textproduct: Sioux Falls

KEY MESSAGES

- Severe weather possible Friday afternoon and evening. Confidence remains low due to strong capping potential.

- Additional moderate to high chances (50-80 percent) for showers and thunderstorms return Saturday night into early next week. Severe risk is low.

- Cooler conditions arrive this weekend into early next week with occasional chances for showers and thunderstorms.

DISCUSSION

Issued at 1251 PM CDT Wed Sep 9 2026

High pressure settle south tonight and should lead to some crisp morning temperatures on Thursday. Look for morning lows from the mid 40s in the lower spots to the lower 50s.

Return flow sets up through the day Thursday with southerly winds likely gusting to 25 mph west of I-29. Highs will generally climb into the 80s, with some 70s across parts of northwest IA and southwest MN.

The leading edge of a mid level wave will sneak into central SD late Thursday night into Friday morning, resulting in increased low to mid level warm advection. While most of the area is capped due to dry air, a small wedge of increased moisture around 8000 feet may bring weak, 200-400 J/kg, elevated instability based around 8000 feet. This could result in some ACCAS on Friday morning, with impacts on the minor side.

This wave will deepen a bit and track just north of the area on Friday afternoon and evening, leading to a wedge of increased temperatures in the low levels. This will lead to widespread highs in the mid 80s to lower 90s. The question then comes to what are the convective chances as this wedge of warm air settle south and cooler air filters in behind on Friday night. The environment ahead of this front will be fairly unstable, 2000-3000 J/kg, with about 40 knots of deep layer shear. The lower levels show a nice south to southwest inflow, suggesting that new updrafts may be on the southwest flank of any development. Given the instability and shear as well as the potential for discrete cellular development, all modes of severe weather will be possible, including golf ball sized hail, wind gusts to 70 mph and isolated tornadoes. The main negative will be the potential for a fairly strong capping inversion. This suggests that there may be a very small window shortly before sunset to get any strong updrafts going that could produce higher end severe weather.

As this system lifts east northeast Friday night, cooler and drier air will settle southward and bring a pleasant Saturday with highs in the 70s and dew points in the 45 to 55 degree range.

A stronger system works onto the Northern Plains Sunday into early Monday and should bring a more widespread area of showers and thunderstorms to the region. The latest ensemble output from the GEFS, EC and Canadian all suggest about a 30-60 percent chance for a half an inch or more of rainfall for much of the area with a slight lean towards the better chances near and north of I-90.

West to southwest flow aloft continues through mid week keeping the chances for showers and thunderstorms in the area during this time. With slightly cooler air in place behind the Sunday system and the potential for clouds and precipitation, temperatures will be a bit cooler with highs in the 70s and lows in the upper 40s to mid 50s.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1149 AM CDT Wed Sep 9 2026

VFR through the period.

FSD WATCHES/WARNINGS/ADVISORIES

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