Roundup, Montana Weather Forecast Discussion

774
FXUS65 KBYZ 191727
AFDBYZ
Area Forecast Discussion...Updated
National Weather Service Billings MT
1127 AM MDT Fri Sep 19 2025
.KEY MESSAGES...
- Dry and warmer conditions through Sunday.
- Weather system late Sunday into Monday brings chance of
  precipitation (20 to 75 percent), cooler temperatures, and gusty
  northwest winds to the region.
- Warmer and drier conditions return by the middle of next week.
&&
.DISCUSSION...
Aviation discussion updated.
Today through Thursday...
Fog is possible this morning over eastern Montana. At this time,
conditions are most favorable around and east of Custer and Powder
River Counties, but river valleys west of these counties could
also see fog. Any fog that does develops should lift by 9AM.
Warmer and drier conditions are expected to develop over the
region today into the weekend as the influence from the upper
level low to our east is finally replaced by low amplitude
ridging. With that said, a weak disturbance looks to drop
southeast through eastern Montana late today into early Saturday,
but increased cloud cover and a bit slower warm up for far
eastern Montana look to be the only impacts. Temperatures will be
in the upper 60s and 70s today and mid 70s and 80s this weekend.
Late Sunday into Monday, a weather system will bring the chance
of precipitation, cooler temperatures, and gusty northwest winds
back to the region. Recent model runs continue to resolve this
system as a fast moving shortwave trough that slows down and
shifts southeast over our region. This system will bring the
chance of precipitation back across our region Sunday afternoon
and evening over western/central Montana and then across the
region Sunday night into Monday. As far as potential precipitation
amounts go, ensembles are favoring south-central Montana and
northern Wyoming for the area of best precipitation. Over the past
24 hours, the chance of seeing a wetting rain (0.10" or more)
increased to around 40 to 60 percent in this area, with the chance
of seeing a half inch up to 30 percent. With that said, locally
heavier rainfall is possible under thunderstorms across the area
as atmospheric moisture pushes 150 percent of normal. Any
thunderstorms that do develop are expected to remain sub- severe.
One thing to keep an eye on with this system is the northwesterly
winds that are forecast behind the front late Sunday into Monday.
These winds may cause downslope warming and drying into Billings
which could lead to less precipitation. Will have to see how
things trend once the high resolution models pick up on this
system. Another thing to note is snow levels are expected to drop
around 10,000 feet by Monday. This means light snow accumulations
are possible over the highest peaks of the Absaroka-Beartooth and
Bighorn Mountains. At this time, the National Blend of Models has
the chance of seeing an inch of more of snow in the high country
at 30 to 60 percent. Those with recreation or travel plans over
the Beartooth Highway late Sunday into Monday should prepare for
potential wintry conditions.
Outside of the precipitation, the cold front passage late Sunday
into early Monday will bring breezy northwesterly wind gusts in
the 20s and 30s (mph) through Monday. Behind this cold front,
temperatures will be around 10 to 20 degrees cooler with highs on
Monday in the 60s to lower 70s.
The forecast for Tuesday through mid-week remains uncertain as
the track of the early week weather system remains uncertain once
it passes through our area. If the system wraps up into a low just
south of our region, cooler temperatures and the chance of
precipitation could linger into Tuesday. If the system keeps
diving southeast, warmer and drier conditions will return by
Tuesday. Either way, warmer and drier conditions look to return
by mid- week, just how fast this happens is uncertain. Arends
.AVIATION...
In far southeast MT near KBHK and K97M, 12z HREF shows a 10-40%
chance of visibility dropping below 1/2 mile from fog and ceilings
below 250 feet from low stratus, between 09z and 15z Saturday.
Otherwise, VFR will prevail for much of the area through 00z
Sunday. RMS
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Sat     Sun     Mon     Tue     Wed     Thu
-------------------------------------------------------
BIL 077 052/083 053/084 053/065 047/072 048/078 052/081
    0/B 00/U    01/U    64/W    10/U    00/U    01/U
LVM 078 045/082 046/079 043/061 038/073 043/078 045/079
    0/B 00/U    03/T    74/W    00/U    00/U    11/U
HDN 079 048/083 049/086 052/066 043/072 043/079 046/082
    0/B 00/U    00/U    54/W    11/U    00/U    00/U
MLS 075 048/080 050/086 055/071 046/073 047/079 051/081
    0/U 00/U    00/U    23/W    10/U    00/U    00/U
4BQ 072 048/077 050/083 055/068 047/067 046/074 051/078
    0/U 00/U    00/U    23/W    21/B    10/U    00/U
BHK 071 045/077 046/083 051/072 045/073 045/078 048/079
    0/U 00/U    00/U    12/W    11/U    00/U    00/U
SHR 077 046/080 047/083 048/064 040/067 041/077 044/080
    0/B 00/U    01/U    46/T    21/U    11/U    00/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings

NWS BYZ Office Area Forecast Discussion