725
FXUS63 KFSD 140412
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1112 PM CDT Mon Oct 13 2025

.KEY MESSAGES...

- Rain returns to the area tonight through Tuesday, with the
  bulk of the rain falling Tuesday afternoon. Expected rainfall
  amounts remain between 0.1" to 0.4".

- Chances for rain remain in the forecast for the middle and end
  of the week, with Thursday seeing the highest chances for
  rain (60-80%) come during the evening and overnight hours.

- After a brief return to near to below normal temperatures
  today and Tuesday, above normal temperatures return for the
  middle and end of the week.

&&

.DISCUSSION...
Issued at 240 PM CDT Mon Oct 13 2025

Nearly quiet conditions persist across the area this afternoon
thanks to high pressure sliding through the Northern Plains. High
temperatures have warmed to upper 50s to low 60s while winds remain
light out of the north. Things will begin to change this evening
though as a shortwave trough currently near to just northeast of the
four corners region will push into the forecast area. Low level warm
air advection (WAA) will strengthen in response to this wave. At the
same time, the upper levels will saturate due to the cooling from
the approaching wave. This will saturate the dendritic growth zone
(DGZ) while omega (upward motion) also increases in the DGZ as well.
However, the previously mentioned surface high will keep dry air in
the low levels through the evening and overnight hours. Have reduced
PoPs a bit, now down to a broad 20-40% chance for rain for this
period of time. While some rain looks to reach the surface, it may
not be all that much given the large amount of dry air in the low
levels. Rainfall totals look to only reach up to a few hundredths
across the area during the overnight hours. With clouds and very
light rain in place, low temperatures will be a decent bit warmer
than this morning, only falling down to the 40s.

Tuesday will see continued light rain across the area as the same
forcing for ascent remains over the forecast area. The high pressure
system will slide to the east, turning low level winds to out of the
southeast. This will advect in better moisture into the low levels
by early Tuesday afternoon, leading to more widespread light to
moderate rain across the area. This overlap of moisture looks to
last only a few hours though before the DGZ dries out. With clouds
and precipitation in place, highs will only warm to the 50s. As the
DGZ dries out during the later half of the afternoon, the low level
will remain saturated. This looks to potentially result in more
drizzle than light rain and persist through the evening and
overnight hours. Will certainly feel like a classic dreary Fall day
across the area. Rainfall totals again look to be light between
approximately one to 4 tenths of an inch. Lows will again fall to the
40s.

An amplified upper level trough will be sitting over Nevada on
Wednesday, keeping more amplified flow across the Plains. This will
keep persistent WAA across the forecast area along with continued
chances for rain/drizzle. The highest chances look to come in the
morning (15-35%) but wane through the afternoon hours as the bulk of
the low level moisture begins to slide to the east. While light
drizzle to sprinkles is possible during the afternoon hours,
Wednesday looks to be a drier day. Cloud cover will be decreasing
during this period of time so highs will be a bit warmer in the 60s
and 70s.

The previously mentioned upper wave over Nevada will begin to eject
into the Plains on Thursday. The mass response from this wave will
transport better quality low level moisture with dew points reaching
up to about 60F. That said, the best quasi-geostrophic (QG) ascent
will remain north of the forecast area over North Dakota. With
warmer temperatures aloft over the area, high temperatures will be
quite warm up to the 70s and just about 80F. The mid levels look to
be generally dry with this wave until the cold front tied to this
wave pushes eastwards. Showers and possibly a few storms look to
develop along the front. Given the greater amplitude to the pattern,
mean flow will parallel the front. Latest deterministic guidance has
the front remaining just west of the forecast area during the
afternoon hours before pushing eastwards during the evening and
overnight hours. The ensembles support this as they generally show
low chances (<30%) for rainfall totals to exceed a tenth of an inch
for the daylight hours. The ensembles then quickly increase their
probabilities up to a 60-80% for exceeding the same amount of rain
on the western fringes of the forecast area Thursday evening and
night. The ensembles show little if any chance for CAPE values to
exceed 500 J/kg with the Canadian ensemble showing the highest
probabilities up to a mere 30% chance. Thus, am not expecting strong
to severe storms at this time. Low temperatures will remain mild in
the 40s to 50s. Depending on how things turn out, some locations
along highway-71 may see lows bottom out around 60F.

The main wave finally ejects into the Northern Plains on Friday.
With the cold front passing through the area through the morning
hours, this will also be the period for the highest chances for
rain, up to a 30-50% chance. Come the afternoon hours, chances for
rain will be decreasing along with a return to sunny skies. Highs
will remain near to above average in the mid 60s to mid 70s.

The weekend looks to be dry as the Northern Plains will be residing
on the backside of the departing upper level wave, resulting in
subsidence across the area. Breezy northwest winds are likely during
this period of time thanks to weak cold advection and stronger winds
around 850 mb being mixed to the surface. Highs each day will remain
near seasonable in the 60s with lows falling to the 30s and 40s.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1110 PM CDT Mon Oct 13 2025

VFR conditions for the first portion of this period. Light easterly
winds will increase after sunrise this morning. Sustained winds
of 10-15 kts with gusts 20-22 kts will reach their peak in the
mid-afternoon, decreasing after sunset.

Clouds continue to flow in from the southwest ahead of an approaching
system. Rain chances will continue to increase through the
early morning hours. Showers will initially be very scattered
and spotty in nature, and these conditions have been covered by
a Prob30 group at all three sites. As we approach daybreak,
shower activity begins to increase and expand in areal coverage.
By early afternoon showers may at times become locally heavy
rainfall. Ceilings begin to degrade to MVFR from south to north
as afternoon shower intensity increases. Visibility may also
decrease to MVFR, possibly dipping to IFR at times under heavier
showers. This is more likely toward the end of the period.
Shower activity will continue beyond the end of this period.

&&

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

&&

$$

DISCUSSION...Meyers
AVIATION...AJP