215
FXUS65 KTFX 061116
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
516 AM MDT Sun Jul 6 2025

Aviation Section Updated.

.KEY MESSAGES...

 - An isolated strong thunderstorm or two is possible along and
   north of Hi-Line in North Central Montana today, with the main
   threats being damaging winds and hail.

 - Hot temperatures on expected on Tuesday and Wednesday, with
   high warming 10 to 15 degrees above normal.

 - Increasing west winds will develop ahead of and behind a
   Pacific front Wednesday afternoon and evening, with the
   strongest winds expected along the Rocky Mountain Front.

&&

.DISCUSSION...
/Issued 153 AM MDT Sun Jul 6 2025/

 - Meteorological Overview:

Shortwave embedded within northwest flow aloft will move over the
Northern Rockies through the day today, which will help to support
one more day of precipitation, mainly north of the US Hwy 12
corridor. Temperatures will moderate slightly today as compared to
that of Saturday, but remain slightly below to near normal. By
Monday transient ridging over the Pacific Northwest will begin to
slide east towards the Northern Rockies, with the aforementioned
ridge moving over Southwest through North Central Montana through
the middle of the upcoming work week. High temperatures will warm
significantly beneath the ridge on Tuesday and Wednesday, with most
locations running anywhere from 10 to 15 degrees above normal. Dry
conditions can be expected from Monday through Wednesday morning,
with increasing chances for precipitation from Wednesday night
through Thursday as a fast, but potent, upper level shortwave slides
east over the International Border from the Pacific Northwest to the
Northern High Plains. This shortwave and associated Pacific cold
front will help to usher in "cooler" temperatures for the day on
Thursday, along with breezy and gusty west winds during the
afternoon/evening hours on Wednesday. Quasi-zonal flow to end the
work week and into the weekend will then help to support moderating
temperatures across the Northern Rockies. - Moldan

 - Forecast Confidence & Scenarios:

Strong Thunderstorms on Sunday :

A rather robust shortwave embedded within northwest flow aloft will
slide southeast and over Northern Montana and Southern Alberta
during peak heating hours on Sunday (today). Hi-Res Ensemble
Forecast (HREF) guidance continues to support isolated to scattered
thunderstorms developing over/near Glacier National Park and the
Canadian Rockies by the late morning/early afternoon hours, with
these thunderstorms then moving east to east southeast over the
plains of Southern Alberta and the Hi-Line of North Central Montana
through the afternoon and early evening hours. 0-6km shear of 30-
40kts, surface based CAPE of 250-750J/kg, and steepening lapse rates
may be sufficient enough for a few storms to become strong to
potentially severe along and north of the US Hwy 2 corridor from Cut
Bank to Harlem. Any storm that does become severe would be capable
of producing large hail to quarter size and damaging wind gusts in
excess of 60 mph.

Heat on Tuesday and Wednesday :

NBM probabilities with respect to temperatures reaching or exceeding
100 degrees generally range from a 10-20% chance for elevations
below 3500ft across the plains of Central and North Central Montana
on Tuesday, with probabilities climbing to between a 20-50% chance
on Wednesday across these same locations.

Gusty West Winds on Wednesday :

Deep mixing ahead of and behind an advancing Pacific front on
Wednesday will bring gusty west winds to the plains of Central and
North Central Montana and the north-south valleys in Southwest
Montana. Winds will be especially strong along the Rocky Mountain
Front and immediate plains out to Cut Bank, with the latest NBM
probabilities for wind gusts in excess of 45 mph ranging from a 50-
65% chance for areas like Cut Bank, Browning, and East Glacier. -
Moldan

&&

.AVIATION...
06/12Z TAF Period

VFR conditons will predominately prevail through the 0612/0712
TAF period; however, morning fog at the KWYS terminal will lead
to IFR/MVFR conditions through 15z this morning. Showers and
thunderstorms are then expected to develop across North Central
Montana and Southern Alberta between 15-18z this morning and
persist through 00-03z Monday. While these showers and
thunderstorms will be isolated to scattered in nature a brief
period of MVFR conditions are possible between mainly 06/18z and
07/00z at the KCTB and KHVR terminals. Main impact from any
thunderstorm that moves over or near the aforementioned terminals
will be gusty and erratic winds. Widespread mountain obscuration
is not expected over the next 24 hours. - Moldan

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  81  51  85  54 /  20  10   0   0
CTB  73  46  80  49 /  30  20   0   0
HLN  82  51  87  55 /  10  10   0   0
BZN  82  47  88  51 /   0  10   0   0
WYS  73  35  79  36 /  10  10   0   0
DLN  79  45  84  48 /   0   0   0   0
HVR  80  50  84  53 /  30  20  10   0
LWT  75  49  79  52 /  20  20   0   0

&&

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

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