688
FXUS63 KFSD 312322
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
622 PM CDT Fri May 31 2024

.KEY MESSAGES...

- Showers and thunderstorms will be capable of lightning and
  locally heavy rainfall late this afternoon and evening.
  Isolated funnel clouds will also be possible. The better
  chances will be southeast of a Yankton to Windom line.

- Ingredients are coming together for a potential severe weather outbreak
  on Sunday afternoon and night. Stay tuned for updates.

- Tuesday will be the next better chance for severe weather, but
  still some question marks, the main one being a potential MCS
  late Monday night into Tuesday morning which could push the
  deeper instability south and really limit Tuesday afternoon
  potential.

&&

.DISCUSSION...
Issued at 207 PM CDT Fri May 31 2024

Showers and thunderstorms with locally heavy rain will continue
through sunset, then gradually diminish and shift east through the
night. Model soundings indicate about 500 to 1000 J/kg CAPE so
instability is marginal and shear is very weak so heavy rain and
maybe some pea hail are the main concerns. One other thing to watch
for will be funnels and possibly a brief landspout. Low LFC`s, 0-3km
CAPE of 125-175 J/KG and weak winds in and above the boundary y layer
are all supportive. Looking like a decent chance for a small area of
1-3 inches of rain, especially in northwest IA and far southeast SD.
With saturated ground and light winds tonight some patchy fog will
be possible. Lows should be mainly in the 50s with a few 40s
possible in central SD.

Saturday should be a fairly quiet day with dry mid levels.
Instability begins to build back to the north into southwest and
south central SD. This is mainly elevated instability as the surface
based instability looks capped. Even the elevated instability will
be fighting a cap so the chances will remain on the lower side for
now with just a small chance for severe weather. Temperatures will
be mild with highs mostly in the mid 70s.

Saturday night into Sunday morning will see some elevated
instability build a little farther north into central SD towards the
James Valley. Elevated instability might approach 1500 J/kg wit h
moderate amounts of shear so at least some isolated hailers
would be possible during this time.

A relatively strong wave and associated cold front will move into
central SD on Sunday afternoon with unstable air in place ahead of
this boundary. The EC ensemble and GEFS both showing a very good
chance for CAPE values to exceed 2000 J/kg which is backed up by the
latest GFS and Nam sounding output. Assuming 2000-2500 J/kg CAPE and
30-40 knots of shear would expect a few supercells in central SD
towards the James Valley with a likely transition to something more
linear between 6-8 pm.

Monday should be a quick quieter warm day as another trough develops
and moves in for Tuesday. Still a lot of question marks for Tuesday
with timing of the wave which will obviously play a role in any
severe potential. If timing does allow for afternoon and evening
thunderstorms and a morning MCS does not suppress instability south
there should be enough support for severe weather. But again, a lot
of question marks.

Wednesday into Friday looks like northwest flow aloft will develop
which should help bring a drier pattern with seasonally warm
temperatures. Lows generally in the 50s with highs in the 70s to
lower 80s.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 617 PM CDT Fri May 31 2024

Showers and isolated thunderstorms from the Interstate 29
corridor and eastward will slowly diminish from west to
east through 06Z with brief heavy rainfall possible. In
addition, IFR ceilings will develop as the precipitation winds
down. These clouds will break up on Saturday morning. Winds will
be light through the TAF period.

&&

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

&&

$$

DISCUSSION...08
AVIATION...JM