mt discuss
Office: TFX
FXUS65 KTFX 130748
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
148 AM MDT Sun Jul 13 2025
.KEY MESSAGES...
- Dry and warm today.
- Transition day Monday, with a cold front bringing gusty winds and
an opportunity for thunderstorms from north to south through the
afternoon and evening.
- Much cooler and wetter Monday night into early Wednesday.
- Trending warmer and drier late week.
&&
.DISCUSSION...
- Meteorological Overview:
An initially anti-cyclonic northwesterly flow aloft will be in place
today. The result will be for another warm day, though by the
evening low-end chances for showers and thunderstorms will develop
as the flow aloft begins its transition to be more cyclonic in
nature. Areas with the best chance to see a shower or thunderstorm
late this afternoon into the overnight is along the Hi-Line, as
well as south of the I-90 corridor in SW MT.
A rather sharp trough diving southeastward within the northwesterly
flow aloft Monday will begin the transition to a cooler and wetter
pattern across the region. A cold front will dive southward from
Canada Monday afternoon and evening, bringing a gusty northerly wind
shift to the region, especially as the front pushes through narrow
SW MT valleys. Ahead of the front temperatures will remain quite
warm through the day, especially in Southwest Montana. There appears
a conditional risk for stronger thunderstorms Monday afternoon and
evening near the cold front, largely associated with the timing of
the front which remains uncertain at this time.
Although cooler air will push in behind the front, surface and
near-surface moisture will quickly rise. PWATs ahead of the front
largely look to be less than 0.75" or so, but quickly rise above
1" behind the front. This moisture, forcing associated with upper
level troughing, and any terrain enhancements will all contribute
to a period of rain across the region. Areas on and adjacent to
the plains are favored for the most rain, while areas near the
Southwest MT and ID border look to be much drier overall. Although
it is July, this system does feature cool enough air to support
mountain peak snow in and around Glacier NP. Further discussion of
snow levels is in the confidence and scenario section.
As mentioned prior, this system will usher in cooler air to the
region. Areas over the plains look coolest, with daytime highs
Tuesday struggling to reach the lower 60s. By Wednesday
temperatures do look to begin trending warmer, but another well
below average temperature day is forecast for the plains. Further
south into the Southwest MT valleys the coolest air will struggle a
bit to make inroads, Hence, although these areas do cool for Tuesday
and Wednesday, they do not look to cool nearly as much as areas
further north on the plains.
This system departs during the day and into the evening Wednesday,
with another period of northwesterly flow in its wake. Deterministic
guidance and ensembles are not yet confident as to whether this
flow aloft will be more cyclonic or anti-cyclonic in nature, but
they do agree that temperatures will at least slowly trend back
toward normal by the end of the week, with much lower chances for
precipitation compared to early to mid-week. -AM
- Forecast Confidence & Scenarios:
This afternoon into the overnight:
A small subset of guidance features a stronger thunderstorm across
portions of the Hi-Line tonight. If this were to play out, it looks
like the stronger thunderstorms would initially develop in
Alberta and move southeastward, crossing the border this
evening/tonight. The confidence that this solution is realized is
low at this time, however.
Monday:
There is still timing uncertainty with the front, with quicker
guidance moving it through as early as Monday morning, while less
aggressive guidance holds it off til Monday afternoon and
evening. The timing of the front will play a large role in
when/where/if a stronger thunderstorm forms.
Another potential concern will be for the cold front pressing
through Central and Southwest Montana valleys. Typically wind prone
areas from northerly wind pushes such as between Helena and Three
Forks and between Whitehall and Twin Bridges have a roughly 20%
chance for a 50 mph gust along and behind the front.
Precip amounts and snow levels Monday through early Wednesday:
Previously bi-modal ensembles (One much drier and a few on the
wetter side) appear to be converging on the wetter solution for the
region. The chance for event total precipitation over a half of an
inch is roughly 50% or so over the plains. Further, the chance for
an inch of precipitation is around 20% or so.
