Mandan, North Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

004
FXUS63 KBIS 250011
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
711 PM CDT Fri Jul 24 2026

.KEY MESSAGES...

- Isolated to scattered severe thunderstorms are possible this
  evening in the James River Valley. The main hazards are
  damaging wind gusts up to 75 mph and hail up to golf ball
  size.

- Very hot conditions will return through the weekend, with
  dangerous heat index values around 100 to 105 degrees.

- Smoke from distant wildfires will make skies hazy today and
  may bring reduced surface visibility tonight into Saturday.

- The combination of hot, dry, and breezy conditions will create
  near-critical fire weather conditions this afternoon and
  again on Sunday, mainly in the southwest and parts of the
  south central.

&&

.UPDATE...
Issued at 702 PM CDT Fri Jul 24 2026

Severe convection has propagated east into the James River
Valley. The Severe thunderstorm watch has been cancelled for
counties west of the Missouri River in south central ND, as well
as Burleigh, Sheridan, Wells and Pierce counties. The watch
remains in effect for Emmons and Kidder county, as well as for
the James River Valley. In addition to the trimming of the
watch, we updated pops through the evening.

UPDATE
Issued at 638 PM CDT Fri Jul 24 2026

Damaging wind gusts of 60 to 75 mph -- and locally potentially
up to around 80 mph -- are the main concern in the James River
valley and parts of south central ND through about 830 pm CDT.
Isolated large hail of half dollar to golf ball size is still
possible.

As of 2330Z, earlier high-based supercells have merged into a
linear convective line that extends from northern Stutsman
County near Pingree, southwest to Medina and Napoleon. This
small but linear convective complex is propagating through an
environment characterized by 2000-3000 J/kg of MLCAPE, deep-
layer shear on the order of 50 kt, large DCAPE, and 0-3-km bulk
shear on the order of 30-35 kt. Several 60 to 75 mph wind gusts
have been observed with this complex, and the downstream
environment remains very favorable for damaging wind gusts. The
highest-end wind gusts near 80 mph have been associated with
large KDP cores that develop and descend from around the
freezing level near 14,000 ft AGL. We will continue to rely on
that signature and embedded supercells to identify which if any
portions of the line may produce wind gusts over 75 mph. Those
embedded supercells may also still produce large hail, though
the linear mode will tend to temper that threat. One caveat to
this scenario is that modest residual capping remains in the
James River valley, as evidenced by MLCIN on the order of 50
J/kg in the RAP-based objective analysis. However, given the
presence of an established cold pool with the linear complex,
the forced lifting along its leading edge is expected to be
sufficient to overcome this and maintain a severe-storm risk
through the southern James River valley. The forward motion may
increase a bit more, closer to 50-55 kt, based on the forward-
propagating MCS motion vectors, but even linear extrapolation
would have the line of storms moving through LaMoure and Dickey
Counties and exiting into southeastern ND by 800-830 pm CDT.

Meanwhile, the main surface trough extends from Carrington to
western Emmons County as of this writing, and the risk of storms
to its west has greatly diminished, as supported by recent
visible satellite imagery. This includes the Bismarck/Mandan
area where the risk of severe storms has diminished.

CJS

UPDATE
Issued at 527 PM CDT Fri Jul 24 2026

** Mesoscale Discussion **

Scattered severe storms with large hail up to around golf ball
size and damaging winds up to 60 mph will continue across south
central ND into the James River valley the next few hours.

Surface temperatures of 100-105 F have sufficiently eroded the
remaining capping in south central ND, especially along and just
ahead of a surface trough that extends from Devils Lake and
southwestward into eastern Morton and eastern Sioux Counties.
Modified RAP and the 18z KBIS RAOB suggest very steep low- and
midlevel lapse rates, favoring high-based storms. Moderate
bouyancy and effective-layer shear on the order of 40 kt favors
organized severe storms capable of large hail. Both the CAPE-
shear setting, SHIP parameter and sounding analogs suggest peak
hailstone sizes up to around golf ball size are possible. Both
RAP and VWP hodographs are straight enough to support the
occasional splitting supercells that have been observed, though
the modest low-level curvature suggests that right-moving
supercells will continue to be slightly favored over left-
splits. In contrast, the high- based nature of the storms, with
the well-mixed boundary layer up to almost 500 mb in south
central ND, will continue to promote outflow that may tend
toward some cluster-type storm modes at time. The hot, deeply-
mixed boundary layer and sufficient low- and midlevel flow
favors damaging wind gusts up to 70 mph. Given weak low-level
shear/SRH and the very high- based nature of the storms, the
tornado risk is very low.

