South Sioux City, Nebraska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

312
FXUS63 KFSD 231048
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
548 AM CDT Mon Jun 23 2025

.KEY MESSAGES...

- Showers and thunderstorms push to the east through the
  morning, with any additional rainfall most likely confined to
  northwestern IA and the lower Missouri River Valley through
  Tuesday. Severe storm chances are low through the period.

- An active pattern will continue through mid week. While some
  uncertainty remains, the better chance for isolated severe
  storms and heavy rainfall will be Tuesday night into
  Wednesday night.

&&

.DISCUSSION...
Issued at 339 AM CDT Mon Jun 23 2025

A broad area of showers and isolated thunderstorms continues roughly
from just east of the Interstate 29 corridor and westward early this
morning - this in association with a cold front pushing across the
region collocated with a series of shortwaves lifting northward on a
southwesterly upper level flow. The frontal boundary is currently
draped from southwestern MN into northeastern NE, and have seen a
few pockets of heavier rain with training cells due to convergence
along the low level jet and a mean flow nearly parallel to the
frontal boundary. This entire area of precipitation is expected to
work eastward and weaken through early to mid morning as the better
upper level forcing drifts to the north and the low level jet veers
to the east. The frontal boundary will completely exit our area some
time by late morning/early afternoon as it pushes into southern IA
and southern NE by the end of the day. While some risk of
showers/isolated thunderstorms will remain over northwest IA during
the day, models would suggest that most of this activity will remain
to the south of our CWA. Any risk of severe storms is low with the
better instability being shunted to our south. It will be a much
more pleasant day in terms of temperatures with cold air advection
behind the aforementioned frontal boundary. Dew points will be
falling through the day (to 40s and 50s for all but far northwestern
IA), and highs will be nearly 20 degrees lower than yesterday - only
in the upper 70s to lower 80s. In addition, winds are expected to be
much lighter than recent days.

For tonight through the day on Tuesday, rain chances will mainly be
confined to areas through the lower Missouri River corridor and
northwest IA as the aforementioned front begins to work back to the
north. Not expecting heavy rain with maybe a couple tenths of an
inch through the period. The better instability remain bottled up to
our south, so the risk of severe storms is low. Temperatures tonight
will be fairly pleasant - mid 50s to lower 60s, with highs on
Tuesday mainly mid to upper 70s under a coolish easterly flow.

For Tuesday night through Wednesday night, rain chances increase
again as the frontal boundary works northward back into our area as
a series of shortwaves traverse the persistent southwesterly upper
level flow. Instability begins to increase a bit through this period
(primarily Wednesday afternoon), though bulk shear looks to remain
on the weaker side. While there may be a low risk of severe storms
during this period, the greater risk may be heavy rainfall. This
will be focused on Tuesday night and Wednesday night - with
increasing moisture flux convergence in the vicinity of the stalled
frontal boundary via an increasing LLJ both nights, this collocated
with PWAT values in the top 1 percent compared to climatology.
Warmer temperatures and humidity look to return on Wednesday with
highs back into the 80s and dew points in the mid 60s to lower 70s.

Rainfall chances look to finally be on a downward trend by the end
of the week (Thursday through Saturday), this as the persistent
upper level jet which has been parked to our west shifts out of the
region and the upper level pattern transitions to a less amplified
flow. Could see a return of shower/thunderstorm chances by the end
of next weekend as an upper level trough drops into the Northern
Plains, though confidence is low. Temperatures for the end of the
week into the weekend will lie on the warmer side of seasonal
averages.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 545 AM CDT Mon Jun 23 2025

Showers and isolated thunderstorms will continue to weaken and
move eastward through mid morning, though shower chances will
remain over parts of northwest IA through the day. MVFR and IFR
stratus associated with the showers will also shift to the
southeast, before lifting in the late morning/afternoon. Shower
and thunderstorm chances will increase again over the lower
Missouri River corridor and northwest IA later tonight, and with
that ceilings will lower into the MVFR range.

Winds will be northwesterly during the day, gusting near 20 kts
into late afternoon. By tonight winds will transition to
northeasterly and become light.

&&

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

&&

$$

DISCUSSION...JM
AVIATION...JM