649
FXUS63 KFSD 061750
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1250 PM 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. Isolated
  amounts up to a 0.10" of an inch will be possible.

- A few stronger storms will be possible by Saturday evening.
  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 isolated amounts of up to a 0.10"
of an inch possible 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 along portions of the Missouri
River Valley and east of I-29. Similar to yesterday, a few pockets
of moderate rainfall will be possible with 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 the northern stream
jet. 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 across our CWA through the
evening hours. However, as instability quickly diminishes as we get
latter into the evening; the greatest threat to this lingering
activity would become time. 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 closer to 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 into the midweek 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 /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1250 PM CDT Fri Jun 6 2025

Mostly VFR conditions expected for this period. Isolated to
scattered light rain showers are possible this afternoon. Under
showers ceilings may decrease to MVFR status. While severe weather
is not expected, a few stronger showers could produce lightning and
wind gust to 40 mph. Near the end of the period KSUX may see
additional showers to thunderstorms. Again, severe is not expected.

Winds are light and variable, with minimal shear through 6000 ft
AGL. There is some weak instability present, and some weak funnels
have been reported. Funnels are possible through around 07.01Z.

&&

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

&&

$$

DISCUSSION...05
AVIATION...AJP