911
FXUS65 KBYZ 101840
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
1240 PM MDT Thu Sep 10 2026

.KEY MESSAGES...

- Please note that the forecast has trended drier over the next
  few days.

- Cold front arrives tonight, bringing cooler weather Friday into
  next week.

- Occasional chances of showers (mainly light) Friday through
  Sunday night. A few thunderstorms possible in southeast Montana,
  especially Sunday night.

- Snow showers in the mountains above 10000 feet Sunday and Sunday
  night; little if any accumulation.

&&

.DISCUSSION...
Through next Thursday...

A warm & dry day is ongoing, ahead of a Canadian cold front which
is moving south of Calgary, where it is currently 52F and
raining. We will see temps well into the 80s to near 90F today.
Temps will be slow to cool along the foothills with lee side
pressure falls this evening, and in fact there should be briefly
breezy downslope winds (gusts 30 mph?) at places like Red Lodge,
Fort Smith & Sheridan between 5-10z. It appears there will be a
pre-frontal wind shift to N-NE this evening, then main cold
advection arrives late tonight into early Friday. Tomorrow will be
notably cooler than today with highs in the lower 60s north to
mid 70s south.

Some light showers are expected tomorrow into tomorrow night per a
weak shortwave on top of the cooler surface with developing
upslope/easterly winds. As a moister surface high settles in,
there is a good chance of low stratus/fog particularly in upslope
areas Friday night into Saturday. This will be something to
monitor but high res models are starting to point in that
direction, which conceptually is to be expected. Low amplitude
ridging develops Saturday but cooler surface high will remain on
the east side of the mountains. With expectation of some low
clouds and upslope/easterly winds, have cooled forecast highs to a
few degrees below the typical guidance. Elevated instability
along a mid level warm front may support a few showers/t-storms in
far southeast MT Saturday night, otherwise there should be a
period of dry wx associated with the brief ridging.

Stronger Pacific low moves thru the PacNW Saturday night and
begins to provide some large scale ascent to our west on Sunday.
However, the track of the low from eastern OR thru northwest MT
does not favor us for precip, but rather dry slotting. This is the
primary reason for the forecast trending drier. Models are showing
lee side pressure falls as this happens Sunday, which would not
only introduce drier downslope winds but also warmer temps. After
cooler days Friday/Saturday it looks as if Sunday will be warmer
especially in central and southern parts of our cwa where highs
could push 80F. Greatest potential for precip seems to be in the
east Sunday night, with increasing elevated instability combined
with the ascent suggesting scattered showers and thunderstorms,
and cannot rule out a few strong storms depending on the evolution
of a surface trof. Western mountains and the north (away from
downslope impacts) should also see some showers as the trof
passes. Southern foothills like Red Lodge and Sheridan will be
mostly (if not entirely) dry over these next few days. Mountain
snow potential has cratered. Look for scattered snow showers with
little to no accumulation above 10kft Sunday into Sunday night.

Monday will be post-frontal and cooler w/ breezy/drier W-NW winds.
Gusts may approach 40 mph over the east. A secondary wave dropping
out of the NW may or may not be strong enough for some showers
into Tuesday but it will help to keep temps cooler than normal
Tuesday and Wednesday with highs in the 60s to lower 70s.
Nighttime lows will be seasonably chilly but the risk of a frost
is under 50%. In fact, frontal winds will keep temps somewhat
elevated Sunday night. Monday night and Tuesday night should be
the coolest nights of next week (lows mid 30s to mid 40s).

Overwhelming model consensus is for building heights, dry and
warmer weather for the latter part of next week. Look for highs in
the 70s (near normal) Thursday, then likely 80+ degrees by the end
of the week.

JKL

.AVIATION...

VFR conditions will prevail through the period. Westerly winds
gusting 15-30 kts are expected through the afternoon and early
evening, strongest along the western foothills (KLVM, K6S0,
K3HT). A dry cold front will bring a wind shift late this evening
into the overnight hours. Winds in the generally wind shadowed
Bighorn Foothills (KSHR) will likely get gusty (25kts) from the
west ahead of this wind shift after 05z, continuing into the early
morning hours until the front arrives and shifts winds northerly.
Northerly winds of 10-20 kts can be expected across the area on
Friday, with showers and isolated thunderstorms dropping in from
the north and west. Local MVFR conditions are possible with the
shower/thunderstorm activity. STP

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 053/066 049/066 048/070 046/068 042/066 044/068 044/073
    02/W    20/E    23/W    21/B    00/B    00/B    10/U
LVM 048/070 043/066 041/068 039/065 035/066 038/069 039/074
    02/T    31/E    23/W    41/N    00/U    01/U    11/U
HDN 049/070 045/070 044/075 043/069 038/070 040/070 040/075
    01/B    20/B    33/T    20/N    00/U    10/B    10/U
MLS 056/069 047/065 046/072 048/067 041/066 044/070 044/073
    01/B    21/E    33/W    61/N    00/U    11/B    10/U
4BQ 057/075 048/071 049/075 048/070 041/067 045/072 044/075
    00/U    21/B    34/W    50/N    00/U    11/B    10/U
BHK 054/074 041/066 041/069 044/069 037/067 040/073 040/074
    00/U    21/E    34/W    71/N    00/U    12/W    10/U
SHR 051/076 042/072 044/078 042/069 037/068 040/071 038/075
    01/U    20/B    22/T    20/U    00/U    11/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Red Flag Warning in effect until 8 PM MDT this evening FOR
      ZONES 123-124-127-133.
WY...None.

&&

$$
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