197
FXUS63 KFSD 150118
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
818 PM CDT Tue Jul 14 2026

.KEY MESSAGES...

- Heat wave continues through the weekend. Highs in the 90s to
  around 100 degrees expected. Dew points remain a bit below
  seasonal normals, aiding in lower relative humidity. However,
  cumulative nature of the heat could lead to some heat impacts.

- Very patchy morning fog is possible daily, but widespread
  dense fog remains unlikely. Fog will likely be confined to
  river valleys and nearby areas.

- Precipitation very unlikely (less than 10%) through Saturday.
  Sunday into Monday chances rise to 15-20%, but confidence in
  timing is very low.

&&

.UPDATE...
Issued at 816 PM CDT Tue Jul 14 2026

The forecasts remains on track with the quiet and clear conditions
continuing into the evening. Similar to the last few nights, breezy
southerly winds will continue to decrease with the loss of diurnal
heating. With higher dew points and lighter surface winds mainly
across northwestern IA, patchy valley fog could develop causing
temporary reductions in visibility through mid-morning Wednesday.
With this in mind, make sure to slow down on those morning commutes.
Otherwise, expect a continuation of the summer heat with the ridging
firmly overhead. With the higher dew points continuing to be
slightly offset from the warmest temperatures, most areas will
likely fall just short of heat advisory criteria (HI>=100) on
Wednesday. With highs expected to be mainly in the low to upper 90s,
expected heat indices (HI) to mirror these temperatures for most
areas. With all this being said, make sure to stay hydrated!

&&

.DISCUSSION...
Issued at 132 PM CDT Tue Jul 14 2026

Overall trends for above normal temperatures continues for the next
several days. For Wednesday and Thursday did lower highs a couple of
degrees and increase dew points a couple of degrees given latest
trends/bias in the guidance. Basically the GFS is too hot and too
low of dew points and that is getting incorporated into the NBM
guidance and producing a trackable bias. The overall effects will
not be significant as heat risks remain below advisory criteria with
afternoon heat indices in the 90s.

Friday looks like it could be the hottest day of the week as a weak
front settles south and some enhanced mixing becomes possible as
surface winds turn more southwesterly. This should be the day with
the better chance for more widespread highs from the mid 90s to 103
or so.

On Saturday, the NBM might be running too high given latest MOS and
raw output as well as the bias corrected data. All point to lower
temperatures. Still far enough out not highly confident on timing of
this weaker boundary. On thing that could happen is the front could
stall in the area and produce a little moisture pooling at the
surface which would bring higher dew points. Something to watch for.

Still some hints that the upper level ridge will break down just
enough Sunday into Monday to allow for some isolated shower and
thunderstorm potential. This continues to be a lower confidence
scenario, especially in terms of timing.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 605 PM CDT Tue Jul 14 2026

Mainly VFR conditions will continue this TAF period as mostly
clear conditions persist this afternoon. Similar to the last
few night, southerly surface winds will gradually weaken overnight
mainly across northwestern IA leading to a few patchy areas of
valley fog. Decided to keep any mention of fog out of KSUX at
this time since confidence is low in development that far west.
However, we`ll have to keep watching as the night progresses.
Otherwise, expect surface winds to become more southeasterly and
increase by Wednesday with gusts between 15-25 mph expected.

&&

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

&&

$$

UPDATE...05
DISCUSSION...08
AVIATION...05