009
FXUS63 KABR 201751
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1251 PM CDT Tue Oct 20 2026

.KEY MESSAGES...

- Temperatures continue to be about 10 to 20 degrees above normal
through Wednesday, with highs in the upper 60s to mid 70s. By the
end of the week temperatures are forecast to be 15 to 25 degrees
above normal, ranging in the 70s to potentially the lower 80s.

- Dry conditions continue through Thursday with rain chances (30-
50%) returning Friday into Saturday. Percent chance of rainfall
amounts of a tenth of an inch or more is 40 to 60% along and east of
the Sisseton Hills with less than a 50% chance for a quarter of an
inch or more at this time.

- Warm, dry, and breezy conditions lead to elevated fire weather
concerns across central South Dakota Thursday with more widespread
concerns Friday.

&&

.DISCUSSION...
Issued at 1250 PM CDT Tue Oct 20 2026

The region continues to be under a broad upper level ridge, in
southwest flow, as the cutoff closed low continues to spin off the
CA coast. At the surface, the region sits between a high to our east
and frontal boundary to our west. This results in ongoing sfc winds
to 850mb out of the south/southwest continuing to usher in warmer
air resulting in warmer than average temps. The ridge flattens a bit
as a weak shortwave tracks east across Canada with its cold front
tracking east/southeast across the CWA this evening and a secondary
weak low developing along the front over western SD and over SD/NE
by 12Z. By this time the front will be extending from northeastern
SD through northern NE with the CWA behind the fropa by the late
morning. With ongoing drier air over the region, no precip is
expected with the only noticeable feature is winds will be switching
to the north then northeast behind it as high pressure moves in.

Behind the shortwave, the ridge amplifies over the region Wednesday
afternoon and continues over the area through Thursday before
tracking eastward Friday. Our attention then turns our next system
as this cutoff low moves onshore over southern CA with split flow as
a shortwave moves in over western Canada. This low becomes a
negatively tilted open wave and will track northeastward (and
northern wave eastward) and somewhat phase together over the
northern Rockies Friday. This leads to the formation and deepening
of its surface low with models indicating the center of the low over
MT Friday morning. However, there is still a bit of a difference in
exact position and intensity of the low with ENS indicating a
~1004mb low slightly southward of where GEFS has the low with GEFS
indicating a bit stronger around ~1000mb. Through Friday evening,
this low will track eastward then northeastward across ND into
Canada with ENS still a bit more southeast with the track and GEFS
more northwest and stronger. By Saturday morning, ENS actually
accelerates the speed of the low and wave (given weaker setup) as
GEFS is slower/stronger (and now more southwest of ENS) as its
positioned either over southwestern or central Manitoba by 12Z
Thursday where it will continue its track northeast and occluding.
So still ongoing low confidence in exact position, track, and
intensity of the low.

As of now these models show the possibility of showers per warm
front over NESD/ND/MN Friday as the front lifts northward with NBM
pops of 25-40% east of the James River. As its cold front tracks
west to east across the CWA Friday evening through Saturday, precip
is again possible ahead and along the front. NBM and models not
really agreeing of QPF coverage just yet, as mentioned, with
broadbrush pops of 20-35% over central SD. It seems like both NBM
and models indicate the best chances and better forcing will be
Friday afternoon/evening (help from diurnal heating) but all depends
on where the cold front will be. As of now, pops of 20-40% lie east
of the James Valley Saturday morning/midday and eastern SD into MN
by afternoon/evening. However amounts overall still look to be light
with a probability of QPF at or exceeding 0.10" at 15-60% with
the probability increasing further east in the CWA, highest
along and east of the Sisseton Hills per mean grand ensemble
(GEFS/ENS/GEPS) with NBM pretty close to this. At or over a
0.25" is 20-30% from south central through eastern SD grand
ensemble and up to 40% NBM. Don`t be surprised if we get a
couple thunderstorms associated with a strengthening LLJ, WAA,
and CAPE within the warm sector Friday! CSU ML guidance does
indicate a 5% chance of severe over north central and into ND
and portions of southern SD Friday afternoon.

With pressure gradients steepening ahead of the low and the 850mb
LLJ ahead of it strengthening to 20-30kts Thursday and 30-50kts
Friday. Shallow diurnal mixing will lead to gusty surface winds with
gusts of 20-35mph, highest along and west of the Mo River Thursday
afternoon with widespread wind gusts by Friday afternoon 30-45mph.
Probability of wind gusts>45 mph is 30-50% over the southern James
Valley and far south central SD Friday afternoon. With ongoing WAA
continued the trend of blending NBM90th for temps through Thursday.
With Collab kept temps near NBM per low confidence and dealing with
more clouds with the system. This results in highs overall in the
upper 60s and 70s for Wednesday and 70s to potentially 80s degrees
for the end of the week. Probability of temps at 80 or above is 40-
80% Thursday afternoon and 40-90% over central SD highest confidence
across south central SD. EC EFI values of 0.8 to 0.99 with a shift
of tails of zero is highlighted for Friday meaning a significant
amount of EC members have shifted away from the reforecast
climatology meaning higher confidence on this occurring. NDFD
records does indicate we could be flirting with record min max temps
Friday and Saturday morning. With gusts winds and warmer temps this
leads to elevated fire danger concerns with GFDI index in the High
Category along and west river Thursday afternoon and widespread
across most the region Friday afternoon.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 610 AM CDT Tue Oct 20 2026

Terminals KABR,KATY,KPIR,KMBG

VFR cigs continue through the TAF period. Winds will remain out
of south/southeast through this evening. A weak cold front will
track west to east across the region late tonight through
Saturday morning. No precipitation expected with winds behind
the fropa shifting north to northeast across the region.

&&

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

&&

$$

DISCUSSION...MMM
AVIATION...MMM