614
FXUS63 KFSD 041750
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1250 PM CDT Sat Oct 4 2025

.KEY MESSAGES...

- Near record high temperatures again today, with widespread
  moderate to locally major Heat Risk due to the unseasonable
  heat.

- South winds gusting 35 to 45 MPH will result in elevated fire
  danger today. Use caution to avoid sparking fire in dry crops
  and grasses as rapid fire spread is likely.

- Low (20-30%) rain chances west of I-29 tonight and in portions
  of northwest Iowa early next week. 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 320 AM CDT Sat Oct 4 2025

Hot, dry and windy will be the words of the day today, as a
low level thermal ridge and associated low level jet become
centered southwest to northeast across the CWA. Model forecast
soundings show mixing to between 900 & 850MB (perhaps slightly
higher in our west). This taps into winds of 35-40kt atop the
mixed layer, which supports largely sub-advisory level wind
gusts of 35 to 45 MPH during peak mixing this afternoon. In
addition to nudging winds today a little higher than the NBM,
also adjusted temperatures/dew points up/down, respectively,
giving preference toward the HRRR/RAP/GFS which tend to handle
these hot/dry/windy scenarios better. This yields high temps
near to just above 90F, which should fall just shy of records
for October 4th, though the warmest model solutions would
suggest a chance at breaking the record in some locations. Drier
dew points mixing to the surface will yield minimum humidity
levels of 23-35%, warmest and driest in our southwest counties.

This all combines to create High to Very High Grassland Fire
Danger throughout the forecast area today, based on some level
of greenness in local grasses. It should be noted, though, that
areas with grasses that are more cured (dried out) or crops
ready for harvest could see locally higher fire danger with near
critical fire weather conditions possible. With the strong
winds today, outdoor burning is not recommended, and extreme
caution is advised if using equipment that could generate spark
in the dry grasses or crops. In coordination with neighboring
offices and MN fire officials, have issued a Special Weather
Statement to highlight the strong winds and associated potential
for rapid fire spread.

The low level jet strengthens in excess of 50kt tonight and
some soundings suggest we could continue to tap into the jet at
times during the nighttime hours, which means strong wind gusts
in excess of 35-40 MPH remain possible into the early morning
hours when the gradient begins to relax with the approaching
cold front. While low level moisture remains limited, we could
also see spotty elevated showers or storms (20-30% chance) ahead
of the front and its associated mid-upper level wave. At this
time, the favored location for showers in our western CWA is
west of the low level jet axis, but we will have to watch for
locally enhanced wind gusts near any showers.

The cold front slides east across the CWA Sunday, and we could
see a rather sharp gradient high temperatures from mid-upper 60s
in our far west to mid 80s along and east of MN/IA Highway 60.
Wind speeds will not be as robust as today, but still breezy
with gusts 25 to 35 mph as direction shifts from southwest to
northwest. Areas of elevated fire danger are again possible in
areas near and east of I-29 as the warmer temperatures and dry
air result in RH values as low as 30-40%.

The front may linger near to just south of our CWA into early
next week, and another wave moving from Kansas into Iowa may
produce some light showers or isolated storms in parts of
northwest Iowa on Monday. Most areas will not see much in the
way of rainfall over the next few days, generally less than
0.10". However, there a low 20% chance for some areas toward
Storm Lake or southeast of Sioux City to see upwards of 0.25"
through Monday.

Temperatures early next week will briefly settle closer to our
early October normals of highs in the mid-upper 60s and lows in
the lower-mid 40s, perhaps even slightly below normal on Monday.
The coldest of this early week air mass looks to remain well
north of the area, though, with sub-zero 850MB temperatures
dipping into portions of North Dakota and northern Minnesota
Monday into Tuesday. Seasonably mild air then builds back into
the northern Plains mid-late next week with a broad northern
stream trough bringing some low (20-30%) rain chances for
Thursday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1250 PM CDT Sat Oct 4 2025

VFR conditions are expected for the majority of the period. Winds
will be out of the south gusting at 30-35 kts. Gusty winds are
expected to continue through the overnight. Aloft the low-level jet
is expected to increase after sunset, LLWS will increase in
response. Speed shear of 45-50 kts is expected for all three TAF
sites. Wind shear slowly diminishes from west to east through the
early to mid-morning hours Sunday.

A few scattered elevated showers and possibly a thunderstorm or two
are possible after midnight tonight west of the I-29 corridor. These
are not expected to become severe, however with dry low-levels,
erratic and strong wind gusts are possible near the surface.
Included Prob30 groups for KHON and KFSD to cover storm chances.
Confidence in storms impacting KSUX were too low to include in the
TAF at this time.

&&

.FIRE WEATHER...
Issued at 320 AM CDT Sat Oct 4 2025

Hot, dry and windy conditions will lead to widespread High to
Very High Grassland Fire Danger today. Afternoon humidity
levels are expected to remain just above critical values
(minimum afternoon humidity 23-35%, with driest conditions in
south central South Dakota). However, south winds gusting as
high as 35 to 45 MPH will overcome the marginal humidity levels,
especially where grasses are more cured or crops are ready for
harvest. With this in mind, farmers and others working outdoors
should be mindful of their equipment usage to avoid sparking a
fire in the dry fuels.

Locations along and east of I-29 will remain breezy and warm
ahead of a cold front on Sunday, with southwest to west winds
gusting 25 to 30 MPH and humidity levels falling to 30-40%. This
will keep the Grassland Fire Danger in the High category in many
areas, so continued caution is advised.

After the cold front passes, much of next week will provide dry
conditions with cooler temperatures and lighter winds allowing
for less dangerous harvesting conditions.

&&

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

&&

$$

DISCUSSION...JH
AVIATION...AJP
FIRE WEATHER...JH