916
FXUS63 KABR 290728 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
228 AM CDT Sat Aug 29 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms will continue early
this morning in east-central 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.

- 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 <15kts from
sfc-850mb) and likely becoming re-established near the Black Hills.
That low level flow and low location leads to the Black Hills and
maybe areas to the north of that being the best chance for initial
development, but could even see an isolated storm develop between
the Black Hills and the Missouri River if there is some local
convergence. Once development occurs, storms will move off to the
east-northeast around 20kts and move into a little better
instability (2-2.5k J/kg in central SD in the evening). Shear
remains the same (30-40kts) across the area, so would expect the
severe potential to continue as storms move into central SD from the
west through the evening. These storms have the potential to produce
1"+ hail and 60mph winds, but would expect an eventual transition to
primarily a wind threat and weakening as storms move into a less
favorable in eastern SD (or dive south into the better instability).
One area of a very conditional threat is if storms develop near the
ND/SD border west of Lemmon towards evening. This would be an area
of increased shear (40-50kts) and SRH (100-150 of 0-3km),
potentially being a favorable environment for supercell
characteristics and hail up to 2" with the elongated and straight
hodographs. One last thing to watch for tonight is a warm front
stretching east across east-central SD. Confidence is low overall,
as the low level jet isn`t as strong (5-15kts), which leads to more
broad/weak WAA in that area. So potential for development is
present, but also low chances (10-20%) at this point.

For Sunday, the upper low moves from the northwest MT and Canada
border on Sunday morning to southern Saskatchewan by Monday morning.
With that track, the best upper level support (q-vect conv) tracks
across the northwest half of ND and potentially brushes our north
central. That being said, we do have the persistent surface low over
central SD and potential warm front stretching east across northeast
SD and a cold front south across the south central. This provides
sources of lift and with 1500-2500 J/kg of CAPE and 40-45kts of
shear, thus a severe potential remains. Looking closer at forecast
soundings, there does appear to be some low-moderate CIN (-50-125
J/kg), which may keep the potential for development in our area to
be more isolated. That matches up with the regional/global models,
which point towards the better chance of storms being tied to
upstream convection that may move into the northern parts of the
CWA. With storm motions to the east to east-northeast and large
scale forcing lifting northeast, will need to monitor expectations
farther to our west and see how they evolve over the next couple
days and influence our severe potential.

For next week, the upper trough that brushes the area on Sunday will
continue to shift northeast into Canada while weakening, allowing
the upper ridge to build back into our area. The ridge axis should
be near or just east of the Dakotas by mid week and remain or slowly
shift eastward through the rest of the week. While the ensemble
clusters vary on the location of that upper ridge axis, the
anomalous upper heights (50-75m above) will lead to temperatures
remaining above normal (80s, with some low 90s in south central SD)
into the first week of September. Precipitation chances will come
down to the location of the ridge axis and any shortwaves moving
around and out of the upper trough off the Pac NW coast (mid week
looks to be the best chance at this point, but largely southeast of
our area). No significant signals for heavy rain during the period,
as the NBM probabilities of 0.1" or more in 12hrs is less than 20%
for all periods. As for severe threat, extended ML products keep the
better opportunity for severe weather to the southeast of our area
for the first half of the week, but then shift it back northwest and
have 5-15% probabilities over the Dakotas for the second half of
next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1221 AM CDT Sat Aug 29 2026

Terminals KABR,KATY,KPIR,KMBG

A cluster of storms is moving towards the KATY terminal at the
time of issuance, while over at KABR we have some weak high
based showers in the vicinity. Otherwise VFR conditions through
the day, with the low probability of storms up towards KMBG late
in the TAF period. Low level flow is mainly out of the east
southeast.

&&

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

&&

$$

DISCUSSION...SRF
AVIATION...07