textproduct: Sioux Falls

KEY MESSAGES

- Showers and very isolated thunderstorms move east this morning. Severe weather is not expected, but isolated gusts around 30 mph may occur on the back edge of showers.

- Showers and isolated storms continue into this evening. Some locations will see a lull in activity late morning into the afternoon. Rainfall lingers longest west of Interstate 29 tonight; severe weather is not expected.

- Additional rainfall amounts will be highest for south central South Dakota into the southern Missouri River Valley, with brief periods of moderate rainfall today. Localized ponding is possible, but flooding/flash flooding are not expected.

- Below normal temperatures and periodic rain/storm chances continue into mid week. Severe weather risk remains low, although an isolated stronger storm is possible Tuesday.

UPDATE

Issued at 322 AM CDT Sun Jun 21 2026

No significant changes to the forecast this morning.

Showers and very isolated storms continue to move east into southeastern SD, with some briefly moderate rainfall. Although severe weather is not expected, a few sites on the backside of the decaying line in south central SD into the James Valley are gusting at times between 40 and 50 mph. Will monitor as this activity moves east.

Guidance still shows a break in the precipitation later this morning into the afternoon for portions of the area as the first wave moves out and the next wave moves in - although isolated to scattered showers are still expected through much of the day. Showers and isolated storms linger longest tonight west of I-29. Severe weather is not expected with the better forcing still off to our south. Additional rainfall amounts are expected to be highest for south central SD into the southern MO River Valley, and quickly taper down to the northeast. Highest additional amounts through early Monday morning around half an inch to an inch in some locations. Rainfall rates at times today may approach 0.25"/hr, with low (20% or less) chances of rates exceeding 0.5"/hr. Flash flooding is not a concern, but areas with more rainfall and heavier rainfall the last 24 hours may see localized ponding.

Outside of precipitation, temperatures today start off in the mid 50s to lower 60s. With precipitation and cloud cover, we'll see a relatively cool start to summer and for Father's Day, with highs in the 60s to lower 70s. Lows tonight fall into the 50s.

DISCUSSION

Issued at 202 PM CDT Sat Jun 20 2026

CURRENTS & TONIGHT: Another seasonable day continues! Taking a look across the area, mostly clear conditions persist this afternoon with most areas sitting in the mid to upper 70s and low 80s. This along with lighter surface winds has made for beautiful conditions weather- wise. Unfortunately, these conditions will be short-lived as cloud cover builds in from southwest to northeast into the evening as our next system approaches. From here, increasing dPVA/frontal forcing along with a weak LLJ (20-35kts) will likely lead to the development of scattered showers with isolated thunderstorms along the Missouri River Valley and portions of southcentral SD initially. Expect coverage to become more widespread overnight as the previously mentioned shortwave zips eastwards across NE just south of the SD/NE boarder leading to a blossoming of development.

While severe weather is not expected; the increasing lift and shear will lead to pockets of moderate to heavy rainfall at times from late this evening through Sunday morning. Nonetheless, any rain for the previously mentioned areas will be welcomed especially since this is where the worst conditions of our D2-D3 drought are set up according to the drought monitor. Taking a closer look, don't think any of this developing activity will touch the 2-3" in/hr rates necessary for flash flooding so we should be in good shape overall. Otherwise, expect the scattered rain chances to continue through at least Sunday morning before additional rain chances move in from central SD with our next system. Lastly, expect another mild night with lows expected to gradually decrease into the mid to upper 50s.

SUNDAY-TUESDAY: Looking into Sunday, the drearier conditions will persist throughout the day as additional rain chances (40%-80%) develop with the an approaching mid-level low. While severe weather is not expected, ample moisture and strengthening dPVA/frontal forcing should do just enough to keep the scattered showers going during the day with a few additional pockets of moderate rainfall. Nonetheless, should see much of the shower activity begin to taper off during the evening with the loss of diurnal heating and as the previously mentioned system tracks into the northcentral NE. Otherwise, quieter conditions should return by Monday as zonal flow returns aloft. Our next chance for precipitation will likely come by Tuesday as a cold front progresses through the area. While the better forcing will likely be to our north across northeastern SD, we could get just enough instability/shear to get a conditional risk for stronger storms during the afternoon to evening hours. However, there is still some uncertainty. Either way, this would be the next period to watch for any organized convection. Lastly, near to below normal temperatures will continue across the area through Tuesday with highs mainly in the low to upper 70s.

WEDNESDAY ONWARDS: Heading into the midweek, quieter conditions should return for Wednesday and Thursday as a surface high tracks through our area. From here, the wave train returns by Friday as quasi-zonal flow helps usher in multiple shortwaves increasing the chances from showers and potentially thunderstorms almost daily (every 24-36 hours) into the following week. While the chances for severe weather are still uncertain at this time, this is another period that will need to be monitored closely moving forward. Lastly, we'll continue to see temperatures build towards more seasonal conditions with highs increasing from the low to mid 70s on Wednesday to the low to mid 80s by Saturday.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 637 AM CDT Sun Jun 21 2026

Periods of showers and very isolated thunderstorms continue through the period. MVFR to IFR conditions are likely with showers/rain, which could be moderate at times. Some patchy MVFR stratus may move through the area as well. Showers linger through the evening and tonight west of I-29.

Showers this morning could produce some wind gusts to around 25 knots. Otherwise, winds from the east increase this morning, with gusts through the evening around 20 to 25 knots. Winds taper down late this evening becoming light and variable tonight into Monday morning.

FSD WATCHES/WARNINGS/ADVISORIES

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