textproduct: Sioux Falls

KEY MESSAGES

- Greatest severe weather threat remains focused south of the Missouri River Saturday.

- Models are a bit more consistent on keeping the heavier rain south of the Missouri River as well. The probability for an inch of rain about 30-50 percent along the Missouri River and closer to 10 to 20 percent along I-90.

- Below normal temperatures and periodic rain chances will continue into the start of next week. Severe weather chances will be low.

UPDATE

Issued at 904 PM CDT Fri Jun 19 2026

Another cool June night is ahead for the area as winds turn light to calm and temperatures drop to the upper 40s to lower 50s. Patchy fog is possible tonight/early tomorrow morning given the light winds and mainly clear skies expected; however, the extent of fog may be limited by the fact that northwesterly low level flow will be ushering in relatively drier air into the area. With that, the better chances (around 30-40%) will be over northwest Iowa and nearby areas of southwest Minnesota and southeast South Dakota where cooler temperatures from today's rain/clouds means less of a ways to go for the temperature to drop to the dew points. But again, these areas will also be fighting that drier flow and this lends to that lower to medium confidence in fog development.

Dry conditions are expected for most of the area for the daytime hours on Saturday, but rain and storm chances will begin to increase through the mid afternoon near and south of the Missouri River Valley corridor as a warm front nudges towards the area. Plenty of shear, but limited instability and modest mid level lapse rates make severe weather unlikely. Highs will generally be in the mid 70s to low 80s Saturday, but depending on whether or not showers arrive prior to or right around peak daytime heating, cooler highs in the low 70s are possible in south-central South Dakota.

DISCUSSION

Issued at 134 PM CDT Fri Jun 19 2026

Showers will exit the area late this afternoon as the weak wave pushes east. Rainfall amounts continue to remain on the light side. A very small chance for an isolated shower/thunderstorm in southwest MN this evening. If something can develop a wind gust to 40 mph will be possible. Otherwise, behind the weak wave that brought these showers, surface high pressure will nudge into the area with temperatures expected to fall into the upper 40s to lower 50s on Saturday morning.

Saturday looks dry and mild with light winds. After the cool morning starts, highs should mostly be in the 70s.

Saturday night into Sunday will see upper level low pressure settle into the area with broad low to mid level warm air advection locking into place. Overall the instability is on the weak side so severe weather chances remain very low. Even the heavy rain threat is pretty muted, with mainly the Missouri River area seeing a chance for an inch or more of rainfall into Monday morning. Given the very dry conditions will need to see much more then 1-2" of rain over a 24 to 36 hour period to have any concern for flooding or flash flooding. And given the expected weaker instability, brief rainfall rates of 2-4" per hour also seem very unlikely.

Next week will see continued northwest flow aloft which will limit any instability that can build into the area. There will be a few waves that move through the area in this northwest flow, but the threat for heavy rain and severe weather will be low. This northwest flow will also keep cooler conditions in place with below normal temperatures expected each day.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 628 PM CDT Fri Jun 19 2026

Winds look to quickly diminish through this evening, becoming light to calm overnight. Skies will be mostly clear, but thinking there will be enough cloud cover to prevent widespread fog development despite recent rainfall. However, patchy fog can't be ruled out (around 30% chance) mainly south of Highway 14 early Saturday morning. Not enough confidence in formation and coverage of fog to include mention in the TAFs at this time. Rain chances look to increase along and south of the Missouri River Valley by afternoon Saturday, bringing MVFR CIGS to mainly south-central South Dakota to end the period. Winds will be mainly light through the day Saturday with the exception of south-central South Dakota where southeasterly gusts approaching 20-25 kts will be possible in the afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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