267
FXUS65 KTFX 022031
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
231 PM MDT Sat Aug 2 2025

.KEY MESSAGES...

 - Scattered to numerous showers and thunderstorms through the
   evening hours across Central and North Central Montana north of
   the Montana Hwy 200 corridor, with isolated showers and storms
   to the south across the remainder of Central and Southwest
   Montana.

 - Relatively dry conditions are expected on Sunday across the
   Northern Rockies, with the exception of Southwest Montana south
   of the I-90 corridor where isolated to widely scatter
   thunderstorms are possible.

 - Temperatures will remain near to below normal through much of
   the upcoming work week, with another round of strong to severe
   thunderstorms expected on Monday.

&&

.DISCUSSION...

 - Meteorological Overview:

Scattered to numerous showers and thunderstorms have developed this
afternoon over North Central and Central Montana, generally along
and north of the Montana Highway 200 corridor, with isolated
coverage further to the south across the remainder of Central and
Southwest Montana. These showers and thunderstorm will persist
through the evening hours tonight before gradually dissipating into
the early morning hours on Sunday; however, a few showers and storms
are likely to linger along the International boundary through
sunrise on Sunday.  As compared to the previous two days overall
storm motions are relatively "fast" across the plains and mountains
of Central and North Central Montana where the highest PWATs of 1-
1.3" reside, with storm motions to the east of generally 20-30 mph.
While some minor urban flooding can`t be ruled out if showers and/or
thunderstorms repeatedly train over a given area, especially across
the Hi-Line where coverage will be the highest through the evening
hours tonight, the small footprints of the showers and storms and
aforementioned "faster" storm motions should help to lower the
threat for widespread flooding as compared to the previous two days.
While the stronger thunderstorms through this evening will be
capable of producing strong and gusty winds approaching 45 and
marginally severe hail of penny to near nickel size the threat for
severe thunderstorms is quite low given little to no shear and low
instability values. With that being said SPC`s non-supercell tornado
parameter was supporting values in excess of 1 along and north of
the US Hwy 2 corridor where the main upper level low is/will be
located through the evening hours, so I can`t rule out an isolated
landspout or funnel here. - Moldan

Storm coverage decreases further on Sunday as the exiting Canadian
low shunts much of the anomalous moisture eastward. Still there will
be some activity in the Milk River Valley and an initial wave of
showers and thunderstorms will creep back into the southwest by the
evening hours in response to a trough moving into the Pacific
Northwest.

An unstable southwesterly flow aloft returns to the Northern Rockies
by Monday, supplying bulk shear over 40 kts and boosting
precipitable water back over the inch mark. There will be waves of
showers and thunderstorms passing through Southwest and North-
central Montana Monday afternoon through Tuesday. The stronger
storms will be capable of strong, gusty winds, hail, and brief heavy
downpours.

The overall weather pattern looks to be much more progressive next
week compared to recent days. Another fast moving Pacific trough
looks to move through the Northern Rockies during the second half of
the week. Although there are timing and depth issues to work out,
there looks to be more showers and thunderstorms with temperatures
dipping slightly below average at least temporarily. - RCG

 - Forecast Confidence & Scenarios:

Daily rounds of showers and thunderstorms continue into next week...

Another round of scattered showers and thunderstorms redevelop again
today, but less instability and a westerly flow aloft is expected to
reduce the overall flood threat for most locations. The one
potential exception to this will be along the Canadian border,
particularly in northern Hill and Blaine counties. With most hires
guidance supporting the heaviest activity remaining over
Alberta/Saskatchewan, no flash flood products are being considered
at this time. Regardless, the stronger storms will be capable of
producing localized heavy downpours, so conditions will continue to
be monitored here given amount of rainfall received in recent days.

There is an expectation of less storm activity for most of Sunday
before an initial wave of storms begins to creep back into Southwest
Montana Sunday evening. Higher moisture levels, wind shear, and
instability will bring a return of northward moving strong to severe
thunderstorms Monday into Tuesday. The primary hazards will be
strong, gusty winds, hail, and brief heavy downpours. - RCG

&&

.AVIATION...
02/18Z TAF Period

VFR conditions will prevail at all terminals during this TAF
Period except during any thunderstorms at the KCTB and KHVR
terminals. The primarily concern will be showers and
thunderstorms across North-central, Central, and Southwestern
Montana. These showers and thunderstorms will produce a brief
heavy downpour, frequent lightning, small hail, and gusty, erratic
winds. At the KHVR and KCTB terminals visibility has the
potential to be reduced to MVFR levels and ceilings to low VFR
levels during any thunderstorm. There will be periods of mountain
obscuration during any thunderstorms. -IG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  84  52  84 /  30  10   0  20
CTB  55  76  49  77 /  50  20   0  20
HLN  54  85  55  84 /  20   0   0  30
BZN  49  84  48  86 /  30   0  10  20
WYS  36  75  40  79 /  30  10  10  20
DLN  45  80  48  80 /  20  10  30  30
HVR  58  82  54  86 /  70  30  10  20
LWT  52  79  52  82 /  30  10   0  30

&&

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

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