505
FXUS63 KABR 161136 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
636 AM CDT Sun Aug 16 2026

.KEY MESSAGES...

- There is a Marginal Risk, level 1 out of 5, for severe storms for
portions of central South Dakota this evening and tonight and a
Marginal Risk again Monday evening through Monday night along and
east of a line from Philip to Sisseton. Main threats include 1 inch
diameter hail and wind gusts of 60 mph. Brief heavy rainfall is also
possible.

&&

.UPDATE...
Issued at 632 AM CDT Sun Aug 16 2026

The aviation discussion has been updated for the 12Z TAFS.

&&

.DISCUSSION...
Issued at 138 AM CDT Sun Aug 16 2026

Zonal flow continues this morning turning northwesterly aloft this
evening as a negative tilted ridge amplifies a bit over the western
CONUS with an ongoing large troughing pattern in Canada. Quiet
conditions expected through this afternoon as high pressure centers
itself over the region. The high pressure system will exit towards
the southeast tonight into Monday morning as a surface trough,
extending from a deepening low tracking across Canada, will track
east/southeast across the region Monday followed by a cold front
plunging southward out of Canada Tuesday.

CAMS keep the storm potential spotty as a cluster of storms are
forecast to move into north central and another area into
central/south central SD, tracking southeast this evening through
tonight. There is timing and coverage differences between the
individual CAMs with NBM doing a good job broadbrushing pops between
35-45% mainly along and west of the Mo River. CAPE generally will be
at and below 1000j/kg but shear will be around 30kts. A lack of a
LLJ will keep the threat low for any organized severe storms or long
lasting storms. With more of an isolated threat, the SPC has a
Marginal Risk, level 1/5, for severe storms over portions of central
SD this evening into tonight.

As the trough tracks eastward across the Dakotas Monday, CAMs
indicate additional spotty chances of showers and thunderstorms
continuing here and there, mainly east of the Mo River during the
day (where the trough will be) and along and east of the James River
in the afternoon and evening as the axis of the trough moves over
this area. Better development (and more of a threat for organized
severe storms) seems to occur to our east/southeast of the CWA, per
HREF. Winds at 500mb will increase between 40-50kts Monday evening
with CAPE values increasing to around 1500j/kg over south
central to northeastern SD/MN, bulk shear of around 30-40kts,
with dps in the 60s. However, there is not much in a way of a
LLJ as speeds are forecast below 20kts nor steep lapse rates.
So this keeps down the threat for long lived severe storms
through the overnight hours. Due to this, the SPC has
highlighted a Marginal Risk again (level 1/5) due to this
isolated threat mainly along and east of a line from Philip to
Sisseton. Hail 1" in diameter and 60 mph wind gusts are possible
along with brief heavy downpours.

The cold front from this system will plunge southward Monday evening
into Tuesday bringing additional shower and thunderstorms chances.
Behind the system, shortwave energy continues and if it can line up
with the surface boundaries over the region, additional threat for
rain and storms continues through the end of the week.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 632 AM CDT Sun Aug 16 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected to prevail at all terminals through
the next 24 hours.

&&

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

&&

$$

UPDATE...Vipond
DISCUSSION...MMM
AVIATION...Vipond