textproduct: Sioux Falls

KEY MESSAGES

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

- Monday night into Tuesday morning is the next opportunity for showers and thunderstorms. Severe weather is not expected but some gusts of 40-45 mph are possible.

- Shower and thunderstorm chances return Wednesday. At this time severe weather is not anticipated. However, trends will need to be monitored.

UPDATE

Issued at 844 PM CDT Sat Jun 13 2026

The forecast as of 9pm remains on track. Winds will decrease overnight becoming light. Lows will fall into the upper 40s to low 50s. Winds will remain northwesterly for Sunday and breezy with gusts of 15-25 mph. High pressure will build into the region through the day Sunday. Conditions will be pleasant with sunny skies and highs in the 70s. Monday the high pressure progresses south of the region and an upper wave and associated surface low will begin to move in from the northwest. Winds at the surface will become westerly and breezy gusting to 25 mph. WAA will boost afternoon highs into the upper 70s to low 80s.

Monday night into Tuesday morning a shortwave will work through the region bringing chances for showers and thunderstorms. Convective parameters over all do not support severe weather. However, there is enough elevated instability to get some lightning. Soundings indicate the air mass beneath the cloud layer is very dry. As a result some storms may produce wind gusts to around 40-45 mph.

Wednesday better chances for showers and thunderstorms exist. Uncertainty in how much instability will be available leaves confidence in any strong or severe thunderstorms low at this time. However, we will need to monitor the trends for changes.

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 /00Z TAFS THROUGH 00Z MONDAY/

Issued at 626 PM CDT Sat Jun 13 2026

VFR conditions are expected for the period. Scattered to broken mid- level clouds will persist for much of the overnight before becoming mostly clear Sunday. Breezy northwest winds will decrease after sunset becoming sustained at 5-10 kts with gusts 12-17 kts. Winds remain northwest Sunday and increase through the morning hours. Afternoon gusts of 17-21 kts are expected.

FSD WATCHES/WARNINGS/ADVISORIES

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