textproduct: Sioux Falls

KEY MESSAGES

- Confidence in increasing in how today's potential severe weather will play out. However, trends are suggesting that severe storm chances will take place along and south of highway-20. The main timeframe for strong to severe storms will be from 5 pm to midnight. Continue to monitor the latest forecast for the most up to date information.

- Any flooding potential will also occur with the severe storm risk late this afternoon and evening. The highest potential for flooding looks to take place south of highway-20.

- Scattered showers and storms remain on the table for Saturday. The highest probabilities (40-50% chance) lie across southwest Minnesota for the daylight hours. Severe weather is unlikely but lightning, brief heavy rain, and gusty winds are possible in any storm that develop.

DISCUSSION

Issued at 246 PM CDT Fri Jul 3 2026

After this morning's storms, cloud cover has cleared across most of the area, allowing for more effective diurnal heating and airmass recovery to take place. There are a few boundaries around that could result in storm development this afternoon and evening. The first is a stationary front located near and north and west of the forecast area. The second is a new outflow boundary that was spawned from the morning convection across south central South Dakota has pushed southeast across the majority of the forecast area, now down to near Sioux City. The main effective boundary is currently sitting near highway-30. This last boundary will be the main driver of new thunderstorm development later this afternoon and evening as a shortwave trough currently ejecting out of the Rockies interacts with this boundary. The previously mentioned outflow boundary also looks to meet this effective boundary at the same time. Thunderstorms look to develop near to after 5 pm on this boundary. As storms develop, they look to be initially discrete with large hail up to 2 inches in diameter. Like the past few days, storms look to grow upscale into a line as the mean flow is mostly parallel to the effective boundary. Once storms grow upscale, damaging winds to 70 mph will become the main hazard. The remaining uncertainty resides in where storms will develop. Most of the latest guidance keeps the convection just south of the forecast area. A few models do bring storms into the highway-20 corridor so can't fully rule out any severe storm chances just yet. It will come down to how far north the boundary can return. Any flooding potential will also come down to the boundaries location as well. With mean flow generally parallel to the boundary, training storms are possible if the boundary can return far enough north. Should storms form in the area, the main timeframe will be from about 5 pm through roughly midnight. A few lingering showers are possible through the night.

High pressure begins to enter the area on Saturday, July 4th. Despite northerly flow across the area, remaining moisture will keep instability values up to about 1,000 to 2,000 J/kg. Vertical shear values will be weaker than what we have seen the past couple of days with magnitudes of 30 knots or less. A weak shortwave trough will push into the Northern Plains as an upper level ridge builds aloft. Latest REFS puts the highest chances (40-50%) over southwest Minnesota. With weaker shear in place, do not expect these storms to be strong to severe. However, brief heavy rain along with gusty winds and lightning are possible in any storm that develop. Stay aware if you will be out any about on Independence Day! Latest hi-res guidance also shows a weakening MCS moving from west to east. Only 1 or 2 models show this MCS making it into the forecast area. Thus, have low confidence in a low end MCS affecting the area at this time.

Upper level ridging continues to build across the western CONUS on Sunday. This will change the overall flow pattern to put the Northern Plains downstream of this ridge with northwest flow aloft. Synoptically, this will result in large scale descent and looks to keep conditions dry for the day. High temperatures look to remain seasonable in the 80s across the area.

The pattern quickly reverts back to nearly zonal for the bulk of next week. Weak shortwaves will push through the flow which could bring daily chances for showers and storms. Tough to say if any chance for storms could coincide with severe storms chances given how vertical shear look to be weak throughout next week. Confidence is not high enough to deviate from the NBM PoPs but something to keep an eye on going forward. Aside from rain chances, high temperatures look to remain seasonable in the 80s across the area. Dew points look to remain in the 60s to potentially low 70s which will keep the Summer time humidity going.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 633 PM CDT Fri Jul 3 2026

VFR conditions remain in place this evening and will continue into the overnight hours. Convection risks have greatly diminished in most locations, outside of a narrow corridor across Highway 20 late tonight. We'll also watch the western Dakotas for a cluster of storms that moves east. This activity is likely to sink southeast into Nebraska after midnight as it reaches for more unstable air. Locally, some scattered mid-lvl clouds will be possible, with some localized fog. Winds remain light and variable into Saturday.

Saturday will feature VFR conditions with rapidly developing diurnal CU by mid-day. Isolated to scattered thunderstorms will form over northern South Dakota and MInnesota and drift southward late in the afternoon and evening.

FSD WATCHES/WARNINGS/ADVISORIES

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