textproduct: Sioux Falls

KEY MESSAGES

- Models are trending the severe chances farther south today. A few strong to severe storms will be possible, but will likely be confined to roughly south of an Elk Point to Sioux Rapids line and possibly south of the area entirely.

- A system wraps north Sunday into Monday and may bring scattered showers and thunderstorms to the area. Currently severe weather chances are low.

- Temperatures heat up this weekend into 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. Be prepared to enact any heat related safety measures.

UPDATE

Issued at 146 AM CDT Fri Jun 5 2026

A decaying MCS will continue to drift east through the early morning hours. Additional rainfall amounts will be on the lighter side. Model trends continue to push the chances for stronger updrafts to the south of the area for this afternoon and evening in the wake of this MCS, so other than roughly near and south of a Sioux City to Storm lake line the chances for any severe weather today are very low. A few updrafts could develop in other parts of mainly northwest IA with a very small chance to reach severe levels. Otherwise a fairly pleasant summer day is ahead for most locations with highs in the 80s and fairly light winds.

This will lead into a quiet and warmer Saturday as a nose of high pressure dips south into the area. Highs from the upper 80s to mid 90s in most locations.

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 /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 610 AM CDT Fri Jun 5 2026

Areas of IFR and LIFR fog have developed over parts of northwest IA early this morning. Right now it looks like this should dissipate by 15-16z. Otherwise a few showers will move through the area with very isolated lightning strikes through mid morning as well. An isolated thunderstorm will be possible in mainly northwest IA this afternoon, but confidence in this is pretty low. Otherwise from mid to late morning mainly VFR conditions are expected.

FSD WATCHES/WARNINGS/ADVISORIES

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