Snow levels with this system look to fall to their lowest Tuesday
morning across the Northern Rocky Mountain Front, including eastern
Glacier NP. NBM 10th percentile snow levels (90% chance for snow
levels higher than this) are briefly around 7,000-7,500 ft or so
Tuesday morning. NBM 50th percentile snow levels (Middle of the road
snow levels) Tuesday morning are in the 8,000-8,500 ft range. -AM
&&
.AVIATION...
13/06Z TAF Period
VFR conditions prevail at all terminals through the period. Light
and variable winds will continue through the overnight before
pickup up to around 10kts in the afternoon. Mid-level clouds will
filter into the Hi-Line by the afternoon ahead of a cold front
with around a 15-20% chance for isolated afternoon showers and
thunderstorms, particularly for KHVR. -thor
Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 94 59 90 52 / 0 10 20 70
CTB 87 55 73 47 / 10 20 50 80
HLN 94 61 92 53 / 0 10 10 60
BZN 94 56 95 52 / 0 10 10 40
WYS 85 45 84 44 / 0 20 20 30
DLN 89 53 90 50 / 0 20 10 20
HVR 93 58 83 51 / 0 30 30 70
LWT 88 57 88 48 / 0 10 20 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls
Office: MSO
FXUS65 KMSO 130843
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
243 AM MDT Sun Jul 13 2025
.DISCUSSION...
KEY MESSAGES:
- Moderate heat risk impacts across low elevations of north-
central Idaho and western Montana this afternoon.
- High confidence for a significant change (>90%) late Monday
into Tuesday across northwest Montana, with much cooler
temperatures and widespread precipitation.
- Strong northeast winds 30-45+ mph Monday and Monday night, with
risk for spotty power outages and tree limb damage.
The hottest temperatures of the week are expected today, as highs
reach into the low-100s for lower elevations of central Idaho and
low/mid-90s across western Montana valleys. These temperatures
will bring a moderate risk of heat impacts. Consider practicing
heat safety by drinking plenty of fluids, and resting in shaded or
air conditioned environments when working outside. Furthermore,
breezy westerly winds will lead to elevated fire weather
conditions.
High confidence exists for a pattern change late Monday into
Wednesday, as a trough of low pressure moves into the region from
British Columbia. Global models suggest a potent cold front will
move across the Continental Divide Monday evening, sweeping into
western Montana Monday night, before reaching central Idaho
Tuesday morning. Strong north-northeast winds of 30-45+ mph will
accompany the front given sharp pressure rises (>10 mb in 6 hrs)
across northwest Montana, including Glacier Park and the Flathead
Valley Monday evening. High resolution model guidance suggests
mountain wave activity with locally higher gusts in excess of 45
mph downstream of mountain crests within Glacier Park and the
Whitefish and Swan Ranges. This is well supported by forecast
soundings that highlight a wind reversal and stable layer near
crest height, creating ideal conditions for mountain wave activity
Monday night. This could trigger spotty power outages, tree limb
damage, and pose a significant risk to those recreating on area
lakes like Flathead Lake.
Widespread precipitation will accompany the front, with rainfall
focusing across Lincoln and Flathead Counties in Northwest
Montana. The higher totals of 0.50-1.00+ will focus along the
divide in Glacier Park, where easterly upslope winds will enhance
orographic precipitation. Rainfall amounts will quickly drop off
along and south of the I-90 corridor, with less than 0.10 inch.
Snow levels will range between 8,000 and 10,000 feet MSL across
northwest Montana. Heavier precipitation rates Monday night into
Tuesday morning could drive the snow down to 7,000 feet in Glacier
National Park. There could be several inches of snow on the
mountain peaks on Tuesday.
By Wednesday, this system will depart the east, with a dry
northwesterly flow pattern taking shape the next several days.
