textproduct: Sioux Falls

KEY MESSAGES

- Scattered non-severe storms are expected near and east of I-29 today.

- Conditional severe risks west of Highway 281 late tonight and west of I-29 Monday afternoon. Confidence in storm development is low (20-30%), but if storms develop, damaging winds and large hail would be the primary threats.

- Temperatures heat up through mid-week. There is a moderate chance (40-90%) of highs exceeding 90F Tuesday and Wednesday, with the highest probabilities coming on Tuesday. Be prepared to enact any heat related safety measures.

- Severe storm chances look to make a return to the region on Tuesday and Wednesday. Details remain uncertain so continue to keep up to date with the latest forecast for the most up to date information.

UPDATE

Issued at 510 AM CDT Sun Jun 7 2026

An isolated shower/weak storm has developed at the leading edge of strong Theta-E/moisture advection early this morning, with low chances lingering mainly in southwest Minnesota until shortly after sunrise. Expect greater coverage of showers/storms to develop near and east of I-29 this afternoon/evening as a mid to upper level wave slides north across the area. Increasing cloud cover will limit instability and storms will have very little shear to support organized development, so severe weather is not expected.

Will still have to watch storms which develop well to our west later today, as still a low (20-30%) chance that this activity could drift into our far western zones after midnight tonight. These storms should be weakening as they progress east into a less unstable air mass, but will need to monitor trends as more aggressive CAMs do still indicate an isolated strong to severe potential.

Monday should generally see storm potential suppressed with rising mid-upper level heights in the wake of the early morning wave. However, a low level thermal ridge noses into our South Dakota counties by afternoon and if temperatures should warm enough to break through a capping inversion, steep mid-level lapse rates could support an isolated large hail threat in the late afternoon-evening.

A more potent mid-upper level trough swings through the northern Plains Tuesday-Wednesday, but as alluded to in the previous discussion, the greater threats for severe weather appear to be focused to our north Tuesday-Tuesday night, and to our east on Wednesday. This is supported by the latest Day 3/4 SPC outlooks which have introduced an Enhanced (Level 3 of 5) risk in North Dakota/north-central South Dakota on Tuesday, with a 30% Day 4 risk farther east in the Upper Mississippi Valley for Wednesday. Details for our area are still rather low confidence. The heat dome that is expected to build into the area on Tuesday should limit daytime development, but a wave sliding northeast by late afternoon/early evening could trigger development. Instability and shear would be supportive of strong to severe storms, it's mainly timing/coverage of development that is lower confidence at this time.

For Wednesday, there is still some disagreement in regard to timing of the cold front, but some models have trended slightly faster with the cold front. Not only would this bring greater relief from the heat/humidity across our western counties, but it could also shift the severe risk farther east as indicated in the latest SPC outlook. Again, this leads to lower confidence in potential severe timing and coverage for Wednesday afternoon, but even the slower models would push the risk of storms east of our CWA by early evening.

DISCUSSION

Issued at 204 PM CDT Sat Jun 6 2026

Quiet conditions persist this afternoon along with high temperatures that have warmed to 80s to low 90s. A weak upper level low currently spinning over the southern Plains will begin to advect northwards this afternoon. The main forcing from this wave will remain south of the forecast area today but could see an isolated shower or storm develop near and south of highway-20 this afternoon and evening. Deep layer shear will be weak at 10 knots or less so severe storms are not expected. Low temperatures will fall to the 60s overnight. Moistening dew points overnight could result in some patchy fog across the area, most likely in river valley's.

The weak upper level wave will advect northwards on Sunday. This wave will result in an increase in cloud cover and slightly cooler high temperatures across the area. High temperatures look to warm to the 80s to touching 90F toward central South Dakota. Depending on how thick the cloud cover gets and the timing of rain with it, some locations may see high temperatures remain in the upper 70s. Chances (20-60%) for showers and storms will return with this wave tomorrow afternoon and evening. As of now, the bulk of the showers and storms look to track northwards for locations along and east of I-29. Instability will be sufficient at or above 1,000 J/kg. However, deep layer shear will remain weak at 10 knots or less. Thus, severe weather is not expected. Given the more scattered nature of the storms, rainfall amounts are not expected to be much with most locations receiving a a few hundredths to a tenth or two of an inch. Isolated higher amounts are possible where storms track over the same area. Chances for rain will be waning through the evening hours as the boundary layer begins to stabilize, preventing and deeper mixing from initiating new storms. There could be a second round of storms that may track eastwards into the area from the western Dakota's Sunday night. As of now, think that this second round of storms will mainly stay off to the north and west of the forecast area where the better vertical shear will lie. If these storms were to hold together as they push into the area, they will likely be on a weakening trend due to the weak vertical shear in place. Perhaps gusty winds could accompany the storms before they completely die out.

