textproduct: Sioux Falls

KEY MESSAGES

- New chances (30-60%) for showers and thunderstorms will move into the area along the Missouri River Valley around sunrise. Severe storms are not expected, but pea sized hail and a brief wind gust to 35 mph will be possible over south-central South Dakota with this activity.

- Strong to severe storms may return to the area this weekend. The first chance comes Saturday evening and night along and west of the James River where an incoming line of storms could bring wind gusts up 65 mph and quarter size (1 inch) hail.

- The second round for severe storms is possible on Sunday. However, there is uncertainty regarding severe storm potential. If storms do develop, large hail up to the size of half dollars (1.25 inches) and damaging winds to 60 mph would be the main hazards. Continue to monitor the latest forecast for the most up to date information.

- Chances (30-60%) for rain will persist through the bulk of next week. However, severe storm chances continue to look low (near 5% or less) through next week.

UPDATE

Issued at 925 PM CDT Fri May 29 2026

An area of steadier light showers continues to lift northward across eastern South Dakota and far western Minnesota, with stronger activity over southeastern Nebraska also lifting north. That stronger activity is weakening as it moves into the more stable regime located closer to our area, and this trend will continue and thus thunder is unlikely until around daybreak. More on that in bit. The aforementioned area of light rain should clear north of Highway 14 over the next couple of hours, and just spotty light showers are possible elsewhere through through the nighttime hours.

Guidance has trended a little bit towards a later arrival time for showers and storms currently located over the High Plains of western Nebraska to move into our area, with this activity likely not reaching the Missouri River corridor until closer to sunrise or just afterwards. There won't be much instability to work with by those hour, with about an 80-90% chance of MUCAPE values less than 1,000 J/kg according to the EC Ensemble, which is also supported by deterministic CAM soundings. These soundings show the highest instability over south-central South Dakota, where around 500-700 J/kg of CAPE is possible. Severe weather is not expected, though can't rule out a stronger gust there up to 35 mph and/or pea sized hail. Otherwise, a warm and fairly muggy night ahead with lows by sunrise mainly in the lower 60s.

DISCUSSION

Issued at 215 PM CDT Fri May 29 2026

Abundant cloud cover and light rain showers persist this afternoon. This has kept high temperatures in the upper 60s, 70s, and low 80s along with some breezy southeasterly winds with gusts up to about 25 mph. Expect on and off showers to persist for the rest of the day as a weak upper level low meanders through the area. Through this evening, minor rainfall amounts between a few hundredths to a few tenths are expected. The highest amounts will be localized and where showers more frequently track over a given location. A brief lull in shower activity is expected this evening before the low level jet (LLJ) begins to strengthen. While the jet will not be that strong with a magnitude up to about 20 to 25 knots, it will be strong enough to initiate a new round of showers and some thunderstorms after midnight. These showers and storms look to develop south of I- 90 initially before pushing north of the interstate through the rest of the overnight and morning hours on Saturday. Severe weather is not expected but lighting and small hail are possible with these storms.

The morning showers and a few thunderstorms will wane through the afternoon hours, slowly decreasing in coverage. Sunshine will gradually return to the area, allowing for high temperatures to warm to the upper 70s to low 80s. While the bulk of the late afternoon and evening hours look to be on the quiet side, strong to severe thunderstorms look to develop across the Black Hills. These storms will congeal into a mesoscale convective system (MCS) and push eastwards. The warm sector supporting the MCS's instability looks to have its eastern edge draped across locations west of the James River Saturday evening. Vertical shear will be weakening with eastward extent. Thus, it seems that the MCS will be weakening as it enters the forecast area Saturday night. For now, think that 60 mph winds and quarter size (1 inch) hail will be the main hazards as the MCS moves into the area. The MCS should weaken below severe limits with eastern extent as it outruns the instability and better shear. Could still see some showers and thunderstorms persist through the rest of the night but these storms are not expected to be severe.

Another round for strong to severe storms is possible on Sunday. There remains uncertainty regarding severe storm potential this day as the upper level wave responsible for Saturday's severe storms will be be pushing off to the north and west, promoting height rises across the forecast area and thus little forcing for ascent. The warm sector could be affected by lingering showers from the previous nights event as well. However, latest guidance does show the previously mentioned warm sector getting pushed eastwards throughout the day. Latest guidance is somewhat split on how strong the cap will be. Latest REFS shows a broad 30-60% chance for convective inhibition (CIN) to remain stronger (more negative) than -10 J/kg, though a few pockets of minimal CIN is present. This seems to be somewhat supported by the NAM3km and FV3 as these two CAMS go out through Sunday afternoon and they both do not show any storms. If storms are able to break the cap and develop, they could be strong to severe with large hail up to half dollars (1.25 inches) and damaging winds to 60 mph. Continue to monitor the latest forecast for the most up to date information.

The omega block pattern looks to persist aloft through Monday and Tuesday before beginning to break down during the middle of the week. This looks to bring zonal flow back to the Northern Plains. However, southerly flow will keep decent low level moisture in the area and continue to chance for daily showers and thunderstorms. As of now, the ensembles show a broad 30-60% chance for rainfall amounts to exceed a tenth of an inch each day next week. Given the weak flow aloft, questions remain regarding the strength of the vertical shear and thus overall severe storm potential. Aside from rain chances, high temperatures look to remain in the 80s with overnight lows falling to the upper 50s to low 60s.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1252 AM CDT Sat May 30 2026

A few light showers are moving across the area to start the period, and we'll continue to see some spotty showers through daybreak. Can't rule out a few rumbles of thunder near and south of the Missouri River through daybreak, with a better chance of showers and embedded storms arriving in these areas near and just after sunset. Confidence has increased enough to warrant mention of -TSRA at KSUX this morning as there will be a 40-50% chance of lightning if any rain moves across the site. This activity will gradually lift towards I-90 through the day today, but low confidence in timing and coverage precludes TSRA mention at KFSD and KHON at this time.

MVFR to locally IFR ceilings over Nebraska will slowly creep into our area through the morning hours, starting in the Missouri River Valley and spreading north. Uncertainly remains as to how far north these lower ceilings make it, but it's at least likely that any showers that can develop over KHON will bring MVFR ceilings along with it during the late morning/early afternoon. Ceilings will then lift through the afternoon back to VFR across the area. Winds will be mainly out of the southeast through the period, gusting up to 30 kts this afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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