textproduct: Sioux Falls

KEY MESSAGES

- On and off showers will persist for the reset of the daylight hours today. Light rainfall amounts between a few hundredths to a tenth of two is expected.

- New chances (40-70%) for showers and thunderstorms will develop after midnight tonight. Severe storms are not expected but lightning and small hail will be possible.

- 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 60 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.

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 /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1242 PM CDT Fri May 29 2026

Latest radar imagery shows on and off showers pushing northerly up along the James River early this afternoon. Expect these light showers to persist through the rest of the afternoon hours while pushing to the north. Latest trends will keep the bulk of these showers along the James River valley though a few could stretch eastwards to around I-29. This round of showers will begin to wane during the evening timeframe. However, another round of scattered showers and some thunderstorms are possible late tonight into tomorrow morning. Tough to say how long rain chances will last any any given point let alone terminal so have not included rain chances in a TAF at this time. Will include mention of rain and potentially thunder as confidence increases. This second round of showers and storms will coincide with ceilings beginning to lower to MVFR/IFR/LIFR levels. While MVFR ceilings will encompass all TAF sites, the lowest ceilings will reside across south central South Dakota. Chances for showers and storms will persist through the rest of the morning hours while ceilings begin to lift to end the period.

FSD WATCHES/WARNINGS/ADVISORIES

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