864
FXUS63 KFSD 151955
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
255 PM CDT Tue Jul 15 2025

.KEY MESSAGES...

- Scattered strong to severe storms are possible late this
  afternoon and evening mainly across southeast South Dakota and
  northeast Nebraska, with 70 mph winds and ping pong ball-
  sized hail as the main threats. Storms develop in central
  South Dakota around 4-5 pm, with the severe threat decreasing
  with eastward extent.

- Dry and cooler Wednesday and Thursday as high pressure settles
  across the region. Daily highs will top out in the 70s.

- Increasing heat and humidity Friday will allow for a return to
  shower and thunderstorm chances.

- Gradual warming trend this weekend into early next week with
  periodic precipitation chances (20-30 percent).

&&

.DISCUSSION...
Issued at 255 PM CDT Tue Jul 15 2025

TODAY THROUGH TOMORROW: It`s another hot and humid day across the
area, with highs around 90 and dew points around 70. This will help
set the stage for potential severe weather late this afternoon
through tonight as cold front residing just to west of the area will
begin to move through. Initial storm development will likely occur
around the Missouri River Valley in central South Dakota around 21-
22Z and quickly grow into east-southeastward moving linear segments.
The initial development will have 2000-3000 J/kg of MLCAPE and mid-
level lapse rates around 7-7.5 C/km, supporting a threat for large
hail up to ping pong ball in size. The only limiting factor to large
hail development will be modest effective shear of 25-30 kts. As
storms develop into linear segments, expect damaging wind gusts to
take over as the main threat as DCAPE values exceeding 800 J/kg will
exist ahead of the storms. However, the greatest instability will be
pushed south of the area into central Nebraska as the storms move
through, and thus, expect a weakening trend in the storms locally
with eastern extent. Storms will reach the I-29 corridor around
midnight and continue pushing eastward by early tomorrow
morning.

Lows tonight drop into the low-to-mid-60s. With the cold frontal
passage and cloud cover lingering through the day Wednesday, expect
much cooler temperatures for Wednesday afternoon. Highs will range
from the upper-60s to low-70s north to the upper-70s south.
Lingering showers will also be around through Wednesday afternoon.

Thursday will be dominated by surface high pressure region-
wide, resulting in dry conditions and a continuation of cooler
temperatures from Wednesday. High pressure drifts eastward
Thursday night into Friday, allowing for return southerly flow
and increasing temperatures/moisture. Quick-moving minor waves
within quasi-zonal flow aloft will interact with increasing
instability and increase the chances for showers and
thunderstorms, especially Friday night. At this time, 12Z GFS is
very aggressive with mid-level warming, resulting in a stout
thermal cap between 5-10 kft. If this holds, any convective
activity would be elevated. For now, broad brush 20-60 NBM POPs
seem reasonable.

This weekend into early next week, quasi-zonal flow appears to
give way to some synoptic ridging, although the degree to which
this occurs varies widely between medium-range guidance. Overall
impact will be to see gradually rising temperatures each day,
such that a return to the low 90s is possible by Tuesday.
Precipitation wise, weak waves topping the ridge will provide
periodic chances for showers and storms, but lack of continuity
precludes anything more than a 20-30 POP at this time, which is
handled well by NBM guidance.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1256 PM CDT Tue Jul 15 2025

Scattered showers and storms are set to increase in coverage around
21-22Z this afternoon near the Missouri River Valley in central
South Dakota. Storms will quickly develop into a line and push east-
southeastwards into tonight. A few storms will be capable of wind
gusts around 60 kts and hail up to ping pong ball in size, though
there is some uncertainty in how long these storms will maintain
their strength with eastward extent. With that said, it is unlikely
the TAF sites will see these types of severe storms as the greatest
threat will be in south-central South Dakota closer to the Nebraska
state line.

Storms will exit off to the east early Wednesday
morning, leaving low MVFR to IFR ceilings in its wake along with
some lingering areas of drizzle. Some smoke may also make it to KHON
overnight, but it is not expected to be thick enough to cause MVFR
visibilities at this time.

A cold front is just to the west of the area to start the period,
which will move across the area into the evening hours from
northwest to southeast. As it moves through, winds will turn from
the south to a more north/northwesterly direction. Outside of any
stronger thunderstorm wind gusts, expect gusts as high as around 20
kts this afternoon before tapering off overnight.

&&

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

&&

$$

DISCUSSION...Samet/Rogers
AVIATION...Samet