&&
.AVIATION...VFR conditions are expected today under a ridge of
high pressure. Scattered mid-high level clouds will move across
Northwest Montana late this morning into the afternoon. Otherwise,
breezy winds will develop once again this afternoon, with gusts of
15-20kts.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...Heat Advisory until 8 PM PDT Monday for Lower Hells
Canyon/Salmon River Region...Orofino/Grangeville Region.
&&
$$
Office: BYZ
FXUS65 KBYZ 130845
AFDBYZ
Area Forecast Discussion
National Weather Service Billings MT
245 AM MDT Sun Jul 13 2025
.KEY MESSAGES...
- Warmer (80s and 90s) and dry into Monday.
- Much cooler with a good chance of precipitation Monday night
through Wednesday.
- Conditions become dry with highs near normal (mid 80s to low
90s) by the end of the week.
&&
.DISCUSSION...
Through Monday Night...
Ridging over the region will flatten a bit today, with warm and
dry conditions prevailing. High temperatures will top out in the
upper 80s to 90s. Winds will be a bit lighter than yesterday. Some
weak energy moving through the westerly flow will bring a few
showers or thunderstorms (15% chance) to the southwest mountains
and adjacent foothills late this afternoon and evening.
Monday starts off warm and dry with pre-frontal conditions in
place. Temperatures will warm into the upper 80s and 90s, ahead of
a cold front passage late in the day/Monday evening. Uncertainty
remains in the frontal timing, as convection near the MT/Canada
border early Monday morning could induce north/northeast winds to
move in earlier than currently forecast. Ahead of the front,
a weak wave moving through the westerly flow and instability over
the region will bring isolated to scattered (15 to 30% chance) showers
and thunderstorms to the southern mountains and foothills during
the afternoon/evening. Cooler conditions, breezy north to
northeast winds and increasing chances for precipitation will move
into the area behind the front, continuing into Tuesday. STP
Tuesday through Sunday...
Tuesday, a 500 mb Pacific wave will be moving into the region
bringing a pattern change to cooler and wetter conditions for
Tuesday and Wednesday. This wave will create elongated surface
low pressure from Wyoming through South Dakota. Northerly winds
associated with this low are expected to advect in moisture from
the north. The ECMWF Ensemble is indicating PWAT values of 1-1.25
which are 150% of normal or greater for this time of year.
Temperatures will also drop significantly behind a cold frontal
passage Monday night. The ECMWF EFI tables are showing areas of -0.9
to -0.95 anomalies indicating well below normal temperatures.
Currently, the NBM is indicating most locations will be in the 60s
F Tuesday and Wednesday. Cool temperatures and high PWATS will
create moist lower levels more reminiscent of a spring system. A
few rumbles of thunder cannot be ruled out, however, little to no
instability should act to limit convective potential. Due to this,
severe storms are not expected with this system at this time.
Precipitation amounts are highly uncertain at this time. WPC
clusters making up about 40% of models indicate lower
precipitation amounts ranging from 0.1-0.5 inches across the
region. The other 60% of models show widespread precipitation
values greater than 0.75 inches for locations east of the
continental divide. Currently the NBM is giving our region a 50%
chance for getting greater than 0.5 inches of precipitation.
The upper level pattern gets messier late in the week as ensembles
are unclear as to what will replace the Pacific trough. There
seems to be good agreement however that the pattern will bring
downsloping conditions warming temperatures back to seasonal
values. Dry conditions are also expected Thursday through the
weekend. Torgerson
&&
.AVIATION...
