975
FXUS65 KTFX 010936
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
336 AM MDT Tue Jul 1 2025

.KEY MESSAGES...

- Very warm to hot conditions continue through Thursday
  with temperatures cooling closer to average heading into the
  weekend.

- Scattered showers and thunderstorms develop over Southwest
  Montana this afternoon and evening with some storms capable of
  localized wind gusts over 50 mph.

- Scattered showers and thunderstorms are expected for
  most locations on Wednesday, the stronger storms may produce
  strong, gusty winds, hail, and brief downpours.

- Daily rounds of showers and thunderstorms continue heading
  into the weekend.

&&

.DISCUSSION...

 - Meteorological Overview:

Ridging aloft will bring very warm to hot conditions over the
next couple days with afternoon temperatures peaking on Wednesday
in the lower and middle 90s for most lower elevation locations. A
weak shortwave is expected to undercut the ridge and interact with
strong diurnal heating for widely scattered shower and
thunderstorm development over Southwest Montana this afternoon and
evening. Dry sub-cloud layers and inverted V profiles in a weakly
sheared environment will make localized strong to severe wind
gusts the primary concern.

Southwesterly flow aloft will become more established over the
Northern Rockies on Wednesday while a trough digs into the Pacific
NW and pushes the ridge axis farther east. A shortwave will pass
through the southwesterly flow and bring 25 to 35 kts of bulk
shear to an environment with MLCAPE around 800 to 1,200 J/kg and
precipitable water approaching the one inch mark. Thunderstorm
hazards for Wednesday will include hail and brief heavy downpours,
but localized strong to severe wind gusts will once again be the
primary hazard. The most widespread storms and threat for severe
weather will be for locations east of I15.

Showers and thunderstorms activity will continue on Thursday, but
west to northwesterly flow in the wake of Wednesday`s shortwave
looks to push the most widespread activity a little farther south
into Central and Southwest Montana. Forecast soundings currently
show profiles with long/thin CAPE with deep saturation. Also
relative humidity values climb some while temperatures fall a few
degrees. This gives the expectation for more rainfall productive
showers and storms with some instances of hail and strong wind
gusts.

A couple of deeper shortwaves moves through for the Friday
through Monday period and bring additional rounds of showers and
thunderstorms with near average temperatures. Similar to Thursday,
this activity looks to be more productive rainfall wise, but
there will still be sufficient CAPE around for at least some
instances of hail and thunderstorm wind gusts. - RCG

 - Forecast Confidence & Scenarios:

Moderate heat risk through Thursday...

Not much has changed in regards to the heat risk expected today
through Thursday. Temperatures are still expected to peak on
Wednesday with highs in the lower to mid- 90s for most lower
elevation locations. Areas southeast of the highway 87 corridor
between Great Falls and Havre (excluding the Lewistown area) will
have the greatest risk where overnight temperatures will hover
around 60 degrees or higher in addition to the afternoon heat.
Northern Fergus and southern Blaine counties currently have an 80
to 100% chance for lows above 60 degrees. Localized areas with
major heat impacts are expected, although it will be only for a 24
to 36 hour period. No heat products are anticipated at this time,
but the situation will continue to be monitored.

Periods of showers and thunderstorms through the weekend...

Most of the moisture will be in the middle and upper level today
with very dry surface conditions. This setup is favorable for high
based shower and thunderstorm development with limited wind shear
for storm maintenance. Localized strong, gusty winds in excess of
50 mph and occasional lightning will be the primary hazard to
watch for this afternoon and evening. The latest HREF guidance
highlights much of Southwest Montana with a 70% + chance for
thunderstorms wind gusts up to and over 35 mph and a 10% chance
for gusts 58 mph or greater. Storms will mostly impact areas south
of I90 and then begin to diminish and end as they move
north/northeastward in Central Montana.

Shower and thunderstorm activity becomes more expansive on
Wednesday as a shortwave adds better upper level support and
moisture. The greatest moisture and instability will east of I15,
particularly for areas south and east of a Great Falls to Havre
line. These areas have around a 10% chance for wind gusts 58 mph
or greater. There will also be the threat for marginally severe
hail and brief downpours.

Most showers and storms shift a little farther south on Thursday,
mostly staying over the southwest and central areas south of the
highway 87/200 corridor. This looks to be temporary with
southwesterly flow aloft and passing shortwaves bringing more
areawide shower and thunderstorm potential heading into the
weekend and beyond. There will be sufficient instability and
moisture for severe weather and productive showers and storms with
the most rainfall generally expected Thursday through Saturday.
- RCG

&&

.AVIATION...
01/06Z TAF Period

The main concern for the TAF period will be isolated to scattered
showers and thunderstorms Tuesday afternoon along and south of
the I-90 corridor. A few strong storms will be capable of
producing gusts in excess of 45kts. Everywhere else, calm winds
and an increase in cloud cover Tuesday evening. -Wilson

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  93  59  93  60 /   0   0  30  30
CTB  88  55  91  58 /   0   0  10  10
HLN  95  58  90  59 /  10  10  40  20
BZN  96  55  93  56 /  20  30  30  30
WYS  86  46  83  46 /  30  40  40  20
DLN  90  52  87  53 /  30  20  40  30
HVR  95  59  98  60 /   0   0  10  30
LWT  88  59  91  58 /   0  10  30  30

&&

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

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