Wildfire in Montana, June 1 to 22, 2025

Area Forecast Discussion
National Weather Service Great Falls MT
1138 PM MDT Sat May 31 2025

Aviation Section Updated.

.KEY MESSAGES...

 - There will be showers across the area on Sunday, with
   thunderstorms during the afternoon and evening. Showers linger
   across the area through Monday.

 - Temperatures will cool down Sunday through Monday with
   temperatures slowly warming up late next week.

&&

.UPDATE...
/Issued 753 PM MDT Sat May 31 2025/
Current forecast is on track. No updates planned for this
evening. Just some passing clouds expected overnight.

The main concern is the thunderstorm potential on Sunday afternoon
over Southwest MT. The best area for strong/isolated severe storms
is mainly south of a line from Dillon to Bozeman, and from about
3 PM until 8 PM. The main threat will be strong winds, but some
hail can't be ruled out.

On Sunday night widespread precipitation is expected to develop
over portions of Central and North Central MT. The forecast models
are still struggling with how much rainfall might fall with this
system, thus confidence remains low. A few areas might receive a
bit more than 1/2 inch of precip, but it is most likely that many
areas will receive less than 1/2 inch from Sunday night into
Monday. Snow levels will generally remain above 6000 feet in
Glacier Park and generally above 7000 feet elsewhere. Brusda

&&

.DISCUSSION...
/Issued 753 PM MDT Sat May 31 2025/

 - Meteorological Overview:

After a warm, dry, and calm day across the area today, a cold
front will push through the area on Sunday, bringing cooler
temperatures, showers, and thunderstorms to the area. The bulk of
this activity will be focused on Southern Montana, with a few
strong to marginally severe thunderstorms possible near and south
of the I-90 corridor. Showers will continue across the area on
Monday as another disturbance pushes through the area, which will
also bring the coolest air mass of the week to the area.
Temperatures will moderate through the remainder of the work week,
with a few chances for showers and maybe a thunderstorm possible
each day. See the previous discussion below for more details.
Ludwig

&&

.AVIATION...
01/06Z TAF Period

Except during any thunderstorm VFR conditions will prevail at all
terminals except for the KBZN terminal. Between 01/15Z and 01/21Z
showers and thunderstorms will begin to effect all terminals except
for the KCTB and KHVR terminals. These thunderstorms will produce
frequent lightning, strong to severe wind gusts (greater than or
equal to 58 mph), and small hail. The greatest risk for any
severe wind wind gust will be at the KBZN, KEKS, and KWYS
terminals. At all terminals except for the KCTB, KGTF, and KHVR
terminals there is a 15 - 40% chance for thunderstorms after
01/18Z through the end of the TAF Period. After 01/21Z through
the end of the TAF period there will be mountain obscuration in
Southwestern Montana. For the first 6 hours of this TAF period
there will be isolated instances of mountain wave turbulence and
low-level wind shear across North-central Montana. -IG

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

&&

.HYDROLOGY...
There is the potential for minor flooding to develop early next
week along portions of the Gallatin River, from near Gallatin
Gateway northward to the Headwaters State Park. This includes
portions of the Gallatin River near Logan.

The flooding would be from a combination of mountain snowmelt and
rainfall from Sunday through Monday. If the rainfall ends up being
on the lighter side, the potential for flooding will be lower.

At this time, any impacts from water that overflows its bank will
be minor, and confined to areas near the Gallatin River. The
current thinking is that if any flood statements are issued for
this event, it would most likely be a flood advisory. However,
should the rainfall be a bit heavier than currently forecasted,
then a flood warning might be needed. Overall, the river is
forecast to fall well below flood stage by Thursday, so if any
flooding does develop, it will be just for a short time. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  71  46  58 /   0  10  80  90
CTB  51  67  40  58 /   0  10  70  80
HLN  58  74  49  63 /   0  20  60  70
BZN  52  77  46  62 /   0  80  90  80
WYS  41  77  42  61 /   0  40  60  40
DLN  51  77  45  63 /   0  70  50  40
HVR  56  72  46  62 /  10   0  40  90
LWT  55  70  42  53 /   0  50 100 100

&&

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

http://www.weather.gov/greatfalls