Sisseton, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

773
FXUS63 KABR 121719 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1219 PM CDT Tue Aug 12 2025

.KEY MESSAGES...

- Shower and thunderstorm chances return Wednesday. There is a
  marginal risk, level 1 out of 5, for severe storms for the
  entire forecast area. Unsettled weather will continue for the
  end of the week into the weekend.

- Heat and humidity return for Thursday with heat index values
  approaching 100 degrees in central SD.

&&

.UPDATE...
Issued at 1006 AM CDT Tue Aug 12 2025

The forecast remains on track this morning. No major changes are
planned.

&&

.DISCUSSION...
Issued at 248 AM CDT Tue Aug 12 2025

After the last of these showers move east looking forward to dry
and seasonally cool conditions this morning and through the day
today with low level northwesterlies. RAP and HRRR also have
limited smoke drifting south of the ND/SD state line so we have
that going for us as well.

A 30-40 knot low level jet Wednesday morning will provide the focus
for weak showers/storms, though the focus for this jet has shifted a
little south and west in the latest GFS/NAM runs - oriented more
into the far southwestern portions of the CWA. Expanded the 20%
chance more broadly over where the NBM has POPs mainly in central
SD.

As we move through the day Wednesday, despite the 2-5C warming
temperatures at 700mb, a shortwave late will provide upper level
support, in concert with daytime heating, a surge in low level
moisture and a subtle lee low/inverted trough out west for possibly
a few surface based storms. The 25th to 75th percentile range for
NBM CAPE on Wednesday Is between roughly 1200 joules per kilogram to
2400 Jules per kilogram with a mean of around 2000. Profiles show
Shear is essentially unidirectional, however below 6k to 8k feet
there will be a southeasterly component. As the late
evening/overnight progresses, more widespread convection is
expected, thanks to redevelopment of a 40-50kt low level jet. Lots
of convective feedback in deterministic models, so tough to
speculate on convective evolution, however unidirectional flow
with modest shear and dry mid levels would suggest a continuation
of a hail/strong winds threat going into the overnight hours.

For Thursday 700 temperatures increase to +13C. Flow aloft remain
zonal, and weakly diffluent, and there will be an inverted trough
situated across the cwa. Cant rule out an isolated storm. nbm 25th
75th percentiles range in CAPE is between 2500 to 4500 joules per
kilogram. This is in an essentially unidirectional shear regime
above the boundary layer, with light surface winds in the vicinity of
the inverted trough.

Little change in temperature aloft Friday, or for the weekend and
even in the first half of next week. 700 millibar temperatures
remain a standard deviation above climatology. GEFS plums indicating
overall little change In 850 to 700 millibar thickness.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1218 PM CDT Tue Aug 12 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected through Wednesday morning.

&&

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

$$

UPDATE...20
DISCUSSION...07
AVIATION...20