766
FXUS63 KBIS 011415
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
915 AM CDT Mon Sep 1 2025

.KEY MESSAGES...

- Patchy to areas of fog, possibly dense at times, expected this
  morning.

- Isolated to scattered thunderstorms possible today and Tuesday.
  A few storms may be strong to severe.

- Cooler weather with highs in the 60s and 70s anticipated mid
  to late week. Overnight lows in the 30s and 40s also forecast.

- Areas of wildfire smoke may also return on Tuesday.

&&

.UPDATE...
Issued at 912 AM CDT Mon Sep 1 2025

Main edit this morning to the forecast was to update SKY grids
based on latest satellite imagery and trends. RAP seems to have
the best handle on the eastward progression of the lower cloud
deck, so was utilized through early this afternoon. Also opted
to extend the Special Weather Statement for fog a couple more
hours based on sfc obs and web cams.

UPDATE
Issued at 652 AM CDT Mon Sep 1 2025

A push of low level moisture continues to bring low clouds and
fog across much of the south and central, and is starting to
impact some north central locations. This may continue into the
mid to late morning hours until an upper level wave moves
through. Made some minor updates to clouds and fog mention based
on the latest trends. Webcams showing areas with fog are
producing some dense fog, although these reports are still
isolated to scattered. Will continue the SPS for fog for a
couple more hours to inform of these scattered fog impacts this
morning.

&&

.DISCUSSION...
Issued at 402 AM CDT Mon Sep 1 2025

Lingering low level moisture combined with light winds is making
for some low clouds and areas of fog across the west and south
central early this morning. Webcams showing dense fog to be
fairly isolated still, although this could change through the
morning hours. For now have issued an SPS to inform of the
threat of at least some areas of dense fog. If this coverage
becomes more widespread then perhaps an advisory may be needed.
A weak shortwave will move across the region today, this could
bring isolated to scattered showers and thunderstorms to the
state. A few showers may start as early as this morning in the
north. Warmer temperatures in the mid 70s to mid 80s will be
found today. This will bring higher instability across the area
today, with MUCAPE up to 1500 J/KG. The upper wave could also
provide for some modest shear around 30 knots today. These
parameters would be enough for some isolated to perhaps severe
thunderstorms. There does remain some capping concerns today
through this evening, as well as how much lift this weak wave
can provide. SPC has maintained general risk across the area
given the uncertainty. Thus the severe weather threat is more
conditional. If a stronger storm can develop, wind gusts to 60
MPH and hail to the size of a quarter would be possible.
Southerly winds will be found to start the day, with the weak
wave possibly bringing some light westerly winds. Thunderstorms
will generally diminish overnight tonight with lows forecast in
the 50s. Tuesday then sees a cold front move across the state
from north to south. Along this front could be showers and
thunderstorms. By the time this front gets to the warmer and
more unstable areas in the south, there could be an isolated
strong to severe thunderstorm. SPC now has a Marginal Risk for
southeastern North Dakota. Winds to 60 mph and hail to the size
of a quarter would be the main threats. Behind this front could
be an increased northerly wind. This front could also return
wildfire smoke from Canada across much of the state on Tuesday
and perhaps into the upcoming week. Showers and thunderstorms
may then linger across the east and south Tuesday night, with
cooler overnight lows in the 40s and lower 50s.

A breezy and cool post frontal day is forecast for Wednesday,
with highs generally in the 60s. Limited chances for
precipitation is currently forecast for Wednesday. Surface high
then moves across the state Wednesday night bringing cool
overnight lows in the mid 30s to mid 40s. Perhaps some frost may
be found Thursday morning as a result, although uncertainty in
overnight lows remains with the track of the high and perhaps
some lingering cloud cover. A weak wave may then move through
Thursday, perhaps bringing some chances for showers in the north
and east. Breezy winds may be found with this wave, although
some slightly warmer temperatures in the 60s and 70s may also be
found. A series of surface highs could then move through in the
northwest flow to end the work week and into the start of the
weekend. This could bring mainly dry conditions with continued
below normal temperatures. Friday morning may not be as cold as
Thursday, with Saturday morning currently forecast to see lows
return in the 30s and possibly bring some frost. Ridging could
then remain through the weekend, although some cluster solutions
break down this ridge earlier and indicate a change to
southwest flow pattern aloft could return later in the weekend.
This could bring slightly warmer and perhaps near normal
temperatures. If any weak waves can move through in this
potential southwest flow then perhaps some showers and
thunderstorms may return, although NBM currently maintains a dry
forecast.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 652 AM CDT Mon Sep 1 2025

Another round of fog and low clouds will linger across the area
this morning. Confidence in fog formation at TAF sites is still
low to modest this morning, although there is slightly higher
confidence in low clouds through much of the morning. Have
limited fog mention in the TAFs at this time, although most
sites now include MVFR to IFR ceilings this morning. Once this
fog and low clouds breaks up later this morning, look for mainly
VFR conditions with a light south wind, perhaps becoming
westerly later in the day, then light and variable in the
evening perhaps coming west northwest overnight tonight.
Chances for showers and thunderstorms still look limited later
today through tonight. Left in PROB30 groups for sites that
already had them in the previous TAF update. Patchy fog may
again be possible tonight into Tuesday morning, although
confidence is low at this time. Some wildfire smoke may also
return to the area late tonight into Tuesday.

&&

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

&&

$$

UPDATE...NH
DISCUSSION...Anglin
AVIATION...Anglin