Pompeys Pillar, Montana Weather Forecast Discussion

744
FXUS65 KBYZ 302131
AFDBYZ
Area Forecast Discussion
National Weather Service Billings MT
331 PM MDT Tue Sep 30 2025
.KEY MESSAGES...
- Isolated to scattered showers and thunderstorms this afternoon
  into tonight. Main threat is gusty and erratic winds.
- Warm, above normal temperatures through Thursday.
- Pattern change to cooler and wetter arrives Friday, lasting
  into early next week.
- Pattern change will bring snow to the mountains, and possibly
  the foothills, this weekend into early next week. Stay tuned.
&&
.DISCUSSION...
Today through Monday...
Isolated to scattered showers and weak thunderstorms will move
northeast through the area this afternoon into tonight with the
passage of a shortwave trough aloft. While no severe thunderstorms
are expected with this activity, gusty and erratic winds could
develop with gusts generally to 40 mph possible. As far as
precipitation amounts go, look for totals to remain generally
light, with localized heavier amounts possible under any
thunderstorm that develops. At this time, the chance of seeing a
tenth of an inch or more of rainfall remains moderate over south-
central Montana and north-central Wyoming.
Wednesday into Thursday looks to be mostly dry as low amplitude
ridging nudges in from the south. With that said, the overall
southwesterly flow aloft will keep low to moderate chances of
precipitation over the mountains and foothills both days.
Temperatures during this time will remain warm with highs in the
70s to lower 80s, warmest over the plains.
A pattern change to cooler and wetter is then expected to arrive
Friday, lasting into early next week. At this time, confidence is
high on the temperatures trending below normal by the weekend.
However, confidence is lower on the precipitation forecast as the
fine details on the evolution of the upper level pattern remain
uncertain, especially Sunday into early next week.
Regarding the precipitation forecast, look for the chance of
precipitation to increase around and west of Billings late
Thursday into Friday (25 to 75 percent chance, greatest over the
mountains and foothills west of Billings). On Saturday, the chance
of precipitation looks to then spread east across the area (30 to
80 percent chance, greatest over the mountains and foothills
south and west of Billings). Through this time, the chance of
seeing a quarter inch or more of precipitation is low to moderate
over the plains, moderate to high over the foothills, and high
over the mountains. Sunday into Monday, the chance of
precipitation continues, but remains lower due to the
discrepancies in the upper level pattern. With the cooler
temperatures, precipitation is expected to switch to snow over the
mountains, and potentially the foothills, this weekend into early
next week. At this time, snow levels are forecast to drop around
10,000 feet Friday before dropping around 8,000 feet late
Saturday. Sunday into Monday, snow levels are currently forecast
to drop around 6,500 feet, with the 25th to 75th percentile spread
being 5,500 to 7,500 feet. Should the lower snow levels be
realized, snow impacts could spread over the foothills. However,
as mentioned above, the precipitation forecast during the time of
lowest snow levels is very uncertain. Therefore, the chance of
seeing 6 or more inches of snow through Saturday is moderate
generally above 8,000 feet. Should precipitation trend heavier
Sunday, greater amounts could be realized.
Regarding the temperature forecast, look for high temperatures to
drop into the 50s and 60s and low temperatures to drop into the
30s to lower 40s by this weekend into early next week. Sunday
night and Monday night, there is even a moderate to high chance of
seeing a freeze (32F or lower) over the foothills and common cold
spots in river valleys. Across the rest of the plains, including
Billings, the chance of a freeze remains lower with this system.
Arends
.AVIATION...
Isolated to scattered showers thunderstorms will begin to develop
over the high terrain this afternoon, before moving over the
plains by 00z. The main threat with any shower/thunderstorm will
be gusty and erratic wind gusts 30-40 kts. Brief periods of MVFR
are possible under any showers/storms. Otherwise, VFR conditions
will prevail through Wednesday. Matos
&&
.PRELIMINARY POINT TEMP/POPS...
Wed     Thu     Fri     Sat     Sun     Mon     Tue
-----------------------------------------------------------
BIL 054/077 052/078 052/069 049/060 040/054 037/058 038/064
    50/U    01/U    24/W    44/W    44/W    22/W    11/U
LVM 045/072 043/071 043/064 040/058 032/051 028/056 030/063
    21/N    13/T    67/T    54/W    44/W    32/W    11/U
HDN 051/079 047/080 047/072 047/060 038/056 034/059 034/065
    50/U    00/U    12/W    54/W    43/W    32/W    11/U
MLS 056/080 051/082 053/076 050/065 041/058 036/061 036/065
    31/U    00/U    21/B    33/W    32/W    21/B    11/U
4BQ 056/078 051/082 052/076 050/061 041/055 037/058 037/062
    21/U    00/U    00/B    34/W    52/W    22/W    11/U
BHK 052/078 049/083 049/078 046/065 038/057 032/059 033/063
    22/U    00/U    10/B    22/W    42/W    21/B    10/U
SHR 047/077 045/081 045/074 042/058 034/053 029/056 030/064
    30/U    00/U    11/B    56/T    65/W    32/W    21/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings

NWS BYZ Office Area Forecast Discussion