textproduct: Sioux Falls

KEY MESSAGES

- Scattered showers and very isolated thunderstorms expected today. Severe weather is not expected and the better chance for thunder will be in northwest IA.

- Periodic chances for showers and thunderstorms are expected Saturday into early next week. A few stronger storms are possible Saturday afternoon into early Sunday morning and possibly again Tuesday.

- A warmup is expected Friday into early next week. Much above average temperatures are expected Sunday and Monday. Sunday morning lows could approach record warm levels.

UPDATE

Issued at 249 AM CDT Thu Apr 9 2026

Overall very few changes to the forecast today and tonight. Latest models still indicate a relatively weak, fast moving wave moving through today. The latest model soundings continue the trend of indicating some weak instability, 300-500 J/kg CAPE, with the slightly higher values in northwest IA. This may allow for a few rumbles of thunder, but severe weather is not expected. A fairly deep stable layer below the elevated instability will likely preclude any stronger winds at the surface and with the freezing level at about 8-9 kft hail is also very unlikely.

Later Saturday afternoon into Saturday night may see some isolated severe hail as a strong LLJ develops, bringing warmer and more humid air into the 850-800mb layer. If this does happen, instability will increase with CAPE values around 1250 J/kg possible. This could lead to a few storms possibly producing quarter sized hail. Will need to monitor trends on this LLJ surge.

DISCUSSION

Issued at 118 PM CDT Wed Apr 8 2026

Breezy northwest winds gusting 25-35 mph will usher in a much drier air mass this afternoon. Relative humidity levels will fall to near critical to critical for a brief period this afternoon. While no fire headlines are planned at this time, caution is still needed to prevent the spread of wildfire. This afternoon a low chance (<25%) of isolated to scattered light rain is possible over northwest Iowa. If showers can overcome the dry boundary layer, very little if any accumulation is expected. Highs this afternoon will climb into the 50s to 60s, with the highest temperatures over northwest Iowa. Winds become light and variable overnight with clear skies. This will help lows cool down to the 20s.

An active pattern looks to be the story for the rest of the week and into next week. Thursday a shortwave passes through the region bringing weak elevated instability and moderate WAA in the mid- levels. This may be enough to trigger showers and possibly thunderstorms. While isolated to scattered storms are possible across the region, any thunderstorms will most likely remain along and south of Highway 20. Severe weather is not expected, however a few stronger storms may produce wind gusts of 40-50 mph and small hail to the size of dimes.

Friday an upper ridge and surface high pressure build into the region. As it does so winds will become easterly to southeasterly. Subsiding air will warm and dry out conditions at the surface. Minimum relative humidity values are expected to fall to around 30% Friday afternoon. Highs will be in the 50s with light winds. Thanks to the milder temps and light winds fire danger will remain low to moderate for most of the forecast area. The exception will be south central South Dakota, where the high category may be reached. Though fire risks are lower, please continue to use caution.

Zooming out and looking at the overall pattern we see a large trough digging south over the Pacific Northwest. As it does so, vorticity waves propagate off the parent wave, compressing the pressure gradients from the surface through the mid-levels. The LLJ and surface winds will increase in response. Afternoon wind gusts of 25- 35 mph are expected with locally higher gusts possible. Good mixing and WAA will help afternoon highs climb into the 60s and 70s. Dewpoints will also increase, reaching the mid to upper 50s. It may begin to feel a bit muggy by Saturday afternoon. In addition, chances for thunderstorms creep into the area. The general trend across multiple models has been an increase in the potential instability across the region. Couple this with moderate to steep lapse rates, and roughly 30 kts of 0-6 km bulk shear and the potential is there for strong to severe thunderstorms Saturday evening into Sunday morning.

Storms clear out for Sunday afternoon and most of Monday. Highs will climb to the 70s and 80s Sunday, slightly cooler in the 70s for Monday. Monday evening storm chances return again, and continue periodically through the first half of next week as the previously mentioned upper trough begins to move out over the central United States. At this time it is too early to say for certain when or where or if storms will become severe. But the potential is there beginning this weekend and continuing into next week. This increase in thunderstorm activity is typical for April in the Midwest. It's important that you know how to respond should severe weather approach your area. Know where the nearest shelter is located. Have multiple ways to receive warnings, especially at night have at least one method that will wake you up! If you have outdoor plans be sure to monitor the forecast closely for updates.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 610 AM CDT Thu Apr 9 2026

VFR through the period. An MVFR ceiling will be possible near KMML through abpout 15z, but should drift north after this. Otherwise some spotty showers will be possible and a very isolated rumble of thunder will be possible near KSUX and KSLB this afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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