699
FXUS63 KABR 101134 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
534 AM CST Fri Jan 10 2025

.KEY MESSAGES...

- A system affecting the region late Friday night through Saturday
night looks to bring snowfall to the area, with forecast
accumulations generally less than an inch. Rain and snow mix will be
possible over central SD.

- An arctic blast (short-lived) returns Monday, with highs back down
into the single digits for northeast SD and west central MN.

&&

.SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/...
Issued at 407 AM CST Fri Jan 10 2025

Sfc high pressure briefly settles over the area today bringing drier
conditions. However, a few flurries are expected this morning east
of the James Valley in cold air advection and some lingering
shortwave activity in the departing upper trough.

The main concern this period revolves around a developing low
pressure system set to affect the Dakotas tonight through Saturday.
Through mid day Saturday this forecast area is in the warm sector of
the low with most of the activity remaining in North Dakota. By
Saturday afternoon as the sfc low progresses into northeast SD, wrap
around moisture in cold air advection filters into northern and
central SD. There could be some enhancement from additional forcing
in a shortwave trough, as well. Generally, moisture availability
will be the limiting factor along with placement of the low. In the
warm sector, temperatures will be warm enough to support a mix of
rain and snow...mainly across central SD. Greater uncertainty
surrounds potential snow accumulations in the Sisseton Hills and
west central MN. 25th to 90th percentiles indicate less than an inch
of snow for everywhere but the far northeastern cwa where amounts
range from 1 to 3 inches through the course of the event.

Neither thermal packing nor the pressure gradient is particularly
impressive, so while northwest winds will increase on Saturday
behind the low they are expected to gust only in the 25 to 35 mph
range across central SD.

&&

.LONG TERM /SATURDAY EVENING THROUGH THURSDAY/...
Issued at 407 AM CST Fri Jan 10 2025

A northwest flow regime will continue to dominate the extended,
with a broad trough across the central/eastern CONUS, with several
waves pinwheeling around the backside. Each will provide a brief
injection of milder air into the region followed by a surge of
Arctic air.

We begin the extended Saturday night with the Dakotas/Minnesota
having just seen the passage of another clipper, and thus in the
throws of the next surge in Arctic air. NAM BUFKIT profiles during
the cold advection period Saturday night into Sunday feature steep
adiabatic lapse rates in the lower levels thanks to strong cold
advection, however these fall short of the dendritic growth zone
initially. Through the late morning, we get more thoroughly saturated,
with profiles within the dendritic growth zone, and steep low level
laps rates with maybe a few j/kg CAPE for convective snow showers.
And there is a secondary shortwave in the mid level waves being
resolved in the GFS/NAM to assist with ascent. As such, have
expanded POPs slightly above NBM. As with most clipper/Arctic
airmass snowfalls, going with a broadbrushed POPs/QPF approach as
finer details are too low confidence to resolve just yet, and any
ensemble probabilities will just be a smear, which is why NBM
probability of an inch of snow is between 0% and 22% and 2 inches is
negligible. These aren`t unachievable numbers mind you, given high
snow ratios. As for wind speeds, mixed winds in BUFKIT are only
about 25kts. This isn`t far off from NBM at this time. Cold
advection and stratus/light snow Sunday means we will also be faced
with non-diurnal temperature trends. Additionally, with this fact in
mind, the 25th/75th percentile also has a range of right around 10
degrees for highs Sunday... so not very confidence with respect to
actual highs either.

Temperatures bottom out Monday/Tuesday with 850mb temperatures a
standard deviation below  climo as a 1036mb high moves overhead.
Return flow follows, though the timing and its degree is in question
with the 25th/75th percentiles for highs Tuesday ranging from 8 to
24 degrees in Aberdeen with the other locations across the CWA
likewise seeing a 12-16 degree spread. Thereafter, we`ll see a brief
warm period with 850mb temperatures upwards of +4 to +7C, or just
shy of a standard deviation above climo.

Another clipper follows for late in the long term (Friday/Saturday)
with

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 531 AM CST Fri Jan 10 2025

Terminals KABR,KATY,KPIR,KMBG

MVFR stratus continues to spread over the region this morning. It
is expected to move into KMBG in the next hour or two, but KABR
and KATY are well covered by the shallow layer. Model guidance is
not handling this stratus well at all so the forecast leans
heavily on satellite trends in the short term.

&&

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

$$

SHORT TERM...Wise
LONG TERM...Connelly
AVIATION...Wise