756
FXUS63 KBIS 291931
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
231 PM CDT Fri Aug 29 2025

.KEY MESSAGES...

- Near seasonable high temperatures in the mid 70s to mid 80s
  today through Labor Day, with lows generally in the 50s.

- Isolated to scattered showers and thunderstorms possible today
  through Sunday, mainly south, shifting to the east on Labor
  Day. The probability for severe weather remains low.

- Patchy fog is possible across much of southern North Dakota
  early tonight through Saturday morning.

- Chances for showers and thunderstorms may linger into mid next
  week, with cooler temperatures possible mid to late next week.

&&

.DISCUSSION...
Issued at 230 PM CDT Fri Aug 29 2025

A somewhat complicated flow pattern is found over western and
central North Dakota today. Though a developing omega-block is
present over much of the northern CONUS this afternoon, an upper
level trough is also attempting to close off over the northern
Plains this afternoon. The influence of this low has allowed for
low to medium chances for showers to develop this afternoon as
well as persistant cloud cover. The highest confidence for
showers is expected to remain to the south of Interstate 94 as
the aforementioned low begins to slide over South Dakota this
evening and overnight, though a few showers further to north
cannot be ruled out. A few storms will also be possible during
this time as moisture continues to stream into southwestern and
south central North Dakota, driving modest model MUCAPE values
to peak up to around 1000 J/KG. Strong storms are not
anticipated at this time, however, as the environment remains
poorly sheared (with model bulk shear values generally around 15
knots or less), and due to the lack of a distinct lifting
mechanism to drive more robust storm development. Otherwise for
today, high temperatures remain near to slightly above
seasonable normals, forecast from the mid 70s southwest up to
the mid 80s in north North Dakota. For tonight, ample near
surface moisture and light winds could allow for the development
of fog across the south, though the persistant cloud cover
overnight may help inhibit some of this development. Have added
patchy fog across much of the area south of Highway 200 early
tonight through the mid morning hours.

The slow progression of the cut off low across the northern
Plains will continue to promote chances for showers and
occasional thunderstorms over the forecast area this weekend,
with the highest confidence remaining over our southern
counties. The synoptic pattern over North Dakota becomes even
more convoluted on Sunday, as the breakdown of the omega block
over the southern Canadian Prairies will allow for a transient
shortwave to butt up against the retreating cut off low to our
south. With this, the low to medium chances for showers will be
allowed to extend further north starting Sunday afternoon. A
slightly more robust convective environment is also anticipated
during this period, with model MUCAPE values peaking well into
the 1000-1500 J/KG range. With this, and isolated storm or two
could become strong enough to produce small hail, though a
complete lack of environmental shear (model MUCAPE values remain
less than 10 knots at this time) mean that severe weather is
unlikely. We then remain in this transitional pattern through
Monday afternoon, with somewhat more widespread low to medium
chances for showers and storms developing across much of eastern
North Dakota. Temperatures throughout this whole period, this
weekend through Monday, remain near normal for this time of
year, broadly in the lower 70s southwest to mid 80s north.

Moving ahead to Tuesday, we return to northwesterly flow scheme
as a a broad upper level trough dive south out of Canada and
into the eastern half of the region. A cold front associated
with this trough will promote more widespread low to medium
chances for showers and across the forecast area late Tuesday
morning through the early Wednesday, with storms again possible
Tuesday afternoon and evening. With the much cooler airmass
moving in across the forecast area, highs temperatures Tuesday
through the remainder of the workweek dip back down into the mid
60s to mid 70s range. Overnight lows during this time are
forecast broadly in the 40s, some potential for lows in the mid
to upper 30s possible as we again fall into our classic cool
setup with high pressure moving into the central Dakotas. The
ensemble currently advertises fairly dry conditions through the
later half of the week as broad upper level ridging pushes in
Great Plains, though there is a minority cluster (approximately
40 percent of model members) that does favor some chances for
showers across eastern North Dakota late Wednesday through early
Thursday due to the slightly delayed eastward development of
this ridge.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 230 PM CDT Fri Aug 29 2025

VFR ceilings and visibility is found at all terminals to begin
the 00Z TAF period. Showers and isolated thunderstorms are
possible across southwestern and south central North Dakota this
afternoon through much of the TAF period, though the highest
chances remain along the North Dakota/South Dakota border. Have
added a PROB30 group for -SHRA at KDIK for late this afternoon,
early this evening. Early tonight through tomorrow morning,
patchy fog is also possible across much of southern North
Dakota. Confidence remains too low at this time to include
visibility reductions at any given terminal, as persistant mid
to high based clouds may keep this fog fairly sporadic.
Otherwise, winds this afternoon are anticipated to become very
light and variable this afternoon through much of the overnight
period, before generally organizing out of the southeast by the
end of the TAF period.

&&

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

&&

$$

DISCUSSION...Adam
AVIATION...Adam