Whitlash, Montana Weather Forecast Discussion

486
FXUS65 KTFX 180757
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
157 AM MDT Thu Sep 18 2025
.KEY MESSAGES...
- Mild and dry to close out the week.
- Gusty winds with low-end chances for precipitation Sunday.
- Another period of mild and dry weather early next week.
&&
.DISCUSSION...
- Meteorological Overview:
A rather complex upper level pattern is in place to start the
forecast. Two closed, or nearly closed, compact upper lows off to
the east in eastern MT and into the Dakotas/vicinity are pivoting
around each other, with the northwestern lobe side-swiping Blaine
and Fergus counties today before moving eastward tonight. Meanwhile
further west, a splitting trough is moving onshore across the
Pacific Northwest. Although the initial setup is quite the mouthful,
impacts locally over the next few days are quite low.
The upper level low side swiping Fergus and Blaine counties today
will result in a roughly 20% chance for a shower or thunderstorm
in portions of those two counties. Otherwise the main concern for
today will be for some patchy fog this morning.
The splitting trough moves across the region tomorrow afternoon.
Other than a 10% chance for a shower across northern areas, the day
looks dry and mild. The dry and mild trend continues into Saturday
as weak upper level ridging moves in briefly.
As quickly as the ridging builds in Saturday, it looks to be broken
down equally as quickly Saturday night into Sunday by robust
troughing diving southeastward out of BC. The main concern with this
ridge breakdown will be for gusty winds over the plains, with areas
along the Rocky Mountain Front most favored for the strongest winds.
The troughing is also potent enough to result in some light
precipitation in the terrain Saturday night into Sunday.
Troughing quickly exits Sunday night with upper level ridging
quickly developing behind it. Thus, another largely dry and mild
period Monday into the middle of next week is forecast. -AM
- Forecast Confidence & Scenarios:
Wind Sunday: Confidence continues to grow in a period of gusty, and
potentially strong, winds Sunday. Areas along the Rocky Mountain
Front continue to be most favored for the strongest winds and
gusts. In fact, the probability for a 60+ mph gust along the Rocky
Mountain Front Sunday is around 50% in wind prone areas. Further
east, the chance for a 50 mph gust in Browning and Cut Bank is
roughly 40%.
What makes the situation more notable and worth highlighting is that
trees that still have their leaves have a greater potential to cause
impacts than in a more typical wind event later in the fall when
trees have already lost their leaves. Those operating higher profile
vehicles such as campers not accustomed to the winds along the Rocky
Mountain Front should be aware of the potential for crosswinds on
north-south oriented roadways. -AM
&&
.AVIATION...
18/06Z TAF Period
Primary concern through the 1806/1906 TAF period will be fog, with
the window for fog development at the KWYS, KBZN, KHLN, and KHVR
terminals being between 08-10z and persisting through 15-17z
Thursday. Confidence in VIS and/or CIGS falling below VFR due to
this fog continues to be low at all of the aforementioned
terminals outside of KHVR where latest HREF guidance supports a
10% chance for VIS to fall to MVFR between 13-16z Thursday.
Otherwise the remainder of the TAF period will be VFR, with no
mountian obscuration. - Moldan
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  79  48  80  47 /   0   0   0  10
CTB  76  44  77  44 /   0   0  10   0
HLN  80  49  80  50 /   0   0   0   0
BZN  78  44  79  45 /   0   0   0   0
WYS  71  33  73  34 /   0   0   0   0
DLN  76  43  77  44 /   0   0   0   0
HVR  76  45  78  48 /   0   0   0  10
LWT  74  45  75  47 /  10   0   0  10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion