textproduct: Sioux Falls

KEY MESSAGES

- Warm and humid conditions continue through the rest of the afternoon hours today. Make sure to take breaks from the heat and drink plenty of water!

- The potential for strong to severe storms will return to the area late this afternoon into tonight. Large hail up to ping pong ball size and damaging winds to 70 mph are the main hazards. An isolated tornado is possible as well.

- Strong to severe storms are possible Wednesday afternoon and evening along and east/southeast of highway-60. At this time, there is only a 20-30% chance for storms to become severe but trends will be monitored.

- High temperatures look to rise to the 90s to 100 degree mark towards the end of this coming weekend and into next week.

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 /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1236 PM CDT Tue Jul 7 2026

Latest satellite shows mainly clear skies across the area with a CU field beginning to develop across parts of northwest Iowa and northeast Nebraska. Thunderstorms developed north of the area earlier this morning and are dragging an outflow boundary into the area. This boundary looks to make it to KHON, turning its winds to out of the north/northeast. Additional showers and thunderstorms are expected to develop later this afternoon and evening. While these storms look to be generally north of the area, the outflow boundary presents some uncertainty about storm location. Will keep an eye on it through the rest of the daylight hours. Additional storms moving in from the west this evening look to make it to KHON and KFSD overnight. These storms look to weaken to just showers into the morning hours tomorrow. Ceilings look to lower to MVFR levels as well along highway-14 and down into parts of the James River Valley late tonight. The ceilings do not look to lift until after the period ends. The previously mentioned weak showers could make it to KSUX but confidence is not high enough to include in its TAF at this time.

FSD WATCHES/WARNINGS/ADVISORIES

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