948
FXUS63 KABR 121232
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
732 AM CDT Wed Aug 12 2026

.KEY MESSAGES...

- There is a Slight risk (level 2 of 5) for severe storms to
  develop late this afternoon across southwest South Dakota and
  migrating into south central South Dakota during the evening
  hours. Main threats include up to 1 inch in diameter hail
  and wind gusts of 60 to 70 mph.

- There is a Marginal risk (level 1 of 5) for severe storms to
  develop late this afternoon west river, migrating east in the
  evening and overnight. Main threats include up to 1 inch in
  diameter hail and wind gusts up to 60 mph.

&&

.UPDATE...
Issued at 727 AM CDT Wed Aug 12 2026

Areas of locally dense fog have cropped up over portions of
central and east central SD. The visibilities in this fog could
drop to 1/4 mile at times. An SPS was issued for the next few
hours because of the fog. This fog should dissipate through the
morning, with the fog in east central SD already starting to
decrease in strength.

UPDATE Issued at 610 AM CDT Wed Aug 12 2026

See below for an aviation forecast discussion for the 12Z TAFs.

&&

.DISCUSSION...
Issued at 1238 AM CDT Wed Aug 12 2026

The 4-Corners upper high weakens and shifts into the southeast
CONUS, though we still remain under a broad west/northwest flow
regime. A plume of mid level moisture lifting out of the
intermountain west crosses South Dakota during the day. You can see
this broad area of mid level clouds over Nevada/Utah Idaho/Wyoming.
This moisture, 600mb and above, also has a very dry subcloud
layer resulting inverted V type soundings. Profiles also have
warm air aloft and while 700mb temperatures are only +8 to +11C
which doesn`t jump out as a strong CAP, 750mb temperature are
closer to +13 to +15C so NAM profiles indicate it will be
difficult for surface based convection but elevated convection
is depicted in CAMS for the evening/overnight hours. HREF MUCAPE
is only about 1500j/kg. Given the profiles, winds are the main
concern with any convection. Given how dry its been, dry
lighting and fires also are a concern.

There is another plume of mid level moisture for mainly Thursday
night into early Friday as well. Profiles are close to moist
adiabatic thanks to cooler mid level temperatures with easterly
stable low level flow with the surface high just across the border
in Canada. NAM BUFKIT profiles show its unstable during the day,
though there is an upper ridge moving overhead with increasing
heights at that particular time.

A southwest flow regime runs through Saturday before flow aloft
becomes more westerly, and ultimately northwesterly for next week.
NBM POPs have trended down this weekend and next weekend in
response, especially as a surface high moves across the region
Sunday/Monday.  Otherwise temperatures with this cooler airmass will
be running about 5 to 10 degrees below normal Thursday through
Sunday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 610 AM CDT Wed Aug 12 2026

Terminals KABR,KATY,KPIR,KMBG

Low stratus and fog (sub-VFR conditions) are developing again
this morning, primarily over portions of central and north
central South Dakota. VFR conditions are expected to be restored
prior to 18Z today (KPIR and KMBG?), and VFR conditions are
forecast for the rest of the TAF valid period.

Caveat: thunderstorms are possible by late this afternoon/early
evening and will probably carry with them a sub-VFR visby in
heavy rainfall. Thunderstorms into Wednesday evening/night could
also produce strong wind gusts in excess of 50kts.

&&

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

&&

$$

UPDATE...12
DISCUSSION...07
AVIATION...10