Oldham, South Dakota Weather Forecast Discussion

552
FXUS63 KFSD 131700
AFDFSD
Area Forecast Discussion
National Weather Service Sioux Falls SD
1200 PM CDT Sat Sep 13 2025
.KEY MESSAGES...
- Well above normal temperatures (10+ degrees), will continue
  through the weekend and into early next week. WBGT values
  reach the moderate levels, especially today, and those
  participating in outdoor activity should use some caution.
- Convection chances remain low into Sunday morning, however
  chances do increase Sunday afternoon into Sunday night. A few
  storms will be possible in central SD tonight.
- Conditional risks for isolated severe storms develop Sunday
  afternoon into the evening. Marginal hail and brief strong
  wind gusts are the primary risks.
- Next reasonable risk for rain arrives Tuesday and continues
  through Wednesday, with cooler temperatures the second half of
  next week.
&&
.DISCUSSION...
Issued at 300 AM CDT Sat Sep 13 2025
A hot and somewhat humid day is ahead with gusty southerly winds
around 25 mph. Highs will generally be in the upper 80s to lower 90s
with dew points in the mid to upper 60s. Model soundings are showing
strong capping so not anticipating any thunderstorm development this
afternoon with this heat and humidity. The one exception where the
capping inversion is a bit weaker is in central SD, west of the
James River, where some potential for development will be possible
very late afternoon into the evening. The better chances most
certainly will be later in the evening and overnight as low pressure
deepens to the west and mid level moisture increases near and west
of the James River. While a very isolated severe storm would be
possible, the main threats will be lightning and locally heavy rain.
An unseasonably strong upper level low pressure swings north into
western and central SD on Sunday. A shot of mid level moisture and
lift spread north into central SD late Sunday morning into the early
afternoon. Expect showers and thunderstorms to develop or move into
the area during this time. Instability and shear very marginal for
any severe, so the threat will be very low. During the evening and
overnight hours the main wave will drift north into southeast SD and
should bring scattered showers and thunderstorms. Model soundings are
somewhat inconclusive on the severe weather threat, but with 1000-
1500 J/kg CAPE suspect an updraft or two will bring the potential
for 60 mph winds and quarter sized hail.
Monday will see mid and upper level ridging build into the area so
more than likely any thunderstorm development will be suppressed.
However, it does need to be noted that an environment will exist
that could support some strong updrafts with CAPE values of 2000+
J/kg and some solid directional shear, albeit not overly strong, in
the lower levels. So again, capping and mid and upper level ridging
will likely keep storms at bay, but if something can develop there
would be the potential for a supercell or two, about a 5% chance.
As this wave rotates to the north a broad trough will develop across
the Northern Plains Wednesday into Friday which will bring periodic
chances for showers and thunderstorms with temperatures cooling back
to around or a bit below normal. Right now Tuesday night into
Wednesday night appears to be the better chance for showers and
storms with the EC Ensemble and GEFS indicating about a 40-60
percent chance for a half an inch or more of rain.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1200 PM CDT Sat Sep 13 2025
VFR conditions expected into the overnight hours. Southerly
winds may occasionally turn gusty as a few afternoon CU develop.
In South Central South Dakota, the intrusion of cooler westerly
air will allow lower stratus to persist into mid-afternoon.
Tonight, a low end risk for scattered showers and thunderstorms
in central South Dakota may bring lowering ceilings to the HON
area, otherwise VFR conditions are likely elsewhere with a
variable to southerly wind.
We`ll have continued cirrus in the sky on Sunday morning, with
perhaps some lingering mid-lvl clouds moving into areas west of
the James River. A few showers may also accompany these clouds,
but greater rain chances look to hold off until Sunday
afternoon. Winds will likely turn gusty by mid-late morning
Sunday as mixing rapidly increases.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...08
AVIATION...Dux

NWS FSD Office Area Forecast Discussion