388
FXUS63 KABR 301537 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1037 AM CDT Sun Aug 30 2026

.KEY MESSAGES...

- A Slight Risk (level 2 of 5) for severe storms across portions
  of north central SD late this afternoon into the evening
  hours, with a Marginal Risk (level 1 of 5) across the
  remainder of the forecast area. Main threats are wind gusts
  from 60 to 75 mph and hail from 1 inch to 1.5 inches in
  diameter.

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

&&

.UPDATE...
Issued at 1034 AM CDT Sun Aug 30 2026

A stratus deck has settled into much of northern SD and west
central MN, so have updated sky cover grids to account for this.
Expectation is for this low cloud deck to burn off gradually
over the next several hours. Otherwise, will be watching threat
for strong to severe storms once again, with activity moving
into portions of central/north central SD by early evening.

&&

.DISCUSSION...
Issued at 1248 AM CDT Sun Aug 30 2026

As of 1230am, there is an impressive supercell moving eastward into
Potter/Sully county, which is located along the northwest side of
the 850mb warm air advection that stretches from there and to the
southeast towards southeastern SD. There were other cells that
developed along the WAA to the southeast of this main storm, but
they`ve since dissipated, but do have other storms to the northwest
of this one which are associated with a shortwave noted on WV
imagery. With the forcing likely to continue to push slowly to the
east-northeast through the night and plenty of instability (2k J/kg)
and shear (40-50kts), not too much to inhibit this storm from
continuing to the east tonight and will likely come down to storm
scale processes over the coming hours. The rest of the convection in
north central SD will lift to the northeast with time this morning.

Behind the early this morning elevated convection, will continue to
see a broad surface low over South Dakota through the day. One of
the main questions for the eastern part of the area is where the
warm front and associated WAA will settle through the day, as this
could lead to some development farther east this afternoon than the
primary threat that will be moving through the north central part of
SD. This area along the warm front will have ample instability (1500-
2500 J/kg of MUCAPE) and shear (40kts), with continued elongated
hodographs leading to the potential for an isolated supercell. Of
course, anything occurring right along the warm front could lead to
a brief tornado threat too. Now for the primary potential for
convection this afternoon and evening. The upper low near
WA/ID/MT/Canada border area will move to the east-northeast through
the day today and into southern Saskatchewan by this evening. The
falling heights and cooling temperatures aloft will be strongest to
the northwest of the area and lead to the convection developing
upstream and along the cold front moving easterly through MT/WY this
afternoon. As the storms move eastward this evening and into the
Dakotas (and some likely developing out ahead of the front), they`ll
encounter increasing instability (going from 500-1000 J/kg to 1000-
2000 J/kg) as they move into western ND and northern SD. The
combination of the forcing and the increase in instability expect
both an increase in coverage (towards linear mode) and a continued
potential for severe storms. This will likely lead to the severe
threat shifting from hail/wind to more wind threat with time. Expect
the severe threat to be focused in north central SD and northward,
with the primary questions being how far south and to the east it
will go. It will either be fighting less forcing (farther south
option) or increase in nocturnal inversion (farther east). CAMS in
general are fairly consistent in a limitation in the southward
extent (generally north of US-212), but vary in the eastward extent
(some dying things in north central SD and others moving it into
north central SD). So will need to continue to fine tune the
expectations through the day today.

The upper level and surface low will continue to the northeast on
Monday, allowing high pressure to build into the region. Expect the
tight pressure gradient over eastern SD to diminish quickly Monday
morning and winds will be light over the area under the high for the
rest of Monday. Slightly cooler temps will be in place for Monday,
although still being around or slightly above normal (low-mid 80s).
Drier air will also move in, with dewpoints falling into the low-mid
50s, so will be a pretty nice and comfortable day. That may change
going into Tuesday, as a shortwave rounds and exits the upper trough
off the west coast and moves through the northern/central Plains.
There does appear to be a more northerly shift to this wave and the
resultant surface features (elongated surface low from somewhere
between southeast SD and southeast NE), leading to an increase in
the precipitation chances compared to 24hrs ago (now 40-60% vs ~20%
24hrs ago). There is the potential for some heavy rain with this
wave, as NBM 90th percentile 24hr QPF amounts are in the 1-2" range
(75th percentile is 0.25-1"), with the highest amounts over the
southeast half of the CWA. As for severe, ML output does hint at
some lower probabilities of severe weather with this wave (ensembles
have 1-2k J/kg of CAPE and 30-40kts of shear), so will need to
monitor that potential over the coming days.

Behind that wave, the upper ridge will build over the north central
CONUS, although there still continues to be uncertainty on the ridge
axis. Latest trends are for it to be around MN and amplifies through
the end of the week. That will lead to temperatures warming into the
mid-upper 80s to low 90s across the area. At this time, not too much
for signals for precipitation for the second half of next week and
into next weekend, as the amplification of the ridge likely keeps
much of the shortwave tracks to the northwest of the area.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 610 AM CDT Sun Aug 30 2026

Terminals KABR,KATY,KPIR,KMBG

There are pockets of IFR stratus near KMBG/KABR/KATY early this
morning. Otherwise once this mixes out VFR conditions with a low
probability of storms between KMBG/KABR.

&&

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

&&

$$

UPDATE...TMT
DISCUSSION...SRF
AVIATION...07