VFR conditions will prevail over the next 24 hours. Torgerson
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Mon Tue Wed Thu Fri Sat
-------------------------------------------------------
BIL 095 064/096 059/065 053/067 053/081 059/085 060/090
0/U 12/T 56/T 64/T 21/U 11/B 10/U
LVM 093 057/094 052/065 045/069 046/084 050/087 051/091
0/U 12/T 57/T 63/T 11/U 12/T 11/U
HDN 095 062/096 057/068 053/067 049/083 056/086 057/090
0/U 02/T 55/T 74/T 21/U 11/B 10/U
MLS 096 064/096 060/069 053/067 052/079 057/086 059/089
0/U 10/U 55/T 64/T 21/U 11/U 10/U
4BQ 093 067/096 061/070 054/067 053/078 059/084 060/087
0/U 02/T 44/T 74/T 21/U 11/U 21/U
BHK 091 062/095 055/067 050/064 047/076 053/083 056/084
0/U 01/U 44/T 64/T 21/B 11/U 21/U
SHR 092 059/093 055/068 050/070 047/082 052/085 055/088
0/U 12/T 46/T 75/T 21/U 11/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Office: GGW
FXUS65 KGGW 130818
AFDGGW
Area Forecast Discussion
National Weather Service Glasgow MT
218 AM MDT Sun Jul 13 2025
.DISCUSSION...
KEY MESSAGES:
1) Hot and dry conditions continue today.
2) Chances for showers and thunderstorms start tonight in the
north and become widespread across the region Monday night and
continues through at least Tuesday night.
3) Cooler temperatures start in the north on Monday and spread to
the entire area on Tuesday and Wednesday.
WEATHER PATTERN OVERVIEW:
Hot and dry weather will prevail over NE Montana today. Meanwhile,
models and ensembles wants to bring a back door cold front at
least part way through the forecast area in the late afternoon and
early evening with gusty NE winds mainly north of the Missouri
River this evening and a chance of showers and thunderstorms north
of the Missouri River tonight. Not sure how much of these NE winds
will reach Fort Peck Lake this evening. Will hold off on a Lake
Wind Advisory for now.
This frontal boundary will be quasi-stationary over the forecast
area for most of the day on Monday. This will result in highs in
the 80s north and 90s south. Models and ensembles have differences
on where the front will be stationary Monday morning and when and
how quickly it moves south as a cold front Monday afternoon and
evening as a shortwave trough approaches the area from the west.
Chances for showers and thunderstorms will remain north of the
Missouri River during the day on Monday but will spread to the
entire region and become likely Monday night as the cold front
moves to the south.
The upper trough will keep frequent chances for showers and
thunderstorms over the area on Tuesday, Tuesday night, and
Wednesday with cooler than normal temperatures for mid July.
The highest QPF is expected Monday night through Tuesday night.
Portions of NE Montana could see precipitation amounts range
between 0.25" and 0.50" during this period.
FORECAST CONFIDENCE & DEVIATIONS:
Confidence is high that hot and dry conditions will continue
today. Confidence is low on temperatures on Monday due to the
uncertainty of the location of the frontal boundary. Confidence
is high on the cool and wet weather that starts Monday night and
continues until Tuesday night or Wednesday. While NBM was largely
followed, a blend with NBM 90 was used for winds this evening and
again Monday night as models frequently underforecast winds behind
a cold front.
&&
.AVIATION...
LAST UPDATED: 0820Z on July 13, 2025
FLIGHT CAT RANGE: VFR.
DISCUSSION: VFR conditions are expected with mostly clear skies
today and a mix of mid and high clouds tonight. KGGW and KOLF
could have an isolated shower or thunderstorm late tonight.
Otherwise, chances for showers and thunderstorms will remain north
of the TAF sites tonight.
WINDS: Light and variable this morning becoming west to SW 5 to 10
knots this afternoon. Around 00z, winds will veer to the north and
NE and increase to 10 to 20 knots at KGGW and KOLF, and 10 to 15
knots at KSDY. Meanwhile, winds will veer to the west and NW at
KGDV at 10 to 15 knots. NE winds will diminish to 5 to 10 knots
after 06z at KGGW, KOLF and KSDY and become light and variable at
KGDV.
&&
.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
weather.gov/glasgow
