069
FXUS63 KABR 242142
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
342 PM CST Mon Nov 24 2025

.KEY MESSAGES...

- Winter conditions arrive Tuesday, with strong northwesterly winds
and snow for many locations. Below normal temperatures are also
expected through the beginning of December, with below zero wind
chills possible over northern South Dakota.

- Light rain this evening through tonight will change over to snow
Tuesday and continue into Tuesday evening. Probability of 4 inches
of snow is 40 to 80% along and north of a line from Aberdeen to
Ortonville, highest over the Sisseton Hills. Over the northern
portions of the Sisseton Hills, there is a 50 to 60 percent chance
of snow amounts exceeding 6 inches. Drifting and blowing snow will
be possible Tuesday into Tuesday evening over north central to
northeastern South Dakota and west central Minnesota.

- Winds will increase out of the northwest overnight through
Tuesday, with gusts of 30 to 50 mph. The strongest winds will be
over south central South Dakota, where gusts near 60 mph are
forecast. Portions of south central South Dakota will jump to the
very high Grassland Fire Danger Index values Tuesday afternoon.

&&

.SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/...
Issued at 341 PM CST Mon Nov 24 2025

The main concern in the short term will be the rain changing to snow
on Tuesday with accumulating snow over portions of north central
through northeastern SD into west central MN. There is still a quite
a bit of uncertainty on where the heaviest snow could fall
(especially along ND/SD border) due to exact track of the low
between the different models. A track more north would mean less
snowfall over our northern CWA and vice versa. Also it depends on
the changeover time, a faster changeover would lead to higher snow
amounts or if snowfall rates per hour become higher than forecasted
Luckily this is quick moving system. The other concerns will be the
highs winds causing for blowing and drifting snow.

By 00Z Tuesday, the upper level shortwave`s axis extends through the
middle of MT and southward into northwestern WY where it will
continue to track east overnight and deepen. By 12Z Tuesday, the
axis will extend through the central Dakotas with the trough
continuing to track eastward with the CWA on the backside of this
wave by Tuesday evening/Wednesday morning as this wave till continue
to deepen as it continues to track eastward into MN/WI through
Wednesday. GEFS continues to be a bit stronger on this wave compared
to ENS/GEPS at this time. Down at the surface, the center of the
~1006mb low will hover over SD/WY border this evening with GEFS a
bit further west than the other models with its center over
eastern/northeastern WY. Through the overnight this low will track
eastward across the ~southern half of SD with the center of the low
over ~southeastern MN by 12Z Tuesday. The CWA will be to the west of
the low and east of the high with this high moving in over the
region Tuesday evening into Wednesday morning.

With the track of this system, latest CAMs/NBM agree really well on
the overall timing of the precip. They indicate rain moving in over
north central SD late this evening into tonight and spreading
east/southeastward over the CWA with the precip transitioning to
snow through Tuesday as CAA filters in on the backside of this
system. It also looks like we could see a brief dry period, per dry
slot, over portions of central SD Tuesday early morning to late
morning before the backside of the system (snow) pushes through. It
does look like the last of the snow/wrap around will exit our far
eastern CWA between 03-06Z Wednesday (Cams model depending). All the
Cams/NBM do indicate the heaver snow will stay up in ND/MN but still
clipping our far northeastern CWA, being on the southern edge of the
potential heavier snow band. HREF snowfall rate generally a quarter
to half inch per hour along the ND/SD border with the possibility of
up to an inch per hour over the Coteau  There is still quite a bit
of uncertainty between the models on exact snowfall amounts given
the exact track of the low and where the band of higher snowfall
ends up. Generally 2 to 5 inches in snow accumulation is possible
over northern to northeastern SD (along the ND border) with higher
amounts of 6 to potentially 8 inches of snow over the Coteau. Snow
amounts decrease further south in the CWA, closer to the center of
the low. There is about a 3 to 4 degree spread in the NBM 25-75th
due to differences in overall snow amounts between models with the
75th percentile ranging from 4 to 8 inches along the ND/SD border
into MN. If we see a more southward track/heavier snow band and
higher snowfall rates, the higher elevation of the Coteau could
receive up to 8-9 inches (90th percentile aka 10 percent chance). So
to summarize, probability of 4 inches of snow is 40 to 80% along and
north of a line from Aberdeen-Ortonville, with the percentage
increasing further north of this line and highest over the Coteau.
Over the northern portions of the Sisseton Hills, there is a 50
percent chance of snow amounts exceeding 6 inches.

