606
FXUS63 KABR 160740
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
240 AM CDT Wed Sep 16 2026

.KEY MESSAGES...

- Southerly winds this morning and early afternoon will gust up to
40 miles per hour over central and north central South Dakota. These
winds will be enough to create some elevated fire weather concerns
west of the Missouri River today.

- Near-normal temperatures continue today and tomorrow, as highs
will be in the low to mid 70s across much of the forecast area.
Friday and through the weekend, expect slightly cooler temperatures,
with highs generally in the upper 60s to low 70s.

- Heavy rain is expected beginning late Thursday afternoon and
continuing through Friday morning to early afternoon. The highest
accumulations are expected over eastern and central South Dakota.
The probability to see two inches of rain or more reaches 50-80%
over eastern South Dakota and 30-60% over central South Dakota
(decreasing elsewhere as you move north and west). This heavy rain
may lead to flooding.

&&

.DISCUSSION...
Issued at 240 AM CDT Wed Sep 16 2026

A southerly low-level jet will move into the area today, reaching
about 30-40 knots at 850mb as it passes overhead. These winds are
expected to mix to the surface late this morning through the early
afternoon over central and north central South Dakota, so gusts up
to 40 miles per hour will be possible. As the low-level jet
progresses eastward, it is expected to diminish, keeping the wind
threat contained to mainly to counties bordering the Missouri River
today. The low-level jet will also be responsible for developing
some light rain showers to perhaps weak thunderstorms, which will
progress from southwest to northeast across the forecast area this
morning to early afternoon. Expecting little in the way of rainfall
accumulation from these showers, perhaps a few hundredths at best.

Thursday into Friday, a Colorado Low will move up into the Northern
Plains, bringing heavy rain into the Aberdeen forecast area. The
bulk of the heavy rain is expected to fall overnight Thursday into
Friday morning. Over the past 24 hours, precipitation totals have
trended upward, particularly over eastern and central South Dakota.
Through the event, ensemble median values now sit around 2"-3" over
much of eastern South Dakota, up from around 1"-2" 24 hours ago.
Similar increases are noted over central South Dakota, now sitting
around 1"-2" medians. This increase is not necessarily attributed to
a northerly shift to the track of the storms. While there was a very
slight shift northward, the axis of heaviest rainfall still remains
to the south over the Sioux Falls CWA. Other ensembles tend to agree
with these precip totals, and show perhaps additional signal for a
shift further north of the highest rainfall totals. Once again the
GEFS shows significantly lower rainfall totals than other models,
with medians less than an inch across the entire forecast area.
Given that this phenomena was present during the most recent
synoptically forced system and did not verify very well, confidence
in these low end totals out of the GEFS is quite low at this time.
Models spreads still sit at around 1"-2" over most of the area, so
still a bit of variability at the moment.

With these high rainfall totals, it is worth looking at the flooding
potential with this event. A fully saturated profile with PWATs well
above the 90th percentile (widespread PWATs around 1.75" for this
event) prove favorable, as does the deep warm cloud layer of 11-12k
feet. Models are resolving storm motion to be around 10-20 knots,
which while not overly favorable, does provide some additional
support for storms lingering over the same area for an extended
period, especially on the lower end of storm motion speeds. The main
question will therefore be the availability of instability in the
area. Models still don`t resolve much, reaching 500-1000 J/kg of
MUCAPE at best. Still, given the other variables in play, this weak
instability may be enough to realize the flooding threat. As such,
there is a Slight to Marginal Risk for Excessive Rainfall Thursday
night into Friday morning (when the heaviest rainfall totals are
expected) and a Slight to Marginal Risk again over eastern South
Dakota and western Minnesota for Friday morning after sunrise.

Behind the low, an nupper-level trough will progress eastward from
the Pacific Northwest to over the Northern Plains. This will allow
for a cooler airmass to take hold, pushing temperatures back down
below normal over the weekend. Additional rain is likely as the
upper-level low moves in. Beyond this weekend, model guidance shows
some disagreement on how the pattern will evolve, but in general
probabilities favor temperatures returning to near-normal.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1240 AM CDT Wed Sep 16 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue to prevail at all terminals through
the majority of this forecast cycle. A slight chance (~20%) for
showers remains in the forecast for the daytime hours. Timing
of rainfall looks to be during the morning hours across the
KPIR/KMBG areas and during the midday and afternoon hours around
the KABR/KATY terminals. Still not confident enough to mention
precip at any of the four terminals. Gusty southeast winds are
expected during the daytime hours today, especially across
central SD where gusts could range between 25-30 knots.

&&

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

&&

$$

DISCUSSION...BC
AVIATION...Vipond