077
FXUS63 KFSD 291142
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
642 AM CDT Fri May 29 2026

.KEY MESSAGES...

- Isolated to scattered showers this morning will become more
  widespread and continue for the rest of the day. Light
  accumulations are expected with up to a 0.10" of an inch or
  two possible through tonight.

- Additional shower and thunderstorm chances (50%-80%) are
  expected over the weekend with the potential for a few
  stronger storms from Saturday night into Sunday. The main
  concerns will be damaging winds up to 60 mph and locally heavy
  rainfall.

- Low chances (<=30-40%) for rain will persist through the bulk
  of next week. However, severe storm chances continue to look
  low (5%) through next week.

&&

.UPDATE...
Issued at 508 AM CDT Fri May 29 2026

Taking a look across the area, we`re continuing to monitor areas of
developing showers lifting out of northeastern NE this morning.
However, with lingering dry air in the lower levels according to
soundings, most of this activity is currently struggling to reach
the ground. Nonetheless, we`re still on track for precipitation
coverage to gradually expand eastwards around daybreak as a mid-
level wave continues to progress through the area and low-level
moisture advects into the region with strengthening southeasterly
surface winds. From here, expect a rinse and repeat for the rest of
the day with pockets of intermittent showers lifting through the
area keeping conditions on the drearier side.

With increasing precipitation chances and persistent cloud cover
expected, decided to taper highs down across areas west of I-29 for
the day. This resulted in highs in the low to mid 70s across
southcentral SD and upper 70s to low 80s everywhere else. Lastly,
could see a brief transition to drizzle this evening as we lose mid-
level saturation. However, we could also an uptick in shower and
thunderstorm development from early saturday morning (4-5 am) onward
across the Missouri River Valley as the Nocturnal LLJ strengthens.
While severe weather is not expected, stronger updrafts could
produce small hail and locally heavy rainfall.

&&

.DISCUSSION...
Issued at 222 PM CDT Thu May 28 2026

High level cirrus continues to blanket the area early this
afternoon. There is enough heating to result in some spotty showers
for the rest of the afternoon and early evening timeframe though.
Some rumbles of thunder and perhaps a few gusts up to 30-40 mph
could accompany the showers. Like yesterday, these showers will be
diurnally driven and will cease as the boundary layer stabilizes by
sunset. However, rain chances will not be done yet as a diffuse
upper level low currently over the central Plains will slowly push
into the area this evening and night. This will bring more
stratiform precipitation to the area with the potential for a rumble
or two of thunder mainly for locations along and north of the
Missouri River and west of I-29. The clouds and rain will keep low
temperatures on the warm side, only falling to the upper 50s and 60s.

Friday is looking to be cooler than previously thought as this same
system will take its time meandering through the forecast area. A
few convective showers to weak thunderstorms are possible on its
front edge where slightly less cloud cover and slightly higher
instability will be present. But with the rain in the area, high
temperatures will only warm to the 70s to low 80s, making for a warm
but dreary day. On top of the rain, southeast winds will be
strengthening in response to as the surface pressure gradient
tightens across the area. Gusts up to 15-35 mph is expected, with
the strongest winds occurring along and west of the James River.
Latest guidance is suggesting that saturation in the dendritic
growth zone (DGZ) could become offset from the better low level
saturation. This looks to potentially lead to some drizzle in
locations that are not saturated aloft. Chances (40-60%) for rain
will persist through the overnight hours. Low temperatures will fall
to the 50s overnight. Rainfall through this period of time looks to
be light ranging from a few hundredths to a few tenths.

The next chance for isolated strong to severe storms will come on
Saturday as an upper level trough grazes the western fringes of the
area. Broad southeast flow will advect higher moisture into central
Nebraska and central/western South Dakota. Deep layer shear will
remain weak at about 20 knots. Instability however looks to
potentially (40-80% chance) exceed 1,000 J/kg across parts of south
central South Dakota. Warm air advection (WAA) in conjunction with
shortwave troughs rotating through the base of the upper level
trough will provide forcing for ascent. Some questions remain as to
whether the instability can overcome the weaker deep layer shear and
where the warm sector sets up. For now, think a conditional risk for
strong to severe storms is on the table. Rain chances look to
continue through the night and on Sunday as well. Severe weather
chances are questionable on Sunday as well since the main upper
level trough`s vort max will be advected well northwest of the area.
Steeper mid level lapse rates may also result in a large cap aloft.
For now, the ensembles show a broad 40-60% chance for rainfall
totals to exceed a tenth of an inch on Sunday. Will keep an eye on
this potential over the next few days. Total rainfall amounts look
to reach up to and possibly exceeding a half an inch by the end of
the weekend. The highest totals look to fall across central and
south central South Dakota. The amount and location of heaviest rain
can still change over the coming days depending on how showers and
storms shake out. Aside from rain chances, the weekend will see
breezy southeasterly winds with high temperatures warming to the
upper 70s to low 80s.

The omega block pattern looks to persist into early next week.
Medium range guidance depicts the omega block beginning to break
down by the middle of next week. For the Northern Plains, it looks
like zonal flow will take over. This pattern change will still keep
rain chances in the forecast as broad southerly flow will advect
sufficient moisture into the area. The ensembles show 30-40% chance
or less for rainfall exceeding a tenth of an inch through the bulk
of next week. Questions remain regarding whether or not vertical
shear will be strong enough to support strong to severe storms. This
uncertainty is nicely shown in the latest machine learning (ML)
guidance as all of the ML models show a 5% chance or less for severe
storms. Aside from rain and storm chances, high temperatures look to
remain warm in the 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 635 AM CDT Fri May 29 2026

Mainly VFR conditions will transition to a mix of MVFR to IFR
and lower this TAF period. Taking a look at radar, lots of virga
on radar right mainly due to drier air in the lower levels.
Should see things saturate by mid to late morning leading to
scattered showers at all TAF sites at times. Decided to go
prevailing since coverage should be widespread. Might have a
brief break this evening as we lose mid-level saturation.
However, could get additional redevelopment by early Saturday
morning with a strengthening nocturnal LLJ. As a result, added
in PROB30s for both KFSD & KSUX for the increased probabilities
towards the end of the period. Lastly, MVFR to IFR (and potentially
LIFR) cigs will gradually spread eastwards overnight leading to
continuous dreary conditions.

&&

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

&&

$$

UPDATE...05
DISCUSSION...Meyers
AVIATION...05