Harrisburg, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

583
FXUS63 KFSD 060928
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
428 AM CDT Fri Jun 6 2025

.KEY MESSAGES...

- Areas of patchy locally dense fog will persist through the
  mid-morning mainly across southcentral SD. Visibilities of a
  mile or less will be possible at times. Make sure to drive
  with care!

- Spotty showers continue during the day on Friday. Pockets of
  heavy rainfall could lead to a quick 0.10" of an inch at times.

- A few stronger storms will be possible by Saturday afternoon.
  With damaging winds up to 60 mph being the primary threat.

&&

.DISCUSSION...
Issued at 426 AM CDT Fri Jun 6 2025

TODAY & TONIGHT: Another dreary day ahead! Taking a look across the
area, overcast skies continue across most of the area with a few
light showers mainly east of I-29 and north of U.S. Highway-14.
We`re also starting to see some patchy fog develop mostly across
southcentral SD this morning. While some high-resolution guidance
does show some potential for locally dense patches as far east as
the James River Valley, not expecting widespread visibility
reductions below a mile at this time. As a result, decided to hold
off on any fog-related headlines for now. However, we will continue
to watch over the coming hours just in case a short-fuse advisory is
needed. With this in mind, make sure to slow down and be prepared
for rapid changes in visibility on those morning commutes. From here,
expect the developing fog to gradually erode though the mid-morning
as temperatures warm into the low to mid 70s for the day.

Looking aloft, the wave train continues as another mid-level wave
dives across western South Dakota and Nebraska providing some
additional lift for a few spotty showers to develop this
afternoon/evening. While coverage will be sparse, won`t be
impossible for developing showers to produce some pockets of
moderate rain at times given the 200-300 J/kg of instability above
the boundary layer and support from a weak jet streak. However, most
accumulations should be light with up to a 0.10" of an inch expected
through this evening. Nonetheless, with most of this activity being
diurnally driven; expect most of this activity to gradually diminish
by through the evening hours. Lastly, expect the dreary conditions
into the overnight hours as temperatures gradually decrease into the
low to mid 50s for the night.

SATURDAY: Looking into Saturday, its rinse and repeat to start the
day as another mid-level wave dives across the western portions of
Nebraska and South Dakota. The combination of increasing lift and a
strengthening jet streak overhead should be enough to get more "pop
up" showers around daybreak mainly east of I-29. Similar to
yesterday, a few pockets of moderate to heavy rainfall could develop
in developing showers with about of 100 J/kg of instability above
the boundary layer. However, most of this activity should push east
of our area heading into the early afternoon. With this, the stage
is set for our next chance for stronger storms. Looking aloft, a
strengthening upper-level low will dive into the northern plains
with the nose of a jet streak. As peak heating is achieved, should
see scattered strong to severe storms thunderstorms gradually
develop across eastern ND and northeastern SD along the approaching
cold front starting around the early afternoon.

With the mean wind aloft paralleling the front, should see this
activity gradually grow upscale into a broken line of thunderstorms
as it progress southeastwards during the late afternoon to early
evening hours eventually reaching our far northwestern zones (Beadle
county) closer to 6 pm to 7 pm. Given the decent instability (800-
1400 J/kg) and 30-40kts of bulk shear ahead of this activity, could
see a few stronger cells hold together along and south of the U.S.
Highway-14 corridor through the evening hours. However, the greatest
threat to this activity would be time as the instability would
quickly diminish with the loss of diurnal heating during the
evening. Nonetheless, with DCAPE values between 800-1000 J/kg and
"inverted V" soundings at the surface, can`t rule out an
occasionally strong wind gust up to 60 mph with collapsing
thunderstorms. Could also see a marginal large hail threat as mid-
level lapse rates approach 6.5 degrees C/km with the front. Given
the environment though, there would likely be more small hail than
large hail this far downstream. Lastly, should see most of this
activity exit the region right around midnight.

SUNDAY ONWARDS: Heading into the extended period, an active pattern
continues aloft as the previously mentioned ULL gradually rotates
southeastwards by Sunday. Periodic scattered showers will be
possible through Monday as multiple shortwaves rotate around the
main low. The highest of these chances (20%-30%) should occur by
Monday afternoon as lift increases lift along and behind an
approaching cold front. With limited moisture in the dendritic layer
according to soundings, accumulations should be light with most
ensemble guidance showing a 30-60 percent probabilities for
measurable accumulations along and northeast of a Huron to Sioux
Falls to Storm Lake, IA line with the highest probabilities in
southwestern MN. With this in mind, temperatures will be seasonably
cooler between Sunday and monday with daily highs in the upper 60 to
mid 70s. By Tuesday, upper-level ridging moves into replace the
departing ULL leading to mostly quiet conditions through Thursday.
Lastly, temperatures will trend warmer as highs increase from the
upper 70s to low 80s on Tuesday to the low to mid 80s by Thursday
with the warmest conditions on Wednesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1046 PM CDT Thu Jun 5 2025

A few light showers persist across the area late this evening.
Should see the showers continue to wane over the next few hours.
Ceilings will lower to MVFR/IFR/LIFR levels mainly along and west of
the James River during the overnight hours. Though MVFR ceilings
could expand further westward into parts of southwest Minnesota and
northwest Iowa.

Light and variable winds are expected throughout the day tomorrow
while ceilings lift back to VFR levels through the morning hours.
Another round of isolated to scattered showers is expected for the
afternoon hours. The showers will wane by sunset, leaving mainly dry
conditions to end the TAF period.

&&

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

&&

$$

DISCUSSION...05
AVIATION...Meyers