155
FXUS63 KBIS 291208
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
708 AM CDT Wed Jul 29 2026

.KEY MESSAGES...

- Hot and smoky conditions continue today. High temperatures
  and heat index values could reach 100 degrees across much of
  the western half of the state.

- Isolated to scattered severe thunderstorms are possible this
  afternoon and evening. Potential hazards include damaging
  winds up to 70 mph and hail as large as ping pong balls.

- High chances (60 to 90 percent) for scattered thunderstorms
  across southern North Dakota on Thursday. A few storms could
  be severe and produce locally heavy rainfall.

- Cooler on Thursday, then becoming hot once again through the
  weekend.

&&

.UPDATE...
Issued at 707 AM CDT Wed Jul 29 2026

Shallow fog has become more dense across a wider area than
earlier expected, but overall coverage remains patchy. A Special
Weather Statement has been issued to address this. Meanwhile, a
rogue thunderstorm is passing by the northwest corner of the
state, but it should mostly remain in Saskatchewan.


&&

.DISCUSSION...
Issued at 530 AM CDT Wed Jul 29 2026

Upper level ridge extends from the Southern Rockies through
Northern High Plains early this morning. North Dakota lies
between high pressure over Wisconsin and a surface trough over
central Montana. Ground-truth reports indicate smoke remains
present in the near- surface layer across northern North Dakota,
and on its own has been reducing visibility as low as 5 miles.
Particulates from the smoke have provided sufficient
condensation nuclei for patchy fog to develop in low-lying areas
of north central North Dakota early this morning. The fog is
not expected to be nearly as impactful as 24 hours ago, but
there have been brief observations of quarter mile visibility
from western Bottineau to northern Ward Counties. Any fog should
burn off by mid morning, but near-surface smoke could persist
through the day, if not longer. A mention of patchy smoke was
maintained in the forecast through this afternoon, with
confidence beyond the afternoon remaining low.

Today is expected to be the hottest day of the work week as the
thermal ridge once again points into the western Dakotas. The
NBM suspiciously increased its 50th percentile high temperature
projections by a few to several degrees, which seems
inconsistent with all other previous and current guidance. We
trended our high temperature forecast closer to the maximum of
NBM/HRRR hourly guidance, which gives a more reasonable forecast
of around 95 to 100 across most of western and central North
Dakota, and is much more consistent with previous forecasts over
the past few days that had shown little to no change. The
hottest forecast temperatures and heat indices are focused over
the Missouri River Valley, and also extend south to the I-94
corridor west of the river. A Heat Advisory has been issued for
these areas, in effect from noon to 8 PM CDT.

Forecast confidence in convective evolution and intensity this
afternoon through tonight is not that high. An inverted lee
trough is forecast along the ND/MT by mid afternoon. CAMs are
consistent that there will be enough forcing from surface
convergence, low level frontogenesis, and weak shortwave energy
ejecting off the Northern Rockies to initiate deep moist
convection along the surface boundary by mid to late afternoon.
Despite hot temperatures and dewpoints only favored to mix down
into the lower to mid 50s, model soundings reveal a skinny CAPE
profile with very high LFCs at around 600 mb. Differences in mid
to late afternoon buoyancy projections range from as high as
2500 J/kg SBCAPE in the RAP to as low as 500 J/kg in the HREF
mean MUCAPE. Think closer to 1000 J/kg is the most likely
outcome, which is still sufficient for severe storms but lower
than previously anticipated. The deep layer shear forecast has
also weakened in the most recent model guidance, with only
around 25- 35 kts in the 0-6 km layer, highest in northwest
North Dakota. Dry- air entrainment and residual CIN also remain
a concern for convective development and sustainment. These
limiting factors are seemingly reflected in CAMs` UH output,
with HREF neighborhood probabilities of UH greater than 75
m^2/s^2 only reaching 10 percent, and only that high in
northwest and north central North Dakota. Previous forecast
thinking on a favored storm mode of linear north to discrete
south remains valid as far as vector orientation is concerned,
but CAMs` reflectivity is more indicative of a mixed/cluster
mode with splitting supercells (which modeled hodographs do
confirm is a possible outcome). Because of the inverted-v
thermodynamic profile, damaging wind is the most likely severe
hazard. Large hail is still possible with discrete storms, but
the decrease of forecast CAPE and shear has prompted us to lower
our most likely maximum hail size forecast to ping pong balls.
The tornado risk in northwest North Dakota, which was already
low to begin with, appears to have lowered even further. But
because there is still potential for a triple-point axis, and
model hodographs at Crosby have actually switched from crosswise
to streamwise vorticity in the 0-1 km layer, will maintain the
mention of a possible tornado in far northwest North Dakota for
now.

CAMs remain inconsistent on convective evolution into central
North Dakota during the overnight hours. The risk for severe
storms is likely to end by around midnight, but one to a few
clusters of storms could persist through the night. On Thursday,
a deeper shortwave is forecast to cross the Northern Plains and
produce widespread showers and thunderstorms, especially across
the southern half of the state. Enough CAPE and shear may be
present to support isolated severe storms, but convection seems
likely to remain elevated. The greatest concern from
thunderstorms on Thursday may actually be heavy rainfall, with
anomalously high precipitable water, high deep layer RH, and the
potential for multiple rounds of storms at any given location.

Increased cloud cover is likely to render Thursday the coolest
day of the week, for which forecast highs have fallen into the
upper 70s to upper 80s. But it could still be very humid on
Thursday with forecast dewpoints in the 60s west to 70s east.
The upper ridge is forecast to rebound over the western CONUS
and pivot back over the Northern Plains Friday through the
weekend, allowing temperatures to heat back up to near 100 in
the west on Saturday and central on Sunday. A low-amplitude wave
rounding the top of the ridge could bring a few showers and
thunderstorms to western North Dakota Friday evening. Ensemble
guidance remains confident on a potent shortwave ejecting into
the Canadian prairie provinces on Sunday, driving a cold front
through the region late Sunday into Monday. Windy and hot
conditions ahead of the cold front could introduce fire weather
concerns for the weekend, particularly on Sunday. The passage of
the cold front should finally provide relief from the heat
through at least the middle of next week, with highs in the 70s
and 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 707 AM CDT Wed Jul 29 2026

Patchy dense fog has developed across northwest and north
central North Dakota early this morning. The fog may approach
KMOT before it dissipates by around 14-15Z, but confidence is
not high enough to carry a visibility restriction in the TAF.
Smoke from distant wildfires will likely persist through the
forecast period. MVFR visibility cannot be ruled out from time
to time, but VFR conditions should mostly prevail. Scattered
showers and thunderstorms are forecast to develop in western
North Dakota late this afternoon and could spread eastward into
the evening and overnight hours. A few storms could be severe
with damaging wind gusts. Winds are otherwise expected to be
southerly at around 10-15 kts this afternoon.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon CDT /11 AM MDT/ today to 8 PM CDT /7
PM MDT/ this evening for NDZ009-010-017>020-031>033-035-041-
042-046-057>062.

&&

$$

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