450
FXUS63 KFSD 261820
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
120 PM CDT Sun Jul 26 2026

.KEY MESSAGES...

- Extreme Heat Warning through 9 PM this evening. Heat index
  values as high as 115 degrees. Heat Advisory parts of
  northeast NE, northwest IA, southwest MN and far southeast SD
  Monday afternoon/evening.

- While details are uncertain and confidence remains low, if
  storms develop in the late this afternoon and evening, some
  may be strong to severe with damaging winds, isolated large
  hail and locally heavy rain possible.

- Next threat for showers and thunderstorms will be on
  Thursday. An isolated storm could be severe.

&&

.DISCUSSION...
Issued at 118 PM CDT Sun Jul 26 2026

The thunderstorm threat is still very low confidence for late this
afternoon into tonight. Quite a bit of cloud cover has lingered into
the early afternoon which is slowing heating. And, as opposed to
yesterday, the mid to upper level wave today is a bit weaker and may
not help to organize activity as efficiently, so will need to find a
way to break the cap. For now these chances look best south of I-90
into northwest IA where the deeper moisture resides. South central
SD shows the weakest cap late afternoon while parts of northeast NE,
far southeast SD and northwest IA see a moderately increasing LLJ
during the evening hours, which could focus some thunderstorm
development.

Winds turn more northerly tonight into Monday which should allow dew
points to settle into the 60s and lower 70s. This will likely keep
heat indices in the 90s and thus heat headlines will not be
necessary. One exception may be across parts of northeast NE and
northwest IA where heat indices should creep above 100 again with
the higher dew points. Will have a heat advisory for these locations.

Monday and Monday night should be quiet as more stable air settles
in. One exception may be later Monday night in central SD as some
upper level support spreads from western SD into that area. Just
some small chances west of the James for now.

Tuesday and Wednesday will be on the northern edge of the upper
level ridging which will keep some westerly flow aloft in place.
This should allow for a couple of weaker waves to move through.
While precipitation is unlikely, some occasional cloud cover and
slightly suppressed temperatures will likely keep the more extreme
heat and humidity at bay, so heat headlines for both of these days
looks unlikely.

A stronger wave moves into the area Thursday and should be the next
better chance for showers and thunderstorms. Should see some
isolated severe storms with this activity.

Temperatures settle back to near normal Friday into next weekend as
northwest flow aloft should bring much more comfortable air into the
region with little chance for showers and thunderstorms.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1213 PM CDT Sun Jul 26 2026

A small band of showers and very isolated thunderstorms across
eastern SD should gradually weaken through mid afternoon.
strong to possibly severe storms may develop late this
afternoon into the evening, but confidence on development is
pretty low. The better chances will be far southeast SD,
northeast NE and northwest IA. Outside of the showers and
thunderstorms, VFR conditions are expected.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Extreme Heat Warning until 9 PM CDT this evening for
     SDZ038>040-050-052>071.
     Heat Advisory from 1 PM to 8 PM CDT Monday for SDZ070-071.
MN...Extreme Heat Warning until 9 PM CDT this evening for MNZ071-
     072-080-081-089-090-097-098.
     Heat Advisory from 1 PM to 8 PM CDT Monday for MNZ081-090.
IA...Extreme Heat Warning until 9 PM CDT this evening for
     IAZ001>003-012>014-020>022-031-032.
     Heat Advisory from 1 PM to 8 PM CDT Monday for IAZ002-003-
     012>014-020>022-031-032.
NE...Extreme Heat Warning until 9 PM CDT this evening for NEZ013-
     014.
     Heat Advisory from 1 PM to 8 PM CDT Monday for NEZ013-014.

&&

$$

DISCUSSION...08
AVIATION...08