textproduct: Sioux Falls

KEY MESSAGES

- A few isolated showers and thunderstorms remain possible through this evening for areas of northwest Iowa. The severe threat has ended, but a few stronger gusts to 45 mph are possible.

- High temperatures remain on track to rise to the 90s to 100 degree mark towards this weekend and into early next week.

DISCUSSION

Issued at 208 PM CDT Wed Jul 8 2026

A few light rain showers persist across mainly northwest Iowa this afternoon. A surface trough and associated cold front continue to track through the forecast area early this afternoon. The mid level clouds associated with these light rain showers continue to sit over mainly northwest Iowa and surrounding locations. This has prevented locations in this area from heating out. The cooler temperatures look to also delay new convective development as the cold front pushes into this area. Still, these clouds look to clear/break up enough to allow adequate instability to develop with a magnitude up to about 2,000 J/kg over the course of the afternoon timeframe. Vertical shear values will be on the weaker side of things with a magnitude of roughly 20-30 knots. Latest hi-res guidance shows that a small, bi-modal severe weather event is on the table for this afternoon and evening. Storms look to develop on both the pre- frontal trough and trailing cold front. Storm development looks to take place across mainly northwest Iowa and adjacent areas this afternoon with a timeframe from from about 4 pm to 10 pm. With the cold frontal forcing, storms look to grow into a line as they push out of the area this evening. While vertical shear magnitudes will be on the lower side, hodographs show a weak but classic veer-back profile. With weak cold advection aloft, lapse rates will steepen just a bit more and allow for a large hail threat. Soundings do show slightly more saturated profiles in the hail growth zone (HGZ) which will tone down the hail threat a bit, with some of the largest stones growing up to half dollar size. DCAPE values will be sufficient with values up to 800 to 1,000 J/kg, keeping a damaging wind threat in place with the strongest gusts up to 65 mph. The large hail threat will come with the initial storm development before transitioning to a damaging wind threat as storms grow upscale. Pockets of moderate to heavy rainfall could result in localized ponding in low lying/urban areas as storms roll through. The storm threat will end this evening, leaving mostly quiet conditions for the overnight hours. Low temperatures will fall to the 60s.

Seasonable and mostly dry conditions will return for the end of the week with high temperatures remaining in the 80s to just touching 90F. Winds will be light, making for a pleasant Thursday and Friday.

Heights begin to rise aloft on Saturday, beginning to warm temperatures with highs rising to the 80s and 90s. Sunday will kick off the first day of near to above normal temperatures as medium range and ensemble guidance show a 600 dam ridge building into the Northern Plains. This ridge looks to persist through the first half of next week, brining hot and humid conditions with it. The ensembles show a 60-100% chance for highs to exceed 90F Sunday through Tuesday near and west of I-29. Chances for exceeding 100F drop to 40-70% for the same period of time with Tuesday having the highest probabilities. The ensembles also show a broad 40-100% chance for dew points to exceed 60F as well. All these probabilities to say that hot and humid conditions are expected late this weekend and into early next week. A few ensemble members show the ridge beginning to flatten next Wednesday which could begin to trend temperatures down. There remains uncertainty regarding how long the ridge remains strong so something to keep an eye on heading forward.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 626 PM CDT Wed Jul 8 2026

Strong thunderstorms have exited to the southeast of our region. A few isolated light showers will remain possible through early this evening for areas of northwest Iowa.

A mix of VFR and MVFR is expected to prevail for the majority of the period. A shallow inversion has begun to form trapping moisture just above the surface. Winds decrease to light and variable after sunset and as the surface continues to cool areas of patchy dense fog are expected to form. Ceilings and visibility may drop to IFR at times in the early morning hours of Thursday. Areas along and east of I-29 are the most likely to see dense fog. Ceilings and visibility improve by mid-morning and the rest of the day will be mostly sunny with light northeast winds.

FSD WATCHES/WARNINGS/ADVISORIES

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