599
FXUS65 KBYZ 152002
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
102 PM MST Sat Nov 15 2025

.KEY MESSAGES...

- Weather system late Sunday into Monday will lower temperatures
  to near normal with an increased chance of precipitation
  (20-50%).

- Further cooling and unsettled conditions middle part of next
  week.

&&

.DISCUSSION...

Today through Friday...

Current satellite and analysis shows the region under northwest
flow with a departing jet to the east. This is keeping low clouds
over east central MT with the remainder of the region seeing mild
and dry conditions. These areas under low clouds will see brief
clearing for a few hours this afternoon before low clouds and fog
set in again this evening lasting through the morning. Mild and
dry conditions will remain through most of Sunday as we
transition to a more southwest flow and increase atmospheric
moisture. This is a result of a disturbance moving up from the
southwest US. The main energy from this low will track into WY and
then clip southeast MT. With ensembles differing on the exact
track, there are still some discrepencies in precip totals. At
this time, probabilities favor the mountains with about a 50-70%
chance of at least a quarter inch of liquid precipitation, with a
30-50% chance for areas of Sheridan, WY up through Roundup west
Sunday night through Monday. Areas east of there are sitting at a
10-20% chance. Additionally, Sunday afternoon through Monday
morning, the development of a low level jet over eastern MT will
being breezy conditions to eastern MT. Gusts 25-40 mph will be
common during this time. As a Pacific weather system moves onto
the coast Tuesday, ensembles depict this energy splitting with
most going south. Wednesday into Thursday, the resulting weak
disturbance brings another chance (20-50%) for precipitation.

High temperatures will be in the upper 40s to low 60s through
Monday, slightly cooling into the 40s for the remainder of the
period. TS


.AVIATION...

18z Discussion...

Weak Gap Flow setup continues in the Livingston area with
southwest gusts in the 40kt range localized there. This pattern
should relax over the next few hours with gusts decreasing into
the 30kt range then 20kts by late afternoon.

Weak backdoor cold air push into northeast zones has low stratus
covering areas from Rosebud county and much of SE Montana this
morning. Models want to keep this layer around for another few
hours with erosion occuring through the late afternoon/early
evening. Given weak flow and some lighter winds in the lower
boundary layer can`t rule out IFR ceilings holding on through the
afternoon and into tonight, possibly evolving into broader fog
development by late evening. For now going with the model
consensus for KMLS and eroding the stratus to scattered by 20z or
so.

Central zones stay west of the cooler air today and will see
mixed westerly winds in the 20 to 30kt range for a few hours this
afternoon, quickly diminishing with the late afternoon sunset.
Winds look fairly weak tonight allowing that cooler high pressure
over NE Montana to sag westward overnight, possibly making it into
the western foothills by sunrise tomorrow morning. Will have to
keep an eye out for patchy fog/stratus development to follow this
shallow airmass into the area tonight. Chambers

&&

.PRELIMINARY POINT TEMP/POPS...

    Sun     Mon     Tue     Wed     Thu     Fri     Sat
-----------------------------------------------------------
BIL 038/057 041/055 038/053 034/046 030/046 029/048 031/050
    01/B    24/W    43/W    24/W    21/B    10/B    01/B
LVM 036/058 039/054 034/053 032/045 026/046 026/047 027/048
    01/E    25/W    53/W    34/W    21/B    11/B    11/B
HDN 035/060 035/053 035/053 032/047 028/047 025/048 025/051
    00/B    25/W    54/W    34/W    31/B    11/B    11/B
MLS 031/057 037/051 035/051 032/046 027/044 024/045 026/049
    00/B    22/W    32/W    22/W    21/B    00/B    10/B
4BQ 035/060 039/051 037/051 033/047 030/045 025/045 027/049
    00/B    23/W    32/W    12/W    21/B    00/B    10/B
BHK 029/056 032/047 030/047 030/045 025/041 022/044 024/047
    00/B    22/W    32/W    21/E    21/B    00/B    10/B
SHR 033/060 034/052 033/053 030/047 025/046 023/047 024/050
    00/B    25/W    53/W    24/W    32/W    11/B    11/B

&&

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

&&

$$
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