Due to the CAA filtering into the low along with a steep pressure
gradient and pressure rises, winds will increase out of the
northwest with gusts of 30 to potentially 60 mph, highest over south
central SD. EC EFI highlights this well with values of 0.7 to 0.8
over central SD with a shift of tails of zero. Luckily the highest
winds are offset from where the heaviest snow could fall. However,
the combination of falling snow and gusty winds up to 45-50 mph
could lead to drifting and blowing snow (especially over/along the
Sisseton Hills) resulting in visibility reductions over portions of
north central through northeastern SD into west central MN. With
expected snow accumulations and the combination of the potential for
blowing snow, a Winter Weather Advisory has been issued from Corson
County and eastward through west central MN. South of here through
east central SD, a Wind Advisory has been issued with a High Wind
Warning over south central SD where we expect our highest winds to
gusts. Over south central SD, the combination of dry fuels and these
wind gusts potentially reaching 60 mph leads to high to very high
grassland fire danger index.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 341 PM CST Mon Nov 24 2025

The long term period starts Wednesday morning with an upper level
low off to our east over WI/MI. This will continue to move east and
another area of low pressure moves onto the Pacific Coast of
Washington/British Columbia. This will dive south and a trough out
of Canada will move across the area Saturday. This will kick off a
parade of troughs moving out of Canada through the end of the
period. The first lower level low moves across the forecast area
Friday or Saturday (models disagree on exact track and timing - some
move across southwestern SD Friday afternoon, others move across
more central SD on Saturday). Once this moves out, it looks like
high pressure moves in, although the GFS has another low move across
the area Sunday night into Monday.

Due to model uncertainty, snow totals for Friday/Saturday are a bit
uncertain. Right now, it looks like snow totals will be generally
less than an inch with the probability of more than an inch in 24
hours ranging from about 30-40%. This is slightly higher than
previous runs. Once the models decide on a track for the low,
confidence should increase on snow totals and the area for heaviest
snow. At the moment, the GFS deterministic run looks a little more
banded than the other models, and if that solution occurs then snow
totals may be a little higher. Also at the moment, the EC and GFS
deterministic models have the heaviest snowfall mainly over central
SD.

Temperatures during the period are going to be about 10-15 degrees
below normal for this time of year, a big change from the last
several weeks. The air behind the early week low is much colder and
we get several shots of CAA through the weekend. Other than some
residual gustiness (around 30 mph, which could result in some
blowing snow) on the eastern side of the Prairie Coteau Wednesday
morning, winds don`t look to be out of the ordinary.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1135 AM CST Mon Nov 24 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will remain in place for the first half of the TAF
period as a high pressure ridge moves east across the area. Then
focus turns to the winter weather system that will quickly move
east across the area late tonight into Tuesday. Expect an initial
period of rain before turning to snow tomorrow morning. The
heaviest precipitation will be across northern SD and hit the
lowest ceilings/visibilities in that area. With the strong
northwesterly winds behind the low and falling snow, feel that sub
1SM vsbys are possible at KABR and KMBG. The snow will come to an
end from west to east during the afternoon and evening hours on
Tuesday.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory from 3 AM CST /2 AM MST/ to 6 PM CST /5
     PM MST/ Tuesday for SDZ003>005-009-010.

     Winter Weather Advisory from 6 AM Tuesday to midnight CST
     Tuesday night for SDZ006-011.

     Winter Weather Advisory from 6 AM Tuesday to 6 AM CST Wednesday
     for SDZ007-008.

     Wind Advisory from 6 AM CST /5 AM MST/ to 6 PM CST /5 PM MST/
     Tuesday for SDZ015>017-034>037.

     Wind Advisory from 9 AM to 6 PM CST Tuesday for SDZ018-019.

     Wind Advisory from noon to 8 PM CST Tuesday for SDZ020>023.

     High Wind Warning from 6 AM CST /5 AM MST/ to 6 PM CST /5 PM
     MST/ Tuesday for SDZ033-045-048-051.

MN...Winter Weather Advisory from 9 AM Tuesday to 6 AM CST Wednesday
     for MNZ039-046.

&&

$$

SHORT TERM...MMM
LONG TERM...13
AVIATION...SRF