150
FXUS63 KFSD 162321
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
621 PM CDT Thu Jul 16 2026

.KEY MESSAGES...

- Hottest conditions are most likely Friday and again Sunday
  where heat indices could climb to around 100, especially west
  of I-29. Saturday should see a slight break from the heat as
  winds turn northerly behind a weak front.

- Very patchy morning valley fog is possible daily, but
  widespread dense fog remains unlikely. Fog could reduce
  visibility below two miles at times.

- Smoke from upstream wildfires could affect the area Saturday
  into Sunday but confidence is a bit low on this for now. The
  better chance will likely be near and east of the Buffalo
  Ridge Sunday morning.

- Precipitation is very unlikely (less than 10%) through
  Saturday night. Isolated to scattered shower and storm chances
  return Sunday evening and night, but confidence is low on
  details.

&&

.DISCUSSION...
Issued at 1247 PM CDT Thu Jul 16 2026

Upper level flow goes through a touch of a transition Friday into
early next week. The first will be a glancing blow from some
stronger northwest flow aloft that drops south through northern MN.
This will bring a weak front into the area Friday night into
Saturday. Ahead of this front temperatures should warm quite a bit
with some enhanced mixing as surface winds turn a bit southwest.
This should lead to highs more widespread in the mid and upper 90s.
With dew points expected to be in the 60s, heat indices in the
afternoon could approach 100 degrees.

By Friday night winds will turn more northerly which will allow for
a bit of a break from the heat for many. Highs will likely range
from the mid 80s in southwest MN to the mid 90s closer to the
Missouri River.

As the next wave approaches the Canadian border Sunday, surface
winds will turn southerly and bring hotter temperatures back to the
area. The hottest will be west of I-29 while east of I-29 the return
flow will be slower to set up. The combination of temperatures and
humidity may push heat indices above 100 near and west of highway 81.

Ahead of this wave later Saturday night into Sunday morning some mid
level moisture and weak instability may allow for some ACCAS
showers/very isolated thunder. Will have to watch trends through the
day Sunday as this mid level moisture could linger and bring some
enhanced cumulus and spotty showers throughout the day. Very low
confidence in this right now however.

As this wave moves through ND into MN Sunday night another front
will sag south and may have enough forcing, instability and moisture
to allow isolated to scattered showers and storms to develop, mainly
north of I-90. Confidence remains a bit low, but an isolated severe
storm will be possible.

Monday is a tough call on temperatures and precipitation chances.
Model agreement on surface frontal position not real high and this
will play a decent role in how hot it gets. Monday could be another
day with heat indices above 100, especially south of I-90. Will be a
bit of a wait and see, especially considering how temperatures have
been coming up short of expectations for several days now.

Tuesday into Thursday should see spotty chances for showers and
storms with near to a bit below normal temperatures, generally
highs in the 80s and lows in the upper 50s to mid 60s.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 620 PM CDT Thu Jul 16 2026

VFR conditions are expected to prevail through the period. Skies
will be mostly clear. Southerly winds will become light and variable
overnight. By mid-day Friday a cold front will be draped
roughly from northeast to southwest South Dakota. Behind the
front winds become northerly and lightly breezy.

&&

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

&&

$$

DISCUSSION...08
AVIATION...AJP