textproduct: Sioux Falls

KEY MESSAGES

- Isolated showers and thunderstorms over northwest Iowa will continue to move south-southeast through about 4 am. Gusty winds to 50 mph and small hail will be possible in the strongest storms.

- Pockets of fog will be possible overnight, especially in areas that saw rain so far tonight/earlier today. Locally dense patches could lead to visibility as low as 1 mile or less at times.

- Near to above normal temperatures will continue into the new week with highs mainly in the 80s to mid 90s.

UPDATE

Issued at 844 PM CDT Sat Jul 4 2026

Isolated showers and storms continue to develop mainly over southwest Minnesota along the many outflow boundaries that have been around the region. With sufficient elevated instability to around 1,500 J/kg expected to continue into tonight and a weak upper wave moving across the area, we will see isolated showers and storms possible through about 2-4 am mainly east of I-29. The better chances (20-30%) will be overall drifting south to southeast with time. The next hour or so we could see a very isolated 50-60 mph wind gust or instance of nickel to quarter sized hail with these storms, but as storms turn elevated overnight this wind threat will diminish and large hail will become unlikely given weak shear and weakening low level lapse rates through the night. Otherwise, some fog looks to develop especially in areas that have seen rain today, and there is about a 20-30% chance of it being locally dense. Any fog should lift by 7-9 am. No major changes to the forecast for Sunday, still looks like it'll be a warm and dry day as ridging aloft builds into the area.

DISCUSSION

Issued at 238 PM CDT Sat Jul 4 2026

CURRENTS & TONIGHT: Taking a look across the area, the focus continues to be across portions of northwestern IA as a lifting outflow boundary continues to spur pockets of convection across portions of northwestern IA. While this developing activity continues to stay mostly sub-severe, the enhanced stretching potential and weak flow aloft has led to multiple funnels being reported mainly near Greenville and Sioux Rapids, IA in Clay County. With this developing activity potentially continuing over the next few hours have decided to issue a special weather statement (SPS) for most of northwestern IA, portions of southwestern MN, and portions of southeastern SD through 5 PM.

Otherwise, we're still on track for a few additional isolated to scattered thunderstorms with an approaching wave this evening. Given the modest CAPE and low shear set up, there is still a decent shot for a few stronger storms with up to half dollar sized hail and damaging winds up to 60 mph being the main threats. While there is still some uncertainty as to how things will evolve, most short- range guidance has now settled in on areas east of I-29 and along the Missouri River Valley as the two areas for potential development through the late evening so make sure to have multiple ways to receive warning information! Lastly, can't rule out some additional chances for patchy fog tonight with the higher dew points. Similar to this morning, locally dense patches could lead to visibilities of 1 mile or less at times through mid-morning before dissipating.

SUNDAY-TUESDAY: Looking into Sunday, quieter conditions will temporarily return as ridging begins to build across the Desert Southwest. With weaker flow aloft and increasing warm air advection (WAA), should continue to see temperatures trend above normal through Tuesday with highs mainly in the 80s to 90s each day. Looking aloft, our next precipitation chances could arrive as early as Monday night into Tuesday as an approaching shortwave intersects a stalled surface boundary roughly draped from the Black Hills to northeastern SD. While there is still some uncertainty as to how far east this boundary sets up, there should be just enough lift with the wave to trigger a few scattered showers and thunderstorms during the afternoon to evening hours with the potential for a few stronger storms. Given another modest CAPE/low shear environment, any developing activity will be quite pulsy. However, current thoughts are an isolated severe risk will be possible mainly along and south U.S. Highway-14 heading into the afternoon and evening hours. Otherwise, additional chances for showers and thunderstorms will return from Tuesday into into Wednesday as another shortwave and an a cold front progress through the area. However, some uncertainty remain so make sure to monitor your local forecast as the details are subject to change.

WEDNESDAY-FRIDAY: Heading into the extended period, the previously mentioned ridging begins to flatten giving way to quasi-zonal flow by Wednesday. With the wave train expected to resume aloft, we could see near daily chances for precipitation through Friday. While the severity of these storms is still uncertain, confidence is not high enough to deviate from the NBM at this time. Otherwise, we'll continue to see near to above normal temperatures through Friday with highs mainly in the 80s to low 90s.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1252 AM CDT Sun Jul 5 2026

A cluster of thunderstorms is located over northwest Iowa and moving south-southeast to begin the period. These storms should remain east of KSUX, with chances of impacts there through 05.08Z low, less than 20%. However, some smoke has settled into KSUX, though an outflow boundary timed to arrive between 05.07-05.08Z should help kick up the wind just enough to disperse it. Elsewhere, in areas that saw rain tonight/earlier today, patchy fog looks to develop, which could be locally dense at times. Any fog should dissipate by 05.15Z in which VFR conditions can be expected area-wide afterwards. Winds will generally be light and variable through the period, though will pick up slightly (sustained to 10 kts) out of the east-southeast this afternoon and evening west of the James River.

FSD WATCHES/WARNINGS/ADVISORIES

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