textproduct: Sioux Falls

KEY MESSAGES

- Weakening light showers will exit the area by mid-morning today, with very low chances of redevelopment east of I-29 this afternoon.

- Seasonable temperatures and dry weather prevails through Thursday with highs in the upper 70s and 80s, and lows in the 50s to lower 60s.

- Warmer and more humid air returns Friday through the weekend with moderate (40-50%) chances for storms late Friday into Friday night.

UPDATE

Issued at 602 AM CDT Tue Aug 25 2026

A lone strong to severe storm which dove southeast from around De Smet to Madison earlier this morning weakened quickly as it continued to progress southeast toward Minnehaha County. This leaves just a couple areas of sprinkles to light showers south through east of Sioux Falls which should move east of the CWA by 13-14Z (8-9 AM).

Question is whether the weak cold front pushing through the CWA today will trigger any additional development as it moves into northwest Iowa/southwest Minnesota this afternoon. Consensus timing of the front places it near Highway 71 or even east of our forecast area by peak heating, and with the exception of the GFS/FV3 which are more extreme in their diurnal heating, models lack any redevelopment in our east this afternoon. Will maintain a mostly dry forecast through the afternoon but later shifts will monitor for changes if needed.

DISCUSSION

Issued at 143 PM CDT Mon Aug 24 2026

Showers and thunderstorms are possible tonight into early Tuesday morning as a wave skirts by to the north and west. For early this evening, instability grows across central SD, with CAPE values of 2000-3000 J/kg, but only marginal shear. Initially storms will be most likely west of the area, but some development could creep into Gregory and Brule counties. Capping may preclude any development, so only low confidence in storms actually developing. Later tonight into early Tuesday morning a tail of convection could build south towards highway 14 and into pars of southwest MN. Here CAPE values of about 1000-1500 J/kg will be possible with minor-moderate shear. Some question as the whether we see an increase in moisture around 800 mb which appears to be needed to produce a few updrafts. Once again this is somewhat lower confidence set up. Isolated severe weather will be possible in bth areas, half dollars and 70 mph winds in central SD and quarters and 60 mph winds in southwest MN.

Warmer air aloft builds into the area Tuesday, but other than northwest IA the threat for showers and thunderstorms will be fairly low. If there is some elevated moisture there could be a little activity in the morning. Northwest IA may see just enough instability and shear on Tuesday afternoon for a couple of strong to severe updrafts.

Behind this cooler and drier air builds into the area which appears to bring dry and seasonally mild conditions for Wednesday and Thursday.

Stronger westerly winds aloft will spread across the area Friday into the weekend. This should bring occasional chances for showers and thunderstorms during this time. Friday night appears to be a better chance right now. As the warmer conditions and somewhat deeper instability build in Friday night into Saturday isolated severe storms will be possible.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 602 AM CDT Tue Aug 25 2026

Localized MVFR ceilings as we start this TAF period, but expect VFR conditions to become more prevalent as we move through the morning. Light winds early this morning will become west to northwest with the passage of weak front, with gusts of 20-25kt at times through the afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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