101
FXUS63 KBIS 041239
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
739 AM CDT Mon Aug 4 2025

.KEY MESSAGES...

- Dense fog this morning over western and central North Dakota.

- Periodic isolated to scattered showers and thunderstorms are
  forecast through the week. Isolated severe thunderstorms are
  possible on Tuesday.

- A gradual warmup is expected through mid-week. Some highs
  approaching 90 return to the forecast Wednesday and Thursday.

&&

.UPDATE...
Issued at 736 AM CDT Mon Aug 4 2025

Dense fog remains well situated over much of western and central
North Dakota, and looks to remain in place through mid-morning
over some locations per latest guidance. Therefore, have
decided to extend the dense fog advisory until 10 AM CDT/9 AM
MDT. By then much of the fog should have lifted/dissipated.


UPDATE
Issued at 630 AM CDT Mon Aug 4 2025

Dense fog continues across much of western and central North
Dakota this morning. There have been some visibility
improvements being observed in the south central. Fog is
forecast to lift after sunrise with low clouds lingering across
the central and east this morning. There is a chance of showers
forming in the James River Valley today. No updates needed at
this time as the forecast remains on track.

&&

.DISCUSSION...
Issued at 439 AM CDT Mon Aug 4 2025

Weak flow aloft will continue through the short term causing
remnant smoke to linger across the region. Dew points in the
60s and low temperatures in the 60s has reached saturation. In
addition cloud condensation nuclei from smoke is promoting
areas of fog across the region. Fog has lead to widespread
visibility reductions across the state this morning. Therefore,
a Dense Fog Advisory has been issued for visibility down to one
quarter of a mile until around 13Z. Fog is forecast to burn off
as temperatures warm up after sunrise. Hazy skies will likely
persist today as there is some elevated smoke aloft.
Temperatures are forecast to warm into the mid 70s out east and
the upper 80s as a weak ridge amplifies across the western
Dakotas this afternoon. Following the upper level ridge a trough
is forecast to dig across the Northern Rockies today leading to
convection over the higher terrain of Montana. The CAMs have
remnant storms moving close to the state line late tonight.
Storms will likely be weakening by the time they approach the
North Dakota border.

Tuesday the trough is forecast to move across the state leading
medium chances of precipitation. Showers and thunderstorms could
linger through the morning hours as they move out of Montana.
There is a chance for isolated to scattered severe storms
Tuesday afternoon and evening. Hi-res models are forecasting
around 1500-2200 J/kg of SBCAPE and around 30 to 40 kts of 0-6
km wind shear. The higher CAPE values will be near the North and
South Dakota border where a slight risk is. The CAMs are
highlighting the strong storms going up in the afternoon evening
hours. The is some uncertainty on the mode of storms if they
will be more discrete or cluster like before coming more linear
by night fall. High temperatures will decrease a few degrees
into the upper 70s to lower 80s. Showers and thunderstorms will
move eastward overnight across the eastern half of the state.

Showers and thunderstorms will carry through Wednesday morning
bringing rain to much of the state. There is a 50 percent chance
for half of inch of rain across south central North Dakota into
the James River Valley from this system. Probability decrease
for an inch but with system being mostly convective, thus I
would not be surprised to see localized areas with an inch or
more of rain. Machine learning is pegging Thursday and Friday
for the return of severe weather. The jet stream returns by the
end of the week with multiple waves moving through the main
flow which could lead to severe weather. In addition
temperatures will warm back up Thursday warming into the 80s to
lower 90s promoting increased instability. The weekend looks
fairly active as an upper level low moves across the region
bringing in widespread precipitation.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 630 AM CDT Mon Aug 4 2025

Dense fog continues across the region this morning. Fog is
forecast to lift after sunrise. Low stratus will linger across
the central and eastern half of the state through the morning
slowly burning off and lifting. Visibility improvements are
already being observed at some site such as KBIS. Winds will
remain light this afternoon generally out of the southeast.
There is a low chance thunderstorms and showers could impact
KJMS this afternoon. Overnight convection is forecast to move in
late tonight into the west. Uncertainty is to high to add
convection to the western terminals at this time.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM CDT /9 AM MDT/ this morning for
NDZ001>005-009>013-017>023-025-031>037-040>048-050-051.

&&

$$

UPDATE...JJS
DISCUSSION...Johnson
AVIATION...Johnson