /  30  90  80  30
WYS  43  78  41  73 /  40  70  70  20
DLN  51  74  47  75 /  20  80  50  10
HVR  55  62  46  70 /  80  90  40  20
LWT  50  56  45  62 /  70 100  90  50

&&

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

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