395
FXUS63 KABR 171751 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1151 AM CST Wed Dec 17 2025

.KEY MESSAGES...

- Wind advisory this afternoon/evening across the Sisseton hills
  and including the Sisseton hills downslope favored areas. Gusts
  as high as 55 mph with locally higher in the downslope region.

- Mild today. Temperatures 15 to 25 degrees above average.

- Strong winds redevelop overnight, with a peak surge of 50 to 65
  mph associated with an Arctic blast. The front may also support
  a band or two of snowfall and low visibility. The timing of
  these snow squalls may impact the morning commute. Rapidly
  falling temperatures could also cause any rainfall still on the
  roads to flash freeze.

- Over northeast South Dakota and west central Minnesota, strong
  northwest winds with gusts in excess of 55 mph and wrap around
  snow may also cause periods of low visibility through the day
  Thursday. Snow accumulations limited to around 1 to 2 inches up
  across the Sisseton hills.

&&

.UPDATE...
Issued at 1140 AM CST Wed Dec 17 2025

Aviation discussion updated below for the 18Z TAFs.

UPDATE Issued at 1022 AM CST Wed Dec 17 2025

Will be watching increasing south-southwest winds across the
region throughout the day, especially in the Glacial Lakes
Sisseton Hills/downslope area where a Wind Advisory remains in
effect. Still expecting mild temps across the region today, with
highs in the 40s and 50s for most areas. Did delay onset of PoPs
this afternoon into the James River valley. Otherwise, still
anticipating more impactful weather overnight into Thursday with
the arrival of a strong cold front and gusty northwest winds
perhaps over 60 mph.

&&

.SHORT TERM /TODAY THROUGH THURSDAY AFTERNOON/...
Issued at 422 AM CST Wed Dec 17 2025

Mild today, more akin to Monday`s warmth with southerly winds and
warming profiles and a strong inversion. Winds aloft are stronger in
comparison however, with 65+kts in the NAM critical layer for the
Sisseton hills downslope areas, though the only caveat is its under
unidirectional flow aloft. Otherwise its highly possible that gusts
in the Peever/Sisseton corridor top out around 70 mph. The rest of
the Sisseton hills is showing up in CAMS so some fraction of these
high winds off the surface translating down supports continuation of
the wind advisory.

Still seeing a dual nature to the frontal system, with the core of
warmest air at 850/925mb through about 00Z, with a shift to
northwesterly winds between 0-6Z. This initial boundary doesn`t
effectively mix winds according to BUFKIT profiles, and we see in
ARW/FV3 a quick bump in winds to around advisory level as they shift
to northwesterly. The HRRR is a bit stronger and would have us into
warning criteria behind the initial boundary. Its still the Arctic
front that presents with the strongest cold advection and best
mixing with BUFKIT still showing 40 to 60kts of potential mix down.
The main pressure bubble still tops out around 14 to 20mb per 6
hours and a central pressure about 984mb over northeast North Dakota
giving us a gradient 20-24mb across the state.

Precipitation initially with the system is rain thanks to the milder
airmasses leading up to the Arctic frontal passage. Profiles
rapidly cool to snow in the post frontal airmass. Still seeing some
CAPE, though the issue is the GFS has just a handful of j/kg while
the NAM is up to 90j/kg  and the RAP is up to 250j/kg. NAM profiles
continue to support about a 3kts thick convective layer well into
the dendritic growth zone and thus the risk for snow squalls with
the initial boundary.

And with recent rainfall, the rapid fall in temperatures presents a
flash freeze threat to travel for the morning commute.

And lastly we have to deal with the TROWAL/wrap around moisture. Low
moisture in the dendritic growth zone and weak ascent means light
snow but overall model QPF is limited with most occurring across the
Sisseton hills. NBM probabilities of measuring (0.01") is only
around 25% at its greatest between 12am and 6am Thursday, and then up
to 70% across the Sisseton hills 6am to noon, meaning confidence for
seeing measurable snowfall outside the Sisseton hills is pretty low
and thus, will maintain the high wind warning and Winter storm
watch. This assessment doesn`t include moisture from the mesoscale
snow squalls as ensembles are likely too low a resolution and would
be statistically washed out by the number of members.

