textproduct: Sioux Falls

KEY MESSAGES

- Scattered showers and isolated thunderstorms will continue across parts of northwest IA this afternoon, with the threat pushing south between about 4-6pm. Severe weather is not expected but a few stronger storms near and south of a Sioux City to Storm Lake line could produce hail to the size of nickels.

- Near to below normal temperatures will continue well into next week with highs mainly in the 70s to 80s expected.

DISCUSSION

Issued at 121 PM CDT Sat Jun 13 2026

Mid level moisture around 700 mb and moderate lapse rates above this layer will lead to CAPE values of about 500-1000 J.kg through the afternoon. This should generally be confined to areas near and south of a Sioux City to Storm Lake line. With elevated shear values sitting around 40-50 knots an isolated stronger updraft or two will be possible with hail to the size of dimes and nickels the main threat. Broad troughiness will push this mid level convergence and steeper lapse rates south of the area this evening, leaving behind dry and cool conditions for tonight.

Broad low pressure across central and eastern Canada will keep cooler northerly flow in place through Monday. Lows in the 40s to lower 50s and highs mostly in the 70s are expected.

There will be a weak piece of energy dropping into the area Monday afternoon and evening, mainly to the north of the area. Decent surface heating should lead to 250 to 500 J/kg CAPE and with a very dry subcloud layer creating a fairly classic inverted V sounding, wind gusts of 40 to 50 mph will be possible.

A strong upper level jet will spill into the Northern Plains Tuesday through Thursday and bring the next chance for showers and thunderstorms. For now it appears that this will bring some very strong elevated shear into the area so it will be a matter of timing and how much instability that this pattern can support to bring a threat for severe weather. For now it appears that instability will be on the low side, but if we can somehow get 1500 J/kg or so with this shear we would see some severe weather, Something to watch out for.

Confidence on any details Thursday into Saturday a little lower as fairly strong northwest flow continues. Any wave will bring warmer temperatures ahead and cooler behind, so that will determine a lot and will need to wait to see how things play out.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1240 PM CDT Sat Jun 13 2026

Scattered showers and isolated thunderstorms will continue across mainly northeast NE and northwest IA into the afternoon, with the threat quickly diminishing and settling south early this evening. Otherwise northerly winds will gust to around 25-30 mph at times through the day. Outside of the wind and storms, VFR conditions are expected.

FSD WATCHES/WARNINGS/ADVISORIES

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