441
FXUS65 KTFX 021517
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
917 AM MDT Wed Jul 2 2025

.KEY MESSAGES...

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

- Scattered showers and thunderstorms develop over much of North-
  central and Southwest Montana this afternoon and evening, with
  the strongest storms producing strong to severe wind gusts and
  isolated instances of hail.

- Daily rounds of showers and thunderstorms continue heading
  into the weekend, with the best chance for wetting rainfall
  Friday and Saturday.

&&

.UPDATE...
Current forecast is on track, with no update planned for this
morning. The only change overall to the forecast is that SPC has
increased the severe thunderstorm potential to a slight risk for
our eastern portions today. The main impact from the storms today
will be strong wind gusts, but some hail is also possible. Brusda

&&

.DISCUSSION...
/Issued 542 AM MDT Wed Jul 2 2025/

 - Meteorological Overview:

Ridging aloft will maintain hot conditions over the next couple
days with afternoon temperatures peaking well into the 90s this
afternoon for most lower elevation locations. Southwesterly flow
aloft becomes more established over the Northern Rockies today
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 600 to 1,000 J/kg and precipitable water
approaching the one inch mark.

This will result in a more expansive brand of showers and storms
across much of North-central and Southwest Montana today, although
the most widespread and strongest activity looks to occur east of
I15. Localized strong to severe wind gusts will once again be the
primary hazard with continued higher based storms and hot and dry
sub-cloud layers; however, there will also be isolated instances
of hail and even some brief downpours, mostly for locations
southeast of a Great Falls to Havre line where instability and
moisture will be greatest. Most showers and storms will diminish
and end in the evening with the loss of diurnal heating, but some
may linger and or redevelop along and ahead of an approaching
Pacific cold front during the overnight hours.

Shower and thunderstorm activity will continue on Thursday, but
the cold front looks to push the most widespread activity a little
farther south into Central and Southwest Montana. With forecast
soundings for Thursday continuing to show profiles with long/thin
CAPE with deep saturation and higher surface humidity, the
expectation for showers and storms producing more rainfall with
some instances of hail and strong wind gusts has not changed.

Confidence for a couple of deeper shortwaves to move through the
Northern Rockies for the Friday through Sunday period continues to
gain traction with more run to run consistency among ensemble
members. Periods of showers and thunderstorms will continue with
temperatures briefly cooling down to near average and even
possibly briefly below average on Saturday depending on how
widespread the clouds and rainfall will be. The cooler and more
humid surface conditions should preclude storms from getting to
strong, but there will still be sufficient CAPE around for at
least some instances of hail and thunderstorm wind gusts,
especially on Friday over Central and Southwest Montana.

Ensembles loosely agree on ridging aloft to move over the
interior NW heading into next week, but there still looks to be
passing shortwaves with timing and impacts uncertainties that need
to be worked out. Overall, there`s an expectation for
temperatures to warm back above average and a continuation of at
least isolated showers and thunderstorms. - RCG

 - Forecast Confidence & Scenarios:

Moderate heat risk through Thursday...

High temperatures peak well into the 90s for most lower elevation
locations today with mild overnight lows hovering around 55 to 65
degrees again tonight. With borderline heat risk criteria today
and temperatures forecast to begin to trending cooler Thursday
through the weekend, no heat products are being considered at this
time.

Periods of showers and thunderstorms through the weekend...

Widely scattered showers and thunderstorms will become more
expansive today, with at least isolated activity expected over
most of the forecast area. Additionally, showers and storms will
initiate earlier in the afternoon, compared to yesterday, with a
few showers or storms persisting or redeveloping during the
overnight hours tonight. The highest moisture and instability will
be over Central and North-central Montana east of I15 where the
HREF continues to highlight around a 10% chance for wind gusts 58
mph or greater. Although strong to severe wind gusts will be the
primary hazard, isolated instances marginally severe hail and
brief downpours may also occur with the strongest cells.

Most showers and storms shift a little farther south on Thursday,
mostly staying over southwest and central areas south of the
highway 87/200 corridor. This does look to be temporary with
southwesterly flow aloft and passing shortwaves bringing more
areawide shower and thunderstorm potential late Friday and into
the weekend. There will be sufficient instability and moisture for
marginally severe weather at times and moisture levels will be
favorable for more productive showers and/or storms, especially
late Friday into Saturday. Deterministic models have been fairly
optimistic with widespread precipitation amounts in the quarter to
one inch mark and even higher in some cases, but the breakdown of
ensemble members fades confidence some with many showing drier
solutions or shifting the locations of heavier rainfall. More
localized higher amounts does make sense with this event being at
least a partially driven by convection. - RCG

&&

.AVIATION...
02/12Z TAF Period

VFR conditions will persist through the TAF period.

Widely scattered showers and thunderstorms develop in a southwest
to northeast fashion today, mostly between 02/18Z and 03/04Z. The
primary hazard will be strong, gusty winds with the stronger
cells will be capable of producing gusts in excess of 45 kts. Most
of this activity will diminish with the loss of diurnal heating
this evening, but some isolated showers or storms may linger or
redevelop during the overnight hours tonight. Otherwise, afternoon
temperatures will exceed 90 degrees again for most locations and
may cause density altitude concerns. - RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  94  60  89  57 /  30  20  40  20
CTB  91  59  84  52 /  20  20  10  10
HLN  91  60  86  56 /  40  30  60  30
BZN  94  55  88  52 /  30  30  60  50
WYS  82  47  76  43 /  30  30  60  50
DLN  89  54  81  50 /  30  30  70  50
HVR  99  60  93  56 /  20  20  10  20
LWT  91  58  84  56 /  30  30  40  50

&&

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

&&

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