FXUS63 KFSD 222328
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
628 PM CDT Sat Aug 22 2026

.KEY MESSAGES...

- The next better chance for showers and storms is Sunday night
  (50-70%). Locally heavy rain and isolated severe storms are 
  possible.

- Otherwise most days through next week will see highs in the
  80s and lows in the upper 50s to lower 60s.

&&

.DISCUSSION...
Issued at 142 PM CDT Sat Aug 22 2026

A quiet night is ahead as high pressure drifts east. Southerly flow 
will develop in central SD later tonight and become more 
established across the area through Sunday. The light winds will 
allow temperatures to fall into the lower 50s, especially east of I-
29. 

The upper level wave responsible for the low level winds turning 
southerly will move into central SD tomorrow morning, and eastward 
and southeast from there through the day. With fairly stout low to 
mid level dry air, mainly an increase in cloud cover is expected 
through the morning. The exception will be south central SD where 
enough moisture may allow for 500-1000 J/kg of elevated CAPE, which 
will support some spotty showers and thunderstorms. Severe weather 
is not expected.

Lift will gradually increase through the day into Sunday night, 
when a moderately stronger LLJ focuses on the area. Given fairly 
weak shear and CAPE values generally under 1000 J/kg, severe weather 
looks unlikely. However with a freezing level around 13 kft, locally 
heavy rain will be possible. Not much agreement on the location of 
the heavier rain with the models pretty inconsistently placing the 
mid level wave across the area. Some hints that the LLJ will focus 
somewhere on the SD side, but confidence is low.

This wave moves out of the area on Monday but another weaker wave 
moves by to the north on Monday night and brings a small increase in 
warm air advection, which could spark a few showers and 
thunderstorms.

Mainly northwest flow aloft continues Tuesday into next weekend. This 
will bring periodic small chances for showers and thunderstorms 
throughout the week with little agreement on exactly when. Otherwise 
lows should mainly be from the mid 50s to mid 60s with highs in the 
80s.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 626 PM CDT Sat Aug 22 2026

very patchy fog is possible late tonight into Sunday morning, 
mainly in river valleys and other low-lying areas. Scattered 
showers and isolated thunderstorms will move into south-central 
South Dakota late tonight and drift southeastward through the 
day on Sunday.

Winds will turn light and variable near and east of I-29 heading 
into tonight. Meanwhile, areas west of I-29 will see winds pick up a 
bit out of the east and then southeast heading towards daybreak 
Sunday. Winds will pick up across most of the area through the day 
Sunday out of the south. Winds will get pretty breezy west of the 
James River Sunday afternoon, where gusts of 25-30 kts are expected.

&&

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

&&

$$

DISCUSSION...08
AVIATION...Samet