587
FXUS63 KBIS 191130
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
630 AM CDT Sat Sep 19 2026

.KEY MESSAGES...

- Cloudy, humid and cool today with areas of fog this morning.

- Rain chances increase south and west of the Missouri River
  today, then medium to high rain chances remain tonight and
  through the day Sunday, before tapering Sunday night.

- Seasonable temperatures through early next week, with highs
  mostly in the 60s and 70s.

&&

.UPDATE...
Issued at 616 AM CDT Sat Sep 19 2026

No changes to the going forecast. We issued a SPS for fog,
mainly along and south of the I-94 corridor. A couple of spots
are down to a quarter mile, but most are 1-3SM or better.

&&

.DISCUSSION...
Issued at 207 AM CDT Sat Sep 19 2026

An upper level lower pressure system currently spinning over
Idaho, will move into Wyoming this evening, and eventually into
western South Dakota by Sunday evening. This will bring abundant
cloud cover to western and southern portions of the forecast
area through the weekend. In addition, areas mainly south and
west of Lake Sakakawea and the Missouri River will see
accumulating precipitation.

Currently, low stratus and fog covered much of southwest and
south central ND. Portions of the northwest and north central
were free of low stratus, but remained covered with mid and high
level clouds. For the most part, western and central ND
remained precipitation free early this Saturday morning.
However, patchy light drizzle remained over portions of the
area. At 3 AM CDT, very light drizzle was falling at WFO
Bismarck. There were a couple of webcams along I-94 depicting
some light drizzle as well. Drizzle was more widespread around
midnight in this area, but there is some still falling. Luckily
the impacts are negligible. There are some lower vsbys, mainly
1-3SM in the south, but with widespread stratus south and high
cloud cover north, the threat for widespread dense fog looks to
be low.

For today, will maintain the forecast temperatures introduced
last evening with slightly cooler high temperatures than
guidance, given the widespread low cloud cover. Will keep a
mention of drizzle in the south central through 12Z and will
re-evaluate. Otherwise just a slight chance of rain along the
slow moving cold fron dropping south from Canada, and slight
chance, increasing to chance pops in the far west central and
southwest, and slowly advancing eastward.

Tonight, and through the day Sunday will bring categorical rain
over the far southwest, with medium to high chances for rain
along the Missouri River. HREF probabilities of 24 hour
precipitation of at least a half inch, from 7 PM Saturday
through 7 PM Sunday, range from 40 to 80 percent, right along
the Montana and South Dakota borders, from northern Golden
Valley County south to Bowman County and from Bowman county east
through Adams County. The probability for at least a tenth of
an inch for this same timeframe, ranges from less than 10
percent just north and east of the Missouri River to greater
than 40 percent only a few miles south and west of the Missouri.

Precipitation is expected to taper from north to south, west of
the Missouri River Sunday night, with dry conditions expected
by Monday morning. It looks like a couple of dry days to begin
the work week, Monday and Tuesday. We then see a couple of low
waves tracking through the area, the first around mid-week and
the next over the weekend. NBM is currently depicting low to
moderate precipitation chances (20 to 40%) with each wave. After
some cooler temperatures this weekend, the NBM is advertising a
warm-up through the work week. Ensemble spreads, at least
through around Thursday, are noticeably tighter than the past
couple of day, thus confidence is increasing that we see a
gradual warm-up through the week. On Thursday current NBM
temperatures range from the lower 70s east to the lower 80s
west.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 616 AM CDT Sat Sep 19 2026

MVFR to IFR and a some LIFR ceilings and visibilities to begin
the 12Z TAF period. Expect fog and ceilings to gradually lift
beginning around mid morning. However, especially over the
southern TAF sites expect mostly MVFR ceilings through the
afternoon, Northern ND, including KXWA and KMOT should see some
VFR conditions this afternoon. Patchy drizzle can not be ruled
out today, especially across the south. Rain is expected to
slowly spread east towards the Missouri River through the day.
Included a PROB30 for rain at KDIK later this afternoon, then
predominately rain after 00Z. For now, this is the only TAF
site to include a mention of rain. Ceilings may lower again
tonight, especially over southern North Dakota. Look for an
east to northeast surface flow 5-15 kts on through the TAF
period.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...TWH
DISCUSSION...TWH
AVIATION...TWH