748
FXUS63 KFSD 020524
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1224 AM CDT Tue Jun 2 2026

.KEY MESSAGES...

- Continued unsettled conditions remain in the region through
  the week. No widespread severe weather risks, but conditional
  and highly localized risks will be possible.

- Focus areas for the majority of the severe weather risks
  ahead will be west of I- 29 and especially along or west of
  the James River valley.

- Temperatures remain in the 80s through the week and rise
  towards the upper 80s by the end of the weekend.

&&

.UPDATE...
Issued at 912 PM CDT Mon Jun 1 2026

A few weak showers and isolated weak thunderstorms have developed
across northwest Iowa this evening. These showers and storms have
developed on a westward retrograding boundary. Think that any
additional development will come to an end soon as the boundary
layer stabilizes, shutting off the ability for surface based parcels
to be lifted to their LFC`s. Showers and storms have already
developed this evening along the high plains across western Nebraska
and western Kansas. This convection is expected to push eastwards
through the rest of the evening and overnight timeframe, paralleling
I-80. Elevated instability will be much weaker across our area, so
any precipitation that does make it into parts of the Missouri River
Valley is expected to be mainly rain with perhaps a stray rumble of
thunder possible.

High pressure sitting over the Great Lakes area will be advecting
drier, more stable area into the area as east/southeast flow
persists through the day tomorrow. This will push the instability
gradient to the west. This gradient looks to end up paralleling I-29
by the late afternoon hours tomorrow. A mesoscale convective vortex
(MCV) looks to develop from the overnights storms. This MCV looks to
interact with this instability gradient and develop additional
showers and thunderstorms. Mean flow is roughly parallel to the
boundary which looks to allow these showers and storms to persist
from late morning through the bulk of the afternoon timeframe. Don`t
think any of these storms will be strong to severe as deep layer
shear is quite weak, on the order of 10-15 knots. However, brief
gusty winds, brief heavy rain, and small hail are possible. The main
impact from these showers and storms is that the look to either
parallel I-29 or develop just to the west of the interstate. Even
though these storms are not expected to be strong to severe, they
can still impact outdoor events. A MCS looks to develop along the
Black Hills and push northeastwards along a surface boundary draped
from northeast South Dakota down into the Black Hills. This boundary
looks to reside within a surface trough and is somewhat supported by
convergence in the low levels. As the MCS progresses northeastwards
along the boundary, it looks to run into a worsening environment as
instability wanes and shear weakens. This still looks to support a
lower end severe weather threat along and west of a Lake Andes,
South Dakota to Huron, South Dakota line where large hail and
damaging winds are possible before the MCS races out of the
available instability and weakens.

Another potential for strong to severe storms is possible on
Wednesday. Wednesday is starting to look more like a line of storms
as another boundary draped within a surface trough pushes into the
area. Shear profiles look to be parallel to the boundary, supporting
the potential for a line of storms. That said, still enough
uncertainty to not say much beyond that as Tuesday night`s storms
could affect Wednesday`s storms.

&&

.DISCUSSION...
Issued at 112 PM CDT Mon Jun 1 2026

THIS AFTERNOON/EVENING: Rather stable conditions across the region
early this afternoon, outside of a lone elevated storm over north
central Iowa.  Satellite shows a weak mid-lvl wave crossing central
Nebraska and lifting towards the Tri-State area. Soundings
closer to home show a very stable layer that should prevent any
surface based convection to develop as temperatures rise towards
the 80s. What this wave may do is briefly slow the rise in
temperatures, but bring a chance for a few high based sprinkles.
A second area we`ll be monitoring today is right along the
eastward edge of the CWA where a bit less inhibition is in
place. With a very weak shear profile, any storm that develops
is not expected to be strong to severe.

TONIGHT: Most of the focus during the overnight hours will be
across the Nebraska Panhandle, Black Hills region, and western
Kansas. As yet another wave ejects out of the central Rockies,
we should see renewed convection develop and quickly try to
congeal into one or more clusters as they cross western
Nebraska and South Dakota. Latest CAMS continue to hint at
these storms trying to slowly lift northeast but should weaken
as they reach a more stable atmosphere. That said, Could
continue to see a limited wind risk into south central South
Dakota and along portions of the Missouri River valley by 3am.
Further north, the abundance of low-lvl moisture combined with
light winds could lead to patchy fog developing.

TUESDAY:  We`ll have to keep a close eye on the progression of the
convection in Nebraska as guidance does show signs of a developing
MCV that may track east and slowly north during the day. At this
point, destabilization of the boundary layer will need to be watched
as we could see pockets of 2000 J/KG MLCAPE develop in a narrow
corridor ahead of this wave.  Isolated to scattered storms could
develop based on the weakening of convective inhibition
somewhere between the James river and I-29. Effective shear
remains very weak. but there may still be appreciable 0-1km
helicity to lead to a few rotating storms/funnels. However the
widespread severe risk remains low and more focused on marginal
hail, but could see future outlooks extended further east.
Better focus for convection will be across far western SD along
a frontal boundary edging into the state. As yet another wave
ejects into the Plains scattered convection along this boundary
should develop and begin to track east northeast. One thing to
note today is that mid-lvl heights may be rising across central
SD in the evening, with 700 mb temperatures also rising. The
more meridional 700:500 flow should prevent a strong eastward
shift after dark.

WEDNESDAY/THURSDAY:  Uncertainty grows with the Wednesday and
Thursday forecast as we remain stuck in this general mid-lvl
southwesterly flow pattern. The aforementioned front will attempt to
slide eastward on Wednesday, though a much more e complicated
forecast in regards to the environment ahead of the front. Yet
another weak mid-lvl area of vorticity tracks through the Tri-State
area, increasing the risks for mid-lvl clouds but also a few showers
and isolated thunderstorms by the afternoon. The area with the
greatest risks for strong convection will be along that frontal
boundary in central South Dakota by mid-late afternoon. Additional
showers and thunderstorms may be possible into the overnight
hours further east as the LLJ intensifies. Latest NBM guidance
suggests 8- 95% PoPs in this timeframe, but my confidence in
overall coverage is not as high as that chance suggests. A bit
of a repeat performance on Thursday, with the greatest severe
risks again focused west of the James River and into
Southwestern South Dakota by the afternoon.

FRIDAY-SUNDAY: MId-lvl troughing moves through the Dakotas on
Friday, potentially pushing strong convective risks further east
into MN/IA.  Confidence is very low in this time period given all of
the various uncertainty associated with the forecast in the days
before.  Confidence rises for next weekend with drier weather and
near to slightly above normal temperatures likely.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1224 AM CDT Tue Jun 2 2026

Showers and thunderstorms that have developed over Nebraska continue
to drift eastwards. These storms will encounter an unfavorable
environment and are expected to weaken. Any chance for rain should
come to an end before reaching KSUX but trends will be monitored.
Another round of showers and thunderstorms looks to be on the table
for late this morning and afternoon. Uncertainty continues regarding
where these showers and storms will set up but it looks to be along
and west of I-29. Will include mention of rain when confidence in
location increases. The showers and storms look to dwindle into the
evening hours. Another round of showers may be possible near KHON to
end the period. Besides rain chances, winds will turn southeasterly
by tomorrow afternoon with gust up to 15-30 knots, strongest west of
I-29.

&&

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

&&

$$

UPDATE...Meyers
DISCUSSION...Dux
AVIATION...Meyers