764
FXUS63 KABR 291135 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
635 AM CDT Fri Aug 29 2025

.KEY MESSAGES...

- Chances for showers to weak thunderstorms increase today (to 50-
  70% over central South Dakota) and will continue through the
  weekend. Severe weather is not expected with this system.

- Precipitation (20-40%) chances on Tuesday, then dry the rest of
  the week.

- Cooler (below normal) temperatures in store by Wednesday and
  Thursday of next week. Highs in the 60s, lows in the 40s.

&&

.UPDATE...
Issued at 627 AM CDT Fri Aug 29 2025

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

&&

.SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/...
Issued at 321 AM CDT Fri Aug 29 2025

Partly cloudy skies over the forecast area this morning with
additional clouds moving in from the west, and a few isolated
showers and weak thunderstorms are lingering. These showers are not
expected to develop further this morning, and other than a stray
lightning strike to two, no hazards are expected.

Chances for showers to weak thunderstorms continue this morning and
increase this afternoon, mainly in central and north central South
Dakota. An upper-level shortwave helps support a weak low over
western Nebraska, and showers will form along a surface trough
extending north from the low into central South Dakota. Weak mid-
level lapse rates keeping surface based CAPE around or below 1000
J/kg will be a main obstacle for storm development, along with
minimal 0-6km shear. Model profiles indicate that wind shear will
not improve above the 6 kilometer mark, so updrafts may run into
problems sustaining themselves for extended periods of time.
Therefore, severe weather is not expected, but these cells could
still potentially produce a strong wind gust or two as they
collapse. This low and associated surface trough will linger into
Saturday, continuing chances for spotty showers through the day.
Environmental conditions will be similar if not less favorable for
thunderstorm development on Saturday, meaning that severe weather is
once again not expected to be a threat.

There is some slight concern for flooding with some areas
potentially seeing a localized 2-3 inches along with the lack of
steering flow aloft allowing for storms to sit over an area for a
few hours and PWATs of 1.3-1.5" around the 90th percentile for
this time of year. However given the nature of the showers and the
lack of a strong updraft, rain rates are not expected to be very
high. Antecedent soil conditions in central to north central South
Dakota are quite dry, and given the potential extended period
over which rain could fall, confidence would be low on any
flooding potential.

The other main consideration in the short term is fog potential both
this morning and Saturday morning. The increased presence of clouds
will prevent some radiational cooling in the morning hours, but for
those areas which can get clear, low temperatures will drop to the
low 60s, close to the dew point values at that time. This is most
likely over northeastern South Dakota and western Minnesota will be
a bit more variable, but chances are still fairly low. Any fog that
does develop is expected to be patchy at best.

&&

.LONG TERM /SATURDAY EVENING THROUGH THURSDAY/...
Issued at 321 AM CDT Fri Aug 29 2025

When the period opens Saturday night, the CWA is stuck under a
rather convoluted upper pattern (split flow with an upper level
closed/cut-off high propagating southward into the southern Canadian
prairie/northern U.S. plains region. All the while, this pesky, slow-
moving upper level low, that is progged to be hanging out over
central/south-central SoDak, is trying to exit the region down into
Nebraska. Lingering PoPs continue Saturday night into Sunday for
this system, although, mostly across the southern/southwestern
forecast zones. Right now, it looks like it`s going to take all the
way into Monday night/Tuesday for northwest flow to shove that
closed/cut-off upper level high off to the east. When it
accomplishes that feat, an eastern CONUS upper level longwave trof
develops and takes up residency, which will render this CWA under
(some decently amplified) northwest flow for the rest of the
forecast period. Models differ on timing/track/strength of energy
moving through this northwest flow pattern on the back side of this
upper level low/longwave trof. There is some confidence, though, in
a north-south moving cold frontal passage on Tuesday, complete with
some potential frontal-forced precipitation chances. Beyond that,
the rest of the extended is currently dry. Various ensemble tools
depict a period of notably cooler than normal conditions, post-
(Tuesday) frontal, for the beginning of September.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 627 AM CDT Fri Aug 29 2025

Terminals KABR,KATY,KPIR,KMBG

Scattered showers have developed this morning over central South
Dakota, with a couple of weak thunderstorms. Based on surface
observations, rain is struggling to make it to the surface in all
but the strongest storms at this point. This will not remain the
case for long, as chances for showers and thunderstorms will
increase through the day today. Generally VFR conditions are
expected, with the heaviest showers to storms bringing ceilings and
visibilities down to MVFR conditions. Of the TAF sites, only KPIR and
KMBG are expected to see these showers, the latter of which have
chances low enough to keep the showers in a PROB30 group for now.
Thunder has also been left out of the KPIR TAF due to the high
uncertainty on if or when any thunderstorms will develop, but
thunderstorms moving over the airport is a distinct possibility.

Another point to note is that some areas of light fog have been
observed this morning over northeastern South Dakota. This fog is
very patchy and extremely localized, but has brought visibility down
to IFR conditions at times. Chances for fog are expected to go away
around sunrise this morning, but may return near the end of the TAF
period early tomorrow morning.

&&

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

$$

UPDATE...10
SHORT TERM...BC
LONG TERM...10
AVIATION...10