North Sioux City, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

681
FXUS63 KFSD 200902
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
402 AM CDT Fri Jun 20 2025

.KEY MESSAGES...

- A multi-day heat wave begins today and continues into Sunday.
  Central SD will see some relief by Sunday, the rest of the
  area by Sunday night into Monday. Afternoon/evening heat
  indices average 100-110 degrees while nighttime heat indices
  only fall to 70 to 80 degrees.

- Southerly winds will gust to 25 to 40 mph at times Friday
  through Sunday. While fire weather concerns are fairly low,
  isolated locations have struggled to get rainfall the past 3-6
  weeks so some locally dry locations may be susceptible.

- An active pattern looks to set up for much of next week.
  Still a lot of details to work out but the position of the
  upper level jet suggests the potential for multiple chances
  for showers and thunderstorms, especially far southern SD,
  northern NE and northern IA.

&&

.DISCUSSION...
Issued at 358 AM CDT Fri Jun 20 2025

In a west/southwesterly upper level flow, the main story for today
through Sunday continues to be hot temperatures and moderately high
dew points - which will result in very uncomfortable conditions
through the period. Ensembles indicate 700/850 mb temperatures in
the 99th or greater percentile with respect to climatology (25 to 32
C) , and highs today through Sunday will mainly range from the upper
90s to lower 100s each day. Dew points will generally be in the
upper 60s to lower 70s each day (the exception being west of the
James River Valley on Saturday when drier air feeds into the area,
dropping dew points into the 40s/50s for a brief period in the
afternoon - though in response, temperatures will warm even more
over that area). All these factors will result in afternoon heat
indices ranging from 100-110 degrees for today and Saturday, only
dropping to 70 to 80 during the overnight period, and heat headlines
remain in effect across the area. Although Sunday will have similar
conditions to today and Saturday, an upper level and surface trough
will begin to encroach on locations over central SD in the
afternoon. This will result in slightly cooler temperatures (lower
90s), thus yielding lower heat indices over that area.

Our next best chance of showers and thunderstorms will come on
Sunday night and Monday as the aforementioned surface trough/cold
front begins to push across the area. At this time, the stronger
bulk shear looks to lag behind the better instability, though cannot
rule out a few isolated strong to severe storms through this period.
850 mb temperatures drop dramatically behind this boundary, and
highs on Monday will be back into the mid 70s to lower 80s.

Models are in fairly good agreement on unsettled weather continuing
for much of next week. The aforementioned boundary remains close by,
meandering across the region into Thursday of next week. Our area
will remain in a southwesterly upper level flow through the period
as a trough persists over the western CONUS, and the boundary may be
the focus for showers and storms as a series of shortwaves traverse
the southwesterly upper level flow. This could result in periodic
severe weather chances along with heavy rain chances - focused on
Tuesday night into Wednesday as outlined in the WPC ERO. At this
time, ensembles would suggest the higher rainfall totals through the
week will reside over far southern SD, northern NE and northern IA.
Temperatures look to be on the lower side of seasonal averages
through the period, with highs in the 70s to lower 80s, and lows in
the 50s to lower 60s.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1051 PM CDT Thu Jun 19 2025

Scattered showers and thunderstorms will be mostly east of
the TAF sites at the start of the period, mainly into southwest
Minnesota and adjacent parts of northwest Iowa. The biggest forecast
uncertainty at the start of the period will be any potential
new development on the north side of a complex of storms over
east- central Nebraska that could impact KSUX through about 8z.
Opted to leave prevailing VCSH to account for this uncertainty,
but an isolated storm cannot be entirely ruled out in and around
KSUX.

After this activity exits the forecast area very early this morning,
we should remain dry for the rest of the period outside of a very
isolated shower or storm Friday afternoon/evening. Mainly clear
skies will prevail throughout the day on Friday, with some thicker
high clouds possibly sneaking in north of I-90 Friday night
associated with anvil tops from storms well north of the area.

The low-level jet will continue to cause wind shear issues
through daybreak. Otherwise, Friday will be a breezy day with
gusts as high as 25-30 kts out of the south. Winds will not die
down all that much after sunset Friday, and with the low-level
jet kicking up again tomorrow night, it will be quite breezy all
throughout the lower atmosphere.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Extreme Heat Warning from noon today to 9 PM CDT Sunday for
     SDZ061-062-065>071.
     Heat Advisory from noon today to 8 PM CDT Saturday for SDZ038-
     050-052-053-057>059-063-064.
     Heat Advisory from noon today to 6 PM CDT Sunday for SDZ039-
     040-054>056-060.
MN...Extreme Heat Warning from noon today to 9 PM CDT Sunday for
     MNZ071-072-080-081-089-090-097-098.
IA...Extreme Heat Warning from noon today to 9 PM CDT Sunday for
     IAZ001>003-012>014-020>022-031-032.
NE...Extreme Heat Warning from noon today to 9 PM CDT Sunday for
     NEZ013-014.

&&

$$

DISCUSSION...JM
AVIATION...Samet