083
FXUS63 KABR 202355
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
655 PM CDT Sun Sep 20 2026

.KEY MESSAGES...

- Light rain moves as far east as parts of the James and Big
  Sioux Valleys tonight. Rain tapers off from north to south on
  Monday. There will be a brief break on Tuesday before rain
  returns Tuesday night and continues off and on through the
  work week.

- Temperatures will remain near to slightly below seasonal
  averages through Tuesday before climbing above normal toward
  the middle of the week.

&&

.UPDATE...
Issued at 655 PM CDT Sun Sep 20 2026

The steady light rain that has fallen over much of central SD
through the daytime hours today is showing signs of weakening.
The latest CAMs indicate that it will have a difficult time
moving as north as previously forecast (fighting the building
ridge over northeastern SD). Light showers will linger over our
far southern counties through much of Monday morning.

&&

.DISCUSSION...
Issued at 1237 PM CDT Sun Sep 20 2026

Easterly sfc flow is almost staving off movement of the rain past
the Missouri River this afternoon. There is a pocket of drier air at
the midlevels that is helping to hold the rain west river even with
ample llm in place. All of that effort will be for nought as the
upper low slowly makes its way east through South Dakota tonight. As
it sinks south and east Monday, the precip will exit with it.

Once again, the NBM is likely too high with its overnight lows given
the cloud cover and rain expected. All hi-res models keep lows in
the low to mid 50s (except in west central MN where some scattering
is possible), but did not blend toward them today in deference to
neighbors and because of the chance for scattered cloud cover in the
northeast. Expect clearing through the afternoon Monday from north
to south as the system exits.

Return flow winds shift back to the southeast and south on Tuesday
ushering in some warmer air. Skies should be mostly clear which will
also help push temperatures above average. That said, models have
shifted the upper level trends a bit for Tuesday moderating the
upper ridge and leaving some remnant shortwave energy around
which could increase clouds, especially along the Coteau.
There`s now also a llj developing Tuesday night so can`t rule
out a shower or two early Wednesday. A 30 kt llj spreads over
the region Wednesday afternoon and increases Wednesday night.
There is some shortwave energy around, though it doesn`t align
perfectly. But, the ample mid level moisture should still allow
for some showers and thunderstorms to develop. A 700 mb low
could help amplify the precip probs through Friday night.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 655 PM CDT Sun Sep 20 2026

Terminals KABR,KATY,KPIR,KMBG

We`re starting out under MVFR to VFR ceilings with the rain
showers currently in between PIR and ATY. Expect MVFR ceilings
to dominate much of the next 24 hours. Light showers will mainly
stay south of ABR, but may impact PIR through 03Z, MBG through
08Z, and ATY from around 04-13Z.

&&

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

&&

$$

UPDATE...06
DISCUSSION...20
AVIATION...06