004
FXUS63 KFSD 240509
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1209 AM CDT Fri Jul 24 2026

.KEY MESSAGES...

- Light to moderate showers will progress through areas along
  and south of I-90 as early as this afternoon. Accumulations of
  a 0.50" to 1.00" of an inch will be possible near and just
  north of the Missouri River Valley.

- Below normal temperatures expected through Friday, then summer
  heat returns over the weekend with multiple days of highs in
  the 90s to possibly low 100s ahead. Heat-related headlines
  may be needed.

&&

.UPDATE...
Issued at 849 PM CDT Thu Jul 23 2026

Only minor changes to PoPs and QPF this forecast cycle. Currently a
mid-level wave is progressing to the southeast through the region.
This is creating light to moderate showers. Severe weather is not
anticipated but a few strikes of lightning are still possible. The
majority of the activity will be south of I-90 along the Missouri
River Valley. However, a few isolated light showers are possible a
county or two north of I-90. Shower activity will continue to move
southeast through the evening and overnight. A few lingering showers
are possible in northwest Iowa Friday morning before they clear the
region entirely. Total rainfall of a couple hundredths to a half an
inch are expected with the highest amounts along the Missouri River.
Isolated pockets of up to an inch are also possible. Low stratus
will keep overnight lows on the warm side, in the upper 50s to low
60s. Some patchy fog is possible early Friday morning along water
ways and low areas. Fog and stratus should improve through Friday
morning, becoming partly to mostly sunny by the afternoon. Enjoy one
last day of cooler highs in the upper 70s to 80s.

Saturday another strong high pressure ridge settles over the central
CONUS. South to southwest winds will usher in warm and moist air.
Highs are expected to climb into the mid 90s to low 100s with the
hottest temperatures over central South Dakota. Sunday will be
similar if not worse with highs again in the mid 90s to low 100s.
Heat index values will be dangerously high, near 100 to 105 with
locally higher values possible over central South Dakota. Heat
headlines may be necessary, but will hold off this cycle for
further refinement of the worst conditions. Please ensure your
outdoor plans take into account the very hot weather.

&&

.DISCUSSION...
Issued at 148 PM CDT Thu Jul 23 2026

An upper level wave and saturation aloft will move through the area
later this afternoon through tonight. While some very weak
instability is expected aloft, thunder is very unlikely. Saturation
aloft is most prominent between I-90 and the Missouri River and with
the dry layer in the low levels not excessively dry, some quarter to
possibly half inch rainfall amounts are possible over about a 6 hour
period.

Friday should generally be dry and mild, maybe a few showers in
northwest IA during the morning. Highs remain below normal, but will
be a bit higher with most locations climbing into the 80s, coolest
in northwest IA.

Hot conditions return for the weekend into early next week. The
latest bias corrected data is running about 5 degrees cooler
than the model output for Saturday through Monday. Will have to
keep an eye on trends as the heat approaches as last weeks warm
up the NBM overdid the heat almost every day. This time around
there will be a better potential for southwest winds at the
surface which generally aids in heating out, so maybe the 3-6
degree warm bias that was seen with the past warm up will be a
little less. Long story short, the bias corrected output falls
just short of a heat advisory both Saturday and Sunday while the
NBM is basically in heat advisory both days.

Convective chances are pretty small through Monday. A slightly
stronger wave will drop south on Sunday and bring a small threat for
severe storms. The better chance should be north and east of the
area. This will be the main time frame to track over the
upcoming days.

Tuesday through Thursday should see upper level ridging just west of
the area with stronger northwest flow aloft just northeast of the
area. This leaves the area in position for above normal
temperatures, but possibly not on the excessive side as weak waves
will at times allow slightly cooler air to move in. With these weak
waves will come periodic chance for showers and thunderstorms but
for now confidence in this activity is low.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1208 AM CDT Fri Jul 24 2026

Scattered light to moderate rain showers continue to move
southeast through the overnight. Severe weather is not
anticipated but a few strikes of lightning are possible, as well
as brief heavy downpours. The majority of the activity will be
south of I-90. A few lingering showers over northwest Iowa are
possible into mid-Friday morning.

The stratus deck is expected to gradually lower over the next few
hours resulting in widespread MVFR with occasional IFR
possible. Some patchy fog is also possible along water ways and
low areas. Stratus slowly begins to rise as clouds erode through
the morning and afternoon.

Winds will be southerly and increase through the morning. Gusts of
15-25 kts are expected with the highest gusts along the Buffalo
Ridge area in southwest Minnesota. Winds decrease in the evening
through the end of the period.

&&

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

&&

$$

UPDATE...AJP
DISCUSSION...08
AVIATION...AJP