Sioux City, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

349
FXUS63 KFSD 050152
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
852 PM CDT Sat Jul 4 2026

.KEY MESSAGES...

- Isolated showers and thunderstorms remain possible into
  tonight mainly east of I-29. Very isolated severe weather
  threat diminishes through 10 pm.

- Pockets of fog will be possible overnight. Locally dense
  patches could lead to visibility as low as 1 mile or less at
  times.

- Near to above normal temperatures will continue into the new
  week with highs mainly in the 80s to mid 90s.

&&

.UPDATE...
Issued at 844 PM CDT Sat Jul 4 2026

Isolated showers and storms continue to develop mainly
over southwest Minnesota along the many outflow boundaries that have
been around the region. With sufficient elevated instability to
around 1,500 J/kg expected to continue into tonight and a weak
upper wave moving across the area, we will see isolated showers
and storms possible through about 2-4 am mainly east of I-29.
The better chances (20-30%) will be overall drifting south to
southeast with time. The next hour or so we could see a very
isolated 50-60 mph wind gust or instance of nickel to quarter
sized hail with these storms, but as storms turn elevated
overnight this wind threat will diminish and large hail will
become unlikely given weak shear and weakening low level lapse
rates through the night. Otherwise, some fog looks to develop
especially in areas that have seen rain today, and there is
about a 20-30% chance of it being locally dense. Any fog should
lift by 7-9 am. No major changes to the forecast for Sunday,
still looks like it`ll be a warm and dry day as ridging aloft
builds into the area.

&&

.DISCUSSION...
Issued at 238 PM CDT Sat Jul 4 2026

CURRENTS & TONIGHT: Taking a look across the area, the focus
continues to be across portions of northwestern IA as a lifting
outflow boundary continues to spur pockets of convection across
portions of northwestern IA. While this developing activity
continues to stay mostly sub-severe, the enhanced stretching
potential and weak flow aloft has led to multiple funnels being
reported mainly near Greenville and Sioux Rapids, IA in Clay County.
With this developing activity potentially continuing over the next
few hours have decided to issue a special weather statement (SPS)
for most of northwestern IA, portions of southwestern MN, and
portions of southeastern SD through 5 PM.

Otherwise, we`re still on track for a few additional isolated to
scattered thunderstorms with an approaching wave this evening. Given
the modest CAPE and low shear set up, there is still a decent shot
for a few stronger storms with up to half dollar sized hail and
damaging winds up to 60 mph being the main threats. While there is
still some uncertainty as to how things will evolve, most short-
range guidance has now settled in on areas east of I-29 and along
the Missouri River Valley as the two areas for potential development
through the late evening so make sure to have multiple ways to
receive warning information! Lastly, can`t rule out some additional
chances for patchy fog tonight with the higher dew points. Similar
to this morning, locally dense patches could lead to visibilities of
1 mile or less at times through mid-morning before dissipating.

SUNDAY-TUESDAY: Looking into Sunday, quieter conditions will
temporarily return as ridging begins to build across the Desert
Southwest. With weaker flow aloft and increasing warm air advection
(WAA), should continue to see temperatures trend above normal
through Tuesday with highs mainly in the 80s to 90s each day.
Looking aloft, our next precipitation chances could arrive as early
as Monday night into Tuesday as an approaching shortwave intersects
a stalled surface boundary roughly draped from the Black Hills to
northeastern SD. While there is still some uncertainty as to how far
east this boundary sets up, there should be just enough lift with
the wave to trigger a few scattered showers and thunderstorms during
the afternoon to evening hours with the potential for a few stronger
storms. Given another modest CAPE/low shear environment, any
developing activity will be quite pulsy. However, current thoughts
are an isolated severe risk will be possible mainly along and south
U.S. Highway-14 heading into the afternoon and evening hours.
Otherwise, additional chances for showers and thunderstorms will
return from Tuesday into into Wednesday as another shortwave and an
a cold front progress through the area. However, some uncertainty
remain so make sure to monitor your local forecast as the details
are subject to change.

WEDNESDAY-FRIDAY: Heading into the extended period, the previously
mentioned ridging begins to flatten giving way to quasi-zonal flow
by Wednesday. With the wave train expected to resume aloft, we could
see near daily chances for precipitation through Friday. While the
severity of these storms is still uncertain, confidence is not high
enough to deviate from the NBM at this time. Otherwise, we`ll
continue to see near to above normal temperatures through Friday
with highs mainly in the 80s to low 90s.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 637 PM CDT Sat Jul 4 2026

Isolated showers and thunderstorms will continue to be possible
through the evening, though low confidence on which areas get
hit with a storm. Enough signs in and around KFSD that one or
two thunderstorms will develop near the area, so added a PROB30
group there through 05.04Z this evening to account for this.
Storms in northern South Dakota are moving southward, but look
to miss KHON to the west or weaken before arriving, but trends
will be monitored.

Patchy fog may develop late tonight/early tomorrow morning, with
guidance favoring areas east of I-29 for the best potential. Not
enough confidence in fog development at the TAF sites, so will leave
out mention at this time. Otherwise, VFR conditions will take us
into the daytime Sunday. Light and variable winds are expected
through most of the period, with east-southeasterly winds increasing
slightly to end the period mainly near and west of the James
River.

&&

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

&&

$$

UPDATE...Samet
DISCUSSION...05
AVIATION...Samet