Harrisburg, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

242
FXUS63 KFSD 231738
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1238 PM CDT Tue Jun 23 2026

.KEY MESSAGES...

- Isolated strong to severe storms will be possible Tuesday
  afternoon into early evening. Ping pong ball sized hail is
  the primary risk, with a few 50 mph gusts also possible.

- Near to slightly below normal temperatures continue through
  the end of the week with passing showers and isolated
  thunderstorms to the north by early Friday.

- Growing potential for an extended period of heat and humidity
  beginning Saturday, but intensifying Sunday into next week.
  Heat and humidity could bring very low probabilities for
  thunderstorms each day.

&&

.DISCUSSION...
Issued at 1234 PM CDT Tue Jun 23 2026

THIS AFTERNOON/EVENING:   Weak frontal boundary continues to drift
southeast early this afternoon. Instability continues to slowly grow
ahead of this boundary, through latest RAP/HRRR MLCAPE estimates
continue to range between 900-1400 J/KG. As we reach convective
temps we`ll begin to see isolated strong or severe storms by mid-
late afternoon. The increase in effective wind shear AOA 40 knots
could drive a few slightly more organized storms, however rather
marginal mid-lvl lapse rates and tall-thin CAPE profiles may
indicate the severe risks may be more limited.  Analog soundings
would suggest hail up to 1.5" will be possible, with very isolated
stronger wind gusts. The latest SSCRAM guidance also points to
greater hail than wind risks through the heart of the CWA by mid-
late afternoon.  The persistent dPVA this evening along with
flattening of the surface front may keep scattered showers and
embedded thunderstorms going along or south of I-90 through the
evening and into the early overnight hours (along Highway 20). The
severe weather risk should diminish quickly by 7-8PM however.

TONIGHT: A light wind will persist for most of the region overnight,
with a slightly increased northwest wind developing by daybreak
Wednesday.

WEDNESDAY-THURSDAY: A pair of quiet days, with cooler temperatures
can be expected for Wednesday and Thursday as surface ridging moves
through the region. Variable afternoon CU may develop through the
region Wednesday afternoon as highs climb into the middle to upper
70s. Light and variable winds may lead to patchy fog Thursday
morning, though we`ll watch for some high level clouds drifting
northward into the MO river valley Thursday morning.  This cloud
cover will be tied to a low-lvl baroclinic zone stretching from the
Black Hills region towards the Omaha area.  Temperatures once again
remain in the middle to  upper 70s.

FRIDAY: A stronger mid-lvl wave ejects out of the Central and
Northern Rockies early Friday. The 00Z ECE/EC continued to be
focused further south than the GEFS/GFS/CMC/CME/NAM with the track
of this wave, associated warm advection, and greatest potential for
light QPF. That said, the probability for more than 0.10" is no more
than 20-30% in any solution.  By Friday afternoon, the advancement
of a warm front and increasing EML should lead to only minor risks
for redevelopment by the evening over central South Dakota.

SATURDAY-MONDAY: A general pattern evolution towards western CONUS
troughing and southeastern CONUS ridging develops quickly Saturday.
This pattern will signal a shift towards much warmer temperatures,
stronger EML development, and convection risks generally driven by
the need for a triggering mechanism to overcome the inhibition. More
impactful will be the arrival of very warm temperatures.
Temperatures Saturday rise toward the middle to upper 80s, however
highs will accelerate upwards Sunday and Monday into the 90s. Latest
NBM/LREF indicate high probabilities (>70) of exceeding 90
degrees with >30-50% probabilities of exceeding 95 degrees
Sunday. One thing to be aware of is the warm bias in GFS and
GEFS surface temperatures as we move through next week which
could skew blends slightly and present some pretty unrealistic
high temperature/CAPE projections.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1158 AM CDT Tue Jun 23 2026

CU field beginning to expand early this afternoon as a frontal
boundary begins to move into the forecast area. We`ll continue
to see gradual shower and storm development over the next 2-4
hours ahead of this boundary, though coverage remains quite
uncertain. A few stronger hail producing storms with 50 mph may
be possible.

The front will clear HON/FSD by early evening, with scattered
showers and thunderstorms lingering near KSUX deeper into the
evening. VFR conditions are likely in this activity with very
brief visibility and ceiling reductions in passing storms.

VFR skies and light winds arrive overnight and continue into
Wednesday morning.

&&

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

&&

$$

DISCUSSION...Dux
AVIATION...Dux