textproduct: Sioux Falls

KEY MESSAGES

- Elevated showers and storms continue through mid morning. Although severe risk is low, an isolated wind gust as high as 60 mph is possible, mainly along US Highway 14 through 4 AM. - Scattered storms return this afternoon and evening. Strong to severe storms are possible along/southeast of a Lake Andes to Sioux Falls to Jeffers line. Main threats are strong winds to 65 mph and hail to quarter size.

- High temperatures rise into the 90s toward 100 degrees this weekend and into early next week.

UPDATE

Issued at 232 AM CDT Wed Jul 8 2026

A muggy and warm start to this Wednesday with temperatures/dew points in the upper 60s to mid 70s. Winds are elevated enough to preclude any fog development. Elevated storms are expanding in coverage along the strengthening LLJ. Main severe risk through the next couple of hours remains along the US Hwy 14 corridor where ample DCAPE exists. Main threat would be a wind gust to 60 mph through 4 AM CDT.

Biggest question for later today is exactly where the boundary ends up, as it will aid in for our later day storm development. Although we'll likely have some cloud cover around, we should recover back into the upper 80s and lower 90s south of I-90. With dew points in the lower 70s, should have modest instability as the cap erodes through the afternoon. Greatest severe risk is across northeastern NE and northwestern IA, where a Slight (level 2 of 5) risk has been introduced. Marginal (level 1 of 5) risk remains along and south from a Lake Andes to Sioux Falls to Jeffers line. Main threats are going to be wind gusts to 65 mph as LL lapse rates and DCAPE increase and quarter sized hail. Potential limiting factor for hail is the 0-6km shear values around 20 kts, although these increase to near 30 kts by the evening.

Isolated activity may linger in our southern forecast area through the early overnight hours. Otherwise, mostly dry weather is expected with slightly cooler temperatures.

DISCUSSION

Issued at 229 PM CDT Tue Jul 7 2026

Quiet conditions persist this afternoon with high temperatures warming to the mid to upper 80s and low 90s. Latest satellite and surface obs show a , outflow boundary from morning storms that is set up along from Huron South Dakota to De Smet South Dakota, to Canby Minnesota. The main effective boundary is also visible on satellite well northwest of the area. These boundaries will serve as the areas for new thunderstorms to develop on later this afternoon as a mid level wave interacts with the boundaries. Large hail up to ping pong ball size and damaging winds to 70 mph will be the main hazards. While the tornado threat will be mostly north and west of the area, a local/isolated tornado threat is possible along the boundary as the mean wind is oriented parallel to it, allowing for a longer resonance time for a storm to ingest the boundary driven helicity. These storms look to develop later this afternoon around 5 pm or later as the mid level wave catches up to the boundary. A second round of showers and some storms will develop across the Black Hills this afternoon and push eastwards. These storms will cross the state of South Dakota and get into locations east river this evening. The environment does not look all that favorable as less moisture (and associated instability) will be available in this area. At the same time, vertical shear will also be weaker in this same area as well. While the strengthening low level jet could keep elevated showers and isolated storms going, any storm that persists into the forecast area is not expected to be strong to severe Any chance for a strong to severe storm will come to an end by 3 am or a little earlier. Though these showers may persist through the forecast area overnight.

Latest guidance shows these showers continuing to persist throughout the day on Wednesday. This will bring some cloud cover to the area which will keep temperatures just a little bit cooler. As the same time, the previously mentioned boundary will be sliding southwards through the area. This boundary looks to slide just far enough to the south that additional showers and perhaps a few thunderstorms could develop on it. Latest hi-res guidance shows these storms developing across parts of northwest Iowa tomorrow afternoon before exiting the area in the evening. While this looks to be the consensus amongst the guidance, some uncertainty regarding how far south the boundary gets remains. If the boundary gets hung up, then severe storm chances could increase during the daylight hours tomorrow. As of now, the latest REFS shows a 20-30% chance for reflectivity values to exceed 40 dBZ. Thus, think the most likely scenario for tomorrow is for elevated showers and weak storms push through the majority of the area. The exception will be portions of northwest Iowa, generally near and south/southeast of highway-60 where a pre-frontal trough where enough surface heating could result in a few severe storms during the afternoon timeframe. Will keep an eye on this potential. Any chance for strong to severe storms will come to an end during the evening hours as the surface boundary and pre-frontal trough push southeast of the area.

Thursday looks to be a pleasant Summer day as high temperatures warm to the 80s and winds stay light out of the north/northeast. High temperatures look to warm to 80s while humidity values remain modest. There looks to be enough instability to develop a few showers to an isolated thunderstorm. Any storm that does develop is not expected to be strong to severe as vertical shear profiles will be weak. As of now, only have a 20-40% chance for these showers to weak storms to develop. Chances for rain will be trending downwards into the evening hours as the boundary layer stabilizes.

Friday will see continued near seasonable temperatures with highs in the 80s to low 90s. Highs will begin to warm as an upper level ridge begins to build on Saturday. Highs will warm a bit more to the mid 80s to mid 90s Saturday afternoon. The ridge looks to build up over the Rocky Mountains on Sunday before quickly translating to over the Northern Plains by early next week. Both deterministic and ensemble guidance places the peak of the ridge up to 597 to 600 dam. This will result in much hotter temperatures returning to the area with high temperatures into the 90s to potentially the low 100s. The ensembles support this as they show a broad 40-100% chance for high temperatures to exceed 90F and a 40-70% chance for highs to break 100F. The highest probabilities lie across central South Dakota. With the center of the ridge places directly over the Northern Plains, the upper level jet and associated gradients will be north of the area. This looks to leave mostly dry and hot conditions Sunday through Tuesday at this time. Humid conditions will accompany the heat so heat headlines will be possible.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1240 AM CDT Wed Jul 8 2026

Showers and thunderstorms are forming along a quasi-stationary boundary over central South Dakota. These are expected to slowly move southeast through the region tonight. Some storms could be strong to severe producing large hail, heavy rain, and wind gusts to 60 kts. Southerly winds will become breezy and variable as the front moves through. Behind the front winds will be northerly and light. Isolated to scattered storms may continue through much of the day over eastern South Dakota and southwest Minnesota.

VFR conditions are expected to prevail except for areas under storms. Ceilings and visibility may decrease to MVFR and briefly IFR under the strongest storms.

By Wednesday afternoon another round of strong to severe thunderstorms are possible along the same slow moving boundary. This time focused over northeast Nebraska, extreme southeast South Dakota and northwest Iowa. Risks will be large hail, heavy rainfall, and gusts to 50 kts. Storms look to push southeast of the region by the end of the end of the period.

FSD WATCHES/WARNINGS/ADVISORIES

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