581
FXUS63 KABR 171134 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
634 AM CDT Sat May 17 2025

.KEY MESSAGES...

- Conditions suitable enough for frost to form are expected later
  tonight into early Sunday morning. Temperatures at or below the
  freezing mark are also possible, especially in low lying areas.
  Portions of northeast South Dakota and west central Minnesota
  are under A Frost Advisory and Freeze Warning for tonight.

- Another round of rain with weak thunderstorms runs from Sunday
  through Tuesday. Probability of exceeding 2 inches over that
  time period ranges from 30% along the ND/SD state line into
  western MN, with a peak of around 60% from central to east
  central South Dakota. Risk for severe weather is low.

&&

.UPDATE...
Issued at 623 AM CDT Sat May 17 2025

See below for an aviation forecast discussion for the 12Z TAFs.

&&

.SHORT TERM /TODAY THROUGH SUNDAY AFTERNOON/...
Issued at 350 AM CDT Sat May 17 2025

At 3am CDT, skies are cloudy. There are a few sprinkles ongoing out
over the Missouri River valley, otherwise, the CWA appears to be
free of precipitation early this morning. Northwest winds are
generally running 15 to 25 mph with gusts up to 35 mph. Temperatures
over the eastern half of forecast zones are in the mid 30s to around
40 degrees. The western half of forecast zones remain generally in
the low to mid 40s.

Today through Sunday morning, mid/upper level heights rise and an
area of surface high pressure is nosing down across the CWA while
moving west to east across the Dakotas. During the day on Sunday,
the flow pattern aloft begins to take on more of a south-
southwesterly orientation as energy re-loading the western CONUS
upper level trof begins to lift out of the intermountain west and
move out across the central/northern high plains.

As the surface high begins to influence the region, these breezy
northwest winds should eventually become more northeasterly around 5
to 15 mph by the end of the day. Much of the low clouds over the CWA
this morning should dissipate with daytime heating/mixing today, as
well. With high temperatures today expected to range from the upper
40s out over west central Minnesota to the lower 60s out over
portions of central/south central South Dakota, the stage will be
set, under a partly to mostly clear sky-condition, for already below
normal cool temperatures to fall down into the low to mid 30s over
northeast South Dakota and west central Minnesota, with slightly
higher readings for lows in the upper 30s to lower 40s across
central/north central South Dakota. Overnight tonight, winds will
also continue their gradual swing around to more of an east or east-
southeast direction but, for the most part maintaining that 5 to 15
mph speed. When temperatures are between 32F and 36F degrees
overnight tonight, frost is expected across northeast South Dakota
into west central Minnesota. Temperatures are forecast to fall to
32F or lower for a few hours across the James River valley as well.
So, a Frost Advisory has been issued for northeast South Dakota and
west central Minnesota, and embedded within that advisory, where
temperatures are expected to fall to freezing or colder, a Freeze
Warning has been issued (Brown/Spink counties).

Rolling into Sunday morning, mid-level WAA may promote some
mid/upper level cloudiness to begin working into the region from the
south or southwest. But, widespread cloudiness is not expected until
much later in the day. While it`s possible some preliminary WAA-
forced rain showers may be produced mainly west-river by late Sunday
afternoon, the majority of the CWA for most of the day Sunday should
remain precipitation-free, as temperatures gradually warm into the
upper 40s to upper 50s.

&&

.LONG TERM /SUNDAY EVENING THROUGH FRIDAY/...
Issued at 350 AM CDT Sat May 17 2025

Warm advection elevated convection in NAM BUFKIT profiles and CAMS
continue into Sunday night, with a warm conveyor of moisture looping
up into Nebraska ahead of the next wave/low. This continues
advecting northeast through the overnight into Monday, with TROWAL
moisture continuing into Monday night/early Tuesday. NBM 25th/75th
24 hour moisture values range difference is in excess of an inch,
however even the low end range is only as low as a 1/3rd of an inch
(far northeast/western MN) to as much as one inch (central SD).
Probabilities of exceeding an inch in 24 hours is a pretty
widespread 70%, with closer to 30% along the ND/SD state line into
western MN. Probabilities of exceeding 2 inches is centered
around Pierre at between 10 and 30%.

There is some question about how quickly the moisture moves out
Wednesday morning with the GFS indicating high pressure while the
Canadian and EC hold onto some lingering precipitation. That said,
the NBM 25th/75th range for low temperatures Wednesday morning is
between low to mid 30s. Since we will continue to have low POPs,
will forgo any mention of frost just yet, but this could be one of
those cases where temperatures during the day Tuesday fail to warm
(probability of exceeding 50 degrees is only about 50/50)...and
if we clear out in the evening with light winds it could result in
an unexpected frost. Right now the probability of dropping to 36
degrees or lower is still 50/50 with just a 10% probability of
falling to 32 or lower.

Zonal flow/ridging develops aloft for the later half of the weekend,
so we`ll see moderating temperatures back towards normal and lower
chances for moisture.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 623 AM CDT Sat May 17 2025

Terminals KABR,KATY,KPIR,KMBG

KPIR has cleared off/returned to VFR. Based off satellite trends,
MVFR cigs at KMBG should go away by 18Z, with KABR/KATY expected
to loose their MVFR cigs between 18Z and 00Z. During the next 24
hours, northwest winds will swing around to the northeast before
settling into an easterly direction around 5 to 15 knots.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Frost Advisory from 1 AM to 9 AM CDT Sunday for SDZ005-007-008-
     010-011-017-019>023-037.

     Freeze Warning from 1 AM to 9 AM CDT Sunday for SDZ006-018.

MN...Frost Advisory from 1 AM to 9 AM CDT Sunday for MNZ039-046.

&&

$$

UPDATE...10
SHORT TERM...10
LONG TERM...07
AVIATION...10