393
FXUS63 KBIS 031540
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1040 AM CDT Thu Sep 3 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms across northwest and
  central North Dakota this morning and afternoon. A few storms
  may be strong to severe, mainly in north central North
  Dakota.

- Critical fire weather conditions are possible in far
  southwest North Dakota on Friday.

- Temperatures warming to well above normal through Saturday,
  then cooling back to near or slightly below normal early to
  mid next week.

- Medium to high chances for showers and thunderstorms Sunday
  through Labor Day.

&&

.UPDATE...
Issued at 1030 AM CDT Thu Sep 3 2026

Current round of convection over our area is now focused mainly
over Wells into Foster Counties, with reports of mainly periods
of heavy rain and small hail. Expect this line to continue
overall moving to the east, though there has been consistent
development on the southern edge given the low level jet in
place.

Elsewhere, mainly isolated showers and a few weaker storms
continue to develop over various parts of our area. Focus then
mainly turns to this afternoon as the next wave moves through,
with the primary focus for stronger to severe storms over north
central North Dakota which is still being focused upon by latest
CAMs. There remains some question as to how this morning`s
convection has affected the atmosphere for the afternoon
development which was mentioned in the early morning discussion.


UPDATE
Issued at 711 AM CDT Thu Sep 3 2026

Thunderstorms continue over portions of northwest and central
North Dakota this morning, with the strongest convection now
over north-central North Dakota where a recent report of ping
pong ball size hail was received. This is on the northern end
of a low-level jet with plenty of elevated instability in
place. Expect the severe threat with these storms to continue
through this morning, along with the potential for locally heavy
rainfall.

&&

.DISCUSSION...
Issued at 535 AM CDT Thu Sep 3 2026

The Northern Plains lie under southwest flow aloft early this
morning between a transient ridge exiting the Red River Valley
and a deep longwave trough over the Pacific Northwest. A nearly-
stacked low pressure system is depicted on water vapor imagery
spinning northward through southern Alberta, with a separate
surface low analyzed in southeast Montana. A broad expanse of
low level warm air advection and moisture transport downstream
of these features has ignited areas of showers and
thunderstorms. One cluster of widely scattered showers and
isolated thunderstorms has been migrating eastward across south
central North Dakota into the James River Valley. Meanwhile,
clusters of much stronger thunderstorms were moving through
northwest and north central parts of the state as of 5 AM CDT.
These strong to at times severe storms are moving through an
environment with up to 2000 J/kg MUCAPE and effective bulk shear
as high as 40-50 kts. Convective evolution through this
afternoon is uncertain, and CAMs offer little consistency in
potential outcomes. The ongoing convection may continue to lift
northeastward into southern Canada by this afternoon. Some CAMs
then hint at trailing redevelopment in north central North
Dakota this afternoon as an upper level jet streak lifts
northeast off the Rockies, but there are obvious questions on
how the environment may be modified by morning convection.
Model soundings and two-dimensional CIN fields suggest a
capping inversion is likely to keep storms elevated through the
day, but UH fields in the HREF broadly support strong to severe
convection in north central North Dakota this afternoon with a
similar CAPE/shear parameter space as mentioned above. Storm
mode could be mixed or clustered as there is no well-defined
surface boundary where convection is forecast, so will leave
our projected hazards at hail up to ping pong ball size and
winds up to 60 mph. Torrential rainfall could also caused
localized flooding, as has already been observed in Williston
and southwest Ward County early this morning.

Mid to upper level ridging is forecast to amplify over the
Northern Plains on Friday as a deep upper low spins over the
Pacific Northwest. This brings the high temperature forecast
into the 90s along and to the south and west of the Missouri
River, along with a strengthening southeast surface flow around
20 to 25 mph. In western North Dakota, RH is forecast to fall
below 30 percent south of the Missouri River, with minimum
values closer to 15 percent in the far southwest along the
Montana border. The greatest overlap in strong winds and low RH
is in Slope and Bowman Counties, where a Fire Weather Watch has
been issued for Friday afternoon and early evening. Surrounding
areas in west central and southwest North Dakota could see near-
critical fire weather conditions on Friday.

The ridge is forecast to become even more amplified on
Saturday, with forecast highs ranging from the mid and upper
80s north to lower and mid 90s south. The low level jet could
induce convection over parts of the region late Friday night
into Saturday morning, but mostly dry weather is otherwise
anticipated from tonight until Saturday night when the deep
western CONUS trough begins kicking shortwave energy into the
Northern Plains. This culminates in widespread low to medium
shower and thunderstorm chances Sunday through Labor Day as a
more potent shortwave lifts northeastward over the region while
the original Pacific Northwest low spins toward the Canadian
Rockies. Temperatures are favored to trend cooler early to mid
next week as the upper low crosses southern Canada.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 711 AM CDT Thu Sep 3 2026

Scattered showers and thunderstorms will continue over northwest
and central North Dakota this morning and afternoon. A few
stronger storms are possible, especially over north central into
parts of northwest North Dakota, with erratic gusty winds and
hail. Categorical flight restrictions to MVFR/IFR are possible
with any thunderstorm, mainly from visibility reductions caused
by heavy rainfall, but also possibly from lower ceilings.
Outside of showers and storms, areas of fog over parts of
southwest North Dakota will result in IFR to LIFR visibility
through mid-morning. At this time, it appears the reduced
visibility should remain south of the KDIK terminal.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Friday afternoon through Friday
evening for NDZ040-043.

&&

$$

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