577
FXUS63 KABR 212319
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
519 PM CST Fri Nov 21 2025

.KEY MESSAGES...

- High temperatures will be 5 to 15 degrees above normal through
  Monday, in the 40s and 50s. Saturday and Sunday will be the
  warmest days.

- Turning markedly colder starting next Tuesday, as temperatures
  drop into the teens at night and 20s and low 30s during the day.

- There is a 20-45 percent chance of precipitation starting Monday
  morning through Tuesday. The precipitation type will be rain
  Monday, before transitioning to snow during the day Tuesday.

- In addition to any falling snow next Tuesday, there is the
  potential for strong northwest winds in excess of 30 mph with
  gusts in excess of 45 mph to develop Monday night into Tuesday,
  creating the potential for high to very high Grassland Fire
  Danger, despite how cold it is expected to be.

&&

.UPDATE...
Issued at 517 PM CST Fri Nov 21 2025

No significant changes to the forecast expected for this evening.
See update to the aviation discussion below...

&&

.DISCUSSION...
Issued at 132 PM CST Fri Nov 21 2025

At 1 PM CST, skies are mostly sunny and temperatures are warming
through the 40s and 50s. Winds are generally out of the south-
southwest around 5 to 15 mph.

Surface high pressure is being forced out by an approaching surface
trof/warm front that is attached to an area of low pressure up in
Canada. This system is riding over the top of the (northern branch
upper jet influenced) upper level ridge in place across the Pac NW
and western Canada. Eventually, this system`s cold front may be able
to back door its way down into the northern tier counties of South
Dakota Saturday morning. However, by the end of the day Saturday,
this frontal boundary is expected to begin retreating back to the
north and east, as low level WAA re-inserts itself into the low
level thermal advection pattern. As such, generally looking at the
majority of the CWA experiencing warmer than normal temperatures for
most of the short term period.

The long term period is a split flow pattern through Monday night,
as a low amplitude upper level ridge pattern builds out the northern
branch jet-stream over the northwest/north central CONUS. Beyond
that, the jet-stream appears to consolidate as a longwave trof works
across southern Canada and the northern plains, knocking down the
upper ridge from Monday night through Wednesday. At the same time
this international border system is occurring, model camps are
continuing to bring an upper level closed low drifting out of the
desert southwest into the deep south Saturday through Sunday, and
then up into the central plains/western Great Lakes region Monday
and Tuesday. Ensemble PoPs are now showcasing a 25 to 50 percent
chance of WAA-forced (rain) precipitation over this CWA between
these two northern and southern branch systems from mainly Monday
morning through Monday night. Then, Tuesday and Tuesday night,
enough cold air appears to be introduced into the column to support
a phase change over to snow, if any moisture being wrapped west and
south behind the northern branch low pressure system undergoes
enough forcing/lift to wring out some light snow precipitation as
far south as this CWA. Right now, the eastern third of forecast
zones holds a 35-50 percent chance of receiving a tenth of an inch
or more of precipitation between 12Z Monday and 12Z Tuesday. Between
12Z Tuesday and 12Z Wednesday, that probability drops to 25-35
percent. The probability of an inch or more of snowfall is the
highest between 12Z Tuesday and 12Z Wednesday at 25-40 percent. In
the wake of this (mid-week) system next week, the
consolidated/unified upper steering flow pattern appears to persist
through Thursday night. After that, another upper level longwave
trof is progged to sweep down along the western CONUS coast, pulling
the flow pattern apart, splitting it, once more, into a northern and
southern branch jet-stream scenario.

The southern Canada/northern plains upper level trof is expected to
sweep a potent cold front through the CWA somewhere between 00Z
Tuesday and 00Z Wednesday. The change in airmasses with this cold
fropa next week will be quite noticeable. Instead of high
temperatures being in the 40s and 50s, highs will only be in the 20s
and 30s starting next Tuesday. Low temperatures are expected to
transition from 20s and 30s down into the teens (possibly single
digits) above zero.

In addition to the significant temperature drop in 24 hours or less,
model guidance is highlighting the potential for, at least, wind
advisory criteria being met once the winds become northwest and ramp
up, post-frontal, Monday night into Tuesday. The probability of wind
gusts exceeding 45 mph Monday night into Tuesday is at or above 50
percent across pretty much the entire CWA, west of the Prairie
Coteau. Discounting the GFS`s solution, for now, as it is the only
12Z model solution generating blizzard conditions on Tuesday. It is
the only model solution right now with such strong southern branch
and northern branch systems happening next week. The Canadian and
ECMWF model camps of solutions appear to be in better agreement
right now, regarding next Monday through Wednesday, in that they
maintain somewhat weaker/more-transient upper systems and
corresponding surface features during said period. Will continue to
watch model flip-flops/trends over the next few days and see how it
all shakes out in the probabilistic/ensemble perspective. For now,
hazardous weather potential over this CWA appears to be strength of
winds/gusts Monday night into Tuesday, and the potential for high
to very high Grassland Fire Danger, despite how cold it is
expected to be.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 517 PM CST Fri Nov 21 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for all terminals. A south southwest wind will
shift to northwest overnight into early Saturday with a weak
frontal passage.

&&

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

$$

UPDATE...07
DISCUSSION...10
AVIATION...07