315
FXUS65 KTFX 171449
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
849 AM MDT Tue Jun 17 2025

.KEY MESSAGES...

- A few showers or thunderstorms today.

- Warm with low humidity Wed and Thu.

- Strong storms possible Thu afternoon and again on Friday.

- Turning much cooler with some mountain snow possible by Sunday.

&&

.UPDATE...

There will be showers and thunderstorms for areas east of I-15
this afternoon through this evening. For the update hourly
temperatures were refreshed. The Pop grids for areas east of the
I-15 corridor were increased for this afternoon through this
evening. The rest of the forecast is on track. -IG

&&

.DISCUSSION...
/Issued 358 AM MDT Tue Jun 17 2025/

 - Meteorological Overview:
The upper level pattern is slowly shifting towards a weak
shortwave upper level ridge building by Thursday. This will result
in a slow warming trend from today through Thursday. The airmass
will still be a bit unstable today, mostly over the eastern
portions of the CWA for a few thunderstorms. Overall, much of
Wednesday we should have stable air over the CWA limiting any
chances for thunderstorms. However, by Thursday, the flow aloft
will shift a bit more southwest with the shortwave ridging
building over the CWA, resulting in a better chance for
showers/thunderstorms by late afternoon over Southwest and Central
MT. A few storms could be on the strong side on Thu afternoon. On
Friday, an upper level trof will begin to approach western MT from
the west, resulting in a stronger upper level disturbance moving
northeast through the CWA on Friday afternoon. Another round of
storms is looking likely Friday afternoon and evening, again with
the potential for a few severe storms along with some heavy rain.
The best area for heavy rain looks to be over the northern
portions of North Central MT at this time.

For Saturday through Tuesday...the upper level trof moves over the
CWA from late Saturday through Monday. This will allow cooler air
to move southward into the CWA, with snow levels lowering quite
low for late June, down to about 5500 to 6000 feet. Accumulating
snow is possible in the higher elevations, especially Glacier Park
by Sunday. Much below normal temperatures are expected across the
entire CWA for Sunday, with temperatures warming but up on
Mon/Tue. The chance for showers for Mon/Tue will be on the lower
side.

 - Forecast Confidence & Scenarios:
The main concern over the next few days will be the warm temps and
lower humidity for Wed/Thu. At this time winds are expected to be
on the lighter side.

For Thu afternoon into Friday...there is the potential for severe
storms once again. The main threat will be strong winds and hail,
but on Friday, heavy rainfall will also be an impact. There is the
potential SPC could increase a risk later this week.

For this weekend...much cooler temperatures area expected across
the CWA by Sunday. The EC/GFS continue to differ on timing and
potential snow levels, but impacts are starting to look likely for
elevations above 6000 feet. Bufkit has about 3 inches of snowfall
on Marias Pass this Sunday, but temperatures all above freezing.
In Glacier Park, snowfall amounts of 3 to 6 inches are possible at
and above Logan`s Pass. This could cause some impacts for those
recreating at higher elevations. We will work with the NWS in
Missoula about possible winter statements for this event later
this week. Brusda

&&

.AVIATION...
17/12Z TAF Period

VFR conditions will prevail across the CWA through the period.
There is a small chance for a passing shower/thunderstorm this
afternoon, mostly over the eastern portions of the CWA. Most of
the storms diminish by 06z Wed. Brusda

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  82  50  85  52 /  10   0   0  10
CTB  79  47  80  48 /   0   0   0   0
HLN  82  52  87  54 /  10   0   0   0
BZN  78  47  86  49 /  20  10   0   0
WYS  70  36  76  37 /  30  10   0   0
DLN  75  45  82  47 /  10   0   0   0
HVR  85  51  86  53 /  20  20   0  10
LWT  74  49  78  50 /  20  10   0  10

&&

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

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