296
FXUS63 KFSD 081124
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
624 AM CDT Sat Aug 8 2026

.KEY MESSAGES...

- Patchy fog will continue through mid-morning mainly across
  our waterways and low lying areas.

- Scattered showers with isolated thunderstorms will be possible
  by Sunday morning mainly north of I-90. If any stronger storms
  were to develop, large hail up to quarter size will be the
  main hazard.

- A somewhat unsettled weather pattern with low predictability
  will continue to bring daily risks for thunderstorms into next
  week. A few of these may be strong to severe.

&&

.UPDATE...
Issued at 418 AM CDT Sat Aug 8 2026

Taking a look across the areas, much quieter conditions persists as
a surface high progresses through the area. Similar to the past few
days, some patchy fog has developed this morning mainly in response
to the lighter winds and smaller dew point depression. However, its
more confined to our water ways and lower lying areas this time.
While visibility could approach a mile or less in some areas, not
expecting any developing fog to persist much past mid-morning. From
here, increased subsidence from the surface high will keep things
mostly quiet for the day as highs peak in the low 80s to low 90s.
Otherwise, as the surface high pushes to the southeast during the
second half of the day; could additional chances for showers and
thunderstorms develop by Sunday morning mainly north of I-90. While
short-range guidance continues to keep the strongest activity just
to our north and northeast. Can`t completely rule out a weakening
thunderstorm or two making it into portions of southwestern MN. If
this happens, marginally large hail up to quarter size would be the
primary threat.

&&

.DISCUSSION...
Issued at 105 PM CDT Fri Aug 7 2026

THIS AFTERNOON: Convection earlier this morning continues to move
east and away from the area early this afternoon.  A cool front also
continues to push southeast, already well into NW Iowa.  Behind this
boundary, periods of very low stratus with drizzle have been
reported. As stronger dry air advection moves southeast, we should
continue to see stratus erode. Temperatures with all the cloud
cover have been stuck in the upper 60s to lower 70s, with a
small areas ahead of the front in the lower 80s. As long as
clouds clear by mid-afternoon, there should be enough time for
highs to still reach the upper 70s to lower 80s.

TONIGHT: High level wildfire smoke will continue to leave a milky
sky overhead.  However we`ve seen little impact on overnight lows
with this smoke, so with the continued dry air advection southward
this afternoon and evening, we are likely to see low temperatures in
the lower 50s by Saturday morning. One area to watch after midnight
will be in central Nebraska into central South Dakota, as guidance
continues to hint as a subtle wave entering the Dakotas.  This wave
should induce a stronger LLJ which in return may produce enough
focused convergence for a few stronger thunderstorms. The general
track of any strong activity should be south southeast along the
elevated instability axis into east central Nebraska. Nevertheless,
if a storm could develop near Gregory County, 1.5" hail would be the
main risk.

SATURDAY:  Forecast confidence remains lower for Saturday regarding
precipitation chances.  Guidance is quite split on where the axis of
stronger low-lvl jet convergence will drift through the day.   Most
of this uncertainty is due to poor model resolution of any weak
vorticity passing through the 700:500 layer. Some models keep the
best lift bottled up south of the Missouri River with an MCS moving
towards western Iowa.  Others have a wave further north, pushing the
LLJ towards I-29 by mid-day and leaving a few lingering showers and
clouds overhead into the afternoon.  What fairly certain is that
MUCAPE will struggle to lift northeast, keeping any very isolated
severe weather risk focused along or south of the MO river into mid-
day.  By the late afternoon and evening, the instability pool does
drift northward, however soundings also show a fairly stout capping
layer overhead that should inhibit convection given weak and
transient lift.  One note: If we do end up with at least a thick mid-
lvl cloud field over the heart of the CWA by mid-day, then high
temperatures could be significantly impacted and convection risks
lower even further. Rain chances may continue Saturday night, though
focus moreso over Iowa and western Minnesota as the LLJ redevelops
and interactions with a developing elevated frontal boundary.
Confidence is very low with these precipitation risks.

SUNDAY: Any nocturnal convection Saturday night could play a role in
redevelopment on Sunday. Again though, the myriad of potential small
shortwaves moving through the NW flow is problematic with model
guidance which shows a wide range of solutions.  Some guidance shows
a mostly dry day and night with subsidence and high pressure moving
through.  Others maintain a surface and elevated frontal boundary in
the area, with increasing lift late in the day and some isolated
strong to severe storms.   Given the spread in models, low
probabilities spread through the evening and early overnight models
continues to be the best way to suggest the potential at this stage.

MONDAY-THURSDAY: There will really be no change in the forecast into
the middle of the week as the region remains under slight
northwesterly flow aloft.  This flow will keep a persistent risk for
daily convection, though with extremely low confidence and
predictability until a day or so before. There continues to be
some focus for lift around the Monday night/Tuesday and again
Wednesday night and Thursday timeframe where an MCS could form.
Temperatures may fall back slightly into the lower to middle 80s
near the seasonal normals, with potential for a larger cooldown
by next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 616 AM CDT Sat Aug 8 2026

Mainly VFR conditions will continue with occasional IFR to LIFR
vsbys mainly due to patchy fog. While these conditions should
persist over the next few hours, should see most of the fog
erode by mid-morning with the return of peak heating. Otherwise,
VFR conditions will return for the rest of the day. Lastly,
southerly surface winds will become a bit breezy with gusts
between 15-25 mph expected at times.

&&

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

&&

$$

UPDATE...05
DISCUSSION...Dux
AVIATION...05