Helena Valley, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

185
FXUS65 KTFX 061803
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1203 PM MDT Tue Oct 6 2026

.KEY MESSAGES...

- Warm and dry conditions persist through Friday.

- Windy conditions on Friday will lead to elevated fire weather
  concerns.

- A shift to cooler and wetter conditions is expected this weekend
  with a chance for impactful mountain snow.

&&

.DISCUSSION...

 - Meteorological Overview:

Low amplitude upper level ridging across the western US will
maintain unseasonably warm and dry conditions across the area
through Friday beneath a west-northwest flow aloft. Afternoon
temperatures will run slightly lower than those of Monday but still
around 15 degrees above early October climatological averages.
Afternoon mixing and a moderate surface pressure gradient across the
Rockies will support some breeziness this afternoon, mainly across
the plains, with overall lighter winds Wed and Thu as surface high
pressure slides east across the Canadian Prairies.

An upper level trough digging southeast through BC Friday will bring
a significant weather pattern change for the weekend with windy
conditions developing Friday as southwesterly mid-level flow
increases ahead of the approaching trough. Warm, windy and dry
conditions Friday will bring elevated fire weather concerns ahead of
a cold front Friday night that brings in much cooler and wetter
conditions for the weekend. Model guidance is in reasonable
agreement to dig the trough southward into the NW US Saturday with
typical differences and spread still at this time range among
models/ensemble members in the eventual evolution of the trough
through the rest of the weekend into early next week.  Hoenisch


 - Forecast Confidence & Scenarios:

With warm and dry conditions expected to continue through the rest
of the week, there is a concern for elevated fire weather conditions
(see FIRE WEATHER for more information).


Wintry Conditions This Weekend:

Confidence continues to increase in the potential for cold
temperatures and widespread snow along the mountains this weekend
with the potential for some lower elevation snow Sunday morning.
Temperatures on Saturday will be 25-30 degrees cooler compared to
Friday and continue to drop another 15-20 degrees by Sunday.

There are hints in the models that some of the heavier mountain snow
could arrive Saturday evening instead of early Sunday morning. This
has the potential to impact more of the Continental Divide and the
island ranges of Central Montana with some additional snow possible
compared to the previous storm totals. The main impacts would be
along mountain passes, particularly Logan and Marias Pass initially
followed by Rogers Pass over the next few hours. Those who plan on
recreating or traveling this weekend should have a plan for cold
temperatures and wet snow.

Across the northern plains there is a potential for snow levels to
fluctuate right around ground level through Sunday afternoon which
could produce a rain/snow mix at times. Additional snowfall
accumulations are expected to be on the lighter side by this point
in the event but a larger concern might be if there is any rain/snow
mix plus daytime melting on Sunday followed by subfreezing
temperatures overnight into Monday morning which could make roads
and sidewalks slick across the area.

Given the level of uncertainty still present in the models it is
hard to pin down exactly how much snow will fall during this event
but there is at least a 50% probability of locations below 5000 feet
seeing at least one inch of snow total. -thor


&&

.AVIATION...
06/12Z TAF Period.

VFR conditions will prevail throughout this TAF period.
Relatively mild winds will occur across the Southwest terminals
(KBZN, KEKS, KWYS and KHLN). For the Central terminals (KGTF and
KLWT), expect westerly-southwesterly winds gusting up to around 20
kts from 20Z to 01Z. KCTB will have westerly winds gusting up to
around 25 kts during this time frame. Cloud cover will begin to
increase around 22Z, mostly over Central/North-Central MT, but
ceilings will remain high. -Dzomba

&&

.FIRE WEATHER...

While wind speeds through Thursday will not be significant, warm
afternoon temperatures and low afternoon humidity will persist with
only moderate to locally poor overnight humidly recovery, especially
over the central MT mountains and adjacent slopes. These condtions
may advance the curing and drying of lighter (grass/shrub) fuels
that are already headed into seasonal dormancy. Increased winds with
potential for gusts in excess of 40 mph Friday, alongside the
continued warmth/dryness will bring an elevated fire weather risk.
Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  45  72  42  75 /   0   0   0   0
CTB  41  67  39  72 /   0   0   0   0
HLN  43  77  43  78 /   0   0   0   0
BZN  42  75  40  76 /   0   0   0   0
WYS  34  73  31  72 /   0   0   0   0
DLN  42  77  40  77 /   0   0   0   0
HVR  42  71  37  73 /   0   0   0   0
LWT  46  73  42  75 /   0   0   0   0

&&

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

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