textproduct: Sioux Falls

KEY MESSAGES

- Scattered showers and non-severe thunderstorms will move north across the area today. A stronger storm may produce pea sized hail, but occasional lightning will be the biggest risk.

- Strong to severe storms may return to the area this weekend. The first chance comes late this evening and overnight 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 later Sunday. However, there is uncertainty regarding storm potential. If storms do develop, large hail up to 2 inches and damaging winds to 65 mph would be the main hazards. Continue to monitor the latest forecast for the most up to date information.

- Moderate 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 530 AM CDT Sat May 30 2026

Waves of showers and isolated thunderstorms will rotate north across the region today as a compact vort lobe in north central Nebraska lifts north through eastern South Dakota. Much of this activity will be in a region of limited instability and shear, so severe weather is not expected. However, occasional lightning could impact outdoor activities and stronger storms may produce small hail this afternoon. Otherwise temperatures will be near late May normals in the upper 70s to lower 80s with breezy southeast winds gusting 30-35 mph this afternoon.

Main severe threat represented by the Level 1 of 5 risk west of the James River Valley will come late this evening, more likely after midnight, as a line of storms rolls east out of western South Dakota. Still some discrepancy among high-res models on the track and intensity of this line as it moves into central South Dakota overnight, but if the line maintains strength into south-central South Dakota, the primary risk would be isolated wind gusts up to 65 mph.

Greater instability and better deep layer shear builds into portions of our forecast area ahead of a dry line by Sunday afternoon, though forecast soundings do depict a weak capping inversion which will have to break to tap into the instability. Mid-level lift is limited in the wake of departing morning convection, but if the dry line can provide enough forcing to break the cap, steep mid-level lapse rates and a potential for rotating updrafts would support large hail, perhaps golf ball to 2 inches in diameter.

No significant changes to the mid-longer range periods of the forecast, with lower rain chances early in the work week ramping up again mid-late week. Temperatures look fairly close to normal as we head into June, slowly warming by the end of the week.

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 /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 632 AM CDT Sat May 30 2026

Scattered showers and isolated thunderstorms will lift north across the area this morning, with greatest coverage near to just north of the Missouri River Valley, including KSUX. Heavier showers will result in a period of IFR visibility, but thunder will be limited in coverage. A broader area of MVFR ceilings will also lift north, with ceilings varying between MVFR and VFR through this period.

Late in the TAF period, a larger complex of showers and storms is expected to move east out of western South Dakota, bringing a greater risk of thunderstorms to TAF sites after 31/06Z. While exact timing is uncertain, attempted to target most likely window for thunder chances late in the period.

FSD WATCHES/WARNINGS/ADVISORIES

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