404
FXUS63 KBIS 181122
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
622 AM CDT Fri Sep 18 2026

.KEY MESSAGES...

- Medium to high chances for rain far south central into the
  southern James River Valley this morning.

- Low to medium chances for showers and possibly a thunderstorm
  west central, northwest and north central today an into this
  evening.

- Medium to high chances for rain in the west through much of
  the weekend.

- Patchy fog possible this morning and again Saturday morning.

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

&&

.UPDATE...
Issued at 602 AM CDT Fri Sep 18 2026

Rain continues across far southern North Dakota early this
morning, with showers and even a few lightning strike in the far
north. Expect rain to exit the south central later today.
Isolated to scattered showers may linger along the International
Border through the day. Think coverage will decrease later this
morning. Later this afternoon into this evening showers and a
few thunderstorms may develop again over this area.

Made some minor adjustments to pops based on latest radar loop.
Otherwise no significant changes to the going forecast.


&&

.DISCUSSION...
Issued at 343 AM CDT Fri Sep 18 2026

Currently, isolated to scattered showers were indicated over far
southern North Dakota. Isolated showers were also located in the
north. Skies were cloudy south and partly to mostly cloudy
north. Low stratus has developed over southwest ND where rain
had exited and skies had temporarily cleared. As of 2 AM CDT
there were no visibility restrictions at observation sites, but
will continue to monitor.

For today, showers will track east across far southern ND, and
may push as far north as the I-94 corridor, but any
accumulations greater than a tenth of an inch will remain along
the South Dakota border. Isolated showers are possible in the
north as well.

This afternoon and this evening, there will be low chances for
thunderstorms from west central into north central North Dakota.
An instability axis remains situated from eastern Montana into
southeast Saskatchewan/southern Manitoba. The elevated
instability, combined with the surface convergence along the
inverted trough extending into Canada, ahead of an approaching
cold front, may produce enough forcing to spark a few
thunderstorms. The threat for severe storms looks to be minimal
but the RAP/HRRR both indicate a narrow area of 1000-1500 J/kg
of CAPE from west central ND into northwest ND this afternoon
into early evening. There is some capping there, but during the
max heating of the day, it becomes pretty minimal over this
area. Bulk shear is generally in the 25-30 knot range. Will
monitor but currently there is only a general thunderstorm risk
from SPC and this seems reasonable. As the Canadian cold front
sinks south into the far northern CWA, showers may linger from
through the evening across the far north.

Saturday, high pressure builds behind the Canadian cold front as
it pushes south through the forecast area. This will tamper out
the elevated instability that is over the north today. The
focus shifts to western ND Saturday through Sunday. An upper
level low moves through the Northern Rockies Saturday through
Saturday night and is situated over the Northern High Plains by
Sunday morning. Saturday will be wet across much of central and
eastern Montana. The question is how far east into North Dakota
will any precipitation extend. At this time it looks like most
activity will remain along and west of the Highway 85 corridor
during the day Saturday, with a better chance of precipitation
making it as far east as the Highway 83 corridor later Saturday
night into Sunday. We`re talking low to medium chances (20 to
40%) for rain making it to the Highway 83 corridor. Medium to
high chances (40 to 90%) for rain remain over western ND during
this timeframe, with the highest of these chances over the
southwest portion of the state. Through the 2 day period of
Saturday through Sunday, the NBM depicts a 50 to 80 percent
chance of qpf amounts of at least a half inch in the far west
central and southwest North Dakota. This tapers quickly to less
than a 20 percent chance from the Highway 85 corridor to the
Highway 83 corridor.

The upper level system remains to our south on Monday with upper
level ridging building over the area through mid to late week.
Currently the NBM is depicting mainly low pops south and east
Tuesday night through Wednesday night as there is low confidence
in a weak wave moving through the area during this timeframe.

Temperatures wise, as was mentioned yesterday, there is a
signal for a gradual warming trend through the week, but with
rising temperatures through the workweek comes increasing
ensemble spread. Currently the NBM is depicting some upper 70s
and lower 80s for western ND by late in the work week, which is
a little above normal (normal highs are in the lower 70s).

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 602 AM CDT Fri Sep 18 2026

Scattered to numerous showers across far southern North Dakota
and scattered showers in the far north to begin the 12Z TAF
period. MVFR to IFR ceiling are expected along and south of the
I-94 corridor this morning, and may linger through the day in
some areas. Across central and northern portions of the forecast
area, there will be some areas of MVFR ceilings, especially
associated with morning shower activity, then mainly VFR
ceilings this afternoon. Afternoon showers and evening showers
and thunderstorms will be possible northwest and north central.
Later tonight expect MVFR to IFR ceilings to once again increase
in areal coverage, covering most of the of the forecast area by
late in the TAF period. Patchy fog will be possible again late
in the TAF period. Generally an easterly surface flow is
expected today around 5 to 15 kts sustained. Surface flow will
shift northeast over northwest ND late in the TAF period.

&&

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

&&

$$

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