766
FXUS63 KFSD 011742
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1242 PM CDT Thu Oct 1 2026

.KEY MESSAGES...

- Dry and seasonably mild conditions will dominate the week
  ahead with only very minor chances (<20%) for showers into
  early next week.

&&

.UPDATE...
Issued at 420 AM CDT Thu Oct 1 2026

Showers did push as far north as portions of Highway 18 in
northwest Iowa early this morning with KSPW recording a little
over 0.25" rainfall & several personal weather stations showing
amounts of 0.50" to locally 1.00" southeast of a Sioux City to
Spencer line. Heaviest rain of 4 to 8+ inches remained south of
the forecast area and no flooding issues have been noted in our
area.

This rain is exiting the far southeast corner of the CWA as of
4 AM, and dry conditions are expected to be much more prevalent
through these first several days of October. Cannot rule out a
few light showers/sprinkles with some weak instability ahead of
a cool front Saturday. However, moisture is limited within the
latest forecast soundings and potential for measurable rain has
decreased as a result.

Today will be a breezier day behind a weak cool front dropping
southeast, with highs today and Friday in the upper 50s and 60s.
A surface ridge moving east into the area tonight will allow the
breezy winds to decrease quickly with sunset. Lighter winds and
clearing skies, along with drier low level air (dew points are
forecast to fall through the 40s today with some mid-upper 30s
dew points possible north of I-90 tonight), could allow temps to
fall near 40 degrees in portions of southwest Minnesota by early
Friday. Farther west, some increase in mid-level clouds should
hold temps in the mid-upper 40s tonight. At this point it does
not look like frost will be a concern in our area tonight, but
later shifts may need to watch portions of southwest Minnesota
and perhaps back toward the I-29 corridor north of Sioux Falls,
as the latest NBM does show low (20% or less) probabilities of
low temperatures reaching 35-36F tonight.

&&

.DISCUSSION...
Issued at 111 PM CDT Wed Sep 30 2026

All indications continue to point towards keeping the heavier rain
to the south later this afternoon and tonight. The high resolution
models only bring about a quarter of an inch of rain to southern
parts of Woodbury and Ida counties with the ensemble output showing
about a 20-40 percent chance to exceed 1 inch of rain, the EC
probabilities a little higher. With 3-4 inches of rain needed to
make any if the rivers really move upwards, flooding concerns are
very minimal.

Fog will again be possible later tonight into Thursday morning, but
for now the model soundings suggest the lower level saturated layer
is much shallower, so a better chance to burn off more quickly in
the morning. A surge of drier air will build southward with dew
points falling into the 40s through the morning. Also looks like the
better chances would be over parts of northwest IA and nearby
locations.

A system will move by to the north Friday into Saturday. While this
will bring some mid level cloud cover into the area, precipitation
chances will remain fairly low with dry air below about 800 mb. Some
very weak instability aloft Friday night into Saturday ahead of an
incoming shot of cooler and drier air may see the need to add some
spotty showers during this time, but confidence fairly low in this
weak instability. Without the weak instability, saturation looks to
occur below the dgz so rainfall would not be expected without the
instability. Overall impacts will be very minor.

Upper level ridging builds into the area Sunday into Monday ahead of
the next wave. This wave will bring small chances for showers Monday
night into Tuesday, but again very low confidence fighting drier air
with the wave well to the north. One thing that this wave will bring
is mild weather to the area. Looking at highs Tuesday and Wednesday
around 70 in most locations. Highs more in the lower to mid 60s are
expected this weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1241 PM CDT Thu Oct 1 2026

VFR conditions expected for the period. Gusty winds up to 20 kts are
possible until a little bit before sunset, clearing out of the
northwest portion of the CWA near KHON first and stretching
southeast through KFSD and down to KSUX. Winds overall trending down
over the period, switching to light and variable for much of the
area around 3-4z. Ceilings to drop slightly through the period,
though non-impactful for category change.

&&

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

&&

$$

UPDATE...JH
DISCUSSION...08
AVIATION...Rafalski/08