textproduct: Sioux Falls

KEY MESSAGES

- Scattered strong to severe storms remain possible through about 1 am tonight mainly near and north of Highway 14 and into south-central South Dakota. 70 mph winds and ping pong ball sized hail will be the main threats, though tornadoes cannot be ruled out.

- Good agreement on the better chance for scattered thunderstorms containing heavy rain to be generally near Highway 14 into tonight. Saturated grounds from last night's storms could lead to some minor flash flooding and potentially minor river flooding.

- While details are far more uncertain, an isolated to scattered severe storm risk will linger into Friday. The greater risks at this time shift southeast into eastern Nebraska, Iowa and far southern Minnesota.

- Temperatures heat up next week. There is an increasing chance (30-60%) of highs exceeding 95 degrees especially near and west of the James River by Wednesday and Thursday.

DISCUSSION

Issued at 336 PM CDT Thu Jun 4 2026

Several boundaries, some left behind from yesterday's storms, are noted across the area by agitated lines of CU and ongoing thunderstorms. Ample sunshine in these areas prior to development has led to 1,500-2,000 J/kg to develop with mid- level lapse rates around 7.5 C/km. Shear is on the weaker side, but large hail to ping pong balls will still be possible given the lapse rates. And with the myriad boundaries in place, will have to watch for the the threat of tornadoes. The main boundary that will be the focus of storms through this evening into tonight stretches from western South Dakota into the east- central part of the state. As a shortwave embedded within the otherwise zonal flow moves across the Northern Plains through this evening, there should be an uptick in thunderstorm development. The storms currently ongoing at the eastern end of this boundary are going to continue to lift north and continue to develop with westward extent as the shortwave encroaches the area. The other concern with these storms will be the heavy rain threat as areas near and north of Highway 14 already have saturated grounds. This could lead to some flash flooding if storms move too slowly over an area. And heavy rain to our north may also cause some minor river flooding issues downstream depending on how much rain is seen.

Another area of storms will develop off to our west. The best shear is located over western South Dakota on the western end of the main boundary. Guidance shows storms developing out there late this afternoon/early evening may take on some bowing segments as it moves eastward towards our area, arriving by 9-10 pm west of the James River. This is where the best chance of damaging wind gusts to 70 mph will be, though storms should gradually weaken as they move eastward as instability wanes through the night. In other words, after about midnight to 1 am, the severe weather threat should come to an end. A few showers will be possible heading into Friday morning, but nothing severe expected. Another upper-wave moves across the northern Great Lakes region tomorrow afternoon and evening, and this could set off some isolated thunderstorms mainly near and east of I-29 and especially towards the Highway 20 corridor. Can't rule out some strong to severe thunderstorms with this activity, but this will be highly dependent on how storms develop tonight. Also, the greater instability will also be south of the area, likely keeping the greatest threat to our south.

Ridging aloft builds in Saturday and so we should finally have a dry day. This will be quickly replaced with another active upper pattern heading into early next week, which will lead to increased shower and storm chances Sunday and Monday. Just like the past few events, ensembles show the instability sufficient for severe weather largely in place, but there will be questions on how much shear there will be with and of course any other mesoscale features that can't be resolved this far out. Heat also looks to build in next week, especially by Wednesday and Thursday when LREF probabilities of highs exceeding 95 degrees are around 30-60% near and west of the James River, with a 10-30% of highs even exceeding 100 degrees in these areas. Recent rainfall may mean that the forecast models could be overdoing potential heating, but this will be something that needs to be watched closely over the next couple of days.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 637 PM CDT Thu Jun 4 2026

Scattered showers and thunderstorms are ongoing at time of issuance. Mainly along and north of Highway 14. These are expected to continue through the evening. A second round of showers and thunderstorms are possible after midnight into Friday morning. Some could be strong to severe with large hail and wind gusts the primary threats.

Winds will become light and variable, allowing for patchy dense fog formation. At times ceilings may degrade down to IFR, especially at KSUX where fog looks to be thickest. Fog should burn off by mid- morning. Skies gradually clear through the afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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