textproduct: Sioux Falls

KEY MESSAGES

- Isolated showers and thunderstorms are still possible into daybreak, but severe weather is not expected.

- Isolated to scattered thunderstorms may be possible during the afternoon and evening hours of the 4th. While widespread severe storms aren't expected, isolated pockets of 40 to 60 mph winds and quarter size hail may be possible.

- All those with outdoor plans on the 4th should continue to monitor the forecast for the late afternoon through sunset.

UPDATE

Issued at 851 PM CDT Fri Jul 3 2026

TONIGHT: Thus far, a quiet evening has prevailed through the region, and this is likely to continue into the overnight hours. Convection over western South Dakota and Nebraska will keep moving on a slow southeast to east track into the overnight hours. Additional convection has been focused well south of the CWA in southern Nebraska and western Iowa. While convection to the west may be slightly driven by mid-lvl vorticity, soundings by time this activity reaches the MO River valley show increasing stability all the way through the 700 MB layer, with any elevated parcel really showing a lack of instability and shear. Thus, not anticipating any severe weather risk with this activity as it tracks closer. Perhaps some additional development can form along and south of Highway 20 by 3am as the LLJ increases, but the quick veering of this low-lvl flow would push any development initially to the northeast and then east quickly. Elsewhere, really not seeing any widespread development other than potential for an isolated non-severe thunderstorm or shower through daybreak.

4th of July: after breaking through a little bit of patchy fog and clouds, we'll gradually warm towards the lower 80 by mid-day on the 4th. While the low-lvl and mid-lvl flow remains very weak, sounding do show convective temperatures being met by mid-late afternoon which, when combined with minor shortwave energy dipping into the Eastern Dakotas from the northwest, could lead to isolated or scattered thunderstorms moving southeast into the evening. Certainly wouldn't cancel any 4th of July plans, but be aware that a storm or two could bring rather gusty winds (40-60mph) and marginally severe hail risks into the sunset hours.

SUNDAY: Outside of morning patchy fog, a spectacular end to the 4th of July weekend is expected Sunday.

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 /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1211 AM CDT Sat Jul 4 2026

Lower stratus remains in place near Sioux City this morning, with a broken to overcast high level cloud deck elsewhere. With dew point depressions small, watch out for patchy fog through most of the area into daybreak.

VFR conditions are expected for most of Saturday as a CU field quickly develops by mid-day. Still a 20 to 30% chance for isolated to scattered thunderstorms in the late afternoon and evening hours. Winds are expected to remain light through the 24 hour TAF period, however stronger winds may be possible in any thunderstorm activity.

FSD WATCHES/WARNINGS/ADVISORIES

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