536
FXUS63 KFSD 292310
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
610 PM CDT Sun Jun 29 2025

.KEY MESSAGES...

- Isolated storms remain possible into early this evening
  southeast of a Tracy, MN to Sioux Falls, SD to Yankton, SD
  line. Primary hazards if stronger storms develop are quarter
  size hail and 60 mph winds.

- A second round of showers and a few storms is expected to move
  in from the west this evening and overnight. While most storms
  will stay below severe limits, an isolated chance for a strong
  to severe storm is possible.

- Chances for showers and storms return for the middle and end
  of the week. While probabilities for rain increase (50-70%)
  heading into the weekend, uncertainty increases in the large
  scale pattern as well.

&&

.DISCUSSION...
Issued at 251 PM CDT Sun Jun 29 2025

A few mid and high level clouds persist across the area this
afternoon. A weak boundary is slowly drifting southeastwards across
the area and looks to potentially serve as the focal point for new
shower and storm development. These storms will be forced by another
weak shortwave trough pushing in from the west. Instability will be
weaker than what we have seen over the past few days with magnitudes
of 1,000 to 1,500 J/Kg. Shear on the other hand be a bit better with
deep layer shear values up to around 35 knots. But, shear further
increases above 6km. Hodographs are generally straight but do show
wind profiles backing with height. Thus splitting storms that may
favor left movers looks to be the main storm mode this afternoon.
This will result in the potential for large hail up to quarter size
and damaging winds to 60 mph. With only weak forcing in place think
that storm coverage will be isolated to perhaps scattered mainly
southeast of a Tracy, MN to Sioux Falls, SD to Yankton, SD line.
This activity will wane during the evening hours before a second
round of showers and storms moves in from the west. Instability will
be weakening as this next round of rain moves in but shear will be
increasing. Thus, think the same hazards are possible though this
potential will be quite isolated due to the weak instability. Should
see showers persist through the night before exiting the area during
the morning hours tomorrow. Low temperatures will fall to 60s
overnight.

The previously mentioned showers will be on the move out tomorrow
morning, leaving mostly dry conditions for the afternoon hours. The
exception will be parts of southwest Minnesota where a deepening
upper level wave will steepen mid level lapse rates enough to
generate minor instability on the order of about 500 J/kg. This
looks to be just enough to develop a few showers and storms across
this area. Good news is that no storms are expected to be severe at
this time. Outside of rain chances, Monday will see high
temperatures warm to the 80s and lows falling to the upper 50s to
low 60s.

Upper level ridging will build over the southwest CONUS on Tuesday,
placing the Northern Plains downstream of the ridge. This will
promote upper level subsidence across the area and will keep
conditions dry. With 850 mb temperatures warming to the mid to upper
teens along with southerly return flow at the surface, highs will
warm a bit more to the mid 80s to up to about 90F west of the James
River. Lows will fall to the 60s overnight.

Upper level ridging persists through the middle of the week across
the desert southwest. While the Northern Plains will remain
downstream of this ridge, there could be weak ridge riding
shortwaves that could bring more chances for showers and storms. The
ensembles show modest probabilities (30-50% chance) for exceeding a
tenth of an inch of rain on both Wednesday and Thursday.

The ridge axis will push east of the Northern Plains on Friday,
resulting in height falls aloft and continued chances for rain
through Saturday. Medium range guidance varies in the evolution of
this wave to have left model blended PoPs in place. The ensembles
become more excited about this potential though as they increase
their probabilities up to a 50-70% chance for exceeding a tenth of
an inch of rain. Will keep an eye on this potential over the coming
days. Aside from rain chances, high temperatures will remain in the
80s and 90s for the middle and end of the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 605 PM CDT Sun Jun 29 2025

Very isolated shower/thunderstorm activity ongoing at the start of
this period, but this should wane with loss of heating by sunset.
Additional showers and scattered storms will move east across the
region later this evening into early Monday morning. While it is
difficult to pinpoint exact timing/location of any thunderstorms,
have included narrow windows of more probable timing for KFSD/KSUX
after 30/06Z.

Any showers/storms may produce erratic gusty winds, but overall
winds will remain fairly light until mixing increases midday
Monday, with gusts 20-25kt expected through Monday afternoon.

&&

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

&&

$$

DISCUSSION...Meyers
AVIATION...JH