865
FXUS63 KABR 301353 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
853 AM CDT Tue Sep 30 2025

.KEY MESSAGES...

- Abnormally warm temperatures (Highs in the 80s, 10-20 degrees
above normal) will be in place through the rest of the work week.

- Gusty conditions will persist through this week. Southerly wind
  gusts of 25 to 35 mph are expected through Wednesday before
  decreasing to 20 to 25 mph for the rest of the week.

- Pattern change for the weekend, with cooler temperatures and peak
chances for moisture (40-50%) Saturday night into Sunday.

&&

.UPDATE...
Issued at 851 AM CDT Tue Sep 30 2025

Forecast is on track, no major updates expected.

.UPDATE...
Issued at 531 AM CDT Tue Sep 30 2025

Aviation discussion below has been updated in accordance with the
12Z TAF issuance.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/...
Issued at 258 AM CDT Tue Sep 30 2025

More of the same is expected in the short term this morning, with
the main forecast highlights being strong southerly winds,
abnormally warm temperatures, and the potential for light showers.

Beginning with a broad look at the setup, the upper-level ridge will
continue to sit over the forecast area through the short term
forecast period. Heights and mid-level temperatures will be above
the 90th percentile for late September, with highs in the mid-80s.
This setup is also conducive to increased moisture remaining in the
region, with dew points in the upper 50s to low 60s, around the 75th
percentile for late September. This added moisture and the warm air
advection from the southerly flow will limit our cooling overnight,
keeping the overnight lows Wednesday morning up in the low 60s
across the forecast area. Record high low temperatures will be in
danger, particularly at the Pierre, Mobridge, and Watertown climate
sites.

Zooming in a bit on the lower levels, a tight pressure gradient
between the high to the east and a low to the west will continue to
support a low-level jet over the region. Jet strength will be about
30 to 45 miles per hour, and as a result, gusts of 25 to 35 miles
per hour are expected to mix to the surface beginning this afternoon
over central South Dakota. Coverage will expand this evening to the
rest of the CWA, and gusts up to 35 miles per hour are expected
through Wednesday afternoon. By the end of the short term period
Wednesday evening, the near-surface pressure centers (and therefore
the low-level jet) will begin to progress eastward, taking the
stronger surface winds along with them. The abnormally moist airmass
mentioned in the previous paragraph will keep the forecast area
clear of any fire weather headlines.

The other impact from the low-level jet is the chance for showers to
pop up over the forecast area. There are already a couple of showers
south of the CWA at the time of this writing (~07Z), and they will
likely be maintained by the jet over the next couple of hours as
they move into central South Dakota. Chances begin early this
morning over central South Dakota, before chances will increase in
northeastern South Dakota and western Minnesota after sunrise and
into the afternoon. Coverage will once again be scattered in nature,
and dry low-lvels will prevent much of the rain from actually
reaching the surface. Therefore have not included any QPF in the
forecast this morning, although areas may still pick up a trace of
rain should a shower pass overhead.

&&

.LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/...
Issued at 258 AM CDT Tue Sep 30 2025

Initially, Wednesday night, there is a low level jet oriented into
western Minnesota, along with a subtle southwest flow wave that came
out of the Pacific, through northern California and then up through
the intermountain west to get to its expected position. Not a great
trajectory when it comes to low to mid level moisture, with NAM
BUFKIT profiles showing saturation up above 10-12kft, albeit with
some instability. A very small area of NBM POPs of 15% is probably a
little underdone in coverage at this time but reflects high
uncertainty as to whether there will be enough moisture aloft for
anything to reach the surface.

That wave continues on, followed by ridging ahead of the approaching
upper trough. Still looking for the formation of a lee low in
western South Dakota and an inverted trough extending northeast. The
low moves overhead late Saturday/Sunday, with QPF depicted mainly on
the backside of this feature, which rapidly moves northeast with an
ejecting shortwave while troughing develops over the Rockies. This
has expanded the area of higher QPF potential into North Central
South Dakota, along the SD/ND state line east into western
Minnesota. Probabilities for 0.25 inches in 24-hours is still at
roughly 40-50% across the aforementioned area. Were also seeing an
increase in the number of higher (>1") precipitation amounts from
ensembles, however also more spread as some members come in with
zero`s for KABR/KMBG meaning its still a low confidence forecast in
regards to moisture potential.

Still looking at 850mb temperatures almost up to 2 standard
deviations above climo, with a peak intensity Thursday/Friday.
Deterministic NBM is just a few degrees shy of records for both
days, and neither day features a favorable mixing wind component.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 531 AM CDT Tue Sep 30 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are once again expected through the TAF period. The
main aviation concern comes from a low-level jet sitting over the
region. Due to this jet, winds are expected to increase over central
and north central South Dakota this morning, before expanding into
northeastern South Dakota by this afternoon. Gusts upwards of 30+
knots will be possible with this setup, and once these stronger
winds settle in over the surface, they will persist through the
overnight hours. At times, the presence of the jet will also create
low-level wind shear over the area. Some mentions of those have been
put in the TAFs, with the main time frame where impacts are expected
being late tonight into early Tuesday morning.


&&

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

$$

UPDATE...13
SHORT TERM...BC
LONG TERM...07
AVIATION...BC