449
FXUS63 KFSD 131137
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
637 AM CDT Mon Oct 13 2025

.KEY MESSAGES...

- Patchy areas of frost are possible this morning mainly north
  of I-90 and into south-central South Dakota.

- An active pattern aloft will lead to increased rain chances
  (40-80%) tonight into Tuesday, with rainfall totals through
  Tuesday night between 0.1" and 0.4" across the area.

- After a brief return to below normal temperatures to start the
  week, near to just above normal temperatures return mid-week.

&&

.DISCUSSION...
Issued at 422 AM CDT Mon Oct 13 2025

Colder air has filtered in across the area behind yesterday`s
frontal passage, and clear skies and calming winds have allowed for
some good radiational cooling especially along and west of the
James River. This is where temperatures have already fallen to
the mid-30s with a few more hours left of nighttime to go.
However, some high clouds moving in from Nebraska will likely
prevent areas from reaching the freezing mark this morning.
Still, patchy areas of frost are possible mainly north of I-90
into south-central South Dakota. Light showers have developed
in southern Nebraska this morning associated with a weak upper
wave and this activity will lift north towards our area and
arrive around daybreak near the Missouri River Valley. A dry
sub-cloud layer will pretty much prevent any of this rain from
reaching the ground and so expect dry conditions this morning.
We`ll otherwise see mostly sunny to partly cloudy skies during
the day today with highs in the upper-50s to mid-60s.

A more well-defined wave will move out of Rockies late this
afternoon and bring some increasing rain chances to the Missouri
River Valley this evening. At first, the northeastward-moving rain
will still have to battle a lot of dry air beneath the clouds, but
with continued rainfall into the dry sub-cloud layer through the
night, the low-levels should gradually begin to saturate and so
there will be better ground coverage by late tonight into tomorrow
morning. The upper-level wave parade continues into Tuesday and so
will the rain chances throughout the day. There will still be some
dry air beneath the clouds for the rain to contend with, but
soundings indicate rising motion within the DGZ at times which
could lead to occasional moderate rainfall making it through the
dry layer especially tomorrow afternoon and evening. All told,
we look to see anywhere between 0.1" and 0.4" tonight through
tomorrow night. Due to the rain chances and cloud cover on
Tuesday, expect a chilly day with highs only in the 50s, though
some of us especially north of I-90 may struggle to even get
out of the 40s tomorrow afternoon!

By Wednesday, an upper-low moving into the west-central US will
begin to eject across the northern Plains into Wednesday night. At
the surface, a low pressure system is set to develop out of the
Rockies and move northeast into western South Dakota by Wednesday
night. It will deepen as it does so and thus winds will likely start
picking up late Wednesday into Wednesday night. The low pressure
system will drag a cold front through the area on Thursday, which
will bring more chances of rain to our area. This will also likely
lead to slightly cooler temperatures on Friday after a mid-week warm-
up, with guidance indicating a reinforcing shot of cooler air
(though still near normal temperatures) to move in for this
weekend. From there, models diverge, with the GFS and EC
showing another trough diving into the Pacific Northwest while
the Canadian has a weaker trough moving across the Northern
Rockies. With that, the Canadian model drags another cold front
through the area on Sunday, while the GFS and EC hold that off
until next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 631 AM CDT Mon Oct 13 2025

VFR conditions expected through the period. A few showers are moving
towards the Missouri River Valley-area in southeast South Dakota to
start the period, but this activity is not expected to reach the
ground due to a dry sub-cloud layer. Cloud bases are around 9-12
kft, so some raindrops may be encountered just below these levels.
These showers should fade through the morning hours as they lift
northeast.

Otherwise, a better coverage of showers is expected tonight as an
upper-wave lifts northeastward across the area. There will likely be
showers in the vicinity of the TAF sites starting around midnight
tonight through the end of the period, though attempted to narrow
down the times when rain will be falling at the airports using
latest short-term guidance as indicated by the prevailing -SHRA
groups. Either way, VFR conditions are still expected in any showers
tonight.

Winds today will be around 5-10 kts, starting out of the northwest
but gradually turning to the north then northeast as a high pressure
system slides across the northern Plains.

&&

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

&&

$$

DISCUSSION...Samet
AVIATION...Samet