626
FXUS65 KBYZ 150657
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
1257 AM MDT Tue Sep 15 2026

.KEY MESSAGES...

- Cooler than normal through Wednesday, then seasonable
  temperatures.

- Increasing chances for showers and thunderstorms Thursday
  through Saturday. Locally heavy rain possible, especially east
  of Billings.

&&

.DISCUSSION...

Through next Monday...

Satellite imagery shows the departing upper low over southern
Manitoba and a flatter W-NW flow over the northern Rockies. There
is an upstream shortwave along the BC coast that will be a player
for us later this week. Winds are decreasing and will shift to
easterly today. Overall it will be a tranquil day with high temps
in the upper 60s to lower 70s (after a chilly start), and much
less wind than Monday. There is also a low risk (<15%) of fog over
our north and east early today, as post-frontal dew points are
close to expected morning lows, but a west wind persisting beyond
sunrise may prevent fog from developing despite the shrinking dew
point depressions.

A weaker splitting shortwave from the NW will glance thru northern
MT tonight into Wednesday. This looks mostly dry but another
Canadian front will sag into the area reinforcing the below normal
temps for another day. Temps should climb into the 70s across the
area Thursday.

Aforementioned BC wave will eventually evolve into a cut off low
over OR/CA/NV by Wednesday. This feature will then track slowly
eastward, within a region of above normal heights, providing
ascent for shower activity and allowing for another surge of high
plains moisture. In fact, pwats are expected to climb back over an
inch over the east half of our forecast area by Friday. Greatest
potential for showers seems to be late Thursday through Saturday.
Thunderstorms are possible Friday, with enough instability and
slow storm motion to bring a risk of heavy rain, especially over
the east. Shear will likely be too low for a risk of severe
storms. Some showers could linger in the east into Sunday, but
consensus is for rising heights and drying from the west by then.
Latest NBM probabilities show a 20-40% chance of 1+ inches of rain
over the east Friday thru Saturday night. Regarding temperatures,
this is a seasonably warm system and snow levels will remain
high, no lower than 10kft. Expect near to slightly cooler than
normal temps Friday/Saturday, then warming into early next week
with the ridging. Should see near 80F by next Monday, along with
dry wx.

JKL


.AVIATION...

There is a small chance for fog/low stratus to develop this
morning for eastern MT. Winds are expected to shift from west to
east through the day with wind gusts to 25 kts in the evening. TS

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 068 045/066 047/073 054/073 051/071 049/075 049/079
    0/U 00/U    00/B    25/T    63/W    21/U    00/U
LVM 069 040/070 042/075 047/071 044/072 044/076 045/079
    0/U 00/U    02/T    57/T    43/W    11/U    00/U
HDN 070 041/067 043/077 051/074 046/071 043/076 043/080
    0/U 00/U    00/B    35/T    64/W    31/U    00/U
MLS 067 050/070 046/075 056/075 051/070 047/074 047/080
    0/U 00/U    01/B    35/T    65/W    32/W    00/U
4BQ 070 054/073 048/076 057/077 052/071 048/075 049/080
    0/U 00/U    14/W    25/T    65/W    31/B    10/U
BHK 068 045/077 041/073 051/077 047/071 042/075 043/079
    0/U 00/U    02/W    56/T    75/W    41/B    10/U
SHR 071 044/070 041/077 050/075 044/070 042/075 042/079
    0/U 00/U    11/B    26/T    64/W    21/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings