692
FXUS65 KBYZ 202030
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
230 PM MDT Sun Sep 20 2026

.KEY MESSAGES...

- Flood Watch in effect until 6 PM MDT for southeast Montana and
  portions of northern Wyoming today.

- Patchy to areas of fog developing tonight into Monday morning.

- Warmer and drier for the work week. Isolated showers linger.

&&

.DISCUSSION...

Today through Saturday...

Showers continue across southeast Montana and portions of
northern Wyoming as an upper low progresses through Wyoming today.
Rainfall rates are not expected to be as high as the past few
days, though heavier showers and a few thunderstorms this
afternoon could produce locally heavy rainfall in southeast
Montana and northern Wyoming. Additional rainfall up to a few
tenths of an inch are forecast into Monday morning. The greatest
accumulations are likely to occur along and south of US-212.
Lighter showers over south- central Montana could bring a few
hundredths of an inch of additional rainfall through tonight.

Flood Watches remain in effect until 6 PM MDT due to the
aforementioned risk of locally heavy rainfall this afternoon. The
greatest risk exists mainly east of Billings.

Patchy to areas of fog are shown developing by several models
tonight, the forecast shows this as well. There is uncertainty on
fog developing versus low stratus prevailing, mainly for
locations west of Billings. Fog could become dense at times into
Monday morning, especially for areas that received a lot of
rainfall over the past few days. This will need to be monitored
overnight as products may be required if fog becomes enough of an
issue.

Looking ahead, the pattern will get warmer with highs in the 70s
Monday through Wednesday. Conditions also look to become drier,
though a shortwave moving through Wednesday morning may bring
elevated showers and maybe a few thunderstorms to southeast
Montana. Otherwise, an additional upper low is shown by ensembles
digging into the Pacific Northwest to end the week. This could
bring more precipitation to the area as well as cooler
temperatures. The latest trends have this system tracking through
northern Montana which could leave our area in flux for
precipitation amounts. Continue to monitor the forecast as the
week progresses. Matos

.AVIATION...

Widespread showers will continue to impact eastern Montana and
northern Wyoming today, gradually diminishing from west to east
this evening into tonight. With that said, light showers may
linger into Monday morning over south-eastern Montana (15 percent
chance). While the chance of thunderstorms is low today, cannot
rule out an embedded thunderstorm over south-eastern Montana and
northern Wyoming this afternoon and early evening (20 percent
chance). The main threat with any thunderstorm is heavy rain.
Otherwise, humid conditions will result in areas of MVFR/IFR
ceilings along with patchy fog today into tonight. Look for the
low stratus or fog to increase in coverage tonight as the
precipitation comes to an end. Fog may become locally dense with
visibility around or below 1/4SM late tonight into early Monday
morning. Any fog that does develop, along with areas of low
stratus, will dissipate around 14Z to 17Z Monday. LA

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 048/072 048/077 053/078 053/082 054/082 053/070 047/066
    10/B    00/U    22/W    00/U    00/U    12/W    22/W
LVM 041/073 043/078 048/077 047/081 050/081 046/068 039/066
    00/U    00/U    11/U    00/U    00/U    22/W    32/W
HDN 045/073 044/080 050/079 047/084 050/085 049/073 043/069
    22/W    00/B    32/W    00/U    00/U    11/U    12/W
MLS 050/069 049/077 053/077 051/084 057/085 054/073 047/069
    22/W    00/U    13/T    00/U    00/U    11/U    21/B
4BQ 050/067 049/076 053/077 052/083 057/084 055/075 049/071
    42/W    00/U    21/B    00/B    00/U    00/U    12/W
BHK 044/066 043/073 047/078 048/084 052/083 051/076 044/070
    32/W    00/N    15/T    10/B    00/N    00/U    22/W
SHR 041/070 041/076 047/075 044/082 049/083 048/074 042/070
    62/W    00/U    22/W    00/U    00/U    01/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Flood Watch in effect until 6 PM MDT this evening FOR ZONES
      29>33-36-37-57-58-138-169-171-173-235.
WY...Flood Watch in effect until 6 PM MDT this evening FOR ZONES
      198-199.

&&

$$
weather.gov/billings