700
FXUS63 KFSD 281115
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
615 AM CDT Thu Aug 28 2025

.KEY MESSAGES...

- Areas of fog, including areas with visibility below 1/4 of a
  mile, continue in portions of southwestern Minnesota, central
  South Dakota, and northwestern Iowa overnight mid this
  morning.

- Temperatures remain near seasonal averages today. Dry weather
  is expected today and tonight.

- More widespread rain chances and cooler conditions return
  Friday through the upcoming holiday weekend. Exact timing of
  highest rain chances remains uncertain. Severe weather is not
  expected.

&&

.DISCUSSION...
Issued at 317 AM CDT Thu Aug 28 2025

NOW THROUGH TONIGHT: Fog, including dense fog across southwestern
MN, continues through the mid morning hours. Visibility below 1/4
mile is expected for portions of southwestern MN, with visibility
below 1/4 mile possible elsewhere. Be prepared for changing
conditions on your morning commute.

Surface boundary lingers across the area this afternoon and this
evening; however, think that sprinkles/showers will be hard to come
with a lack of instability and other forcing, as well as a dry sub
cloud layer. Although not completely out of the realm of
possibility, confidence is too low to include any mention. If we`re
able to develop showers or sprinkles, pattern is favorable for some
funnel clouds with the boundary in place, some enhanced stretching
potential, and weak surface vorticity. Would not expect any of these
to touch the ground, and with parameters slightly offset, confidence
is low that these can develop (even if we get some sprinkles).
Otherwise, a mix of clouds and sun today with light easterly winds.
We`ll warm near seasonal normals today with highs in the mid 70s to
mid 80s.

Tonight, expect conditions to remain dry as the first wave and
surface low pressure begin to move into western SD and upper ridge
moves east. Some CAMs bring showers into our south central SD
counties through the overnight along the edge of WAA and the upper
jet; however, still think we`ll be lacking enough moisture and
defined forcing for any precip. Lows tonight drop into the upper 50s
and lower 60s, with increasing clouds.

FRIDAY THROUGH LABOR DAY: Guidance continues to struggle with the
evolutionary details of the weekend`s synoptic pattern, so will talk
about the pattern fairly generally. The aforementioned wave moves
east Friday, with northwesterly flow aloft continuing through the
weekend. Upper level ridging dives south through the early part of
the weekend, with upper low pushing into the northern Plains by
Saturday night. Meanwhile, the next mid level wave transitions to a
more closed off low across the Dakotas into WY/MT (depending on
which model you choose to look at) sometime between Saturday
afternoon and Sunday morning. Surface low pressure meanders across
the central and northern Plains as well. Northwesterly flow remains
in place on Monday.

This pattern favors periodic shower and isolated storm chances
through the weekend and into Labor Day. Much of the area may see
beneficial rainfall during this time, with the probability of 0.5"
of rain through Monday night near/above 50% for the entire forecast
area (highest over south central SD). Deterministic guidance shows
some locations could see over an inch of rain, but vary on where.
Outside of precipitation chances, cooler than average temperatures
are expected with prevailing cloud cover. Highs in the 70s to lower
80s, with cooler days Saturday and Sunday.

Severe weather is not expected this weekend, as even with model
uncertainty, it appears as though the times/locations with better
instability will be offset in time and space from the better shear.
Additionally, those values are generally on the more marginal side.

TUESDAY-WEDNESDAY: Given the variance in details for the weekend,
confidence is low in the details for early next week. A more defined
trough axis dives south Tuesday night through Wednesday. Expect
periodic rain chances to continue through this time, with even
cooler temperatures on the way for mid to late next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 608 AM CDT Thu Aug 28 2025

Watching patchy MVFR/IFR fog continue to develop this morning,
especially near KHON toward KMHE and KSUX into eastern NE and
another area across southwestern MN. This area across
southwestern MN has had widespread visibility at or below 1/4 SM
near and north of a line from KCNB to KJYG. Fog should mix out
by mid morning.

Outside of fog, expect VFR conditions with cumulus development
this afternoon. Most of the area stays dry during the period,
although showers may move into south central SD by 12z Friday.
Winds remain light and somewhat variable, with any prevailing
direction east to southeast.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...Dense Fog Advisory until 9 AM CDT this morning for MNZ071-072-
     080-081.
IA...None.
NE...None.

&&

$$

DISCUSSION...SG
AVIATION...SG