465
FXUS63 KABR 120858
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
258 AM CST Fri Dec 12 2025

.KEY MESSAGES...

- A system will bring a band of snow tonight through Saturday
morning with accumulations of 2 to 4 inches, mainly along and south
of a line from Mobridge to Miller. A Winter Weather Advisory is in
effect for this area 9pm tonight through 9am CST Saturday.

-Cold air will remain in place through Sunday. The coldest
temperatures will be Sunday morning, with lows of -5 to -20. Wind
chills of -20 to -35 are forecast Sunday morning.

&&

.SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/...
Issued at 254 AM CST Fri Dec 12 2025

As of 230am, mainly overcast skies are present with light snow
showers clipping far northeastern SD associated with a cold front
attached to its low over Manitoba. Over the next few hours we will
continue with chances (20-35%) of snow before the fropa exits the
region. Otherwise flurries could be possible over south central SD
early this morning ahead of the incoming system. We have already
seen our highs today, which around 2am ranged in the upper teens to
the upper 20s, warmest over south central SD. For today a high will
be positioned to our northwest in Canada with an area of low
pressure and a northwest to southeast oriented frontal boundary
positioned over the Northern Rockies. Between these systems, and
help from another shortwave moving in from the northwest, a band of
accumulating snow will set up northwest to southeast from northern
MT, through SD, and into northeastern NE today through Saturday. For
our CWA, CAMs overall agree on light snow moving in west of the
Missouri River this morning through the midday with the band of snow
expanding southward and eastward during the overnight/early morning
hours and exiting our far southern and southeastern CWA by late
Saturday morning. CAMs also indicate that between ~09Z-12Z there
could possibly be a very narrow, more moderate transient band of
snow (0.50-0.75" per hour/HREF), within this larger band of snow
setting up over south central SD. The highest pops of 80-100% will
lie along and west/southwest of a line from Mobridge to Miller
between 00-12Z Saturday with the 90-100% pops from southeastern
Dewey through Sully/Hughes and into Buffalo counties where the
CAMs show this potential for a moderate band of snow setting up as
mentioned.

The good news with this system is that the ptype will be all snow
this time around as the entire saturated column will sit below zero
C. NAM soundings at KPIR/KMBG both indicate that this saturated
column, and its vertical motion, pretty much sits within the DGZ
zone this evening through Saturday morning (when we have the highest
pops), therefore, leading to higher snow ratios (better dendritic
formation of snowflakes). NBM snow ratios range from 16:1 to 21:1
which fits right in the ballpark with this system. Model consensus
between the global and short term ensembles along with NBM/WPC all
indicate QPF values ranging from 0.1 to ~0.25" for this band of
precip along and south/southwest of a line from McIntosh to Miller
with snow amounts for this area ranging from 2-4", with isolated
areas of 5", highest over south central SD. Probability of 6" is 25%
or less for portions of south central SD per NBM and 5% WPC. There
is a 1/10 chance of snowfall amounts of 5-7" if we see a heavier
band setup than forecasted. Also, any shift north or south in the
track of the system will lead to a shift in where the higher
snowfall amounts occur. A Winter Weather Advisory has been issued
for all of south central SD and portions of north central SD from
03Z-15Z Saturday. Blowing snow should not be an issue during this
time as winds overall remain less than 20kts for the advisory area.

With cold arctic air plunging southeastward today, temps will
continue to drop with temps by 18Z only ranging in the single digits
above zero to the lower teens. 925mb temps overnight range from -16
to -25C. This along with snowpack I went below guidance with lows
ranging in the single digits below zero to the single digits above
zero. WInd chills will range in the teens and twenties below zero.
Highs for Saturday are only expected around zero to the single digits
above zero.

&&

.LONG TERM /SATURDAY EVENING THROUGH THURSDAY/...
Issued at 254 AM CST Fri Dec 12 2025

Opening at the end of the day Saturday, we have a 1040mb high
pressure system more or less overhead, with the core of coldest
850mb temperatures across northern Minnesota. These temperatures
represent a standard deviation below climo for mid-December. It also
puts the CWA under ideal radiational conditions.  High temperature
Saturday is right around zero, so while the NBM is down to 10 to 20
below for a low, the 25th/75th range adds an additional 5 to 10
degrees of wiggle room on the lows. Given the setup, especially for
Aberdeen, 20 below seems warmly optimistic. NBM does bring in some
cloud cover, however looking at the GFS/NAM BUFKIT there is little
moisture in the profile. Farther west, for the Missouri valley,
return flow after midnight may aid in just enough mixing to arrest
temperature falls, though this area will have ample fresh snow
cover.

Return flow (southerly) for the day Sunday means slight warming but
with a very cold start, and a intensifying gradient, wind chills
will not improve rapidly during the morning so thinking is any
headline will have to reflect this. BUFKIT profiles show the
development of a rather extreme inversion just off the surface,
though with a due south wind, limiting mixing. Will need to monitor
the Sisseton hills downslope area for enhancement as well.

A ridge aloft upstream helps buckle the jet northwards early next
week bringing an end to the northwest flow regime. This allows for a
modified Pacific airmass to migrate into the region Monday with much
warmer air aloft. 850mb temperatures increase to a standard
deviation or two above climo. Monday we are under a weak surface
high, with light winds which limits mixing thanks to our snow cover.
NBM 25th/75th spread is greatest across the far northeast and
western Minnesota with the lower bounds in the mid 20s and upper
bounds in the mid 30s. Looks like deterministically, the forecast
for much of our area falls closer to the 25th percentile.

A low in central Canada increases low level westerlies across the
Dakotas, and with the better mixing profile, more confident in an
actual warmup Tuesday. There may be a period in the morning with
some Sisseton hills downslope potential but snow cover out there got
heavily modified and uncertain if anything recent has fallen and is
thus blowable after our last mid-week thaw. Regardless, overall
doesn`t appear to be a prolonged event as winds shift to westerly.

As is typical with this flow pattern for the middle-end of next
week, overall not a lot of confidence in regards to timing and
strength of waves/systems, but overall trends are for weaker systems
in comparison to the recent pattern and thus just some low chances
for moisture.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1132 PM CST Thu Dec 11 2025

Terminals KABR,KATY,KPIR,KMBG

MVFR CIGs with pockets of IFR CIGs will continue to affect the
region through much of the TAF period. Although, there are
indications of improvements to VFR later Friday afternoon.
Northwest surface winds will increase overnight and gust between
20 and 30 knots with the arrival of an arctic air mass. With the
arrival of colder air comes pockets of -SN overnight and have
included PROB30 mention for MVFR VSBY. Otherwise, next round of
snowfall will arrive Friday evening for KPIR.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory from 9 PM CST /8 PM MST/ this evening to
     9 AM CST /8 AM MST/ Saturday for SDZ003-015-033>037-045-048-
     051.

MN...None.
&&

$$

SHORT TERM...MMM
LONG TERM...07
AVIATION...TMT