942
FXUS63 KABR 291721 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1221 PM CDT Thu Oct 29 2026

.KEY MESSAGES...

- Small chances (20-40%) for light rain Friday night into Saturday,
with amounts generally less than 0.25".

- Better chances (60-90%) for more widespread/heavier rainfall
Sunday night through Tuesday as low pressure moves into the Plains.
Low confidence on the track of this system and rainfall amounts at
this time. As of now, rainfall amounts of or exceeding a half inch
is 45 to 75%, highest from south central through northeastern SD.

&&

.UPDATE...
Issued at 1220 PM CDT Thu Oct 29 2026

Aviation discussion below has been updated in accordance with
the 18Z TAF issuance.

UPDATE Issued at 942 AM CDT Thu Oct 29 2026

Patchy fog this morning has begun to burn off, but minor
visibility reductions will remain possible for the next hour or
so with any lingering patches of fog. Made some near-term
changes to the PoP forecast this morning to better capture
ongoing trends in some light showers over central South Dakota.
A layer of dry air in place may make it difficult for rain to
reach the surface, and any that does will likely be in the form
of sprinkles. These light showers are expected to track
northeast across the region the rest of this morning through
afternoon, maintaining their current strength and outputting
little to no rainfall accumulation.

UPDATE Issued at 626 AM CDT Thu Oct 29 2026

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

&&

.DISCUSSION...
Issued at 102 AM CDT Thu Oct 29 2026

As of 1am, not a cloud in the sky over the region which is leading
to a good amount of radiational cooling with current temps in the
lower 30s to the lower 40s (coldest over north central SD) and winds
calm to light out of the west and northwest. This flow is also
helping to keep fog from forming, however, starting to see some
patchy fog forming over portions of southeastern SD. ConsShort still
tries to indicate slight viz reductions occurring over portions
of northeastern SD through the morning but as mentioned this
should be very patchy at most and not as thick as yesterday
morning.

Mostly dry conditions and near normal temperatures are expected
today through the day Friday as the region is within a broad ridging
pattern and a 1023mb surface high pressure over the area. However,
within this zonal to slight southwest flow, weak spotty shortwave
activity tracks northeast/east within the ridge as CAMs indicate
there could be just enough 700mb lift/moisture to produce spotty
showers that would track across the CWA early this morning
through the afternoon. NBM shows the potential for this but
keeps pops about 10-20%. ECAM of course shows a bit higher pops
ranging from 20-40% while REFS also keeps chances low. This is
likely due to the dry air at ~800mb to the surface which will
make it hard for any rain to reach the surface. So if it does,
then mostly likely sprinkles or it will stay as virga. Not
enough confidence to use the ECAM (or even a blend at this
point) and stuck with the NBM. This may need to be adjusted if
in fact we do see precip. Otherwise, this ridge amplifies Friday
(and tilts negatively from west central Canada and
southwestward) as this high pressure exits the region to the
east/northeast. Additional high pressure (and stronger) develops
(and merges with the previous one) that extends from south
central Canada and southeastward through WI/MN. This will track
southeastward through Friday, which will clip the northern and
northeastern CWA.

Our next chance of precipitation will be Friday afternoon into
Saturday as a large closed mid level low is forecast to hover just
off the Pacific Northwest coast and really just spinning in place
through Saturday. This results in a negatively tilted shortwave
developing on the PVA side of it as it will track north and
northeastward from NM/TX into the central plains. In combination
with a surface warm front also lifting northward, rain showers will
track north/northeast and entering south central SD ~late Friday
afternoon with the light rain expanding across the CWA before
exiting the northeastern CWA late Saturday morning/midday. This
looks to be a weak system therefore NBM pops range from 20-50%,
highest over south central through east central SD with pops
diminishing further north you in the CWA. Probability of QPF of
0.10" or more is 20 to 40% east of the Missouri River with the
highest pops over east central SD.

As this large wave moves onshore Sunday and tracks east over the
Intermountain west, a Colorado low (with an inverted trough
extending northward through the Northern Rockies) develops late
Sunday/early Monday and will track eastward/northeast (becoming
quite elongated) through early next week. As of now ENS is further
northwest with the position of the low than GEFS by 06Z Monday with
GEFS being more southerly with the track than ENS along with GEFS
indicating a few millibars stronger with the low. So high confidence
on this setup but low confidence on exact track/strength which leads
to low confidence on QPF amounts and where the highest amounts will
be at this time. Latest NBM has widespread 60-90% pops moving in
early Monday with the rain tracking eastward with pops diminishing
west to east across the CWA ~Tuesday night or early Wednesday (model
depending). As of now the bulk of the rain (and highest pops) looks
to fall Monday morning through Tuesday morning. Probability of a
half inch of rain 12Z Monday-12Z Tuesday is 30-50% (lowest north
central SD) per grand ensemble mean (ENS/GEFS/GEPS) with ENS being
the most aggressive on this QPF chance while GEFS is less aggressive
(give more of a southerly track for now). NBM is 40-75%. Again low
confidence in exact totals but all models indicate the bulk of the
precip will be from south central through NESD/MN. This system will
have moisture to work with as higher PWAT values of 0.75 to 1" will
expand northward on the warm side of the low with values running 3
to 4 standard deviation above climo per NAEFS. It is also
interesting to note that EC EFI is already highlighting values
of 0.6 to 0.8 for QPF with a shift of tails of 1 for Monday. So
still kind of on the low side meaning most members are near the
reforecast climatology and the "boom" potential is low for now.
However, this is several days out. As mentioned, Ptype is
expected to remain as rain as surface to 850mb are forecast to
stay above freezing. Otherwise high pressure moves in behind it.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1220 PM CDT Thu Oct 29 2026

Terminals KABR,KATY,KPIR,KMBG

This afternoon, main aviation concern is some light showers making
their way across north central and into northeastern South Dakota.
Under the strongest showers, a brief reduction to MVFR visibilities
may be possible, and have included a TEMPO group at KABR to
highlight this potential. Otherwise, VFR conditions are expected
through this afternoon and evening, with the only other potential
concern being wind gusts of 20 to 30 knots over central and north
central South Dakota this afternoon.

Overnight tonight, chances for fog will return. The main area of
concern will be over  parts of north central South Dakota. While fog
is expected to be patchy, visibility may drop to MVFR or IFR status
at times. A TEMPO ground in the KMBG TAF has been introduced at this
time to cover the potential for reductions, but confidence is still
somewhat low. The other potential area of concern for fog
development will be on the eastern side of the Sisseton Hills, where
upslope flow will assist in fog formation. This fog is not
anticipated to impact any TAF sites at this time.

&&

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

&&

$$

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