534
FXUS63 KBIS 011728
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1228 PM CDT Fri Aug 1 2025

.KEY MESSAGES...

- Areas of smoke will continue through at least tonight across
  much of western and central North Dakota, potentially
  limiting visibility and impacting air quality at times.

- Below average temperatures are expected through the weekend,
  with highs mainly in the lower 70s to lower 80s and lows in
  the lower 50s to lower 60s.

- Periodic low to medium chances of showers and thunderstorms
  (20 to 60 percent) are possible through the weekend and into
  early next week.

&&

.UPDATE...
Issued at 1223 PM CDT Fri Aug 1 2025

The vort max mentioned below continues to spin and push
east, now over northwest South Dakota, with associated clouds
and a few light showers. Ahead of this feature, we have
destabilized though bulk shear is weak. Will maintain chance
POPs with a still marginal threat for severe weather given the
combo of MLCAPE and forcing, most likely pulse convection later
today.

UPDATE
Issued at 935 AM CDT Fri Aug 1 2025

Embedded vorticity maximum over southeastern Montana continues
to generate showers and at times a few lightning strikes
southwest this morning. This cyclonic circulation very visible
on satellite imagery. Elsewhere, areas of smoke persists, with
reduced visibility at most observing sites across North Dakota.

The aforementioned embedded wave will continue to slowly move
east along the ND/SD border area this afternoon and evening, and
will maintain a chance for showers and thunderstorms over the
next 12-18 hours. Enough CAPE and shear for a few stronger
storms later this afternoon/evening, given the forcing of this
feature across our far south. SPC did push the Marginal Severe
potential north into our far south and agree with this.

Otherwise, just some cosmetic updates to the forecast for today.

UPDATE
Issued at 620 AM CDT Fri Aug 1 2025

Showers and storms did end up moving into southwest North Dakota
over the past couple of hours, but lightning activity has all
but ended now. A stray bolt or two cannot be ruled out but these
showers should continue to diminish as they drift east.
Visibility reductions continue from near surface smoke with a
few sites across the northwest and north central down in the 2
to 4 mile range. For this update, just blended in the latest
observation to the going forecast.

&&

.DISCUSSION...
Issued at 345 AM CDT Fri Aug 1 2025

As of early this morning, an upper level ridge axis was located
near the Montana/North Dakota border. At the surface, expansive
high pressure was centered in the vicinity of the Great Lakes
with a weak surface low spinning over central Montana. A
stationary front extended to the southeast of this low towards
the Montana/North Dakota/South Dakota tri-border area.

Scattered showers and thunderstorms remain ongoing east of the
aforementioned boundary, moving very slowly east. Thus far,
most lightning activity has either remained in southeast Montana
or western South Dakota but we have had a few flashes barely
over the border in Bowman county at times.

Given the rather stagnant flow aloft and stationary boundary at
the surface, convective activity should be somewhat limited over
our area with most of higher precipitation probabilities to our
west and south. CAMs do not have a great handle on this
current activity but the best guess is that storms will
gradually dissipate as they move east through the morning with
some redevelopment possible across the far south central and
southeast by mid to late afternoon. Widespread showers and
storms are not expected through the day north of the South
Dakota border, but some CAMs do suggest some isolated activity
over the southern part of the state. For this reason will
continue to hold onto low to medium (20 to 40 percent)
precipitation probabilities for the southern half of the area.
There will be some instability floating around through the
afternoon but shear will be low given weak flow aloft. Thus,
the severe weather threat should remain south of our area but a
stronger storm isn`t out of the question along the South Dakota
border.

The other story through tonight continues to be more smoke from
distant wildfires, some at the surface and quite a bit aloft.
The HRRR- Smoke model continues to suggest that we will see areas
of smoke across much of western and central North Dakota at
times through at least tonight. Smoke may linger into Saturday.

Saturday will feature another day with low to medium chances
(20 to 40 percent) for showers and storms. A complex of showers
and storms/remnant MCV may be ongoing Saturday morning
somewhere across South Dakota, potentially lifting close to the
North Dakota border by the afternoon in the vicinity of the
James River Valley. Most CAMs have this activity remaining in
South Dakota but a few do suggest some development in our area
before the afternoon is over. Severe weather is not expected a
this time. A southern stream ridge will break down by Saturday
night while a northern stream ridge extends well into northern
Canada. This pattern keeps western and central North Dakota in a
weak/stagnant flow aloft but will allow little impulses to
meander through periodically. One of the stronger waves could
impact the west Saturday night and the central on Sunday night.
Chances for showers and storms will be a bit higher on Saturday
and Sunday (40 to 60 percent), and while severe weather is not
expected, slow storm motions/high PWATs could lead to some
locally heavy rainfall.

After ridging builds back in on Monday, most guidance has mean
troughing moving in through midweek. This will keep near daily
low to medium chances (20 to 50 percent) of showers and storms
in the forecast through the week. While there is not a clear
signal for severe weather in the longer range, CSU Machine
Learning guidance does continue to advertise low chances for
severe weather midweek.

Regarding temperatures, highs will remain below average for this
time of year through the weekend, ranging from the lower 70s to
the lower 80s. Lows will mainly range from the lower 50s to the
lower 60s. We will then start to warm closer to average next
week with highs in the mid 80s returning on Monday and some
upper 80s back in the forecast by Wednesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 620 AM CDT Fri Aug 1 2025

Near surface smoke continues to be the biggest challenge for
the first part of the 12z TAF period. MVFR visibilities have
developed across portions of the northwest and north central,
thus far impacting KMOT. Smoke should hang around through most
of the period, so additional MVFR visibilities are not out of
the question for any of western and central North Dakota. We
should see some scattered lower clouds today with some chances
for brief MVFR ceilings but outside of these patches and MVFR
visibilities from smoke, expect VFR conditions. We could see a
few showers in the vicinity of KDIK this morning and then we
will see a low chance of a shower at KBIS later this evening.

&&

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

&&

$$

UPDATE...NH
DISCUSSION...ZH
AVIATION...NH