576
FXUS63 KABR 050209 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
809 PM CST Wed Dec 4 2024

.KEY MESSAGES...

- Potent cold front will bring strong northwest winds (35-50+ mph
  gusts) and areas of blowing/drifting snow (Glacial Lakes region)
  until sunset. Winds will slowly diminish through the evening.

- Milder temperatures for Friday and the weekend with highs/lows
  forecast to be some 10 to 25 degrees above normal.

&&

.UPDATE...
Issued at 803 PM CST Wed Dec 4 2024

Sustained winds and gusts have come down below advisory criteria
range early this evening, but expect 15 to 25 mph sustained
northwest winds with gusts up to ~35 mph to persist for much of
the overnight generally east of the James River valley. No more
falling snow, so mainly just some occasional ground level drifting
snow on these breezy northwest winds. Further west, where the
nose of surface high pressure is establishing, winds should be
trending toward calm/light and variable by morning. No changes
planned to the low temperature forecast at this time.

UPDATE Issued at 554 PM CST Wed Dec 4 2024

See below for an aviation forecast discussion for the 00Z TAFs.

Also, the Wind Advisory will be allowed to expire on time at the
top of the hour.

&&

.SHORT TERM /THIS EVENING THROUGH THURSDAY NIGHT/...
Issued at 238 PM CST Wed Dec 4 2024

Snow showers continue east of the James Valley this afternoon.
Northwest winds gusting 40 to 50 mph also persist. The winds
combined with the snow showers are resulting in intermittent
visibility reductions to 1 mile or less (higher elevations, near
iced over lakes). Most of these reductions have been short-lived,
generally 20 minutes or less and very spotty. Still, brief travel
snags will continue until sunset when instability diminishes and sfc
high pressure shifts farther southeast into the Dakotas.

Winds will take a bit longer to diminish given the steep lapse rates
and vertical northwest profile with 70 kts at 700mb in place until
6z. Luckily, the strongest winds have not managed to mix down today.
We`ve generally been capping at 850mb 40 to 45 kts.

The cold Canadian 1030s high builds in tonight and Thursday, though
the exiting upper trough will help to moderate the airmass enough to
allow in some waa from the west by afternoon. The high will bring
lighter winds and dry conditions. The exiting upper trough will keep
a wide temp spread over the cwa, from low teens for highs in the
east to upper 20s west river. Overnight lows tonight will range in
the single digits above and below zero. Lows will keep to the single
digits above zero in the east Thursday night.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 238 PM CST Wed Dec 4 2024

Friday morning we are in northwesterly flow aloft with high pressure
at the surface. This high pressure will give way to a trough at the
surface Saturday. A surface low moves in Sunday with a cold front
moving northwest to southeast across the Dakotas. The upper level
low moves in later Sunday into Monday morning. A second surface low
looks to pass right by us to the northeast Monday morning. Tracks
across models are not exactly the same but are fairly similar. Both
the cold front on Sunday and the low Monday are expected to bring
some colder air to the region but we get some strong WAA Wednesday
to bring temperatures back up.

As for precipitation, there aren`t too many chances for snow through
the period. We start with some 15 to 25% chances for rain along the
ND/SD border Sunday morning. Towards evening this will change over
to rain/snow mix becoming just snow by late Sunday night. Monday
morning, 25 to 35% snow chances reach as far south as Clark and
Watertown in eastern SD and to Gettysburg in central SD.
Accumulations are expected to be light, with maybe a few tenths of
an inch in eastern SD, mainly around the Coteau. Otherwise, the long
term is expected to be dry.

As mentioned already, the latter portion of the period is expected
to be cooler, however, we do have some warmer days ahead of that.
Friday, temps west river are expected to be 10 to 15 degrees above
average. Saturday, the whole forecast area is expected to be above
average - 10 to 15 degrees east of the James River, 15 to 20 degrees
between the MO and James Rivers, and 20 to 25 degrees west river. We
will still be above average on Sunday, just slightly cooler with
highs 10 to 15 degrees above east of the MO river, and 15 to 20
degrees above west river. We expect temps to cool down to around
average for Monday through the end of the period. Sunday into Monday
as that cold front comes through we could get some gusts of 35+ mph,
especially west river. Otherwise, winds will be about normal.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 554 PM CST Wed Dec 4 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue except near KATY where there are
ongoing snow showers with blowing snow. MVFR cigs and occasional
IFR/MVFR vsby will occur near KATY for just a little while longer,
ending soon, though, with loss of daytime "heating/mixing". Strong
northwest winds are expected to diminish significantly by 03z.

&&

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

$$

UPDATE...Dorn
SHORT TERM...Wise
LONG TERM...KK
AVIATION...Dorn