South Sioux City, Nebraska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

381
FXUS63 KFSD 261128
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
628 AM CDT Tue May 26 2026

.KEY MESSAGES...

- After lingering showers and thunderstorms dissipate this
  morning, additional chances for redevelop will be possible
  this evening mainly east of I-29. While severe weather is not
  expected, an occasionally strong wind gusts up to 50 mph will
  be possible.

- Quiet and warm conditions continue through the middle of the
  week.

- Rain chances increase by Friday and continue periodically
  through the weekend though recent trends have been drier.
  Severe weather risks remain low as temperature gradually cool
  back toward seasonal normals.

&&

.UPDATE...
Issued at 404 AM CDT Tue May 26 2026

Taking a look across the area, we`re continuing to monitor a few
scattered showers with isolated thunderstorms lifting out of
northeastern Nebraska with the previously mentioned shortwave. While
this lingering activity will likely persist over the next few hours,
current thinking is things should gradually weaken with the
nocturnal LLJ as it approaches the I-90 corridor. With that being
said, an occasional strong gust between 40-50 mph will be possible
at times. From here, we`ll probably keep the anvil plume across most
areas to start the day with the potential for some additional
redevelopment across portions of southwestern MN as the weak
shortwave lifts through. Not expecting anything severe with the
limited instability and shear. However, stronger updrafts could
produce some smaller hail and pockets of heavy rainfall if things
can get going.

Otherwise, a warm and marginally breezy day is ahead as highs
approach the upper 80s to mid 90s. Shifting gears to our
precipitation chances, confidence continues to trend lower in this
evening`s activity mainly due to a lack of strong forcing. Similar
to yesterday, the main forcing mechanism is supposed to be the
approaching shortwave. However, with increased subsidence with the
mid to upper-level ridging firmly overhead; most of your better
forcing is being pushed into central and southern MN. While we can`t
completely rule out a few scattered showers with isolated
thunderstorms east of I-29, the severe weather threat looks low but
not zero. Inverted "V" suggests there could be the potential for
stronger winds if a stronger updraft can get going. With this in
mind, portions of far eastern SD and southwestern MN are now
outlined in an SPC Day 1 Marginal with the main focus being on
strong winds.

&&

.DISCUSSION...
Issued at 1246 PM CDT Mon May 25 2026

THIS AFTERNOON/EVENING: Temperatures continue to rise through the
80s this morning, on their way to the 90s in a handful of areas.
Aloft, mid-lvl moisture AOA 600 mb continues to pivot east across
the MO river valley into NW Iowa. Further development can`t be
ruled out, but profiles suggest no more than sprinkles as this
area of clouds move east. Some slight modification of high
temperatures over NW Iowa may be possible due to these clouds.
Dew points have risen into the 60s in portions of the area.

Later this afternoon we`ll begin to watch CU field expected to
develop over central and western Nebraska where increased
surface convergence along a weak boundary may spark a few
thunderstorms. Further northeast, despite the increase in mid-
lvl lapse rates and resultant MLCAPE near 2000-2500 J/KG,
soundings continue to show convective inhibition hanging around
near 750mb into the early evening along the northeastern extent
of this boundary which may extend into southwest Minnesota by
00z. CAMS indicate scattered Nebraska convection may tend to
drift northward into south central South Dakota this evening as
low-lvl lapse rates are steeper and inhibition is less. The
development further northeast into eastern South Dakota and
southwest Minnesota along the boundary is MUCH less certain and
may be isolated if it does form. The consequence of mixing
deeper in south central South Dakota may result in lower hail
potential, but more gusty outflow with high inverted V
soundings as storms move northeast.

The gradual ramp-up in the LLJ after 00Z, but especially near or
after 03Z may result in additional isolated to scattered convection
into the early overnight hours further north towards I-90.
Should the boundary layer be cut-off any parcel lifted off the
850mb surface would still have 2000+ J/KG MUCAPE, however
effective shear may be marginal for any persistent rotating
structures.

The increase in weak dPVA through northern Nebraska into central
SODAK may result in a bit of an uptick in convective risk through
daybreak. While sharply veering by daybreak, the LLJ convergence
favors areas along and east of I-29. MUCAPE lowers through
the night, but there may still be sufficient instability for
isolated hailers into daybreak. The lack of meaningful shear
will keep organized storms to a shorter duration. Hazards this
evening and overnight include ping-pong ball size hail and brief
60+ mph gusts through mid-late evening before boundary layer
stabilization occurs.

TUESDAY: Some elevated convection may linger in SW Minnesota through
mid-morning but rapid dissipation is likely as forcing moves off to
the east. A very warm  is expected Tuesday with temperatures rising
into the upper 80s to 90s. Drier air mixing eastward off the Western
Plains should lower dewpoints slightly, keeping heat index values
near their air temp.

WEDNESDAY-THURSDAY:  An elongated NW to SE oriented mid-lvl ridge
builds from central Canada into the southeastern United States.
We`ll reside under this ridge axis through Thursday which will keep
winds aloft very weak, and temperatures in the middle  80s.

FRIDAY-SUNDAY: The brief Omega block will weaken as we move into
next weekend with a stronger wave rotating southward into the
Central and Eastern Great Lakes by Friday and Saturday.  Meanwhile,
meridional low-lvl return flow will be focused more towards the
western Dakotas and Nebraska, keeping shower and thunderstorm
chances focused over the western CWA into Saturday. Perhaps the best
risk for any rain locally will move in Saturday into Sunday should
the cooler Great Lakes airmass reach this far to the west.  There is
quite a bit of spread in ensemble guidance for next weekend, with
the GEFS/GFS showing considerably more precipitation risks that the
ECMWF/ECE.  The official forecast has lowered PoPs for next weekend
towards the 10-30% range, with minimal shear really prohibiting
any severe risks. NBM mean temperatures still in the lower 80s
may be a touch warm, but do fall right in the middle of a
reasonable 25/75th spread from the mid 70s to the mid 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 620 AM CDT Tue May 26 2026

Mainly VFR conditions are expected today. Taking a look at
radar, scattered showers with isolated thunderstorms continue to
progress through the area this morning promoting occasional
MVFR vsbys with heavy rainfall. While these conditions will
likely persist over the next few hours as things lift to the
north and east, should see things clear out by mid to late
morning. Otherwise, southerly surface winds will become a bit
more breezy with gusts between 20-30 mph expected. Lastly, could
see some additional redevelopment mainly across southwestern MN
by late evening potentially promoting occasional MVFR vsbys with
pockets of moderate to heavy rainfall.

&&

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

&&

$$

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