textproduct: Sioux Falls

KEY MESSAGES

- Warm and humid conditions continue for Tuesday. Heat index readings peak between 90 and 100 degrees. Please ensure you are hydrated and take breaks out of the heat!

- Isolated to scattered severe storms capable of half dollar size hail and 60+ mph winds will again be possible from late Tuesday afternoon into early Wednesday.

- Temperatures will rise towards the middle 90s to 100 degree mark by next weekend.

UPDATE

Issued at 335 AM CDT Tue Jul 7 2026

Cluster of thunderstorms continues to move into southern Minnesota early this morning. An occasional updraft capable of quarter size hail and 50-60 mph has been observed early this morning. Generally though, this risk will shift away from the CWA over the next hour.

A look at the 06Z model guidance remains consistent but has shown trends towards pushing the surface warm front further north towards far northern South Dakota this afternoon. South of the boundary soundings still show inhibition holding on into the early evening hours. Additional convection is likely to form over Western South Dakota by late afternoon. As a synoptic wave ejects eastward in the evening, we'll watch for the clustering of storms both to our west, but also north. The greatest uncertainty into the overnight hours is how far east (or south) this convection can track before it runs into a more stable airmass. Low-lvl temperatures remain very warm and would likely lead to any elevated clusters that track into the area struggling to remain strong to severe. The greatest potential for any severe activity (mostly strong wind gusts) remains along the far western and northern CWA into the early overnight.

The only other modification to today's forecast was to boost dew points slightly in most areas through mid-day. With the front lifting further north, this does increase potential for further mixdown of dew points into the middle to upper 60s (higher near the warm front), with high temperatures deeper in the 90s west of I-90 where low-lvl flow will be stronger. This will push heat index values near the upper 90s.

DISCUSSION

Issued at 230 PM CDT Mon Jul 6 2026

CURRENTS & TONIGHT: Taking a look across the area, we're continuing to watch a broken line of scattered showers with isolated thunderstorms progress across western and central SD this afternoon mainly in response to the approaching cold front. With a small cap in place aloft according to soundings, the general expectation is for this activity to gradually weaken upon approach. However, as diurnal heating persist and eventually erodes the rest of the cap; short-range guidance continues to show additional convection developing with the cold front this evening initially across northeastern SD and potentially southcentral SD. Both areas of convection will likely meet in our area during the late evening to early overnight hours mainly along and north of I-90 with the main hazards being up to quarter-sized hail and strong wind gusts up to 60 mph. Otherwise, should see this activity gradually weaken past the I-90 corridor as instability wanes with the loss of diurnal heating. Lastly, expected another warm night with lows mainly in the upper 60s to low 70s.

TUESDAY-THURSDAY: Looking into Tuesday, quieter conditions will return for the first half of the day as quasi-zonal flow continues aloft. With similar conditions to today in place, expect another dose of the summer heat as highs to peak in the upper 80s to upper 90s for most areas with heat indices in the low to upper 90s. With this in mind, make sure to stay hydrated and to take frequent breaks when working outdoors. Otherwise, the main focus continues to be the severe weather potential from late Tuesday into Wednesday. Looking aloft, we're still on track for scattered showers and thunderstorms to track from central SD through areas along and north of I-90 with the surface front during the evening to overnight hours. However, the main question continues to be how does this developing activity evolve during this time and will it be severe. With the better forcing continuing to sit closer to the ND/SD border, we'll continue to hedge our bets on the better severe risk being north of us.

However, still can't completely rule a few isolated gusts up to 60 mph north of I-90 if strong cold pools can develop with a few weakening thunderstorms. Otherwise, gradual weakening should continue through Wednesday morning as this activity progresses southeastwards with the surface front into a more stable environment. Slight cooler conditions will be possible by Wednesday as cooler air funnels in behind the previously mentioned boundary leading to highs mainly in the 80s to low 90s. Additional showers and thunderstorms could develop along/ahead of the boundary by Wednesday afternoon mainly across northwestern IA and the lower Missouri River Valley. While an isolated severe risk can't be ruled out mainly across the Highway-20 corridor and portion of northwestern IA, the location will be highly dependent on where the surface boundary ends up setting up during the afternoon. Lastly, mostly quiet conditions should return by Thursday as highs slightly decrease into the low to upper 80s for the day.

THE WEEKEND: Heading into the extended period, an active period will continue aloft as quasi-zonal flow continues into the weekend. Multiple waves will progress through the plains leading to at least some smaller chances (<30%) through Saturday. With the ridging expected to strengthen over the western CONUS during the upcoming weekend, we could see the return of oppressive temperatures mainly in the 90s to low 100s as early as Sunday. With heat indices potentially reflecting similar values, make sure to stay hydrated and to monitor your local forecast!

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 558 AM CDT Tue Jul 7 2026

Scattered mid-lvl cloud layers continue to move through the Tri-state area this morning. A surface warm front bisects the area, currently south of Highway 14. This front will shift northward today allowing a breezy to occasionally gusty southerly wind to develop areawide. Occasional CU will also develop this afternoon, before thinning by late afternoon as dew points lower.

Most convection is expected to stay north of the CWA into the evening with eyes pointed towards thunderstorms that develop to our north and west. This activity may move eastward, generally weakening as it does so. However gusty winds will still be possible. Given uncertainty on coverage, will only utilize a PROB30 to show potential.

FSD WATCHES/WARNINGS/ADVISORIES

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