textproduct: Sioux Falls

KEY MESSAGES

- Isolated to scattered showers and thunderstorms are expected this afternoon. While severe weather is not expected, an occasionally strong wind gust up to 45 mph will be possible.

- After warmer temperatures through Thursday, conditions will cool towards more seasonal temperatures over the weekend with lower precipitation chances (30% or less) concentrated along and west of the James River Valley.

UPDATE

Issued at 324 AM CDT Wed May 27 2026

Taking a look across the area, we're continuing to watch a few scattered showers develop across southwestern MN mainly in response to weak shortwave intersecting a backdoor cold front roughly stretching from northeastern SD down into central and southeastern MN. However, the environment isn't doing this activity any favors. With limited instability and shear underneath a mid-levl high pressure system; most of this develop activity is quickly diminishing just as quick as it gets going. With this in mind, we're expecting this trend to continue intermittently through daybreak before things quiet down temporarily. From here, another warm day is ahead as highs once again peak in the upper 80s to mid 90s with the warmest conditions along and west of the James River Valley.

As the previously mentioned cold front gradually works its way southwestwards by early afternoon, the combination of warmer temperatures and dew points in the upper 50s to low 60s will likely lead to additional showers and thunderstorms developing. While severe weather is not expected, collapsing thunderstorms could produce decently strong cold pools leading to occasional gust up to 45 mph with some additional redevelopment downstream at times. However, with most of this activity being mainly diurnally driven; should things gradually wind down around sunset (around 6-8 pm). Lastly, the warmer conditions will extend into the overnight hours as temperatures only decrease into the low 60s for the night.

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 spatial 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 /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 622 AM CDT Wed May 27 2026

Main VFR conditions with isolated MVFR vsbys are expected this TAF period. Taking a look at satellite imagery, mostly clear conditions persist this morning. While these conditions will continue through early afternoon, could see a few scattered showers with isolated thunderstorms develop in the heart of our area ahead of an approaching cold front promoting MVFR vsby at times. With this in mind, added a PROB30 to KFSD to better capture the timing of development. Should see any lingering activity gradually dissipate after sunset. Lastly, light and variable winds this morning will become more easterly by late afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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