Helena Valley West Central, MT 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

367
FXUS65 KTFX 261120
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
520 AM MDT Tue May 26 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Very warm temperatures through the week with the hottest
temperatures expected across the Northern Plains.

 - Daily chances for showers and thunderstorms through the week. A
few may become severe with the main threat being strong wind and
hail.

&&

.DISCUSSION...
/Issued 1252 AM MDT Tue May 26 2026/

 - Meteorological Overview:

Well above normal temperatures will continue through the rest of the
week with highs remaining above 80 through at least Friday. The
upper-level trough will migrate south this afternoon with the
associated low starting to become more cutoff by Thursday morning.
Throughout the rest of the week it will largely remain in this area,
ejecting multiple shortwaves out towards Montana which will allow
for daily chances for showers and thunderstorms. There is a chance a
few storms may turn severe with the primary threat being strong
winds and a secondary threat of hail.

 - Forecast Confidence & Scenarios:

Heat this Week:

Tuesday is generally expected to be the hottest day across the
region with many lower elevation locations reaching the upper 80s to
upper 90s.

The main concern with Tuesday through Wednesday is that across
northern Blaine county the overnight lows are only expected to dip
down into the mid 60s which when sandwiched between two mid to upper
90 degree days could create additional heat stress for those living
in the area. Considering the potential impacts, the decision was
made to put northern Blaine county in a Heat Advisory through
Wednesday.

Additional locations across North-Central Montana are near advisory
criteria but given that there is enough confidence in temperatures
cooling off sufficiently overnight, no additional zones were added
at this time. But folks in Hill and Chouteau counties should be
prepared for very warm temperatures and the potential threat for
heat-related illnesses, especially for those spending a significant
time outdoors. Additionally, there are heat-related concerns along
the Upper Missouri Breaks such that anyone recreating in that area
should be prepared for poor overnight temperature recovery,
particularly along the lower valley which could cause additional
stress if recreating.

Warm temperatures will continue across North-Central Montana through
the rest of the work week. For now, given the levels of uncertainty
with how hot it will get each day and how cool it will get each
night, no additional products will be issued at this time. But folks
should be prepared for the longest stretch of 90+ degree weather we
have had so far this year.


Thunderstorms Chances this Week:

For Tuesday afternoon, there is some persisting uncertainty as to
how moist it will get and whether the moisture will arrive in time
to impact convective development. The moisture profile generally
looks better Wednesday through Friday as the southerly flow
continues to work some moist air into the region. Throughout this
week the bulk of the uncertainty will revolve around whether the
highest instability is able to overlap with the highest shear which
would create a higher potential for severe weather. In the case
where shear remains lacking, there is a concern that storms may
still form but without a driving force they may linger over an area
for too long and become more of a flash flood threat.  -thor


&&

.AVIATION...
26/12Z TAF Period

VFR conditions will prevail across all terminals during this TAF
Period. Showers and thunderstorms will affect all terminals during
this TAF Period. Showers and thunderstorms will begin to affect
Southwestern Montana between 26/17Z and 26/20Z. Showers and
thunderstorms will then move northward through the afternoon. By
around 27/01Z showers and thunderstorms will begin to make it up to
North-central Montana. All thunderstorms will produce frequent
lightning and gusty, erratic winds. The strongest thunderstorms will
produce small hail and wind gusts in excess of 50 kts. During this
TAF Period there will be isolated instances of low-level wind shear
across North-central, Central, and Southwestern Montana. -IG


&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  90  55  83  55 /  30  70  30  20
CTB  89  53  80  52 /  20  80  50  50
HLN  85  51  82  53 /  50  70  40  30
BZN  82  46  82  48 /  80  60  40  20
WYS  72  38  79  40 /  70  30  30  10
DLN  75  44  78  46 /  80  20  40  20
HVR  97  59  94  57 /  10  40  20  10
LWT  89  52  84  53 /  10  30  30  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon today to 9 PM MDT Wednesday for Northern
Blaine County.

&&

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