216
FXUS65 KTFX 161058
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
Issued by National Weather Service Missoula MT
458 AM MDT Thu Jul 16 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Strong to severe thunderstorms possible this afternoon and
   evening, particularly across central and southwest MT with a
   risk for heavy rain, strong winds and large hail.

 - Another round of strong to severe thunderstorms is possible
   Friday.

 - Intense rainfall rates with storms today and tomorrow could
   produce localized flooding, particularly if occurring over burn
   scars or urban areas.

&&

.DISCUSSION...
/Issued Issued by National Weather Service Missoula MT/

 - Meteorological Overview:

MT remains on the fringe of an expansive mid-upper level ridge
covering much of the CONUS from the Rockies eastward. An upper
level low initially centered offshore of the OR coast will slowly
lift around the NW periphery of the ridge into BC by Saturday
then across western Canada this weekend, temporarily flattening
the northern margins of the ridge before it builds back to the NW
early next week.

The upper level system clipping the Pacific NW will maintain an
enhanced southwesterly mid-upper level flow across the Northern
Rockies today and tomorrow. This combined with still elevated
lower to mid level moisture in place across the area and more
efficient daytime heating with lower cloud-cover than recent days
will support moderate instability for thunderstorm development
today and again Friday with with sufficient wind shear for some
organized/strong-severe storms.

Elevated moisture/instability will maintain a risk for
afternoon/evening showers/thunderstorms on Saturday with mainly
dry conditions expected Sunday as the upper level system passing
north of the area turns winds aloft more westerly. Moisture looks
to circulate back into the region early next week however as the
ridge rebuilds and flow aloft turns back to the southwest.
Temperatures gradually warm over he next several days with most
areas peaking this weekend with afternoon temps in the mid 90s.
Hoenisch

 - Forecast Confidence & Scenarios:

Thunderstorm initiation is expected over SW MT this afternoon with
hi-resolution model ensembles focusing the greatest coverage of
thunderstorms from northern Beaverhead county NE through central
MT with more isolated activity to the north through western
portions of north-central MT. Late day thunderstorm development
over Northern ID may clip across NW portions of the forecast area
overnight tonight. Large hail is a hazard with severe storms this
afternoon across central MT with the greatest overlap of
CAPE>1500 J/kg and shear >35kts along a corridor from southern
Lewis and Clark county east through southwest Judith Basin County.
A similar setup exists on Friday with broader coverage of
moderate CAPE and shear which may lead to a more organized wind
hazard.

Anomalous moisture remains in place across the area (PWAT`s >
1.00" with 50-60F dewpoints) for a risk of heavy downpours with
any thunderstorms today and tomorrow. A Flash Flood Watch remains
in effect through this evening for the particularly sensitive
landscape near the Horse Gulch burn scar, but any areas that
experience intense rainfall rates or repetitive storms today
could see some quick runoff into low-lying or urbanized areas.
Hoenisch

&&

.AVIATION...
16/12Z TAF Period

Primary aviation concern will be thunderstorm development across
southwest MT late this afternoon with storms generally tracking
northeast/east across central MT this evening. There is a risk
for large hail, gusty winds and brief heavy downpours with
stronger storms across central MT including the KHLN terminal.
Brief MVFR/IFR conditions may occur with storms, otherwise VFR
conditions prevail with mainly clear skies through this morning
before cumulus initiates this afternoon. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  89  61  94  62 /  10  20  30  60
CTB  85  59  89  60 /  20  30  40  50
HLN  91  63  94  63 /  50  40  50  70
BZN  91  59  93  58 /  30  30  40  60
WYS  87  50  87  50 /  30  40  50  60
DLN  88  57  89  56 /  20  30  50  60
HVR  91  62  96  63 /   0  20  10  50
LWT  84  55  89  57 /  30  20  20  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from 2 PM MDT this afternoon through this
evening for Big Belt, Bridger and Castle Mountains.

&&

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