436
FXUS63 KBIS 121433
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
933 AM CDT Sat Sep 12 2026

.KEY MESSAGES...

- Notably cooler temperatures this weekend, with highs about 10
  to 15 degrees below average.

- High chances for rain showers (~70-100%) Sunday night into
  Monday. Greatest chances over central and eastern North
  Dakota.

- Becoming windy late Sunday, with the strongest winds expected
  on Monday before diminishing Monday night. Gusts to 50 mph
  possible over western North Dakota.

&&

.UPDATE...
Issued at 933 AM CDT Sat Sep 12 2026

A line of showers oriented west-east continues across southwest
North Dakota, driven by the nose of a 300mb jet streak and a
weak embedded vort max at 500mb. Although they show up well on
the Bowman radar, we have yet to see any evidence of measurable
rain at the surface, likely due to cloud bases around 10k feet.
Will continue mention of a low chance of rain through the
morning to account for anything managing to make it to the
ground. Otherwise, winds are a bit breezy to start the day, but
are expected to diminish as surface high pressure pushes in and
weakens the pressure gradient. No changes needed to the gridded
forecast with this update.

UPDATE
Issued at 636 AM CDT Sat Sep 12 2026

Radar continues to indicate the possibility of some isolated
showers along the South Dakota border, therefore will leave
ongoing low chances in place. Going forecast remains in good
shape.

&&

.DISCUSSION...
Issued at 415 AM CDT Sat Sep 12 2026

Current surface analysis places low over northwestern Ontario,
with frontal boundary dropping through the upper Midwest into
the central plains. High stretches from Alberta and western
Saskatchewan through central & eastern Montana into the far
western Dakotas. Upper level analysis places low over far
northeast Manitoba, with trough dipping south-southwestward into
the eastern Dakotas. Modest ridging noted over the Rockies
ahead of a low spinning offshore from the Pacific Northwest.
Over our area, some very light rain showers continue to straddle
the North Dakota and South Dakota border, but have been mainly
hanging a bit to the south.

For today, low chances for rain showers will continue through
the morning along the NoDak/SoDak border, diminishing by mid-
day. Northwest winds will remain a bit breezy over central North
Dakota in the wake of yesterday`s frontal passage, while over
the west winds will be lighter as surface high pushes in.
High temperatures will also be notably cooler, running about 10
to 15 degrees below average. Winds then go light overnight with
skies clearing over the north. This will lead to some cold
temperatures with guidance suggesting mid 30s possible over
northwest North Dakota. Will have to take a close look at this today
to see if any frost headlines may be needed.

Sunday starts out quiet with upper ridging developing ahead of
the Pacific upper low which is expected to move onshore by
morning, sliding towards the northern Rockies through the day.
In response, a lee side surface low develops with increasing
southeasterly winds in the afternoon, primarily over southwest
North Dakota.

Sunday night into early Monday, upper low moves quickly over
the northern Rockies into the plains, but some question does
remain on whether at this point it will take a bit more
northern track through the southern Prairie Provinces, or hang
more towards the international border, which would also be
reflected in the potential path for the surface low lifting
northeastward. Either way brings elevated precipitation chances
to our area, but a more northern path would result in lower
precipitation accumulations. Right now NBM guidance is holding
a 50 percent or greater chance for seeing a half inch or more of
precipitation along and east of a line from Bismarck to Minot,
but is now lower for western areas than what we saw yesterday.
Precipitation pushes north/east exiting the area Monday
afternoon/early evening with the potential for a little to wrap
back in over far northwestern areas a bit later, depending on
the aforementioned track.

As the surface low lifts northeast, winds will shift westerly
over our area through the day on Monday, strongest over western
North Dakota where ECMWF EFI focuses a broad area of 0.7 to
0.8, in line with going forecast of potential wind gusts of
around 50-55 mph, though will have to watch this trend closely
to see if there is an upward shift at all as there is the
potential of some stronger winds mixing down.

Quieter weather expected in the wake of the system for Tuesday,
though temperatures do remain on the cool side. For the
remainder of the work week latest NBM guidance does show some
spread in high temperature forecasts, but overall trend does
appear to be upward. Precipitation forecast remains a bit tricky
as some questions remain on the path of a potential upper trough
as it approaches the plains.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 636 AM CDT Sat Sep 12 2026

Isolated rain showers will be possible along the South Dakota
border this morning, but any visibility restriction is expected
to be minimal. Over far northern North Dakota, localized MVFR
ceilings have developed, but expect these to erode later this
morning. These low ceilings are expected to remain north of the
KXWA and KMOT terminals. Otherwise, VFR conditions are expected
to prevail.

&&

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

&&

$$

UPDATE...Jones
DISCUSSION...JJS
AVIATION...JJS