textproduct: Sioux Falls

KEY MESSAGES

- Strong to severe storms look to return to the area by late afternoon tomorrow. The overall area for strong to severe storms will be along and east of a De Smet, South Dakota to Plankinton, South Dakota, to Burke, South Dakota line. Locations along and south of I-90 have the highest chances for seeing strong to severe storms. Damaging winds up to 65 mph and large hail up to 2 inches in diameter are the primary hazards.

- Temperatures will remain above average to begin next week but will trend closer to seasonable as the week progresses.

- Chances for rain (30-50%) will remain for next week. Showers and thunderstorms are possible but severe weather is not expected.

UPDATE

Issued at 859 PM CDT Sat May 23 2026

Showers and storms are ongoing over eastern and central Nebraska this evening, but this activity has mostly stayed south of the area. This looks to remain the case for the rest of tonight. The upper wave will continue to move across the region overnight, but weak instability combined with the nocturnal inversion will preclude any new development of showers during the overnight hours.

Otherwise, light southerly flow will remain in place across the area, which has already helped increase dew points to around 50 degrees as far north as the Huron area. With mainly clear skies on top of this, added some patchy fog to the forecast starting around 2-4 am. Fog should dissipate across the area by 8-9 am Sunday, so be sure to use extra caution on the roads if driving through fog early tomorrow morning. Dense fog can't be ruled out, but chances for visibility of a quarter mile or less is low, less than 20%. Otherwise a mild night is ahead for the area with lows a degree or two on either side of 50 degrees by sunrise.

DISCUSSION

Issued at 218 PM CDT Sat May 23 2026

Quiet conditions persist this afternoon as weak surface ridging remains in place. This will change over the next few hours as weak thunderstorms look to develop along the Missouri River valley. These storms are not expected to be severe as instability values will weak on the order of about 500 J/kg and deep layer shear be modest at about 30 knots. DCAPE will be modest at around 800 J/kg, contributing to the chance for gusty winds. Isolated wind gusts up to 40-50 mph is possible in the weak storms before they dissipate during the late evening timeframe. Low temperatures will fall to 40s to low 50s tonight.

Sunday will be mostly dry during the day as Saturday's upper level wave will push east of the area, promoting subsidence on its backside. The subsidence along with steepening mid level lapse rates from an arriving EML will result in warm temperatures up to the 80s to just about touching 90F. The warmest temperatures look to occur in south central South Dakota. This also looks to be the same area where convection initiates as these high temperatures will come close to reaching convective temperatures and have minimal inhibition. This looks to be along a weak dryline like boundary before spreading eastwards. These storms will push into a much more unstable environment with CAPE values up to around 2,000 J/kg. Though dry air entrainment may lower CAPE values closer to 1,500 J.kg. The low levels will be on the drier side though which looks to result in inverted-v like soundings. Thus, DCAPE values up to 800 to 1,000 J/kg are expected which look to contribute to damaging winds up to about 65 mph. Hodographs reveal generally long and straight shear profiles. Some curvature in the low levels is possible as the low level jet (LLJ) strengthens in the evening. However, with such dry air in place, LCLs will be higher, based near 850 mb. Thus, a tornado threat is not expected. With long mid and upper level shear profiles shown by the hodograph, mid level and upper level venting can occur, which will contribute to a large hail threat with hail up to 2 inches in diameter. 0-6km shear magnitudes of about 40 knots will keep the severe storm threat going into the evening timeframe before nocturnal stabilization and increasing inhibition end severe storm chances. There remains some uncertainty about the coverage of storms though as remaining CIN could prohibit more widespread thunderstorm coverage. At the same time, mid level heights will be rising aloft. In fact, 500 mb heights look to rise about 6dam aloft! This is not as favorable for severe storms though not completely harmful as mesoscale processes can overcome this limitation. Still, something we will continue to monitor. Could see weak showers persist into the night east of I-29. Low temperatures will be on the warmer side, only falling to the 50s to perhaps low 60s overnight.

Warm temperatures continue through Monday as upper level heights continue to build aloft. Highs look to reach up to the 80s about 90F across the area. The warmest temperatures look to occur across central and south central South Dakota. The warmth looks to continue as heights look to continue to rise aloft and stay that way through the entirety of next week. Medium range guidance, along with the ensembles strongly support an omega block pattern aloft. The ridge axis looks to be parked over the central Plains. While the upper level pattern would support warmer temperatures, latest guidance suggests that a surface highs will push into the Great Lakes region and will result in cooler, easterly flow. Thus, high temperatures look to slowly cool from the 80s to low 90s down to the 70s and 80s throughout the week.

Precipitation chances look to remain modest at about 30-50% through the week. These probabilities can change though depending on how the low levels set up. The good news is that this pattern is not expected to result in any appreciable wind shear across the area. Enough low level moisture could result in sufficient instability though, leading to shower and storm chances. The good news is that no organized severe weather threat is expected though non-severe storms remain possible for the week ahead. Continue to monitor the latest forecast for the most up to date information.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 639 PM CDT Sat May 23 2026

VFR conditions expected through the period. Scattered showers and storms have developed over parts of northern Nebraska this afternoon, but are generally weakening as it approaches our area. That combined with a downward trend in forecast instability within the latest guidance, did remove TSRA mention at KSUX. Still can't rule out some showers there, but the chance of lightning is now less than 20%. A better chance for storms arrive on Sunday afternoon and evening, but the higher chances of impacts to the TAF sites will be just after this current forecast period ends.

Winds will be mainly light and variable this evening, with southerly winds increasing through Sunday morning and into the afternoon. Strongest gusts will be around 20-25 kts mainly south of I-90 Sunday afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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