214
FXUS63 KABR 290526
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1226 AM CDT Sat Aug 29 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms are expected early
Saturday morning in eastern South Dakota. A Marginal Risk (level 1
of 5) for severe weather is in place. Hail of one inch in diameter
and wind gusts of 60 miles per hour will be the main severe hazards.

- Saturday evening, A Slight Risk (level 2 out of 5) for severe
weather is in place across north central SD, with a Marginal Risk
for areas along and west of the James River Valley. Hail of one inch
in diameter and wind gusts of 60 to 70 miles per hour are once again
the expected severe threats.

- Storm chances (30-50%) return once again Sunday during the late
afternoon and evening, where another Marginal Risk for severe
weather is in place, this time covering the entire forecast area.
The greatest chances will be over northern South Dakota, then
decreasing to 20 percent south of US-14. Hail of one inch in
diameter and wind gusts of 60 to 70 miles per hour will be the main
severe threats.

&&

.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