493
FXUS63 KABR 291129
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
629 AM CDT Sat Aug 29 2026

.KEY MESSAGES...

- There is a Marginal Risk (level 1 out of 5) for severe
thunderstorms this weekend. The greatest potential is during the
late afternoon into the overnight hours both today and Sunday. The
greatest chances (30-60%) are over north central South Dakota, with
the chances decreasing to 20% towards Pierre, Chamberlain, and
Watertown. Any severe storms that occur have the potential to
produce hail to 1 inch in diameter and wind gusts to 60 mph.

- Temperatures will remain 5-7 degrees above normal (80s to lower
90s) through much of next week.

&&

.DISCUSSION...
Issued at 1121 PM CDT Fri Aug 28 2026

Lee of the Black Hills surface low and a tight gradient in place to
the east of it has led to a strengthening 30-40kt low level jet over
eastern SD (near and east of the James River Valley). KABR VAD
profile has highlighted that increasing LLVL jet since around 01Z.
As that started to develop, the convection increased in portions of
east-central SD and expect that to be the main driver of the severe
threat through the early morning hours. Based on the SPC MesoA data,
the best WAA focuses farther to the southeast and into southeastern
SD, so may see the storms trend that direction with time. That
matches up with the latest 02Z HRRR run, keeping storm threat in
east-central and southeast SD. Severe hail/winds are possible with
any storms tonight, especially hail initially before storms move
eastward and into lower instability (drops from 2.5k J/kg MUCAPE to
1-1.25k over eastern SD). If there is any organization, wind would
become a greater threat. The storms should move out of the area
between 4-7am. Finally, any storm may produce heavy rain, as PWAT
values are 160% of normal on the 00Z KABR sounding and storm motions
are around 25 mph.

Behind this morning`s convection, expect a lull across most of the
area, as the low level jet veers to the WSW and focuses into MN and
the temp advection follows suit (as the surface low shifts into NE).
Still have enough mid-upper level moisture moving across the area
(as seen on upstream WV imagery across the mountain west) to lead to
a partly cloudy sky. Models even hint at some short wave energy
trying to move through and that likely is why a few models are
showing some weak returns across northern SD towards late morning
and into the afternoon. With bases up around 12-15kft and fairly dry
air sub-cloud, didn`t include any PoPs, but did add some sprinkle
mention to the northern counties as that slides through.

Later this afternoon and evening, confidence is low on thunderstorm
potential and location. This is due to the weakening low level flow
around the broad/weak low over the area (northeast winds