826
FXUS65 KTFX 052348
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
548 PM MDT Thu Jun 5 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Gusty west to southwest winds develop on Friday across the
   plains of Central and North Central Montana, especially along
   the Rocky Mountain Front.

 - Temperatures will briefly warm up on Friday before a cold front
   brings slightly cooler temperatures on Saturday.

 - Well above normal temperatures are expected across the region
   Sunday through Tuesday with highs reaching the upper 80s to low
   90s for many locations.

 - Cooler and wetter pattern possible starting the middle of next
   week.

&&

.DISCUSSION...
/Issued 249 PM MDT Thu Jun 5 2025/

 - Meteorological Overview:

Northwesterly flow aloft will prevail over the Northern Rockies
through Saturday, with near to slightly above normal temperatures
persisting beneath this regime. Isolated to scattered showers and
thunderstorms will remain possible throughout this timeframe;
however, the coverage of said showers and storms will be
significantly lower than earlier in the week and will decrease each
successive day. Light and variable winds through tonight will begin
to increase into the day on Friday over the plains of Central and
North Central Montana, especially along the Rocky Mountain Front.
Winds will remain breezy and gusty into the day on Saturday in wake
of a cold front diving south from Canada, with this cold front
helping to drop temperatures some 5-10 degrees on Saturday from
where they were at on Friday.

H500 ridging begins to build east in earnest from Sunday through
Monday, with high temperatures warming well above normal from Sunday
through Tuesday. While and isolated shower or storm can`t be ruled
out on Sunday and Monday beneath the ridge, predominately dry
conditions are expected across all of Southwest through North
Central Montana. By Tuesday a shortwave will begin to dig into the
Pacific Northwest, with the upper level flow backing to the
southwest as the ridge axis over the Northern Rockies begins to
shift east over the Northern High Plains. While continued well above
normal temperatures will continue into the day on Tuesday the threat
for showers and thunderstorms will begin to increase and Pacific
moisture is advected northeast and over the Northern Rockies. Shower
and thunderstorms chances will increase further into the day on
Wednesday and Thursday as a series of shortwaves lift east to
northeast and over the Northern Rockies, with temperatures cooling
slightly but remaining above normal. - Moldan

 - Forecast Confidence & Scenarios:

Gusty Winds on Friday:

A strengthening pressure gradient along the Rocky Mountain Front and
increasing cross barrier flow will lead to gusty southwest to west
surface winds over the plains of Central and North Central Montana,
most notably along the Rocky Mountain Front and adjacent plains out
to the I-15 corridor. Latest NBM probabilistic data generally
supports between a 70-80% chance for wind gusts to exceed 34kts
(i.e. 39 mph) across the East Glacier Park Region, Browning, and Cut
Bank Areas, with a 15-40% chance for gusts to exceed 41kts (i.e. 47
mph). Winds will be especially strong and gusty for those recreating
above tree line along the Continental Divide.  - Moldan

The main concern is related to those recreating or traveling to
various vacation destinations. Anyone recreating or traveling
through the area, especially if they are not accustomed to
stronger winds, should take extra precautions while heading out.
The greatest concern for crosswinds will be along north-south
oriented roads including I-15 north of Choteau. High-profile
vehicles and those towing trailers should be on the lookout for
sudden stronger gusts that may pose a hazard.


Well Above Normal Temperatures Monday and Tuesday:

Confidence remains high in the potential for well above normal
temperatures on Monday and Tuesday. Temperatures are currently
expected to be 10 to 20 degrees above normal with support for
these abnormal highs coming from the NBM as well as the ECMWF EFI
(Extreme Forecast Index). Some NBM probabilities for high
temperatures are as follows:

North-central Plains
 - >80% chance of exceeding 85 degrees on Monday and Tuesday
 - 50-70% chance on Monday and 20-40% chance on Tuesday of
   exceeding 90 degrees

Helena Valley
 - >80% chance of exceeding 85 degrees on Monday and Tuesday
 - 40% chance on Monday and <20% chance on Tuesday of exceeding 90
   degrees

Valleys of Southwest Montana
 - 50-70% chance of exceeding 85 degrees on Monday and Tuesday
 - <20% chance of exceeding 90 degrees on Monday and Tuesday

When considering impacts, there are some minor concerns for heat-
related illness among those recreating and/or spending a
substantial amount of time outdoors. But the good news is lows
Monday night into Tuesday morning dip into the 50s which means
that although Tuesday may be another warm day across the region,
there is ample recovery overnight to ease any concerns for longer
duration impacts.

The dangers of cold water along area lakes and rivers is a side
effect concern of this warm-up. Despite temperatures being warm,
snowmelt runoff from the mountains continues to keep our lakes and
rivers cold. Those recreating on the water need to be prepared for
this drastic change in temperature and the impact it can have on
the body.


Cooler and Wetter Pattern Middle of Next Week:

Confidence increases in a cooler and wetter pattern setting up
during the middle of next week allowing for daily chances of
showers and thunderstorms from Tuesday through at least Saturday.

Tuesday (6/10) to Saturday (6/14) Morning Precipitation Chances
 - 0.10": Widespread >80% chance
 - 0.25": Widespread 60-80% chance
 - 0.50": Widespread 30-50% chance across central and north-
   central Montana
 - 1.00": Generally less than 20% chance with some higher
   probabilities (up to 30%) along the Island Ranges

In general, the finer details remain uncertain at this time and
minor shifts in the track could significantly chance the current
picture.  -thor


&&

.AVIATION...
06/00Z TAF Period

Scattered showers and isolated thunderstorms, mostly impacting
areas over and near higher terrain, will slowly diminish through
06/04Z. Partial clearing takes place during the overnight hours
with primarily VFR conditions expected for the duration of the TAF
period. Some deterministic models highlight patchy fog
development in the KWYS area between 06/09 and 06/15Z, but
confidence in the scenario is low and probabilistic guidance for
visibility reductions below 3 miles is running less than 20% at
this time.

Northwesterly flow aloft will send another shortwave trough the
region on Friday, resulting in increased mid- to higher level
cloudiness, a few isolated showers, and gusty west to northwest
winds. The strongest winds will be Friday afternoon and evening
along the Rocky Mountain Front and adjacent high plains west of
I15 where gusts will exceed 35 kts. - RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  72  45  79  52 /  10   0   0   0
CTB  72  43  76  51 /  10   0   0  10
HLN  73  44  80  54 /  10   0   0   0
BZN  70  37  77  45 /  10   0   0   0
WYS  64  29  69  35 /  30  20   0   0
DLN  67  37  74  44 /  10  20   0   0
HVR  76  45  83  53 /  10   0  10  10
LWT  67  42  75  49 /  20  10   0   0

&&

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

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