220
FXUS63 KABR 301510 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1010 AM CDT Sat Aug 30 2025

.KEY MESSAGES...

- Showers and weak thunderstorms will continue through the
  weekend. Severe weather is not expected with this system,
  though cold air funnels are possible in the afternoons. Heavier
  rain or stationary storms may also pose an isolated flooding
  threat.

- A cold front will move through on Tuesday, with a 20 to 40
  percent chance of rain. The remainder of the week is expected
  to stay dry.

- Below normal temperatures are expected during the second half of
  this upcoming week. Highs will be in the low to mid 60s, 10 to
  15 degrees below normal.

&&

.UPDATE...
Issued at 1009 AM CDT Sat Aug 30 2025

The forecast remains on track this morning. No major changes are
planned.

&&

.DISCUSSION...
Issued at 254 AM CDT Sat Aug 30 2025

Scattered showers with embedded weak thunderstorms persist this
morning, supported by a surface trough emanating from a surface low
to the south. This low will slowly slide east through the day today
and Sunday, continuing to bring showers and weak thunderstorms to
the forecast area. Areal extent of rainfall is expected to increase
today, and central South Dakota expected to see up to 2 inches of
rainfall today. Storms will be slow-moving and under a moisture
regime around the 90th percentile, so localized flooding is once
again a potential concern. However, a moderately shallow warm cloud
layer (6000-7000 feet), little CAPE (<500 J/kg), and soil moisture
in that area still being fairly low will all work against flooding
potential today. The most likely case will be a similar situation to
how yesterday played out, where storms were just progressive enough
as to not be problematic.

There are some chances for isolated patches of fog this morning,
particularly over northeastern South Dakota where cloud cover will
be a bit sparser through the morning allowing for full diurnal
cooling. There remains low confidence on location, and any fog that
does develop is expected to be patchy at best.

A cold front is set to move through on Tuesday, and will bring the
next chances for rain along with it. Severe weather may be possible
with this frontal passage, but it will likely be a fairly marginal
setup. Long range models place a plume of 1000-1500 J/kg along the
front coupled with 20-30 knots of shear. Early looks at mid-level
lapse rates are about 6 C/km, so would like to see those increase
before putting serious consideration for hail as a severe hazard.
The wind threat looks a bit better, with lower-level lapse rates of
8-9 C/km, dry mid-levels, and DCAPE values around 1000 J/kg. This
remains an early look, so this can be taken with a grain of salt for
now, but will be watching model trends on this system over the next
couple of days.

From mid-week and beyond, ensemble clusters are in agreement that a
deep upper level trough is set to bring strong northwesterly flow
aloft mid-week. This will help reduce high temperatures across the
forecast area to the low to mid 60s, 10-15 degrees below normal for
early September and two standard deviations below the mean. Although
flow aloft is expected to be strong at the end of the week, the near-
surface pressure gradient will be broad enough to where high wind is
not expected to be a concern despite a favorable direction.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 625 AM CDT Sat Aug 30 2025

Terminals KABR,KATY,KPIR,KMBG

Scattered showers continue to be the main aviation concern this
morning, and these showers to weak thunderstorms are expected to
continue across the area through the TAF period. Highest chances for
storms are over central South Dakota this afternoon, and -TSRA
has been indicated in the KPIR TAF in a PROB30 group for now.
Other sites, with the exception of a couple higher confidence
intervals, have mainly been kept within PROB30 or TEMPO groups due
to the scattered nature of the showers. These showers may drop
ceilings down to MVFR at times, but minimal visibility reductions
are expected except under the showers producing the heaviest
rainfall.

There have also been a couple of observations of light fog over
northeastern South Dakota this morning, dropping visibility to MVFR
but reporting ceilings of IFR to LIFR. Fog is still expected to
remain patchy and not very dense, and MVFR to IFR visibility at the
lowest is the current expectation. Fog chances will stay contained
over northeastern South Dakota and west central Minnesota, and
cloudier areas to the west will remain clear of fog.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...20
DISCUSSION...BC
AVIATION...10