925
FXUS63 KABR 220651
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
151 AM CDT Tue Sep 22 2026

.KEY MESSAGES...

- Spotty rain showers (30-55%) return this evening through Wednesday
morning across central South Dakota. Additional rain (60-90%) is
expected Wednesday morning through Thursday morning. Chance of
rainfall of a quarter inch or more is 40-80%, highest east of the
James River through western MN.

- Occasional rain chances continue for the end of the week with the
best chances (40-65%) occurring Friday through Saturday morning.

- Temperatures will remain near to slightly below seasonal average
today before climbing above normal Wednesday through the week.

&&

.DISCUSSION...
Issued at 141 AM CDT Tue Sep 22 2026

The mid level circulation that brought rain and clouds to the area
yesterday, its center is currently circling over northeastern IA and
MN/WI border with the large surface high pressure system stretched
from the Great Lakes through through Ontario. Ongoing moisture,
being pulled in per east/southeast flow at the lower levels,
continues to spread north and westward from IA/MN and will continue
through the morning. Drizzle/low viz/patchy fog has been reported at
KATY occasionally through the overnight. This is backed up by your
classic drizzle setup on Rap sounding. Therefore, added in this
mention over far southeastern CWA through 12Z as CAMs do not show
really enough deep saturation for rain. Besides the clouds expanding
northwestward, RAP indicates the possibility of drizzle
expanding as well through the James Valley. ABR sounding
indicating this setup through the late morning before drier air
moves in west to east. Not enough confidence in expanding this
mention beyond the southeastern CWA yet but will watch through
the morning and add in if needed. There is also mid level
moisture/clouds over western SD from a very positive titled
shortwave that has developed along the eastern side of a ridge
that extends over the Rockies. As the low continues to track
southeastward, the shortwave aloft deepens a bit and elongates
northwest to southeast from northwestern SD through northeastern
NE. It will slowly track northeast across SD through the
afternoon and evening as the ridge tracks eastward. This setup
and moisture will bring the return of clouds over central SD as
the eastern half of SD will already be dealing with clouds from
behind the low. However, with this drier air moving in models
show a period of clearing skies west to east to the James River
this afternoon and evening before clouds move back in James
River overnight/Wednesday morning per shortwave.

Any precip chances from this shortwave looks to stay west and
southwest of the CWA per CAMS until it starts shifting east with
pops (15-30%) potentially clipping far south central SD late this
afternoon. CAMs differ a bit on exact placement whether the bulk of
the precip will clip this area (NAMnest/RAP) or stay more
south/southwest(HRRR), so lower confidence on this and stuck with
the NBM. An increasing llj (25-35kts) develops over central SD this
evening through Wed AM (as it tracks/expands eastward) and really
pumps in moisture per return flow. This WAA flow and shortwave
energy will bring additional chances (30-55%) of showers across
central SD to about the James Valley through Wednesday morning.
CAMs keep the potential more spotty in nature and differences
in overall coverage. Through the midday Wednesday the weak ridge
will be over the CWA with the last of the exiting shortwave
over eastern SD/MN.

Our next more organized shortwave (that originated over southern
CA/Pacific tracking northeast) will be negative tilted over WY/MT
12Z Wednesday with southwesterly flow out ahead of it over the
region (and ongoing return/southwesterly flow at low levels). It
will continue to track northeast across the Dakotas and eastern
ND/MN/Canada by early Thursday. With moisture, per southerly to
southwesterly flow aiding in dewpoints rising into the upper
50s/60s, and a surface trough, this will interact with energy
aloft will bring the return of showers and potentially weak
thunderstorms. Models indicate first across north central SD
Wednesday morning with precip expanding east and northeast
across the CWA. High confidence in this occurring with NBM pops
of 60-95%, highest James Valley and eastward by Wednesday
evening through Thursday morning. Less likely to see moisture
from PIR and southwestward per storm track. Precip will end west
to east across the CWA through late Thursday morning. PWAT
values are forecast between 1-1.25", which is about 3 standard
deviations above climo per NAEFS. However, nothing anomalous for
QPF expected per EC EFI as of yet. ENS/GEFS (and their AI
models) agree on deterministic values between 0.1-0.4" highest
over NESD into ND/MN. Probability of 24 rainfall>0.25", ending
12Z Thursday is 40 to 80%, highest along the ND/SD across
central SD and through northeastern SD/MN (especially along and
east of I29). Prob of a half inch is 20-55% for this location
again highest over far NESD/MN. Otherwise, behind this wave dry
weather is forecast Thursday afternoon through Thursday evening.
Ongoing southeast to southwest flow at low levels and
additional shortwaves will bring additional chances of rain
through early next week with this continuing overall -PNA setup.

With the increased pressure gradient Tuesday and setup of the LLJ,
winds will increase Tuesday afternoon with gusts of 25-35kts mainly
along and west of the Mo River with these gusts spreading eastward
with the jet across the CWA through Wednesday afternoon. Overall
gusts will be between 20-35kts highest over central SD. Prob of
advisory level winds are very low per NBM. Otherwise, winds
diminishing through Thursday morning behind the system before
increasing again across west of the Mo River Friday.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1234 AM CDT Tue Sep 22 2026

Terminals KABR,KATY,KPIR,KMBG

Increasing low low level moisture is evident on satellite
imagery early this morning with a shroud of stratus draped
across eastern SD and western MN. East to southeast low level
flow is advecting this layer of low clouds back toward the west
and northwest into the James Valley. IFR cigs have already set
in at KATY where there has been intermittent light drizzle
during the late evening. Would anticipate this could become more
of a trend through the pre-dawn hours at this terminal. MVFR
cigs will eventually set in at KABR within the next 3-6 hours.
Until then, they may experience some light fog. KPIR may also
see some fog through the early morning until MVFR/IFR cigs set
in there through the early morning. KMBG is currently seeing a
VFR cloud deck around the terminal but they will also get into
MVFR/IFR cigs closer to 12Z. The low stratus will eventually
scatter out closer to late morning and midday but MVFR cigs will
remain possible through the afternoon. KATY may actually see
more of an improvement back to VFR this afternoon as some drier
air tries to work back into the area.

&&

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

&&

$$

DISCUSSION...MMM
AVIATION...Vipond