062
FXUS63 KABR 161649
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1149 AM CDT Mon Jun 16 2025

.KEY MESSAGES...

- There is a slight risk (2 out of 5) for severe thunderstorms
  along and east of a line that parallels the SD/MN state line
  just east of Brookings to just east of Sisseton. Isolated storms
  along a front could develop in the afternoon in far eastern
  South Dakota and western Minnesota before moving out of the
  forecast area. Hail and strong winds are primary threats.

- A marginal risk area (1 of 5) will cover the next system that
  moves from west river into central/north central and northeast
  South Dakota during the overnight hours. Isolated storms could
  generate hail to 1" and wind to 60 mph.

- Temperatures are forecast to warm to 10 to 20 degrees above
  normal by the end of the week, where there is a 40 to 60 percent
  chance temperatures could climb to or above 100F degrees.

&&

.UPDATE...
Issued at 1113 AM CDT Mon Jun 16 2025

Just a quick update to move the chances for precipitation around
to match the progression of fronts and the upper wave. We had a
boundary clear the CWA early, with the front now around the
Aberdeen area but pushing east fairly quickly. This is the focus
for storms later this afternoon, however with the upper level
support overhead and moving east, with weak mid level ridging in
its wake, the environment is not nearly as favorable compared to
earlier forecasts. Still, CAMS are showing a random storm or two
in the far eastern CWA so the severe weather threat remains,
albeit on a smaller scale with the better environment into
Minnesota. Still looking for the second wave to come in later for
more activity out west moving through overnight tonight to present
a risk as well - but details regarding that activity will wait
till the main AFD issuance. No other changes of note...

&&

.DISCUSSION...
Issued at 351 AM CDT Mon Jun 16 2025

At 3 AM CDT, showers and thunderstorms are moving east and northeast
through the CWA. Some of this convection has been warned at times
for large hail or strong winds (or both). A bowing line segment that
was working into Corson County earlier, has diminished some in
intensity. But, strong to potentially severe thunderstorms are
expected to persist for a few more hours early this morning. At
times, sub-synoptic winds influenced by these early morning
thunderstorms had been gusting in excess of 60mph. Wind speeds have
come down some now, but some areas of central South Dakota are still
gusting up to 45 mph. Temperatures are running generally in the 60s
this morning. Winds are chaotic at this time.

Overall, the steering flow pattern through the end of the upcoming
weekend over the CONUS is dominated by an upper level ridging
pattern (particularly over this CWA). Upper level longwave troffing
develops across the western third of the CONUS late in the period.
It`s a low to moderate amplitude ridge pattern for the most part,
with multiple smaller transient mid-level shortwaves of low pressure
progged to move west to east across the region, the strongest of
these impulses appearing to move through on Tuesday/Tuesday night.
The synoptic-scale pattern through today supports gulf moisture
remaining in place over the region, meaning surface dewpoints, at
least, in the 60s over the CWA and plenty of instability 2500+ J/kg
CAPE at peak heating time through this afternoon.

The SPC Day 1 outlook has the southern and eastern portions of the
CWA in a slight risk for severe weather, with the far southeastern
couple of counties included in an area of enhanced risk. The current
convection will probably generate, for a third consecutive day, an
MCV that will spin across the eastern Dakotas into Minnesota from
mid-morning through late afternoon, creating its own little region
of maximized WAA-forcing and UVV`s for shower/thunderstorm
generation. Depending on the amount of boundary layer recovery that
can be had today, thunderstorms may be able to develop along a
boundary that is forecast to extend down across northeast South
Dakota, and back across south central South Dakota by the end of
peak heating today. Deep layer instability/shear should be
sufficient to support super-cellular convective mode, if any storms
can get going along this boundary later today. Low level conditions
capable of supporting a tornado or two does not look as good for
today as it did yesterday for today. But, progs still support a
marginal tornado risk between 19Z and 23Z out across the far
southeastern forecast zones (between Watertown and Brookings), and
perhaps trailing back into Buffalo and Hand counties through early
this evening. Otherwise, the next discernible mid-level shortwave of
interest over northern Nevada appears to be heading for southern
Idaho/southwestern Montana early this morning, and should time
itself out into the northern high plains region of
southern/southeastern Montana over into northeast Wyoming by late
this evening. Some of this convection may once again spill over
into, mainly, the west river forecast zones of this CWA later
tonight into early Tuesday morning.

This boundary that moves through today should scour out the higher
end low level moisture content, at least, for a couple of days. So,
while the severe thunderstorm potential wanes considerably for
Tuesday through Thursday, there could still be a couple of chances
for rain. More than likely, though, while high pressure at the
surface, and aloft, is over the region, dry condition through the
middle of the week stand a better chance of happening. Return flow
sets up Thursday night and allows for a return of higher amounts of
moisture in the low levels for the weekend, and likely, better
chances for showers/thunderstorms over the weekend.

Low level thermal progs still show a steady diet of warming
conditions underneath this ridge aloft for the second half of the
week into this upcoming weekend. Later in the period, low level
thermal progs and ensemble S.A. table temperature anomalies do
indicate that some fairly toasty temperatures are on the way for the
end of the week, into the weekend. High temperatures should easily
exceed the 90 degree threshold across portions of the CWA Friday and
Saturday. Right now, the probability of temperatures reaching or
exceeding 100F degrees is appx 40-60 percent south of U.S. Highway
212.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1113 AM CDT Mon Jun 16 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for all terminals today. Might be a period in
which we see fog develop early Tuesday for KABR/KATY. Breezy
northwest winds for KPIR/KMBG will eventually become light
northerlies overnight. As for chances for storms, looks like at
worst we could see an isolated storm early afternoon for KATY
before storms move east, but for the most part it should remain
dry for all terminals today. Overnight from west to east we could
see isolated convection. KMBG/KPIR around midnight and KATY/KABR
during the early morning hours Tuesday.

&&

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

$$

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