181
FXUS63 KABR 051739 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1239 PM CDT Sat Sep 5 2026

.KEY MESSAGES...

- There is a Marginal risk (level 1 out of 5) for severe storms
  over central and northeastern SD and west central MN this
  afternoon into tonight, as well as on Sunday and Monday. The
  primary hazards will be 1 inch in diameter hail and 60 mph
  wind gusts.

- Our warming trend continues into the weekend, peaking at 15 to
  20 degrees above normal today. Highs in the low 80s over
  northeastern SD to upper 90s over central SD are expected.
  Higher humidity values over central SD will lead to heat index
  values in some places to get into the triple digits.

&&

.UPDATE...
Issued at 1235 PM CDT Sat Sep 5 2026

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 805 AM CDT Sat Sep 5 2026

No changes planned to the today period forecast. The forecast
contains some locations running heat index values up to ~97-102F
degrees this afternoon across central/north central South Dakota
for maybe 3 or 4 hours. Satellite and surface obs hint at a
cool/stable boundary layer over the CWA in the wake of last
night`s/early this morning`s convection. So, unless there were
to be some new (elevated) mid-level WAA-forced showers/storms
out across the northeast corner of CWA, there shouldn`t be any
further areas of precipitation over the CWA today. Will likely
have to wait for daytime heating to destabilize the BL and for
the shortwave energy noted back over Wyoming and Utah to make
its way over into this region many hours from now. By late this
afternoon, models depict plenty of instability (RAP13 has
~2000-3500J/kg CAPE) and deep layer shear (RAP13 has ~20-35
knots) will be around for multi-cellular to super-cellular storm
modes, continuing into tonight. Best low level jet tonight is
currently progged to set up across northeast South Dakota,
eastern North Dakota and the northern half of Minnesota. This is
probably also where the best low/mid-level WAA and moisture
advection juxtaposes with the strongest deep layer shear around.

UPDATE Issued at 628 AM CDT Sat Sep 5 2026

Aviation discussion updated below for the 12Z TAFs.

&&

.DISCUSSION...
Issued at 140 AM CDT Sat Sep 5 2026

As an upper-level shortwave has moved over SD last night into this
morning, scattered showers and storms continue to pop up and move
over areas east of the Missouri River. The low level jet has set up
over the area and has been helping to develop and support these
showers and storms and it will continue to support them into the
morning. Confidence in the timing of showers and storms is a bit low
this morning, as the high-res models have had a harder time
correctly showing what is actually happening when they initialize,
which makes a person have a harder time trusting what the models
have happening later on in the run. With warm, moist air continuing
to move into central and northeastern SD, the environment is primed
for showers and storms to continue to develop early this morning.
CAPE values this morning are between 1000-2000 J/kg over central and
northeastern SD. There are mid-level lapse rates of 7-8 C/km and
about 30-40 kts of shear in the environment. While so far the
scattered pulsy showers and storms haven`t become severe, if they
are able to get strong enough to tap into the environment and the
support of the low level jet, then they could become severe. If that
happens, then the storms could have hail up around 1 inch in
diameter and wind gusts of 60 mph. After the low level jet dies back
this morning, the showers and storms will likely back off for a few
hours.

More warm, moist air will be pushing into central and northeastern
SD today. Temperatures will be getting up into the low 80s over far
northeastern SD and increase to the west with highs in the upper
90s. The higher humidity values will cause the heat index values
over central SD to increase and get into the triple digits in some
areas. After the showers and storms move through this morning, the
heat and humidity will help to increase CAPE values back up to 1000-
3000 J/kg this afternoon and tonight. 850mb temperatures will also
be warmer today, with models showing temperatures between 20-28
degrees C. These temperatures will help to place a pretty decent cap
over central and northeastern SD. This will likely be a similar
situation to yesterday, where there will be scattered junky and
pulsy showers and storms that start to pop up in the afternoon along
the surface trough in the Rockies and the attached frontal boundary
that stretches from northwestern to southeastern SD and showers and
storms will continue this pattern through the night. However, with
the potential for an upper-level shortwave to provide support to the
storms at some point as well as an environment conducive to severe
storms if they can break through the cap, some storms could become
severe. Lapse rates late this afternoon into tonight will be between
7-8 C/km and bulk shear will be between 35-45 kts. With this
environment in place, there is a Marginal risk (level 1 of 5) for
storms to become severe, with hail up around 1 inch and wind gusts
of 60 mph possible. Confidence in timing for these storms is low due
to the cap that will be in place and not knowing where and when
something might be able to break through a weak point.

While moisture will continue to move in over central and
northeastern SD Sunday and Monday, the surface temperatures will
cool slightly. High temperatures these days will be in the low 80s
to low 90s. Instability will start to increase again over central SD
Sunday, with CAPE values in the afternoon into the nighttime hours
between 1000-2000 J/kg. As more upper-level shortwaves move over SD,
they will be able to provide support for showers and storms to
continue to develop along the surface trough and frontal boundary
that have parked themselves over the state. Slightly cooler
temperatures aloft will help to weaken the cap slightly, however
with 850 temperatures still looking to be between 18-24 degrees C,
there will still be a cap to limit storm development. As with
yesterday and today, there could be junky, pulsy scattered showers
and storms through the afternoon and night in this environment.
Lapse rates look to be slightly weaker Sunday, between 6-7 C/km, as
well as a bit weaker shear over the area compared to today. If a
storm is able to break through the cap, there is a marginal chance
(level 1 of 5) it could become severe Sunday afternoon through the
overnight. The primary hazards will be hail up to 1 inch and wind
gusts of 60 mph. While the start of Monday looks to have similar
conditions, an upper-level trough will be pushing the ridge that
sits over the area out, while also providing support for a cold
front to push through overnight Monday into Tuesday. This will have
more storms along it, but once the front pushes out of central and
northeastern SD, we will finally get a little break from the pattern
we have been stuck in as well as some cooler temperatures.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1235 PM CDT Sat Sep 5 2026

Terminals KABR,KATY,KPIR,KMBG

Generally VFR conditions are forecast during the TAF valid
period. There is a threat for -shra/tsra activity early this
evening (KMBG). And then additional chances for rain are
forecast late tonight into the day on Sunday. Inserted PROB30s
into the TAFs, particularly for KABR and KATY.

&&

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

&&

$$

UPDATE...10
DISCUSSION...12
AVIATION...10