Pierre, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

840
FXUS63 KABR 120527
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1227 AM CDT Tue Aug 12 2025

.KEY MESSAGES...

- Light showers and weak storms will persist across eastern South
  Dakota for the next hour or two.

- Shower and thunderstorm chances return Wednesday. There is a
  marginal risk, level 1 out of 5, for severe storms for the
  entire forecast area. Unsettled weather will continue for the
  end of the week into the weekend.

- Heat and humidity return for Thursday with heat index values
  approaching 100 degrees in central SD.

&&

.UPDATE...
Issued at 620 PM CDT Mon Aug 11 2025

The strongest storm we`ve had so far this afternoon near Bowdle
was accompanied by 40-45mph winds. Once the storm moved off the
southwest to northeastern oriented boundary it quickly weakened.
We`ll continue to monitor the southeastern half of the forecast
area through the evening for additional pulse type showers and
storms.

&&

.DISCUSSION...
Issued at 253 PM CDT Mon Aug 11 2025

As of 230pm, high clouds are positioned over central SD associated
with the cold front, with cumulus clouds popping up over south
central SD. Smoke continues to drift eastward with the last of it
over portions of northeastern SD into west central MN as current obs
still show a slight reduction in viz with haze reported in the obs.
This will continue to drift away from the CWA this evening per HRRR
smoke model. Temps are ranging in the upper 70s to the upper 80s,
highest over south central SD and dewpoints in the mid to upper 60s.

Troughing pattern continues over the region with more reinforced
energy/shortwave moving in from the northwest this evening. The
better shortwave energy looks to stay mainly in ND/MN through Canada
with not much upper level support over our CWA as we lie a bit south
of this better lift. Its surface trough/cold front will continue to
shift southeastward over the CWA with the James River Valley and
eastward still ahead of the front by 00Z. Along the front will be
the focus for showers and thunderstorms, mainly in the form of
isolated cells to possibly clusters and possibly expanding in
coverage over northeastern SD/western MN as the low level jet
increases to 25-30kts over this area and northward into ND/MN. CAMs
do show storms growing into a more organized line as they push east
mainly over eastern ND/western MN. However, a few of the CAMS (HRW
NSSL/ARW) indicate our far northeastern CWA could be clipped by
stronger storms associated with the forming line with HRRR keeping
convection more clustery along the front in our CWA. With any
convection, atmospheric profiles indicate dry air at the surface to
about ~8-10K with weak/skinny cape above it, and some mid level
saturation. However, a low level inversion looks to stick around
that may inhibit some surface convection as RAP/NAMNest/GFS
soundings show this. The difference is how strong the cap is and if
it will erode with the fropa. The best area for this potential is
over northeastern SD into west central MN where the highest pops lie
(30-40%). If we do get convection, SB/MUCape values of 1000-1500j/kg
are forecasted, highest over this area with DCAPE up to a 1000j/kg
or so. With a lack of stronger instability/shear keeps the overall
several threat marginal. So SPC has this marginal risk, level 1/5,
for severe storms along and northeast of a line from Ellendale to
Sisseton where wind gusts of 60mph and quarter size hail are
possible with this setup. South of here storms should remain below
severe criteria, however, with this inverted V sounding, we could
see a gust of 50-55 mph possible with any stronger storm and small
hail.

High pressure moves in behind the cold front, and departing
shortwave, as the center of the high is forecasted over the WY/SD
border by 12Z Tuesday and shifting east/southeast over the region
through Tuesday evening keeping conditions dry. Ridging aloft moves
in overhead for Wednesday ahead of a stronger shortwave, and forming
a mid level low, that will push across Canada. Being on the northern
edge of a weak low level jet pushing into central SD and weak
shortwave pulses will bring a 15-20% chance of WAA showers and
thunderstorms Wednesday morning. As the LLJ strengthens and warm
front shifts northward per a weak lee surface low low level, low
level heating and moisture will increase along with instability
leading to pops 40-60% Wednesday evening into Thursday morning
mainly east of the Missouri River. With this setup, There is a
marginal risk, level 1/5, for severe thunderstorms over the entire
CWA. As this shortwave moves across Canada through the end of the
week so will its surface low/cold front bringing the chance for
additional showers and thunderstorms Thursday/Friday.

Temps will be cooler for Tuesday with highs behind the fropa with
highs ranging in the mid/upper 70s east of the James River and upper
70s to mid 80s west of here. As this ridge moves in from the west,
WAA will increase with highs back in the 80s to upper 90s, warmest
over central SD. Our warmest day looks to be Thursday with
widespread upper 80s to the upper 90s. With the return of strong
level level moisture per return flow, dewpoints will rise back into
the upper 60s to the lower 70s. The combination of heat and humidity
could lead to heat indices possibly pushing or near 100 in central
SD. Depending on timing of the cold front passage for Friday, highs
will cool back into the lower to mid 80s with temps ahead of the
front still in the lower to mid 90s.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1224 AM CDT Tue Aug 12 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for all terminals. Light showers will impact the
KATY terminal for the next hour or so. Winds primarily from the
west will eventually shift to southerly late in the TAF period.

&&

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

$$

UPDATE...06
DISCUSSION...MMM
AVIATION...07