textproduct: Sioux Falls

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 (30-70%) 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 /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1040 PM CDT Wed May 27 2026

A few very isolated showers continue late this evening. VFR conditions prevail through the period with mid and high clouds across the region. Light and variable winds tonight give way to southeasterly winds Thursday morning into Thursday night. Gusts through the day will be around 15-25 knots, approaching 30 kts for south central SD.

FSD WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None. IA...None. NE...None.