471
FXUS63 KBIS 050606
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
106 AM CDT Sat Sep 5 2026

.KEY MESSAGES...

- Chances for showers and thunderstorms increase through the
  holiday weekend. A few strong to severe thunderstorms could
  develop Saturday through Sunday.

- Well above normal temperatures through Saturday, followed by
  a gradual cooling trend through the middle of next week.

&&

.UPDATE...
Issued at 105 AM CDT Sat Sep 5 2026

A cluster of strong to severe thunderstorms has been impacting
far northwest North Dakota since around 11 PM CDT. These storms
are likely sampling CAPE on the order of 1500 J/kg and effective
bulk shear around 40-50 kts. Despite this convection being
located at the nose of a strong low level jet, CAMs were very
poor in properly simulating it. To the southeast, widely
scattered showers and thunderstorms are more prominent east of
Highway 83, which had been anticipated. Most of this activity
has been tame compared to the northwest as it has existed in a
lower CAPE/shear environment, but MUCAPE is forecast to
increase over the next few hours in response to strengthening
low level moisture transport.

UPDATE
Issued at 1045 PM CDT Fri Sep 4 2026

Storms continue to expand across the southeast into the James
River Valley and there are few storms in the northwest. The
forecast remains on track.

UPDATE Issued at 651 PM CDT Fri Sep 4 2026

There is an areas of thunderstorms going up the southwest and
will likely stay sub severe as there is a lot of CIN that will
prevent storms from strengthening. However, there is decent
shear and CAPE that could support a stronger storm or two if
they can over come the CIN. Added PoPs to match the current
storms across the southwest. There is another wave that is
moving across the north central South Dakota that could clip the
southern James River Valley in North Dakota later tonight. The
current forecast remains on track as of this time.

&&

.DISCUSSION...
Issued at 308 PM CDT Fri Sep 4 2026

Critical fire weather conditions continue to be possible across
the southwest through this evening. RH values have been slow to
lower, although there appears to be a dry line now pushing
through these far southwest areas. Thus will continue current
Red Flag Warning as breezy southeast winds are still expected
with these lowering RH values. Developing surface low in
western MT will develop a warm front across northern and eastern
ND tonight. Some weak showers are already forming along this
boundary, with shower and thunderstorm activity forecast to
increase somewhat this evening through tonight. The threat for
severe weather remains low, although there remains high amounts
of MUCAPE tonight. Shear is only modest, although hodographs
would indicate some rotating cells are possible. Thus some near
severe hail is possible. DCAPE and 0 to 3 km shear are also
increased tonight, indicating some near severe winds are
possible. The main threat tonight could be heavy rain, as PWAT
values near 1.5 inches are forecast. Otherwise mild lows in the
60s are expected today with a steady southeast wind. Increased
dewpoints will be found through the night bringing high RH
recoveries. This could lead to some low clouds or perhaps fog
tonight, although confidence was not high enough to place in fog
in the forecast given the steady winds tonight. Surface low
stalls across the area for Sunday as well as the mentioned warm
front. A morning upper level wave could push overnight
convection eastward through the morning. The stalled warm front
will bring another hot day with highs in the mid 80s to mid 90s.
This combined with continued high dewpoints will bring ample
instability for Saturday. Shear remains modest for Saturday,
although increases Saturday evening through the night. The
result could be isolated severe thunderstorms Saturday through
Saturday night. SPC has broaden the Marginal risk as a result
for Saturday. It may still be somewhat conditional risk, as mid
level ridging and warming overhead could cap the atmosphere
somewhat. However, with high CAPE and modest shear, any storms
that do develop could be come severe. High pwats of 1 to near 2
inches will also bring a heavy rain threat.

Surface low shifts slightly eastward and stalls Sunday and
Monday, while influence from a broad upper trough moves in the
state. The result will be increased chances for showers and
thunderstorms for the rest of Labor Day Weekend. SPC has
maintained a broad Marginal Risk for Sunday given high
instability and at least modest shear. Isolated severe
thunderstorms could continue into Labor Day, although
instability is not as high. High pwats of 1 to 2 inches will
also remain Sunday and Monday, bringing a localized heavy rain
threat each day. With the stalled warm front across the state,
temperatures will remain mild, especially in the south. From
Tuesday to Wednesday, a stacked upper level low is projected
over the southern Canadian prairie provinces on Tuesday before
it quickly jets toward the northern Great Lakes and New England.
This favors drier, slightly cooler, and windier conditions for
western and central North Dakota Tuesday and Wednesday. Tuesday
especially could see at least advisory level west winds. This
combined with some lowering of RH could bring the next near
critical to critical fire weather day especially in the west.
Flow aloft may then transition to quasi- zonal by the end of
next week, which could moderate temperatures to near normal
values and return periodic lower chances for rain.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 105 AM CDT Sat Sep 5 2026

Isolated to scattered showers and thunderstorms are possible
throughout the forecast period. Other than at KJMS late tonight,
confidence in if and/or when a shower or storm could move over
a terminal is very low. The strongest storms could produce heavy
rain reducing visibility to IFR levels, erratic wind gusts, and
small hail. VFR conditions are otherwise expected through the
forecast period, although there is a low chance of MVFR/IFR
ceilings developing in northern parts of the state early
Saturday morning. Winds will primarily be southeasterly to
easterly around 10-15 kts.

&&

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

&&

$$

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