464
FXUS63 KBIS 250224
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
924 PM CDT Sun Aug 24 2025

.KEY MESSAGES...

- Well below average temperatures through Monday, then a
  gradual warming trend.

- Monday morning lows in the upper 30s to lower 40s, with
  pockets of mid 30s in western and north central parts of the
  state.

- Low chances for showers and thunderstorms return late in the
  work week.

&&

.UPDATE...
Issued at 924 PM CDT Sun Aug 24 2025

The forecast remains on track. There will be some high clouds
moving down from Canada overnight, but do not anticipate they
will be thick enough to greatly impede radiational cooling.

UPDATE
Issued at 559 PM CDT Sun Aug 24 2025

High pressure will continue to dominate regional weather this
evening through Monday. No significant changes were made with
this update, but did slightly increase the areal coverage for
patchy frost early Monday morning from around Beulah/Hazen to
Hettinger, and across parts of the far northern tier of
counties.

&&

.DISCUSSION...
Issued at 239 PM CDT Sun Aug 24 2025

This afternoon, a nearly stationary upper level low was parked over
Ontario, with cyclonic flow over the Dakotas in between the low and
an upper high over the Four Corners region. A seasonably cool
surface high pressure was centered just over the International
Border across from north central North Dakota. Fair weather cu was a
bit more widespread across the central and east than previously
forecast, so have bumped up cloud cover further, while out west is
mostly sunny. Afternoon highs will be mainly in the 60s, with some
lower 70s possible in the west.

Main forecast concern over the next few days is low temperatures
tonight into Monday morning, with an abnormally cool and dry air
mass for late August over the region. The surface high will slide
south this evening and overnight, leading to calm winds and clear
skies. Local research shows this synoptic setup is one where lows
end up colder than forecast, so did blend down lows in line with
previous forecasts to produce upper 30s to lower 40s, with a few
mid 30s in our typical cold corridor from Hettinger to
Beulah/Hazen area. Current thought is that any frost that does
develop would be very patchy and in low lying areas, so not
expecting enough areal coverage to warrant an advisory. Main
area of frost in gridded forecast is in southern Mercer County
and the immediate vicinity.

For the first half of the work week, temperatures will warm
notably as upper ridging begins to build across the western and
into the central CONUS. Highs on Monday will still be cooler
than average, in the upper 60s to mid 70s, with highs then in
the widespread lower to mid 80s on Wednesday. Chances for
precipitation are very low during this period, and winds will
be relatively light as well, so should be a nice stretch of
weather.

Late in the week is when there are potentially some questions on the
progression of the synoptic pattern. Ensemble clusters are still in
relatively strong agreement regarding the placement of the ridge
axis, and NBM temperature spreads at this point are small enough to
provide confidence in highs generally in the upper 70s to lower 80s
Thursday through Sunday. There is a bit more variety in
precipitation solutions, with around 25 percent of ensemble members
favoring a wetter solution to end the week. Although this is not the
majority of members, it is worth noting all clusters are advertising
at least a small increase in precipitation chances across the region
for the holiday weekend. The latest NBM has a broad 10 to 25
percent chance for showers and thunderstorms, highest across the
southwest and on Friday and Saturday.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 924 PM CDT Sun Aug 24 2025

VFR conditions and light winds are expected through the forecast
period.

&&

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

&&

$$

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