476
FXUS63 KFSD 071129
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
629 AM CDT Mon Jul 7 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms likely return this
  afternoon and evening. Some of these storms could become
  severe especially west of I-29 with up to 2 inch hail and
  wind gusts up to 70 mph wind gusts being the primary threats.

- Additional chances for showers and storms will continue from
  late Wednesday through Friday. While the details are
  uncertain, a few stronger storms could develop so continue to
  monitor your local forecast for updates.

- Seasonal temperatures will continue through Tuesday with highs
  mainly in the 80s. Could briefly see the return of some 90s on
  both Wednesday and Thursday mainly west of the James River
  Valley.

&&

.DISCUSSION...
Issued at 242 AM CDT Mon Jul 7 2025

TODAY & TONIGHT: A risk for stronger storms ahead! Taking a look
across the area, mostly clear conditions continue this morning with
a few isolated thunderstorms developing across the western portions
of the state. As this developing activity continue to progress
eastwards over the next several hours, it will likely outrun the
better corridor of shear leading to a gradual weakening overtime.
With this in mind, not expecting this activity to reach our area.
From here, mostly quiet conditions will persist for the first half
of the day with temperatures likely peaking in the low to mid 80s.
As light and variable winds become more southerly ahead of our next
system, dew points will increase into the mid to upper 60s setting
the stage for our next severe weather chances. Looking aloft, could
see some scattered activity develop along the lower Missouri River
Valley during the late morning to early afternoon hours as pieces of
vorticity associated with a weak shortwave interact with an
advancing surface warm front.

While this activity is not expected to be severe, the push of
developing showers and potentially thunderstorms could do just
enough to briefly stabilize the atmosphere across the U.S. Highway-
20 corridor ahead of our main system. Getting back to the main show,
as a mid-level wave traverses the Dakotas; expect showers and
thunderstorms to initially develop across western SD during the mid
to late morning then gradually spread eastwards into central and
southeastern SD during the afternoon to evening hours. With minimal
inhibition according to soundings, developing semi-discrete
thunderstorms will have access to 1500-1800 J/kg of instability and
35-45 kts of bulk shear which will lead to a few stronger storms.
Give lapse rates between 6-7 deg C/km, large hail up to hen egg (2
inches) size would be the initial threat with the focus across
southcentral SD. However, as developing thunderstorms congeal into
linear segments and become more cold pool dominant; expect the
threat to shift towards damaging winds with gusts up to 70 mph
possible. With all this in mind, the best chances for stronger
storms looks to be between the 4 pm-10 pm timeframe with most of the
activity exiting our area around midnight.

TUESDAY-THURSDAY: Looking into the rest of the week, northwesterly
flow will return aloft by Tuesday as weak ridging sets up across the
western CONUS. Periodic shower and thunderstorm chances will
continue from the midweek onwards as a series of waves moves through
the area almost daily. While there is still some uncertainty as to
the severity of this activity, machine learning guidance seem to
have latched on to higher probabilities around the Day 4 (12z Thu -
12z Fri) timeframe. Since SPC also has portions of the northern
plains outlined in a Day 4 slight risk (15%) for the same timeframe,
this will likely be our next time period to watch for any organized
activity. Otherwise, expect temperatures to hover near to above
normal with daily highs in the 80s to low 90s.

THE WEEKEND: Heading into the extended period, could be an active
start to the weekend as a quick mid-level wave pivots through the
area on Friday promoting increased rain chances (30%-50%). However,
quieter conditions will return for the rest of the weekend with
temperatures hovering near to above normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 618 AM CDT Mon Jul 7 2025

Mostly VFR conditions with occasional MVFR vsbys will be
possible this TAF period. Taking a look at satellite imagery,
some patchy valley fog has develop across the Missouri River
Valley this morning leading to occasional MVFR vsbys. While
these conditions won`t last much past day break, should VFR
vsbys return by mid morning.

From here, occasional MVFR vsbys will return as the chances for
showers and thunderstorms increase this afternoon/evening. With
this in mind, decided to add tempo groups to all TAF sites to
fine tune timing details. Otherwise, light and variable winds
this morning will become light southerly winds this afternoon
before once again becoming more variable tonight.

&&

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

&&

$$

DISCUSSION...05
AVIATION...05