textproduct: Sioux Falls

KEY MESSAGES

- Thunderstorms should increase in coverage into tonight. Locally heavy rain, possibly as high as 4-5 inches, will be the main concern across the area. A secondary concern will be wind gusts to 65 mph and hail to the size of quarters mainly in south-central South Dakota.

- While many locations will receive a beneficial half an inch to two inches of rainfall, the higher amounts could lead to localized flash flooding in urban and flood prone areas.

- Showers will linger into the day on Friday, with increasing winds through Friday morning. Winds will gust to around 35 mph at times, though isolated pockets of gusts pushing 45 mph can't be ruled out Friday afternoon east of I-29.

- Dry conditions and seasonable temperatures return for the weekend. For next week, shower and storms chances will return Monday night into Tuesday.

DISCUSSION

Issued at 229 PM CDT Thu Jul 30 2026

Scattered showers and storms are moving across areas mainly near and east of the James River this afternoon, with some clearing occurring behind this activity. This should allow for greater destabilization in south-central South Dakota this afternoon and thus have issued a Severe Thunderstorm Watch for Brule, Gregory, and Charles Mix Counties. Damaging winds to 65 mph and quarter sized hail are the main threats locally through the early evening hours. The greater severe weather risks looks to be south and west of our area where the better instability lies, but still be sure to remain weather aware. Elsewhere, the environment has been pretty worked over and thus severe weather is less likely. The one exception is over southwest Minnesota where we've been able to warm to the low to middle 80s out ahead of this early afternoon activity. However, with the current rain and clouds moving in and growing increasingly thicker in those areas, the threat for severe weather is diminishing there as well. There's also some clearing over north-central South Dakota, so this will be another area to watch for storm development, with any activity there moving east-southeast through the evening into tonight.

Heading into the night, the main wave will close off into an upper level low, with a surface low developing east of I-29 by daybreak Friday. This will all combine to keep rain and some storms in the forecast tonight through Friday morning and potentially as late as Friday afternoon near and east of I-29 as moisture wraps around the low. Any severe threat will greatly diminish after midnight, so this will transition to mostly a heavy rain threat as showers and storms will continue to push through the area. This could lead to localized flash flooding primarily in urban and flood prone areas, so be sure to remain weather aware. For the good majority of the area though, this should be beneficial rainfall, with additional totals generally between a half an inch to two inches through Friday afternoon. Locally higher pockets of 4+ inches remain possible, but that will be for areas that see multiple thunderstorms move over that same area. With recent dryness, those rainfall totals won't be much of a concern for rural areas. But urban areas could see some flash flooding with that kind of rainfall, so that will be the main concern tonight. Another thing to note is that the aforementioned surface low will be deepening over the area, so it will be a bit breezy on Friday, with gusts to around 35 mph possible. Isolated pockets of 40+ mph wind gusts can't be ruled out mainly east of I-29 Friday afternoon, but doesn't look like it will be widespread enough to warrant wind headlines at this time.

We'll dry things out heading into Friday night, and depending on how quickly clouds clear out, we could see widespread lows in the 50s by Saturday morning! If clouds take a little bit longer, we'll still likely see some 50s west of I-29, it's just that places east of there where clouds clear the latest may only drop to the lower 60s. So still much cooler than we have been! Dry and sunny conditions will be in store for the weekend, with a pleasant Saturday expected with highs only in the upper 70s to lower 80s across most of the area. Southerly flow returns on Sunday, making for it to be a little hotter, though not nearly as hot as it has been. Only south-central South Dakota has a shot of reaching 90 degrees on Sunday, but heat indices there will likely not stray too far from the air temperature. After Friday, our next chance of appreciable rain/storms will be Monday night into Tuesday as a cold front moves through the area. Not a lot of time to look into details given the focus on today and tonight's forecast, but it does look like there will be enough instability and shear to at least have some strong to severe thunderstorm risk, though details remain low. It does look likely though that another round of cooler air will filter in behind this front, making for an overall pleasant first week of August.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1257 PM CDT Thu Jul 30 2026

Scattered to numerous showers and storms are expected to continue and progress east-southeast through the afternoon and into the overnight hours. An isolated strong to severe storm is possible with this activity especially this evening, with wind gusts to around 50 kts the main threat along with heavy rainfall. Showers and storms will start to become more scattered to isolated in nature by early Friday morning as moisture wraps around a deepening low pressure system. This will also bring MVFR to IFR stratus along with it heading into Friday morning.

Winds will be mainly out of the southeast through the remainder of the afternoon, gradually turning more to the northwest and then north/northeast tonight into Friday morning as a low pressure system swings across the area from northwest to southeast. This deepening system will also bring breezier conditions to the area Friday morning with gusts up to around 30 kts possible starting after sunrise Friday morning.

FSD WATCHES/WARNINGS/ADVISORIES

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