textproduct: Sioux Falls

KEY MESSAGES

- Clearing skies with decreasing winds will lead to fog development into early Thursday, especially near and west of Interstate 29. Visibility may fall below a mile (20-50% chance). Fog dissipates by mid morning.

- Rain chances with some isolated thunderstorms return early Friday morning and continue through Saturday and again early next week.

UPDATE

Issued at 631 PM CDT Wed Oct 28 2026

Severe weather risk has come to an end as the initial cold front and area of convergence has moved to the east of the forecast area. Stratus is clearing behind the secondary front/CAA and as surface high pressure moves into western SD. Expect some showers/drizzle as the stratus tracks east and clears through the late evening hours and early overnight. Fog is expected to develop as winds become light, with some low to moderate (20-50%) chances of visibility below one mile into Thursday morning. Greatest risks for fog remain near and west of I-29, with most guidance highlighting the James River Valley in particular. Lows tonight may fall into the lower 30s west of the James, with 30s to lower 40s elsewhere. Fog lifts by mid morning, with a pleasant day on tap for Thursday in the mid 50s to mid 60s.

No adjustments to the forecast outside of this evening/tonight. Rain chances return with some isolated thunderstorms possible Friday into Saturday.

DISCUSSION

Issued at 131 PM CDT Wed Oct 28 2026

Over the next couple of hours, showers and storms are expected to develop over parts of eastern South Dakota and western Minnesota ahead of a cold front. Cannot entirely rule out the possibility of strong to severe thunderstorms, although the best environment will be to the northeast further into Minnesota. Still, a Marginal Risk clips the northeastern-most part of the forecast area, and hail is the main potential severe threat. Strong storms that do develop in that area are expected to exit the forecast area fairly quickly this afternoon. Further south, expectations are that showers will remain fairly light, and just a few hundredths of rain will fall.

Behind the cold frontal passage, a high pressure center will move into the area overnight tonight. After an initial shift to the northwest, winds will become light and variable overnight tonight as the high pressure center moves overhead. There is some signal in high-resolution guidance for some fog development once again tonight due to the light winds and clear skies promoting strong radiative cooling. The main area of concern for fog development is over southeastern South Dakota, particularly the James River Valley. Confidence in the areal coverage is still somewhat low at the moment, but pockets of dense fog may reduce visibility below a mile at times.

The next chances for rain come on Friday into Saturday. Rainfall will move in from the south beginning Friday before expanding to cover the entire forecast area Friday night into Saturday. Generally light rain rates are expected, but perhaps a quarter of an inch or more (20-40%) could fall over parts of northwestern Iowa, northeastern Nebraska, and southwestern South Dakota.

Another low pressure system is set to move into the region early next week, bringing renewed chances for rain into the region. Monday through early Wednesday, chances are fairly high (50-70%, increasing moving from north to south across the forecast area) to see an inch of rainfall accumulation or more. However, there is still significant uncertainty with this system in timing, location, and amounts. 25th/75th spread is generally around two inches for that same time period, so still a lot to resolve as the system comes into focus over the next couple of days.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1036 PM CDT Wed Oct 28 2026

Outside of KSLB, stratus has moved out of the area. However, already seeing fog develop on the western edge of the Buffalo Ridge (KBKX to KPQN) and west toward the James River Valley. Guidance still shows a 25-55% chance of visibility below 1SM into mid Thursday morning, mainly along the James River Valley and by KBKX. MVFR and IFR fog should diminish by mid morning, although some guidance is holding on to fog into late morning with a slower increase in winds. May also see some stratus below 1kft develop with the fog which should also clear out through the morning. Winds increase and shift southeasterly, around 10 knots through the day Thursday with gusts to 20 knots in south central SD. VFR conditions expected after fog lifts through most of Thursday night.

Light and variable winds late Thursday night could lead to additional patchy fog development.

FSD WATCHES/WARNINGS/ADVISORIES

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