961
FXUS63 KFSD 050341
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1041 PM CDT Sat Oct 4 2025

.KEY MESSAGES...

- Low-medium (<40%) rain chances west of I-29 tonight and in
  portions of northwest Iowa Sunday. The risk of severe weather
  is low, but storms tonight may locally enhance already gusty
  winds.

- Sunday will be a transition day in temperatures (still warm
  east of I-29 but much cooler toward central SD). Near normal
  daytime highs briefly return early next week, but slide
  upward again mid-late week.

&&

.DISCUSSION...
Issued at 233 PM CDT Sat Oct 4 2025

Hot, dry, and windy conditions continue this afternoon and evening.
High to Very High Grassland Fire Danger is expected across most of
the region. Minimum relative humidity values are expected to fall to
around 30-40% with areas west of the James River Valley falling to a
minimum of around 27%. This combined with afternoon wind gusts of 35-
40 mph will result in elevated fire danger. Some green is still
present in vegetation through the region, but localized areas
where crops and grasses are completely cured (dry and brown) the
danger will be near critical. As mentioned in the previous
forecast, outdoor burning is not recommended today. Please use
caution with machinery that gets very hot and/or creates sparks,
and report any fires immediately. The Special Weather Statement
issued this morning continues to highlight the strong winds and
potential for rapid fire spread through 8 pm this evening.

Strong WAA in the low to mid-levels will warm temperatures in the
850 mb layer to 20-24 deg C. Model soundings indicate good mixing
through this level and even higher for areas along and west of the
James River. At the surface this will translate into hot highs in
the upper 80s to low 90s. Forecasted highs will come close to record
highs for the 4th of October. Will any temperatures rise enough to
tie? Stay tuned. Lows for tonight are warm, in the 60s. Several
record warm low temperatures are in position to be broken tonight.

As mentioned in the first paragraph, breezy winds today and into
tonight thanks to good mixing tapping into the stronger winds aloft.
Southerly sustained winds of 25-30 mph with gusts of 35-40 mph have
been widespread through the region. Gusty winds are expected to
continue this afternoon and into the overnight. After sunset, the
low-level jet begins to increase. Winds within the jet may reach
speeds of 50+ kts. With weak to no capping expected overnight we may
occasionally tap into these stronger winds aloft, resulting in
surface gusts of 40-45 mph at times. The SPG relaxes as the base
of a surface trough begins to pivot into the western portions
of our area overnight. Winds will decrease in response but
remain gusty at 30-35 mph for areas west of I-29, 35-40 mph to
the east.

Surface analysis shows a low pressure sitting roughly over central
South Dakota with a cold front draped from northwestern Minnesota
through eastern North Dakota, connecting to the low. To the south
another cold front drapes from the low into western Nebraska and
southeastern Wyoming. This front is expected to continue to drift
slowly southeast through the next 24 hours. As it does so it brings
low-medium (<40%) chances for rain to central South Dakota in the
early Sunday morning hours. A general lack of moisture limits the
potential for showers, especially during the day Sunday.
Occasional spotty light showers are possible, but in general
think most areas will stay dry. Through the day, southerly winds
will advect modest moisture into the area, increasing dewpoints
into the 50s with some low 60s east of Highway 60. This
moisture will pool ahead of the front over northwestern Iowa. By
Sunday evening, the cold front will be draped roughly along a
line from Spirit Lake to Ida Grove, where additional medium
chances (35-45%) of rain are possible. In both instances,
instability will be elevated and weak, 500 J/kg or less. Lapse
rates are minimal, with marginal deep layer shear. Strong storms
are not expected, but a few strikes of lightning is possible. A
larger concern is strong wind gusts out of any storms that
develop. With the dry low and mid-levels, evaporative cooling as
rain falls could enhance down draft strength to 50 mph gusts.
Highs Sunday will depend highly on how fast the front moves
through. Areas west of a line from Yankton-Sioux Falls-Marshall
will see highs in the upper 60s to upper 70s with the cooler
temperatures over central South Dakota. East of that line highs
will climb into the low to mid 80s. Overnight lows will be in
the 40s.

Monday the front looks to stall just to the southeast of our area
for most of the day. Some mid-range guidance indicates showers may
be possible through the day over northwestern Iowa and northeastern
Nebraska as a very weak shortwave works northeast through the low to
mid-levels. But the better chances and dynamics lie southeast of our
region. As far as rainfall totals are concerned, through midnight
Tuesday morning, a couple hundredths to maybe a tenth is possible.
Areas along and south of a line from Spirit Lake to Ida Grove may
see up to a tenth or two.

Conditions through the first half of next week will be dry and
seasonable. Highs Monday and Tuesday will be in the 60s. Wednesday
highs creep back into the low 70s. Thursday and Friday highs will be
in the mid 70s. Thursday brings the next chance for showers and
thunderstorms, though long-range guidance at this time is in low
agreement. Stay tuned for updates as the week progresses.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1040 PM CDT Sat Oct 4 2025

Gusty southerly winds will continue across the area tonight,
though with a 60 kt low level jet overhead all TAF sites will
experience LLWS. Isolated showers and weak thunderstorms may
push into central SD by 06Z, tracking eastward and weakening as
they approach the Interstate 29 corridor late.

A few showers may then develop over portions of northwest IA
on Sunday, though at this time they are expected to remain east
of KSUX. Southwesterly winds will remain gusty on Sunday,
though transition to west/northwesterly in the late afternoon
and evening as a frontal boundary moves through the region.
Winds will decrease on Sunday evening.

&&

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

&&

$$

DISCUSSION...AJP
AVIATION...JM