&&

.LONG TERM /THURSDAY EVENING THROUGH TUESDAY/...
Issued at 422 AM CST Wed Dec 17 2025

By Thursday evening, the upper level wave that brought the winds and
wintry weather will be to our east with northwest flow over the
region as a slight positive tilted ridge moves in over the area
overnight into early Friday morning. A large positive tilted trough
will sit over the Gulf of Alaska for the end of the week, pumping
weak embedded shortwaves along the northern Conus/Canadian border as
winds turn zonal over much of the western third of the CONUS through
Saturday. By Sunday we get into more of a broad ridging pattern
through at least the middle of next week in this -PNA setup with a
large/broad trough hanging out over the Pacific. Obviously the
further out in the forecast the Cluster ensembles diverge on exact
placement and intensity of these synoptic features.

With this embedded shortwave Friday, its low pressure system is
forecast to move in over Alberta by 12Z, with its surface trough
extending southward through the lee of the Rockies/western Dakotas.
With the high exiting to our east and this incoming low, pressure
gradients will steepened up with a probability of wind gusts>30mph
ranging from 40-70% over the Leola Hills and east of the James
River, with the highest percent over the Coteau. Prob of 40 mph is
25% over the Coteau. Global ensembles seem to keep any precipitation
to our north, obviously, a more southern track of the low would lead
to the possibility of precip skirting along the ND/SD border. EC
meteograms hint at a 20-35% chance of precip with a 10% chance or
less of freezing rain/wintry mix while GEFS is less excited (5% or
less of freezing precip) for portions of north central and
northeastern SD. So we will have to keep an eye on that. There is
however a slight chance (15%) of precip over the Coteau Friday
evening in the form of freezing drizzle to snow. EC meteograms at
Waubay do highlight this potential, although very low at 5% or less
with NAM soundings trying to show this if low levels can saturate.
NBM shows this potential ptype too so left it in the grids. The cold
front will pass over the region Friday evening as the low tracks
eastward. A low over WY may bring a slight chance of snow over the
northern half of the CWA early Saturday morning per GEPS/ENS with
GEFS staying dry. NBM indicates pops of latest pops of 20-30.
Otherwise overall dry weather Sunday through the middle of next week.

With the exception of cooler air moving in behind the cold front
Saturday, temperatures Friday through early next week will range
between average to above average for this time of year.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1140 AM CST Wed Dec 17 2025

Terminals KABR,KATY,KPIR,KMBG

Strong/gusty southerly winds becoming west to northwest by tonight
into Thursday morning. Gusts over 50 knots are possible overnight
into early Thursday morning. Low-level wind shear (LLWS) will
also be a concern through the TAF period as well. An area of -RA
is forecast to move east across the area this evening, with
limited impacts other than perhaps MVFR VSBY. Areas of -SN/-SHSN
will also develop late tonight into Thursday morning, with periods
of reduced VSBY into MVFR/IFR, more so across northern/northeast
SD.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Watch from late tonight through Thursday afternoon
     for SDZ007-008-011-019.

     High Wind Warning from 4 AM to 6 PM CST Thursday for SDZ020>023.

     High Wind Warning from midnight CST /11 PM MST/ tonight to 3 PM
     CST /2 PM MST/ Thursday for SDZ003>005-009-010-015>017.

     High Wind Warning from 3 AM CST /2 AM MST/ to 3 PM CST /2 PM
     MST/ Thursday for SDZ006-018-033>037-045-048-051.

     Wind Advisory until 9 PM CST this evening for SDZ007-008-011-
     019>023.

MN...Winter Storm Watch from late tonight through Thursday afternoon
     for MNZ039.

     High Wind Warning from 4 AM to 6 PM CST Thursday for MNZ046.

&&

$$

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