887
FXUS63 KFSD 301923
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
223 PM CDT Wed Jul 30 2025

.KEY MESSAGES...

- Potential for some very localized heavy rain this afternoon
  and evening, mainly south of I-90. A few funnel cloud are also
  likely.

- Below normal temperatures settle in through early next week.

- Some smoke mainly aloft will be possible the remainder of the
  week.

- Sunday should be the next chance for a few severe storms but
  for now this threat appears to remain isolated. Tuesday night
  appears to be the next chance for severe storms after Sunday
  with what looks to be a bit better chance for scattered severe
  storms. However, uncertainty remains in the coverage and
  severity with this potential activity.

&&

.DISCUSSION...
Issued at 222 PM CDT Wed Jul 30 2025

Today should be the final day of the deeper moisture that has been
aiding in producing almost daily thunderstorms across the area. A
weak MCV will continue to weaken in southeast SD this afternoon.
This should be the focus for a few showers and thunderstorms. The hi-
res models that have this suggest the an storms that develop should
be mainly south of I-90. That area has had quite a bit of rain the
past week. Storm motion looks pretty slow and model soundings have
relatively weak CAPE (500-1000 J/kg) with the freezing level around
12-13 kft, so likely some efficient rainers. The HRRR and ARW seem
to be handling things best thus far. The Nam 3KM and NSSL have
convection in northwest IA from 12-15z this morning which is not
happening so they are being ruled out. The models handling the MCV
better are producing a small area of 1-3", possibly up to 4" which
would fall over a short period of time with the focused area south
of I-90 in far southeast SD then into northwest IA. For now the
better chances will be between Sioux Falls and Sioux City, but will
monitor for any changes in this subtle, weakly forced environment.
Along with the threat for pockets of heavy rain will be a few funnel
clouds. Winds in the lowest few thousand feet are very light and a
weak boundary is also in place in far southern SD and northwest IA
along with very low LFC/LCL. All of this hints that a few funnels
are likely during the initial updraft phase but for now production
of a tornado looks unlikely.

Any shower and thunderstorms activity should pretty much follow the
diurnal cycle with most activity done by 10 pm to midnight. Through
the night drier and more stable northeast flow will bring quieter
weather Thursday into Friday with seasonally cool temperatures.
Highs will be in the 70s to around 80 with lows in the 50s to near
60.

On Friday night troughiness to the west develops and swings a mid
level wave into central SD. The LLJ increases with a focus more to
the west of the area, but this forcing does creep towards the James
Valley. Overall instability looks pretty low so only very isolates
severe is expected.

Saturday into Saturday night continues to indicate a decent LLJ into
the area with troughiness and a mid level wave rotating through.
This will keep chances for showers and thunderstorms in place, but
the severe threat continues to look very isolated.

Sunday will continue the chances for showers and thunderstorms with
a slight increase in the threat for a few severe storms. The upper
level troughiness begins to slip eastward with a bit stronger
northwest flow aloft providing a bump in shear. Will continue to
monitor trends with upcoming model runs.

Thunderstorm chances continue into early next week. There may be a
lull Monday night into Tuesday, but by Tuesday afternoon into
Tuesday night a stronger jet/wave moves onto the Northern Plains
and could bring the next better chance for scattered severe storms.

Temperatures Tuesday into Wednesday will climb back to around
normal.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 113 PM CDT Wed Jul 30 2025

Occasional MVFR ceilings are expected through the afternoon, but
after sunset mainly VFR conditions are expected. Also of concern
this afternoon into the evening will be scattered showers and
isolated thunderstorms mainly south of I-90 into northwest IA.
The main threats with the storms will be lightning, brief funnel
clouds and locally heavy rain.

&&

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

&&

$$

DISCUSSION...08
AVIATION...08