450
FXUS63 KABR 121520 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1020 AM CDT Sat Sep 12 2026

.KEY MESSAGES...

- Cooler temperatures take hold this weekend, with highs in the
  60s to low 70s expected. This trend will continue through the
  start of next week, with the possible exception of a brief
  warmup to near-normal on Monday.

- Additional chances for rain showers to perhaps weak
  thunderstorms come Sunday and Monday mornings. Over both days,
  much of the forecast area will see between half-an-inch to an
  inch of rainfall in total.

&&

.UPDATE...
Issued at 1011 AM CDT Sat Sep 12 2026

Satellite indicates increasing clouds moving in west of the Mo
River out of WY/MT per mid level moisture and shortwave energy.
These clouds will continue to spread eastward over the region.
There are still some light returns on radar over northwestern
and portions of north central SD, however, with the surface high
dominant, much if any of this is not hitting the ground and if
so, will only be light sprinkles for the next few hours. High
pressure will remain dominant over the area for the rest of the
day and this evening with dry weather expected. Temps are
currently in the upper 50s to the lower 60s and dewpoints in the
40s. Forecast remains on track with more chances of light rain
overnight over portions of the CWA.

UPDATE Issued at 629 AM CDT Sat Sep 12 2026

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

&&

.DISCUSSION...
Issued at 220 AM CDT Sat Sep 12 2026

There are a few light showers lingering over parts of central South
Dakota early this morning (as of ~06Z). Expectations over the next
few hours are that showers will continue to move into the area, but
will dissipate shortly after moving in. By this afternoon, expect
skies to be clear of rain showers, although cloudy skies may persist
today.

Chances for rain will return on Sunday. A jet streak will develop in
the right entrance region of the departing upper-level trough to the
east, providing the divergence aloft that will help with development
of showers and storms. CAMs highlight two main areas for storm
development early Sunday morning, one over north central and
northeastern South Dakota and the other over central to south
central South Dakota. The latter area shows a bit more organization
and better chances for storms, but severe potential has waned in
that area. Even heavy rain is looking less likely, down to about a
10-30% chance to see a quarter of an inch through Sunday morning.

An upper-level trough to the west will help to develop another low
pressure center and associated frontal boundary set to track across
the region Monday. Along and ahead of this front additional chances
for rain are expected early Monday morning. Latest NBM probabilities
show a bit of an increase from 24 hours ago in the probability to
receive half an inch of rain. Through Monday evening, chances now
sit at about 60-80% of half an inch (and 20-45% for one inch) over
most of the forecast area. Expectations for the highest totals are
along the North Dakota/South Dakota border. Euro and Canadian
ensembles are fairly in line with these same probabilities, but
interestingly the GEFS shows less than a 5% chance for half an inch
of rain across the board. Perhaps the possible explanation for this
seemingly extreme scenario is that the colder near-surface
environment may limit deeper convection with this system. However
with nearly 40 knots of speed shear above the warm layer and the
presence of the front, showers to weak thunderstorms will likely
still be able to form. At this point conditions do not appear
favorable for severe weather from these storms.

After the passage of yesterday`s front, temperatures will take a
drop into the 60s to low 70s over the weekend, about 5-10 degrees
below normal for mid-September. This trend will continue into the
start of next week, with the exception of a brief warmup to near-
normal for central and north central South Dakota on Monday. Longer
range models show sings of a warmup by the end of next week to at
least near-normal temperatures across the forecast area.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 629 AM CDT Sat Sep 12 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast for all terminals with a north
northwest wind component. Isolated high-based
showers/sprinkles/virga are expected across the region during
the TAF valid period. Will make adjustments to TAFs as needed.

&&

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

&&

$$

UPDATE...MMM
DISCUSSION...BC
AVIATION...10