280 
FXUS63 KFSD 281118
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
618 AM CDT Thu May 28 2026

.KEY MESSAGES...

- A few spotty sprinkles to very light showers will be possible
  this afternoon with minimal accumulations.

- After warmer temperatures today, slightly cooler and more
  seasonal conditions will return over the weekend with low to
  moderate precipitation chances (40-80%) concentrated along 
  and west of the James River Valley.

- Low chances (30% or less) for rain will persist through the
  first half of next week. However, severe storm chances
  continue to look low over the next week.

&&

.UPDATE...
Issued at 340 AM CDT Thu May 28 2026

Taking a look across the area, quieter conditions continue this 
morning with high-level cirrus moving through the area. Most areas 
will wake up to another warm start with temperatures expected to be 
in the low to mid 60s. With the return of mixing after daybreak, 
should see temperatures top out in the upper 80s to low 90s by early 
afternoon with breezy southeasterly winds. Similar to yesterday, a 
cumulus "Cu" field should develop by mid to late afternoon given the 
couple hundred Jules of instability above the mixed layer. Can't 
rule out a spotty sprinkle to very light shower at times this 
afternoon. However, a dry sub-cloud layer according to soundings 
should keep most accumulations at bay through this evening. 

Looking aloft, as the ridge axis shifting further eastwards; 
southeasterly flow will allow for slightly better moisture return in 
the evening to overnight hours. With this also coinciding with a 
strengthening nocturnal LLJ and approaching shortwave, we could see 
a few scattered showers lifting out of central NE into areas along 
an west of the James River Valley. While accumulations will be 
mainly light, could see this festering activity persist 
intermittently throughout the morning hours on Friday before 
coverage gradually expands eastwards into the afternoon. With all 
this in mind, slightly increased POPs from 00z Fri through 00z Sat 
to show the gradual eastward expansion of our precipitation
chances.

&&

.DISCUSSION...
Issued at 157 PM CDT Wed May 27 2026

Beginning to see some CU develop early this afternoon. This CU field 
looks to mature just a little bit more to produce weak 
thundershowers across the area over the next few hours. With weak 
instability in place (~500 J/kg) and deep layer shear values on the 
order of 10-15 knots, severe weather is not expected. With dry low 
levels and high LCLs, DCAPE values will be high, near 1,000 J/kg. 
Thus, gusty winds are possible with any weak storm that forms. The 
strongest gusts could reach up to 40-45 mph. Lightning is also 
possible as well which could impact outdoor events. The good news is 
that these weak storms will be diurnally driven so they will quickly 
dissipate by sundown. Low temperatures will remain on the warm side, 
only falling down to the low to mid 60s.

The omega block pattern will persist through Thursday, with broad, 
weak southeast flow persisting across the area. This will keep high 
temperatures in the upper 80s to low 90s. Dew points will remain in 
the 50s which will result in lower humidity values across the area. 
There could be a few showers though moisture quality is a bit 
uncertain. Thus, have left the forecast dry for Thursday afternoon 
and evening. Winds will strengthen out of the south east with gusts 
up to about 30 mph. With dry conditions in place, there could be 
locally elevated fire danger in locations that received little to no 
rain recently. Otherwise, low temperatures will remain warm, only 
falling down to the upper 50s to low 60s. 

Friday looks to be another dry day for the majority of the area. 
High temperatures will begin to cool this day with highs warming to 
the 80s to up to about 90F. Breezy southerly winds will persist 
though the strongest winds will take place west of I-29 and 
especially west of the James River as the surface pressure gradient 
will be tighter in this area. Gusts up to 20-35 mph is expected with 
isolated gusts potentially reaching up to about 40 mph. A closed low 
that is spinning over the western CONUS will begin to push 
eastwards. This trough will not make it fully to the forecast area 
but begin to brush up against the area Friday evening. This could 
result in some showery activity along and west of the James River 
though chances for rain are low (<=30%) at this time. 

Chances for rain will only increase for Saturday and Sunday as the 
trough edges closer to the area. The highest chances for rain will 
come Saturday night as a warm air advection (WAA) strengthens aloft 
in tandem with weak shortwaves rotating around the base of the upper 
trough. The ensembles show a 40-70% chance for rainfall amounts to 
exceed a tenth of an inch for this period of time, highest along and 
west of the James River. Chances for rain will decrease for the day 
on Sunday, down to a 30-50% chance for exceeding the same amount of 
rain. Some instability looks to be in place, signaling the 
potential for thunderstorms though shear values remain weak, 
precluding severe storm chances. With rain chances hanging around 
for the weekend, high temperatures will be a bit cooler, only 
warming to the 80s. 

The omega block pattern looks to persist through the first half of 
next week. High temperatures will remain on the warm side in the 
80s. While forcing for ascent will be weak, the ensembles continue 
to show a <=30% chance for rainfall amounts to exceed a tenth of an 
inch, signaling low end chances for rain during this period of 
time. With the ridge axis centered over or near the forecast area, 
wind shear looks to remain weak. While thunderstorms will be 
possible, severe weather chances look to remain low at this
time.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 614 AM CDT Thu May 28 2026

VFR conditions will persist this TAF period. Taking a look
across the area, high-level cirrus continues to progress
through the region this morning as mostly quiet conditions
continue. Besides a few scattered showers overnight mainly west
of James River Valley, not expecting any significant aviation 
concerns. Lastly, southeasterly winds will gradually increase
with gusts between 20-30 mph expected to end the TAF period.


&&

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

&&

$$

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