515
FXUS63 KBIS 160320
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1020 PM CDT Tue Sep 15 2026

.KEY MESSAGES...

- Seasonable temperatures through the end of week, with highs
  mostly in the 60s and 70s. Lows tonight and Wednesday night
  could fall into the upper 30s in northern and central parts of
  the state.

- Low chances for showers on Wednesday, then medium to high
  chances for rain late in the work week into the weekend.

&&

.UPDATE...
Issued at 1019 PM CDT Tue Sep 15 2026

The near-term forecast remains on track. Current conditions and
trends were blended in for this update.

UPDATE
Issued at 739 PM CDT Tue Sep 15 2026

No significant forecast changes are needed for this update. We
did decrease our low temperature forecast tonight by a few
degrees at some locations based on the latest NBM hourly
temperature projections. This is also in line with observed
dewpoints being lower than earlier guidance had suggested. The
updated forecast brings lows into the upper 30s across parts of
northwest and north central North Dakota, extending to areas
south of Lake Sakakawea. Some patchy frost cannot be ruled out,
but this potential should be mitigated by increasing clouds and
wind later in the night.

&&

.DISCUSSION...
Issued at 245 PM CDT Tue Sep 15 2026

Northwest flow will lessen tonight under weak ridging. Some
trapped moisture aloft in this northwest flow could continue
some low clouds through the evening, with some partial clearing
expected tonight. This partial clearing will influence low
temperatures tonight, with lows generally in the 40s. Some clear
areas with light winds could see lows into the 30s, perhaps
bringing isolated frost. As a surface low develops to our
west, light winds will become a steady southeasterly flow later
tonight especially in the west. Inverted surface trough then
moves through Wednesday, combined with a weak mid level
wave/warm front then trailing cold front. The result will be
some chances for showers mainly central, north, and east. Some
weak and elevated instability could provide for a few isolated
thunderstorms as well on Wednesday. Shear is high Wednesday, but
will likely not be full accessible given the elevated nature of
any thunderstorms that develop. Slightly warmer temperatures
will also be found on Wednesday, especially in the southwest,
with highs generally forecast in the 60s north and east to 70s
elsewhere. Breezy southerly winds may also be found as well at
times on Wednesday. Cold front moves south out of Canada
followed by a surface high Wednesday night into Thursday
morning. This will bring cooler lows in the mid 30s to mid 40s.
Depending on winds and cloud cover some patchy frost is
possible, especially across the north.

Surface high will bring mainly dry conditions on Thursday,
although a stalled front and return flow could bring some
showers and thunderstorms to the southwest. Most of the
precipitation is expected to remain to our south Thursday,
perhaps clipping some southern portions Thursday night. Winds
will again be easterly, and could be breezy in the southwest.
Cooler highs in the 60s to near 70 can be expected behind
Wednesday nights cold front. Abundant moisture combined with a
broad upper low could then bring widespread shower and
thunderstorm chances of Friday. How far north and east this
plume of moisture and the upper low goes will determine where
the precipitation sets up. Current PoPs favor the northwest and
some southern portions of the state for Friday. Temperatures
warm slightly for Friday, and generally in the 70s. Broad upper
low and trough slowly moves into the area this weekend keeping
temperatures near to slightly below normal. As a result broad
chances for showers and thunderstorms will be across the state
through the weekend. Actual location of precipitation will be
highly dependent on intrusion of dry and limited synoptic lift
at times. Even so NBM still showing 40 to 60% chance for 0.5" or
greater of rain through the weekend, mainly along and west of
Highway 83. Limited instability and shear should also limit the
thunderstorm threat for the weekend. With high RH values at
night there could be some patchy fog at times this week into the
weekend. Highly dependent on winds and precipitation though.
Thus have left it out of the forecast for now. With cloudy skies
this weekend, lows should be mild limiting the frost potential.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1019 PM CDT Tue Sep 15 2026

VFR conditions are expected through the forecast period.
Scattered rain showers could develop from northwest to south
central North Dakota Wednesday morning, shifting eastward
through the afternoon. Brief visibility reductions from rain
cannot be ruled out, but most of the rain should remain light.
Winds will become southeasterly tonight into Wednesday morning,
increasing to around 10-20 kts. A low pressure system entering
the state Wednesday afternoon will turn winds to the north-
northwest across western North Dakota.

&&

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

&&

$$

UPDATE...Hollan
DISCUSSION...Anglin
AVIATION...Hollan