667
FXUS63 KFSD 290352
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1052 PM CDT Thu Aug 28 2025

.KEY MESSAGES...

- Most areas tonight will stay dry. However there is a low
  chance (<20%) for isolated light showers over central South
  Dakota, and along Highway 14.

- Widespread rain chances and cooler conditions return Friday
  through the upcoming holiday weekend. Severe weather is not
  expected, however some stronger storms may produce lightning.

- Rainfall totals for this weekend vary widely across the
  region. Most areas will see a quarter to an inch of rain.
  Areas of north central South Dakota southeast into
  northwestern Nebraska, southeastern South Dakota, and
  northwestern Iowa may see 2-3 inches with isolated pockets of
  higher totals possible.

&&

.DISCUSSION...
Issued at 233 PM CDT Thu Aug 28 2025

THIS AFTERNOON AND TONIGHT: This afternoon looks to be pleasant and
mostly dry with seasonably warm highs in the upper 70s to mid 80s.
Lows for tonight will be in the upper 50s to low 60s. A region of
enhanced stretching potential as well as increased environmental
vorticity along a weak surface boundary may result in brief funnels
this afternoon. Funnels are most likely along and north of I-90.
Confidence is low due to the very dry subcloud layer and relatively
high LCLs. In addition, vorticity and stretching do not line up
particularly well. Still, it is worth noting and monitoring through
this afternoon and into the evening.

Tonight, a weak surface boundary may be enough to trigger light,
isolated showers over central South Dakota, and along Highway 14.
Bufkit soundings indicate that saturation in the DGZ is possible,
but a dry mid-layer will likely prevent any rain from reaching the
ground. Therefore confidence in shower development is low and kept
mention of PoPs to less than 20%.

FRIDAY THROUGH MONDAY: By Friday morning a mid-level wave and
surface low pressure will be situated over western to central South
Dakota. As it progresses east we will see storms move in from the
west. Severe weather is not expected due to weak mid-level lapse
rates (< 6 deg C), and weak 0-6 bulk shear (< 25 kts). However,
there will be areas of weak instability around 800-1200 J/kg. This
instability may at times combine with the shear and weak impulses in
the upper pattern that results in scattered, brief heavy rainfall,
and possibly weak thunderstorms. Highs for Friday will be cooler, in
the low to mid 70s with lows in the upper 50s to low 60s.

By Saturday morning, the main mid-level wave and surface low
pressure will begin to push into the region. This stronger forcing
will result in increased shower activity Saturday afternoon and
evening. Again, we are not expecting severe weather, but a few weak
thunderstorms are possible. Saturday night into Sunday morning the
upper wave will close off and eastward progression of the system
slows down. The upper and surface lows spin over central South
Dakota through Monday morning before they accelerate southeast out
of the region. Monday evening will see the majority of the shower
activity cease, but the break will be brief. Highs for Saturday and
Sunday will be in the lower to mid 70s with lows in the 50s.

Guidance on rainfall totals from midnight Friday morning until
midnight Tuesday morning vary widely. However, they are in
fairly good agreement on where the highest totals will be. Most
areas will see between a quarter to an inch of rain. A swath of
higher totals looks to fall from roughly north central South
Dakota southeast through northeastern Nebraska, southeastern
South Dakota, and into northwestern Iowa. Here totals could
climb to 2-3 inches with isolated pockets of higher amounts
possible. As this is still uncertain, please keep an eye on the
forecast, especially if you are going to be located in the areas
of potentially higher rainfall.

TUESDAY AND BEYOND: Hot on the heels of the weekend system a strong
upper trough will be digging south into the region Monday night into
Tuesday morning. While the long term models all indicate this
feature, timing and track remain highly varied. Some guidance
indicates a better storm environment for this round, while others
are more conservative. All that to say, keep an eye on the forecast
for next week, especially if you have outdoor plans. Temperatures
recover back into the mid to upper 70s for Tuesday. But following
the cold front Tuesday afternoon temperatures quickly fall into the
low 50s Tuesday night. Highs through Thursday will be in the
60s.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1049 PM CDT Thu Aug 28 2025

Scattered showers moving through western and central South Dakota
will push into our area mainly west of the James River early
Friday morning. Nothing too heavy with this activity and
thunder is unlikely, but enough confidence to add a PROB30 group
for VFR showers at KHON. The combination of ample moisture and
light winds will favor patchy fog development; however, cloud
cover will prevent it from becoming too widespread. Thinking
there may be enough breaks in the cloud cover at KSUX for some
fog, but it`s not expected to be dense at this time. Additional
showers and storms look to develop late Friday afternoon into
Friday night, but there is low confidence for any direct impacts
at the TAF sites due to the expected scattered nature of the
activity. Winds will be mainly light tonight, picking up out of
the southeast around 5-10 kts through the day Friday.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...AJP
AVIATION...Samet