664
FXUS63 KFSD 161920
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
220 PM CDT Thu Oct 16 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms most likely west of
  highway 81 this afternoon into the evening. Severe weather is
  not expected.

- Strong wave moves through on Saturday but moisture is
  limited. Scattered showers, possibly some thunder, and windy
  behind the cold front in the afternoon and evening.

- Cool and dry Saturday night into Sunday with near normal
  temperatures. Small threat for frost on Sunday morning.

- Above normal temperatures Monday before another cool front
  drops temperatures back to near or a bit below normal the
  remainder of the week.

&&

.DISCUSSION...
Issued at 218 PM CDT Thu Oct 16 2025

Broad warm air advection ahead of an incoming upper level wave along
with relatively weak instability, generally less than 600 J/kg, will
allow for scattered showers and thunderstorms into the night. The
better chances for thunderstorms will be before about 10 pm. Severe
weather is very unlikely. The low level dry air is fairly shallow
which does not support enhanced downburst potential and the freezing
level is close to 12 kft which would need a fairly strong updraft to
produce larger hail that could fall through the 2 miles of above
freezing air, and 600 J/kg CAPE is not going to produce that strong
of an updraft. So, the main threats from any thunderstorms will be
brief heavy rain and lightning and if a storm can get strong enough
pea sized hail. Otherwise temperatures will be very mild, especially
near and east of highway 81 with lows from the mid 50s to lower 60s.
Cooler air will begin to filter into central SD later tonight with
lows in the mid 40s more likely.

Friday should be a mild day in the wake of the exiting wave and
ahead of the next wave expected later Friday night into Saturday.
Westerly surface flow and temperatures in the upper 60s to lower 70s
are expected under sunny skies. Fire weather should be kept mostly
in check with surface relative humidity expected to remain at or
above 40 percent.

Late Friday night into Saturday a wave will dive southeast and bring
the next shot for showers. Precipitation chances will remain
scattered with some weaker elevated instability. The main concern
with this wave will be some gusty winds with gusts of 35 to 40 mph
possible. This may bring some elevated fire weather concerns but
once again the afternoon relative humidity is expected to remain
above 40 percent.

An active upper level pattern will not leave much room for lighter
winds as we head into Sunday and early next week. Cooler air will
filter in behind the wave Saturday, dropping lows into the 30s and
lower 40s Sunday morning. It does look like wind will remain around
5 to 10 mph so the threat for frost is fairly low. If winds can drop
off long enough Sunday morning then there may be a few more
locations in the mid 30s and we could see a little frost.

Another fast moving system will move through on Monday but
precipitation is not expected. The flow will remain fairly active
throughout the next week, but precipitation chances are pretty low.
Temperatures should be near to a touch below normal.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1211 PM CDT Thu Oct 16 2025

The main concern for this period will be the shower and
thunderstorm potential. The thunderstorm potential should be
mainly west of highway 81 through the evening. Outside of any
shower and thunderstorm potential mainly VFR conditions are
expected. A brief period of MVFR ceilings will be possible on
Friday morning but confidence is low.

&&

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

&&

$$

DISCUSSION...08
AVIATION...08