textproduct: Sioux Falls

KEY MESSAGES

- Temperatures continue to rise towards the 90s this afternoon, and may lead to isolated thunderstorms over SW Minnesota this evening. Marginally severe hail (1") and localized downburst winds of 50-60 mph may be possible.

- Temperatures remain warm into mid-week, with isolated to scattered storms again possible Wednesday afternoon. An isolated strong storm is possible, but not expected.

- Temperatures cool slightly heading into the weekend, with a continued uncertain but generally low rain risk each day. Severe risks remain very low.

DISCUSSION

Issued at 1257 PM CDT Tue May 26 2026

THIS AFTERNOON/EVENING: Weak MCV continue to track east into Southern Minnesota early this afternoon, with slightly weaker and smaller vort max within the 700:500 mb range drifting eastward along Highway 14. Temperatures continue to warm through the 80s, and will eventually end up in the lower 90s in some locations. Most area won't reach record levels, but Huron and Sioux City are likely to be close to record levels this afternoon. By late afternoon, we may begin to reach convective temperatures near extreme eastern South Dakota and portions of Southwestern Iowa, with MLCAPE approaching 1500 J/KG. Lingering vorticity may be just enough to spark a storm or two later this evening, but most of the activity may be confined towards the remnant MCV in southern and southeastern Minnesota, but also along a weak convergence boundary over north central Minnesota. Hail risks continue to look low, but deeper inverted V soundings would suggest localized downburst potential this evening.

OVERNIGHT: Most of the local activity will wane with the loss of diurnal heating, but we will watch northern multicell clusters over northern and northwestern Minnesota drop southward overnight. Most of this activity will be on a weakening stage after midnight, but could bring some brief gusty winds to SW Minnesota after 3am through 7am.

WEDNESDAY/THURSDAY: Stuck under the elongated mid-lvl ridge on Wednesday, winds from the surface to 300 mb are expected to be extremely light and variable. This however may not mean we'll be completely dry as some guidance hints a weak backdoor cold front or perhaps remnant outflow boundary moves southeast into the Tri- State area in the afternoon. Point soundings across the I-29 corridor show a loss of convective inhibition by mid-afternoon with tall and skinny MLCAPE near 1500 J/KG at the same time. Mid-lvl lapse rates are very marginal and shear profiles suggest no storm organization, but would not rule out an isolated stronger storm or two into Wednesday evening.

A nearly identical setup on Thursday with a slightly stronger southeasterly wind converging into the Tri-State area in the afternoon. Once temps reach the middle to upper 80s, we'll again reach convective temps and should be capable of a few diurnally based thunderstorms. Will keep PoPs low given uncertainty on development and spacial coverage.

FRIDAY-MONDAY: The persistent Omega block ridge axis will remain very near to the Tri-State area during the end of the week and through the upcoming weekend. Medium range guidance and ensembles continue to provide better focus on temperatures and precipitation chances through the holiday. Most guidance now continues to push the best northward return flow towards the Western Plains through the weekend, keeping the edge of the CWA along the periphery of the best rain chances each day. With such weak shear, any storm that does develop won't reach severe limits given poor environmental shear. Temperatures may actually trend downward slightly with greater influence of cooler easterly winds from Great Lakes high pressure. That said, highs should climb into the lower to middle 80s into early next week.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 647 PM CDT Tue May 26 2026

VFR conditions will prevail through Wednesday. Very isolated high-based showers or storms will be possible over southwest Minnesota and toward the Iowa Great Lakes (north of KSPW) this evening, but impacts to TAF sites are not expected.

Later tonight, a cluster of storms may drop southward through western Minnesota, bringing a potential for gusty winds to portions of southwest Minnesota and northwest Iowa. Elsewhere, light and variable winds are expected overnight into Wednesday morning.

Additional isolated to scattered high-based showers/storms will be possible Wednesday afternoon, again bringing a potential for scattered gusty winds. However, confidence in coverage/location of storm development is too low to include mention in any of the TAFs at this time.

FSD WATCHES/WARNINGS/ADVISORIES

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