954
FXUS63 KFSD 010823
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
323 AM CDT Tue Jul 1 2025

.KEY MESSAGES...

- Chances for isolated to scattered (30 to 50%) showers and
  storms return late tonight through Wednesday night. Although
  risk is low, an isolated strong to severe storm is possible
  Wednesday into Wednesday night. Quarter sized hail and 60 mph
  wind gusts are the main hazards in stronger storms.

- Shower and storm chances continue Independence Day through the
  holiday weekend. Currently, highest chances (40-70%) are on
  Friday afternoon into early Saturday. Severe weather is
  currently not expected, but locally heavy rain is possible.
  Keep an eye on the forecast if you have outdoor or travel
  plans.

- Temperatures generally near to above normal through the next
  week. Wednesday through Friday could see heat index values
  approach 100 degrees.


&&

.DISCUSSION...
Issued at 322 AM CDT Tue Jul 1 2025

CURRENTS-TODAY: Surface high pressure prevails over the area today,
leading to mostly clear skies and dry weather through the daytime
hours. Southerly surface flow and WAA will aid in warming
temperatures into the 80s to lower 90s for highs - warmest west of
the James River. Aloft, northwesterly flow sets up as ridging begins
to build to the west. This brings the return of shower and
thunderstorm chances tonight with waves moving through this regime
mid week.

TONIGHT-THURSDAY: By this evening, a mid level wave/vort max moves
into central SD and continues to move east tonight. WAA also
increases becoming more focused through the overnight hours. These
mechanisms along with the LLJ should allow for scattered showers and
storms to develop. Severe weather risk looks to remain to the west
of the MO River into south central SD during the evening and early
nighttime hours were instability is greatest (closer to 1500 J/kg).
However, an isolated stronger storm tonight into early Wednesday
could produce some dime sized hail and wind gusts to 50 mph.

Northwesterly flow prevails through mid week. Another vort max is
progged to move through the forecast area during the day Wednesday
along with more WAA and an upper level jet streak to the north. An
isolated storm or two during the daytime hours Wednesday into
Wednesday night could be on the stronger side, with quarter sized
hail and wind gusts to 60 mph. Confidence is low though, given the
potential for overnight convection. Mid level lapse rates are around
6.5 deg C/km, but the highest lapse rates (near 7-7.5 deg C/km) are
offset from most of the greater instability (1500-2000 J/kg) and
shear (40+ kts). Storms should move to the east Wednesday night into
Thursday morning as the wave and upper jet move northeast.

Outside of storm chances Wednesday, expect warm and humid conditions
with south to southeast surface flow. With highs in the mid 80s to
mid 90s (warmest again along/west of the James River) and dew points
rising into the upper 60s, heat index values may approach 100
degrees.

Largely expect Thursday to be dry but warm, humid, and breezy as the
mid/upper level ridge axis slides overhead. More prevalent dew
points in the upper 60s to lower 70s along with widespread
temperatures in the 90s again leads to heat index values near in the
upper 90s to 100 degrees.

JULY 4TH-THE WEEKEND: Ridge axis aloft slides east for July 4th,
with troughing moving into the western Dakotas and NE. Guidance
remains varied on the details, but unsettled weather with showers
and storms across the region for the 4th. Greatest chances still
look to be focused in the late afternoon through the nighttime hours
as the surface low and main mid level trough/wave move east into
Saturday morning. Severe weather risk looks low at this time with a
lack of shear and meager mid level lapse rates. Shower and storm
chances continue Saturday as the main wave moves east in the
morning. Locally heavy rainfall is possible during this period with
PWAT values in the top 5% of values compared to climatology.
Additionally, deep warm cloud layer and efficient moisture transport
support locally heavy rainfall with thunderstorms.

Pattern flattens into the latter half of the weekend, with
a couple of weak perturbations moving through. So anticipate at
least some lower end shower and storm chances to continue through
Sunday night.

Hot and humid conditions expected on the 4th with another day with
heat indices in the 90s to near 100. Highs through the holiday
weekend in the 80s and 90s, highest on the 4th.

EARLY NEXT WEEK: More zonal to northwesterly flow prevails early
next week, allowing for continued shower and thunderstorm chances.
Given model divergence in solutions, confidence is low in the
details. Temperatures continue to be near to above normal.


&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1025 PM CDT Mon Jun 30 2025

VFR through most of the period. A chance for showers and
thunderstorms will come after about 3z with the better chances
north of I-90, but for now confidence is fairly low.

&&

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

&&

$$

DISCUSSION...SG
AVIATION...08