Monday looks to be quiet during the daylight hours as the wave responsible for Sunday's storms lifts into Canada. There could be another round of showers and storms Monday evening but this will be dependent on if the cap can be broken. Latest ensembles show relatively high probabilities between 40-80% that the cap remains stronger (more negative) than -25 J/kg. Tough to say if temperatures could warm enough to overcome the cap let alone reach convective temperatures. If the cap could be broken, then low end severe storms would be possible as vertical shear begins to strengthen aloft. If the cap remains strong, then no storms and little rain would be on the table. Something to keep an eye on going forward.

Attention then turns to Tuesday and Wednesday of next week. Medium range guidance is in agreement in a strong, longer-wave upper level trough digging into the Northern Plains during this period of time. Before diving into storm chances, high temperatures look to be hot across the area with highs warming into the 90s and potentially touching 100F to 101F on Tuesday. The ensembles support this as they show moderate to high probabilities (50-90%) for high temperatures to exceed 90F on Tuesday. These same probabilities drop a bit to a 40- 70% chance on Wednesday. These hot temperatures will coincide with more humid conditions as dew points moisten to the 60s and 70s. The hot and humid conditions will result in areas of moderate to major heat risk. If you will be out and about on either of these days, please follow the necessary safety precautions to stay safe in the heat.

Thunderstorms look to persist across the area as the upper level wave begins to eject into the Northern Plains on Tuesday. With southwest flow over the Rockies, lee cyclogenesis will occur, tightening low level pressure gradients and strengthening the low level jet (LLJ). This will increase vertical shear profiles across the region. Instability will be more than sufficient with the previously mentioned hot and humid conditions in place. Thus, strong to severe storms will be possible. As of now, Tuesday evening and night looks to be the main time period for severe weather due to the strengthening LLJ. The main wave finally ejects on Wednesday, continuing severe storm chances. If current model trends hold, Wednesday could see the strongest storms between both days as an exit region of an upper jet looks to push into the Northern Plains. While the deterministic models, ensembles, and clusters support this exit region, details about how this wave tracks remain a bit uncertain. Mesoscale details are also much more uncertain this far out. Especially considering that Wednesday's storm potential will be dependent on how Tuesday's storms pan out. Latest machine learning (ML) models give a little bit more clarity into this potential. Currently, the bulk of the ML models have the highest chances for severe storms in North Dakota on Tuesday and then across parts of Minnesota, Wisconsin, and Iowa on Wednesday. Details can still change over the next couple of days but continue to monitor the latest forecast for the most up to date information.

Chances for rain could persist through the rest of the week but this will depend on how the upper level wave evolves and if low level moisture gets pushed south of the area. High temperatures look to fall back closer to seasonable in the upper 70s to 80s.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 637 AM CDT Sun Jun 7 2026

VFR conditions to start the period will deteriorate from south to north, especially along and east of the I-29 corridor as areas of light rain with embedded thunderstorms lift north out of Iowa. Confidence is slightly higher that KSUX could see an occasional thunderstorm in the late afternoon/early evening so will continue a TSRA mention there. Lower confidence at KFSD at this time, so have shifted this back to -SHRA for now. Cannot rule out brief thunder, but feel most of the period should be thunder-free.

MVFR-IFR ceilings are expected to persist near/east of I-29 through the latter half of the TAF period while areas west of I-29 favor VFR conditions. A low chance that showers/storms could reach KHON late in the period, but again, confidence is too low to include TS in the KHON TAF at this time.

FSD WATCHES/WARNINGS/ADVISORIES

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