In time, the storms will gradually move into the James River
valley, where surface dewpoints have held in the mid/upper 60s F
owing to a deeper moist layer and less-robust mixing further
away from the low-level thermal ridge axis. This may result in
some gradual intensification of storms in a few hours as they
reach that area, though that could also be countered by at least
somewhat by residual capping aloft.

CJS

&&

.DISCUSSION...
Issued at 231 PM CDT Fri Jul 24 2026

Potential severe weather remains the primary forecast challenge for
this afternoon. WAA off an amplifying ridge over the Rockies, along
with a passing weak surface frontal boundary, may help to
initiate thunderstorms this afternoon. With rapidly rising
temperatures in the southwest and south central, capping would
seem like less of an issue as indicated by the SPC mesoanalysis
page. This would also explain why some CAMs are initiating
convection further west than previously thought. That said, the
18Z KBIS sounding shows very dry air in place, while not even a
few bubbles of a cu field are present on satellite. What also
seems interesting is that the left exit region of the upper
level jet appears to be located closer to the International
Border. Overall, there remains a conditional severe threat for
the forecast area, though wondering if the better dynamics
overall will wind up lining up further north and east.
Nevertheless, with ample MLCAPE and plenty of deep layer shear,
there remains plenty of opportunity for severe weather this
afternoon and early evening.

The primary threats for today remain wind gusts of 70 mph and
golf ball size hail. In regard to the tornado threat, while
model forecast hodographs suggest some curvature in the lower
levels mainly over the south central east of the Missouri River,
LCLs are also increasing. This overall seems to favor strong
wind gusts over tornadogenesis from the James River Valley and
west. Still, cannot completely rule out a tornado if
thunderstorms were to persist into the evening hours in the
James River Valley.

Once any thunderstorms clear out this evening, dry conditions
are expected tonight through Saturday. A few isolated
thunderstorms are possible Saturday night and Sunday, though
severe weather is not anticipated at this time. With the
amplifying ridge sliding further east, expect very hot
conditions to return Saturday and Sunday. Very dry conditions
along and west of the Missouri River will see minimum relative
humidity drop down into the teens (possibly low 20s in the
Missouri River Valley) off mid 40 to mid 50 degree dewpoints,
while highs reach up to 105. East of the Missouri River Valley
will see highs up to 100 albeit with dewpoints in the 60s. With
these very hot conditions, issued a Heat Advisory for Saturday
afternoon through the day Sunday. In the far southwest where the
driest conditions are anticipated, near critical fire weather
conditions are expected this afternoon and possibly again on
Sunday.

For next week, above average temperatures are expected to
continue. While there might be a slight "cooling" trend, NBM
forecasts are still mostly in the 90s. Periodic low shower and
thunderstorm chances are in the forecast for next week, with the
highest probabilities during the middle of the week. A few
storms could be severe on any given day, though no day next week
is currently worthy of enhanced messaging at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 702 PM CDT Fri Jul 24 2026

Thunderstorm in the vicinity of Jamestown to begin the 00Z TAFs,
which will continue through 01Z. Otherwise VFR conditions are
expected through the period at all TAF sites. Will monitor for
possible fog early Saturday morning, but too uncertain to add to
any Terminal at this time. Generally light winds 15 knots or
less through the period.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM CDT /noon MDT/ Saturday to 9 PM CDT /8
PM MDT/ Sunday for NDZ017>020-022-023-025-031>033-035>037-
040>044-046>048-050-051-057>062.

&&

$$

UPDATE...TWH
DISCUSSION...Telken
AVIATION...TWH