textproduct: Sioux Falls

KEY MESSAGES

- Additional showers will lift through the U.S. Highway-20 corridor in northwestern IA this afternoon/evening. Rainfall amounts mainly less than 0.25 inch are expected, but totals nearing 0.50 inch may push into far southern portions of Ida and possibly Woodbury Counties.

- Drier and mild conditions settle into the area with only very minor chances for showers through early next week.

DISCUSSION

Issued at 111 PM CDT Wed Sep 30 2026

All indications continue to point towards keeping the heavier rain to the south later this afternoon and tonight. The high resolution models only bring about a quarter of an inch of rain to southern parts of Woodbury and Ida counties with the ensemble output showing about a 20-40 percent chance to exceed 1 inch of rain, the EC probabilities a little higher. With 3-4 inches of rain needed to make any if the rivers really move upwards, flooding concerns are very minimal.

Fog will again be possible later tonight into Thursday morning, but for now the model soundings suggest the lower level saturated layer is much shallower, so a better chance to burn off more quickly in the morning. A surge of drier air will build southward with dew points falling into the 40s through the morning. Also looks like the better chances would be over parts of northwest IA and nearby locations.

A system will move by to the north Friday into Saturday. While this will bring some mid level cloud cover into the area, precipitation chances will remain fairly low with dry air below about 800 mb. Some very weak instability aloft Friday night into Saturday ahead of an incoming shot of cooler and drier air may see the need to add some spotty showers during this time, but confidence fairly low in this weak instability. Without the weak instability, saturation looks to occur below the dgz so rainfall would not be expected without the instability. Overall impacts will be very minor.

Upper level ridging builds into the area Sunday into Monday ahead of the next wave. This wave will bring small chances for showers Monday night into Tuesday, but again very low confidence fighting drier air with the wave well to the north. One thing that this wave will bring is mild weather to the area. Looking at highs Tuesday and Wednesday around 70 in most locations. Highs more in the lower to mid 60s are expected this weekend.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 649 PM CDT Wed Sep 30 2026

Rain continues to spread into the Highway 20 corridor tonight, bringing mainly MVFR conditions, but also a few pockets of IFR. Not enough confidence to add IFR conditions to KSUX at this time, but trends will be monitored as at this point, it looks like the heaviest rain will stay south and east of the airport. This rain should push off to the east heading into tomorrow morning.

Elsewhere tonight, patchy fog will be possible, though chances remain low (around 30%) focused over northwest Iowa just north of where the aforementioned rain ends. Winds will be mainly light and variable through this evening, with winds gradually picking up from the north-northeast late tonight into tomorrow. Winds could occasionally gust to around 20 kts mainly Thursday morning into the early afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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