210
FXUS63 KABR 161520 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1020 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.

&&

.UPDATE...
Issued at 1017 AM CDT Wed Sep 16 2026

Some elevated scattered showers continue to move over south
central SD and portions of north central SD. These showers
should continue to move northeast through the morning into the
afternoon before dissipating. There are a few more showers
that continue to move into south central SD than expected, so
the precipitation chances over that area were increased to
cover these continuing showers.

UPDATE Issued at 631 AM CDT Wed Sep 16 2026

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

&&

.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 upper-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 /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 631 AM CDT Wed Sep 16 2026

Terminals KABR,KATY,KPIR,KMBG

Mid to high level cloudiness will continue to filter in from the
southwest and thicken through the morning hours. CIGs will lower
through the morning into the afternoon but VFR conditions are
expected to prevail. A few showers will possible across central
SD this morning and across northeast SD closer to late morning
and early afternoon. Rain chances remain fairly low(20% or less)
so not confident enough to include mention of anything in the
forecast. Will just have to monitor radar and amend the forecast
if needed. Southeast winds will turn gusty between 20-30 kts
today, especially at KPIR/KMBG terminals.

&&

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

&&

$$

UPDATE...Vipond
DISCUSSION...12
AVIATION...Vipond