152
FXUS63 KBIS 310546
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1246 AM CDT Sun Aug 31 2025

.KEY MESSAGES...

- Patchy to areas of fog expected to return tonight into Sunday
  morning.

- Showers and isolated thunderstorms, mainly south, through Sunday.
  Another round of showers and storms across the east on Labor
  day. The probability for severe weather is very low.

- Near seasonably temperatures mainly in the mid 70s and mid 80s
  through Labor Day. Cooler weather with highs in the 60s and 70
  then anticipated Tuesday through the remainder of the coming
  workweek.

&&

.UPDATE...
Issued at 1245 AM CDT Sun Aug 31 2025

A few showers are forecast to linger across the southwest
tonight, while patchy to areas of fog form across much of the
area. Currently limited fog reports have come in, although some
sites are starting to report lower visibility under haze and
mist. Will continue to monitor for any potential fog highlights.
For now made some minor updates to patchy fog mention based on
recent observations.

UPDATE
Issued at 927 PM CDT Sat Aug 30 2025

Shower activity has pretty much dissipated across most of the
forecast area. What remains is associated with the mid-upper
level circulation over the western Dakotas. Showers may linger
on an off here through the night. The other forecast concern is
the potential for fog again late tonight into Sunday morning.
With the low level moisture and light surface winds it seems
like a good be we will see at least some fog. CAMS have been
trending more towards fog over the south central into the James
River Valley. The thicker cloud cover in the southwest may
inhibit fog development here. Previous shift had a pretty good
area for fog, so no major changes here. Made some changes to
Pops based on latest radar and new short term guidance through
tonight and into Sunday.

UPDATE
Issued at 547 PM CDT Sat Aug 30 2025

Scattered showers and thunderstorms continue across western and
south central ND this Saturday afternoon. This area is within an
area of 500-1500J/KG of MLCape but with very little shear. As
has been the case the past couple of days, we occasionally see a
stronger non-severe cell resulting from outflow boundary
interactions. A funnel cloud can not be completely ruled out
either given the setup. We did expand pops a little farther
north through the remainder of the afternoon. otherwise no
significant changes to the going forecast.

&&

.DISCUSSION...
Issued at 230 PM CDT Sat Aug 30 2025

Flow over the northern Plains is fairly convoluted this
afternoon. While generally organized out of the northwest,
analysis places a cut-off low over central South Dakota and an
upper level high over the southern Canadian Prairies, with all
of this being shuffled eastward by an incoming shortwave trough.
All of that is to say things are evolving quite slowly, and
conditions today are very similar to what we experienced
yesterday. Scattered showers developing along the northern edge
of the upper level low in South Dakota will continue through
much of the day today. The majority of these showers are
anticipated to stay along and south of Interstate 94, though the
most recent CAMs continue expand these showers northward with
each run. Ongoing near surface moisture flux into south central
North Dakota has promoted a modest convective environment this
afternoon, with model MUCAPE values approaching the 1000-1500
J/KG range. With this a few isolated thunderstorms have
developed over portions of the southwest and south central,
though the lack of environmental shear and a strong forcing
mechanism means that strong to severe storms are not currently
anticipated. Of note is that a few cold air funnels were
observed yesterday (08/30) across the border in northern South
Dakota. With conditions so similar today, another cold air
funnel or two is not out of the question. Otherwise for today,
pervasive cloud cover across will keep temperatures across
southwestern North Dakota fairly cool in the upper 60s to mid
70s, while highs in the upper 70s to mid 80s are expected across
the north and east. Overnight low temperatures dip down into
the 50s across much of the forecast area. Much like last night,
saturated conditions and weak winds will allow for fog
development across much of western and central North Dakota,
mainly along and south of Highway 200. Any fog that does develop
is anticipated to lift by the mid to late morning.

Conditions on Sunday are broadly expected to dry out through
the morning as the previously mentioned upper level trough
begins to displaces the odd blocking pattern we`ve been stuck
under. While conditions across the east are expected to remain
fairly clear as high pressure slides in from Manitoba, mostly
cloudy skies are anticipated across the west where a surface
boundary lingers. A few showers and storms are possible along
the southern extent of this boundary during the afternoon and
evening in the southwest. Through the late evening and overnight
into Monday (Labor Day) this trough is expected to be picked up
and displaced eastward by aforementioned upper level wave,
promoting widespread low to medium chances for showers across
much of central and eastern North Dakota. These showers are
expected to continue pushing eastward through much of Monday
afternoon, with chances for thunderstorms also increasing during
this period. While shear is still lacking during this period,
the better forcing and moderately unstable environment could
allow a stronger storm or two to develop over central North
Dakota Monday afternoon capable of producing small hail and
gusty winds, though the probability for severe weather remains
low.

The main cold front associated with the upper level trough is
progged to cut across North Dakota on Tuesday, again producing
medium chances for showers and storms through the afternoon and
evening. With the better forcing along this front, and with a
notably uptick in shear behind it, a few stronger storms are not
out of the question. Behind this front, gusty northwest winds
and a much cooler airmass moves into the region. Seasonably cool
high temperatures mainly in the 60s and 70s are anticipated
through the remainder of the coming workweek, though some areas
across the north may only peak into the upper 50s on Wednesday.
Overnight low temperatures during this period get very cool,
with the ensemble currently advertising lows mainly in the upper
40s to lower 40s Wednesday through Friday. Notably, we are
expected to again fall into our cool weather setup during this
period, with high pressure settling over an axis from central
North Dakota through eastern South Dakota. In this setup, low
temperatures in some locations dropping into the mid or even the
lower 30s is not out of the question. Conditions throughout
this period are expected to remain fairly dry once showers move
out of the area Wednesday morning, as a broad ridge develops
over the Rockie Mountains and we settle into a dry northwesterly
flow pattern.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1245 AM CDT Sun Aug 31 2025

Patchy to areas of fog may return tonight into Sunday morning
bringing some IFR to LIFR conditions. Included this fog mention
in the KBIS and KDIK TAF. Elsewhere will see mainly VFR
conditions, although some MVFR ceilings are possible in the
southwest, including at KDIK. Any fog that can develop will
diminish mid to late Sunday morning. VFR to perhaps some MVFR
ceilings could then linger through the day and perhaps evening
Sunday. Shower chances will generally linger across the
southwest and south central tonight through Sunday. These could
impact the KDIK TAF, although confidence was not high enough to
include at this time. Light and variable winds tonight will
eventually become a light southerly wind on Sunday.

&&

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

&&

$$

UPDATE...Anglin
DISCUSSION...Adam
AVIATION...Anglin