634 
FXUS63 KBIS 251706
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1206 PM CDT Sat Oct 25 2025

.KEY MESSAGES...

- Above normal temperatures for late October today in western
  and most of west of central ND, but with low clouds and 
  cooler temperatures James River Valley in to eastern North 
  Dakota.

- Precipitation chances return Sunday night and continue into
  Monday night/Tuesday. Greatest chances central into eastern
  North Dakota Monday (50 to 80 percent).

- Near normal temperatures expected for the upcoming work week.

&&

.UPDATE...
Issued at 1136 AM CDT Sat Oct 25 2025

Low stratus remains over the far south central and into the James
River Valley. Forecast RAP/HRRR low level RH indicates the
stratus will linger through the day, limiting afternoon highs.
Farther west, high level clouds are slowly on the increase but
shouldn't hinder high temperatures as much. Forecast adjustments
were made to lower temperatures and bump up sky cover over 
eastern portions of the forecast area.

UPDATE
Issued at 932 AM CDT Sat Oct 25 2025

Stratus/fog continue to advance northward through central and
eastern ND. SPS continues for patchy dense fog. Adjusted sky
cover to better depict the low stratus. Western edge of the
stratus may dissipate but think the stratus will probably remain
through the day around the JRV and points east. Updated text 
products will be transmitted shortly.

UPDATE
Issued at 623 AM CDT Sat Oct 25 2025

Fog and low stratus development remains on track across the
southern James Valley, with patchy fog elsewhere central and
north. Surface observations and web cams indicate decent
visibility at the moment in the fog, so for now will hold off on
any fog headlines.

&&

.DISCUSSION...
Issued at 410 AM CDT Sat Oct 25 2025

Currently, high amplitude upper level ridge across the Northern
Plains this morning, with a long wave trough developing across 
the western CONUS. Southerly flow across the Dakotas with 
surface high pressure over the Great Lakes region and a 
developing sfc trough in the lee of the Northern Rockies. 
Scattered upper level clouds rotating around the ridge axis 
aloft, with a mild boundary layer contributed to morning 
temperatures mainly above freezing early this morning. High res 
models continue to portray fog development across the James 
River Valley this morning, with this underway now as evident via
satellite imagery. Area of low stratus also advecting northward
across the South Dakota James Valley towards my southeast 
counties. Will be monitoring this area for potential fog 
headlines. Right now aerial coverage is limited and some 
uncertainty what the stratus will do to any fog. 

Gradient forcing increases across the Dakotas today as the lee 
side sfc low continues to develop in response to the above
mentioned upper trough developing east today. The increase in 
return flow/mixing and the position of the upper ridge axis
will all contribute to sustained WAA and another day of very
mild temperatures today (mid/upper 60s-lower 70s 
forecast...with normal high temps in the lower 50s).

The initial evolution of the overall weather pattern remains 
unchanged from previous model runs late this weekend. The upper
trough continues to develop eastward Sunday, with a strong 150 
knot jet streak poking into the Pacific Northwest. Initial 
closed upper low develops within the trough, lifting 
north/northeast into central Alberta/Saskatchewan Sunday/Sun 
night along with an associated sfc low. Another strong embedded 
impulse and strong dynamics on the nose of the upper jet will 
amplify the mid/upper level trough Sun night into Monday, with 
an associated sfc trough/frontal boundary developing from across
eastern Colorado north/northeast across central South and North
Dakota. This feature coupled with multiple embedded waves 
lifting north/northeast from the base of the trough across the 
Dakotas will be the focus for accumulating rainfall. Models/NBM 
have shifted back west with the sfc trough/frontal boundary 
placement, and thus have shifted west for POPs and QPF. Decent
accumulations are also advertised by NBM (quarter to 3 quarters
of an inch central and east), and agree given the overlap of 
Div Q forcing and low level forcing/frontogenesis. Rain chances
gradually taper over the west overnight Monday, with chances 
gradually tapering elsewhere from west to east early Tuesday.

Afterwards, a fairly progressive pattern is favored amongst 
ensembles for the remainder of the work week, with models 
showing the potential for a mid level shortwave/frontal 
passage mid to late next week. Temperatures are also favored to
be closer to normal for next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... 
Issued at 1136 AM CDT Sat Oct 25 2025

Widespread stratus remains over portions of eastern North Dakota
to begin the 18Z TAF period. This will impact the KJMS TAF with
low stratus expected through much of the afternoon, and
potentially through the entire TAF period. Otherwise only high
clouds expected over the remaining of the TAF sites today. 
However, the stratus is forecast to expand westward this evening
and overnight, bringing the potential for low stratus and fog 
to KBIS and KMOT. Western TAF currently forecast to remain VFR. 
A strong south to southeast surface flow is expected through 
the TAF period over central ND, with LLWS tonight. Western ND, 
including KDIK and KXWA will see lighter southeast winds than 
central ND and will shift to the west Sunday morning.

&&

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

&&

$$

UPDATE...TWH
DISCUSSION...NH
AVIATION...TWH