884
FXUS63 KBIS 150504
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1204 AM CDT Sat Aug 15 2026

.KEY MESSAGES...

- Showers and isolated thunderstorms will continue to diminish
  from west to east through tonight.

- Mainly dry Saturday into early Sunday, with rain chances
  returning west to east late Sunday. Near daily low to medium
  (20 to 60 percent) chances for rain are then expected for the
  work week.

- Below average temperatures this weekend, followed by a brief
  warm up on Monday, then below average again through mid-
  week.

&&

.UPDATE...
Issued at 1153 PM CDT Fri Aug 14 2026

Showers and isolated thunderstorms continue to taper from west
to east across central and eastern ND. Precipitation has pretty
much exited the west and low stratus and fog will continue to
develop south and west across the areas as rainfall exits. No
significant changes needed.

UPDATE
Issued at 1032 PM CDT Fri Aug 14 2026

A narrow band of showers with infrequent lightning continues to
track eastward through far south central North Dakota late this
evening. For most of its existence, this convection has not
been observed to be as strong as its radar reflectivity features
would indicate, but just prior to this writing there was a 34
mph gust at an NDAWN site along the Grant/Sioux County border.
The most likely outcome is that these heavier showers with
occasional thunder will gradually decrease in intensity as they
move into a more stable air mass over the next 1-3 hours.
Analyzed effective bulk shear remains strong, but mid level
lapse rates and DCAPE are very poor.

Rapid refresh guidance has shown an increase in the coverage of
fog across northwest and north central North Dakota later
tonight into Saturday morning. Visibility has already broadly
fallen into the 2 to 5 mile range across this part of the state,
with a couple of one half to one mile observations northwest of
Minot. Confidence on how dense the fog may become remains low,
as the processes driving the fog formation are neither clearly
radiative nor advective.

UPDATE
Issued at 739 PM CDT Fri Aug 14 2026

At 630 PM MDT, a broken line of low-topped thunderstorms
extended from near Richardton to Hettinger. SPC mesoanalysis
shows these storms to be in an environment with 1000-1500 J/kg
CAPE and 30 kts of effective bulk shear. But they are also now
moving into an area of increased CIN, and mid level lapse rates
are mostly anchored to the moist adiabatic lapse rate. It
therefore seems unlikely that the intensity of convection will
increase beyond what has already been observed. Forecast
adjustments for this update were driven by current observations
and trends, but no major changes were made. Showers and
thunderstorms should diminish from west to east through tonight.
Did add a patchy fog mention to western parts of the state
tonight into Saturday morning. This would mainly impact higher
terrain areas where clouds could lower to the surface.

&&

.DISCUSSION...
Issued at 218 PM CDT Fri Aug 14 2026

Current surface analysis places inverted trough over the
western Dakotas, with high over eastern Manitoba into Ontario.
Upper level analysis places high over the southern Mississippi
Valley with ridge through the Midwest. To the west, trough
noted over the west coast resulting in southwest flow over the
Northern Plains. Over our area, broad area of rainfall continues
over much of central and western North Dakota.

For the rest of this afternoon into this evening, broad area of
rain previously mentioned will continue to gradually track
towards the east-northeast. Towards the backside where rain had
tapered off over southwest North Dakota, CAMs have been
consistently showing some convection developing, some of which
is showing up on radar over western South Dakota. Over our
area, this is right in line with a narrow instability corridor
advertised on the RAP of CAPE values pushing around 1500 J/Kg.
So, cant rule out a stronger cell producing some small hail over
this area, but believe the severe threat should remain limited.

As we go through the night precipitation will gradually exit
the area. With the low level moisture in place there was some
concern for fog developing over the west, but believe this
should be limited by the expected north-northwesterly winds, but
do expect low ceilings to develop and possibly a few patches of
fog particularly in higher terrain.

Quieter weather expected over the area on Saturday as ridge
starts to rebuild over the Rockies, though temperatures will
remain on the cooler side of average. Flow remains
west/northwesterly on Sunday, but a wave moving through the flow
may produce some showers/storms late Sunday into the overnight
hours.

Temperatures warm to near average for Monday before a strong
short wave and affiliated cold front push into the area, which
will bring cooler temperatures and medium chances (about 40 to
60 percent) for precipitation on Tuesday. Remainder of the
work week looks to remain a bit active with occasional low
chances for precipitation.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1153 PM CDT Fri Aug 14 2026

Showers continue across central North Dakota with a few
thunderstorms south of KBIS, moving eastward. No VCTS will be
needed at KBIS to begin the 06Z TAF period though. Heavy
downpours could still reduce visibility to MVFR/IFR levels in
the convection south of KBIS, but these should remain south of
KBIS and KJMS. Rain should diminish from west to east through
tonight.

Low ceilings are forecast to spread across much of western and
central North Dakota into Saturday morning, with IFR and
occasional LIFR over KXWA and KMOT. Fog may also reduce
visibility to at least IFR levels tonight into Saturday morning,
mainly across the northwest and north central. The low clouds
and fog should lift and/or scatter by around late morning/early
afternoon Saturday, with VFR conditions expected thereafter.
Winds will become northwesterly around 10-15 kts on Saturday,
with some higher gusts in the afternoon.

&&

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

&&

$$

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