446
FXUS65 KBYZ 161832
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
1232 PM MDT Sat May 16 2026

.KEY MESSAGES...

- Colder with periods of precipitation tonight through Monday.

- Accumulating snow possible (60% for greater than 6 inches) for
  the western mountains tonight (above 5000feet), and across the
  Beartooth/Absaroka, Pryor, and Bighorn mountains/foothills
  Sunday night.

- Breezy winds expected across the area tonight. Gusts 30-50 mph
  are expected (strongest near the Dakotas border).

- Widespread frost/freeze likely Sunday and Monday night. Make
  sure to protect sensitive plants.

- Warmer conditions return for the middle of next week with low
  chances for precipitation each day.


&&

.DISCUSSION...

Rest of Today through Friday...

A cold front will move through the forecast area tonight. Ahead of
the front this afternoon a couple of areas of precipitation
potential to watch will be over western areas where the 700mb
frontogenesis is getting its act together and over the
Bighorn/Pryor mountains into far SE Montana where the nose of a
low level southerly jet and some upper level jet energy will be
pushing into the area providing lift. Precipitation chances will
be highest with the western area as stronger frontogenetic forcing
will be in play as the front slowly advances into the area late
afternoon into this evening, with a few embedded thunderstorms not
out of the question. The other area will be more isolated to
scattered in nature, but will be primarily thunderstorms working
northward into the area. Despite decent shear values (0-3km SRH
200-400 m2/s2), MUCAPE values peak under 500j/kg. So, not
expecting strong storms, however HREF is showing indications of
wind gusts in the 35 to 50 mph with any thunderstorms or stronger
showers that do form east of a Miles City to Broadus line this
evening into the overnight hours mainly a result of the stronger
low level jet momentum getting pushed to the surface by any
precipitation as opposed to storm dynamics.

Speaking of winds, 2 to 3 mb/hr pressure rises are forecast as the
cold front moves through the area tonight. This will induce gust
northwest winds across the area in the 20 to 40 mph range, with
isolated stronger gusts possible especially near precipitation
areas.

Precipitation amounts look highest west of Billings where band of
showers will set up for several hours before the front accelerates
to the east limiting precipitation latency for areas further east.
probabilities for over a quarter of an inch of precipitation
through tomorrow morning are over 60% for areas west of a Roundup
to Columbus line. For Billings and Baker the probability of a
tenth of an inch is around 40%, with most locations in between
showing less than a 20% chance for a tenth of an inch tonight.

Snow is expected over the western Beartooth and Crazy mountains
tonight with probabilities for over 6 inches of snow through
Sunday morning sitting around 60%. Temperatures will get cold
enough for some light snow down to 4000 feet by sunrise Sunday
which bring Livingston and the Paradise valley into the equation.
However precipitation chances will be trending down by that time
and with warm ground temperatures do not expect any travel issues
and maybe a dusting to half an inch on grassy surfaces. Areas
further east including the Beartooth mtns above Red Lodge and the
Bighorn/Pryor mountains are not looking at any significant snow
accumulations tonight.

Upper low responsible for tonights cold front will drop southward
Sunday and split into two pieces, leaving our area in a cool but
breezy (downslope NW winds) and mainly dry portion of the system
Sunday.

Southern piece of the system ejects northeast Sunday night into
Monday, spreading upper level divergence over the area. At the
same time low level winds shift to the north and deepen up some
colder Canadian air over the area. The cold upslope winds combined
with the upper dynamics from the upper low will bring a period
of snowfall to the southern mountains and foothills Sunday night
through Monday morning. While snow may be observed in other
portions of the forecast area during this time (snow levels down
to 3500feet) impactful accumulations will be limited to the Red
Lodge and Beartooth Foothills along with the Pryor and Bighorn
mountains. Winter weather advisories have been posted for Sunday
night through Monday morning for these areas. Should the upper low
track further north, which some ensemble members of the GFS/EC/Can
are showing, accumulating snowfall and higher precipitation
amounts may shift further north as well, so stay tuned as this is
a dynamic Spring storm system.

Storm system exits to the east on Tuesday, for warmer and drier
conditions. General northwest flow is expected over the area
Tuesday through the rest of the week. This time of year northwest
flow is synonymous with isolated to scattered afternoon/evening
precipitation chances, and that is reflected in the current
forecast. There are several weaker systems embedded in this flow,
though the cores stay mainly north of the area, that could bring
some enhancement to those lower precipitation chances at times. So
there is at least some probability for getting precipitation just
about every day next week, just no stronger systems past Monday.
Chambers

.AVIATION...

Scattered showers, and a few weak thunderstorms, will spread west
to east this afternoon and evening ahead of a cold front. The
best chance (10-20%) for a thunderstorm is over the mountains and
foothills west of KBIL and near the Dakota border. With the
frontal passage, winds will turn out of the northwest, with
widespread gusts of 20 to 35 kts through Sunday morning.
Widespread MVFR ceilings, with a 20% chance of IFR ceilings near
KBIL and north, are expected tonight into Sunday. Expect mountain
obscuration. Archer

&&

.PRELIMINARY POINT TEMP/POPS...

    Sun     Mon     Tue     Wed     Thu     Fri     Sat
-----------------------------------------------------------
BIL 040/056 036/048 032/063 039/069 043/071 046/076 047/078
    73/W    24/W    10/U    02/T    31/B    12/T    21/B
LVM 030/048 028/045 026/059 032/062 036/068 039/071 041/075
    +6/T    65/W    20/B    03/T    31/B    23/T    32/T
HDN 039/058 034/047 031/063 035/071 040/071 043/077 045/078
    43/W    25/W    10/B    01/B    21/B    12/T    21/B
MLS 045/059 036/047 034/059 036/070 042/070 044/076 046/077
    72/W    13/W    21/B    01/B    11/B    12/W    21/B
4BQ 043/059 035/043 032/056 034/068 040/068 043/074 046/075
    51/E    36/W    51/B    01/B    12/W    12/T    12/W
BHK 042/058 032/043 029/053 031/067 039/067 041/073 045/074
    64/W    25/W    52/W    01/B    22/W    12/T    22/W
SHR 036/052 030/041 026/055 029/065 035/066 037/073 040/074
    25/W    89/W    32/W    02/T    23/W    12/T    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect from 6 PM Sunday to noon
      MDT Monday FOR ZONES 56-66-171.
WY...Winter Weather Advisory in effect from 6 PM Sunday to noon
      MDT Monday FOR ZONE 198.

&&

$$
weather.gov/billings