Kevin, Montana Weather Forecast Discussion

276
FXUS65 KTFX 071916
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
Issued by National Weather Service Missoula MT
116 PM MDT Sun Sep 7 2025
.KEY MESSAGES...
- A few stronger thunderstorms this afternoon and evening across
   Southwest Montana.
- Smoke advancing further northeastward through the afternoon
   into the overnight.
- A bit of a lull in thunderstorm coverage Monday before
   coverage, and intensity, increases toward mid-week.
- Still some uncertainty on how the late week and weekend will
   play out, though there does look to be a period of rain at some
   point with cooler temperatures.
&&
.DISCUSSION...
- Meteorological Overview:
Southwesterly flow aloft ahead of an approaching trough off the
Pacific Northwest coast is winning out against the weakening
ridge that has been in place across the west. Initial impacts have
been smoke making better inroads across Central and North-central
Montana. The bulk of the most dense smoke near the surface looks
to move east of the region by Monday morning, though pockets of
smoke will remain.
Another impact of the switch to a southwesterly flow aloft will
be for increasing coverage of showers and thunderstorms through
the week. The main concern today will be for the showers and
thunderstorms that develop across Southwest Montana. This area has
seen smoke move away, and as such is seeing a stronger impact
from diurnal heating. Deep mixing as a result of this stronger
insolation will support thunderstorms capable of gusty outflow
winds today, with the greatest risk for a severe caliber gust
along and south of I-90. Further north coverage of thunderstorms
looks to be less, partly due to smoke reducing insolation.
Brief shortwave ridging looks to be timed well Monday afternoon
to limit coverage of showers and thunderstorms, even with the
aforementioned trough approaching the Pacific Northwest coastline.
This troughing moves even closer Tuesday and stalls out across
the interior Pacific Northwest through Thursday. A strong fetch of
southerly to southwesterly flow will persist across the region as
a result, which will help support development of showers and
thunderstorms each afternoon Tuesday through Thursday. Ensemble
guidance favors Wednesday and Thursday as the days with the best
opportunity for a more organized thunderstorm threat.
Heading toward Friday and the weekend the upper troughing shifts
toward the Northern Rockies, though specifics become murky quite
quickly. The exact track and speed of this troughing will play a
large part in which days will see the best opportunity for
accumulating precipitation. Further complicating the situation
will be for additional troughing attempting to move in behind the
initial upper disturbance late this weekend into early next week.
The main takeaway at this point continues to be for periods of
rain Friday into the weekend. Although the pattern is largely
unsettled, there does look to be breaks in precipitation at times.
-AM
- Forecast Confidence & Scenarios:
Confidence in the broad scale pattern is high, with a transition
to a more active period of thunderstorms this week followed by a
more stratiform type of rain at times late week into the weekend.
Finer scale details such as the when and where for stronger
thunderstorms is lower confidence for the Tuesday through Thursday
timeframe. Shear does not look overly impressive any of these
days, but there does look to be enough instability to cause at
least localized stronger thunderstorms. Confidence in timing and
location will increase closer to each day playing out.
Confidence in specifics decreases further toward Friday and the
weekend. A period of more stratiform rain is forecast with the
initial push, which is most likely to occur Friday, though even
that event is lower confidence with timing. Ensembles still show a
wide array of timing for precipitation Friday into the weekend,
associated with the initial upper troughing on top of additional
waves that attempt to build in behind the initial push. Over 72
hours ending 6 AM Sunday there is around or greater than 50%
chance for a half inch of rain along and north of I-90. -AM
&&
.AVIATION...
07/18Z TAF Period
Initial concern this TAF period will be for haze and smoke across
Southwest and portions of Central Montana reducing both surface and
slant-range visibility. A round of showers and thunderstorms is
then forecast this afternoon and evening, with greatest confidence
in storm coverage across Southwest Montana, mostly after 21Z.
Additional showers and thunderstorms will be much less numerous
further north. Gusty and erratic winds as well as lightning are
the main concerns today from thunderstorms. Smoke continues to
press northeastward through the remainder of the day into tonight,
making it to most plains locations by tonight. -AM
Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  53  82  50  83 /  20  20  10  20
CTB  51  79  47  80 /  20  20  10  20
HLN  54  82  52  81 /  20  20  10  40
BZN  48  81  47  81 /  30  10   0  30
WYS  37  72  37  71 /  40   0   0  50
DLN  46  78  47  74 /  30   0   0  40
HVR  55  81  51  84 /  20  10  10  10
LWT  53  79  50  81 /  20  20  10  20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion