textproduct: Sioux Falls

KEY MESSAGES

- Isolated showers on Thursday could produce wind gusts to 40 mph.

- Strong to severe storms could return on Saturday along with locally heavy rain. Specific details are uncertain, but as of now, the highest probabilities for severe storms remains south and west of the area.

UPDATE

Issued at 856 PM CDT Wed Jun 17 2026

Scattered showers and very isolated thunderstorms continue to pivot across mainly southwest Minnesota associated with an upper low moving towards the northern Great Lakes. This activity, along with some showers moving southward across northern South Dakota, will fade over the next hour or two as we lose daytime heating. To our south, a few showers may develop along a boundary over northern Nebraska. Even if this activity were to clip far northeastern Nebraska south of Highway 20 tonight, a dry sub- cloud layer will more than likely prevent any of it from reaching the ground.

Otherwise, winds will continue to diminish through the overnight hours, though they won't go completely calm. This should prevent any fog from developing, but can't rule a little bit of it if winds can go calm in any areas that saw rainfall today. Chances of this are quite low, less than 15% at this time. Below normal temperatures are expected tonight, with lows ranging from the around 50 north to closer to 60 south.

The forecast for rain chances tomorrow remains on track, see discussion below for details. Otherwise, we'll have a pleasant late spring day for Thursday with highs in the 70s and lighter winds (outside of the stronger gust potential with showers).

DISCUSSION

Issued at 144 PM CDT Wed Jun 17 2026

A strong jet max continues to wrap around the south side of an upper level low, bringing strong winds to the area. Peak mixing suggests that wind gusts could approach 50 mph. Model soundings also indicate some weaker surface based instability this afternoon, which will likely generate scattered showers and isolated thunderstorms. The main concerns from any of this activity will be the potential to mix down even stronger winds, possibly 60 to 65 mph. These stronger winds will remain much more isolated.

Thursday will see deep, but weakening northwest flow across the area. We will likely see a threat for isolated showers with locally gusty winds to 40 mph as surface based peak mixing CAPE climbs to about 200 J/kg.

Thursday night into Friday a weak wave will approach and bring some elevated moisture return and very weak instability. For now any impacts from this will be very minor.

The next system of interest will come Saturday, but with some differences from model to model. The 6z EC Ensemble is bringing a 20- 30 percent chance for 2+" of rain to around the Missouri River into parts of northwest IA while the 12z GFS ensemble and 12z Canadian ensemble leave these better chances farther south and closer to I- 80. Classically the heavier rain many times falls between roughly the surface to 850 mb boundary and for now that remains south of the area, but will need to be monitored in case it drifts north. Regardless, flooding potential is fairly low as rainfall has been spotty at best lately.

Below normal temperatures and periodic chances for showers and thunderstorms are expected Monday through Wednesday next week. A few shortwaves are expected to move through, with slightly better chances Monday and Wednesday.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 631 PM CDT Wed Jun 17 2026

Scattered showers and isolated thunderstorms will gradually fade through the evening, leaving VFR conditions across the area for tonight and tomorrow. Can't rule out some fog by early Thursday morning as winds turn lighter overnight, but chances are very low, less than 10%. Additional scattered showers and isolated storms look to develop again Thursday afternoon, but coverage is expected to be lower than today and mainly confined to southwest Minnesota.

Gusty northwest winds will continue into the early evening, but should diminish after sunset. These winds will generally drop down to around 5-10 kts by midnight and stay that way through daybreak Thursday. Winds will gradually increase through the day Thursday, but these northwesterly winds won't be nearly as strong as today, only gusting up to around 20 kts in the afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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