textproduct: Sioux Falls

KEY MESSAGES

- Showers will continue along a Marshall, Minnesota, to Sioux Falls, South Dakota, to Lake Andes, South Dakota for the rest of this evening and into the early overnight hours.

- Widespread rain chances (60%-90%) are expected from Sunday into Monday. Confidence continues to increase in accumulative amounts of 1+ inches of rain through Tuesday morning with the focus west of I- 29.

- An active pattern aloft will lead to additional rain chances from Tuesday night into Wednesday.

UPDATE

Issued at 918 PM CDT Sat Oct 24 2026

A line of showers currently stretches from approximately Marshall, Minnesota, to Sioux Falls, South Dakota, to Lake Andes, South Dakota this evening. Expect to see rainfall expand along this line through the rest of the evening hours as slightly stronger dendritic forcing pushes through the area. The bulk of this forcing and associated rain will exit the area after midnight, leaving drizzle to perhaps light rain showers for the rest of the night. Only light rainfall amounts from a few hundredths to a tenth or two is expected in this round of light rainfall.

A second round of rain will push into the area tomorrow morning as additional dendritic forcing along with weak warm air advection (WAA) arrives. The bulk of this light rain will fall during the morning and early afternoon hours for locations mainly along and west of highway-60. Latest guidance suggests that light rain could persist all day long for locations along and north of highway-14 and on the western edge of the forecast area. Abundant cloud cover is expected but some uncertainty exits for mainly northwest Iowa. If cloud cover could clear out a bit, then temperatures could warm to the 60s. If the cloud coverage remains widespread, then temperatures will only warm to the 50s. Highs will remain in the 40s and 50s everywhere else.

The third round of rain will come Sunday night. This round will be much more widespread as an upper level wave begins to eject out into the Plains from the Rockies. This wave with strengthen low level WAA and provide stronger omega (upward motion) in the dendritic growth zone (DGZ). The 850 mb front will also strengthen in response to the wave and right entrance region of an upper level jet as well, further contributing to sufficient lift across the area. This round of rain remains on track to not only persist through Sunday night, but also through the vast majority of Monday as well. This will keep highs contained to the 40s and 50s again. There remains the potential for parts of northwest Iowa to see highs break into the 60s. As of now, the ensembles show a tight gradient ranging between a 30-70% chance for highs to break 60F. Still looking at this round of rain to push northeast of the area Monday night.

Rainfall amounts remain on track with the heaviest rain falling west of a Yankton, South Dakota to Sioux Falls, South Dakota to Slayton, Minnesota line where accumulations of 1+ inches is most likely. Though the latest guidance does suggest negative equivalent potential vorticity (EPV) above the 850 mb front, suggesting that higher rainfall amounts are possible. Rainfall amounts look to remain near and below a half an inch east of the previously mentioned line.

DISCUSSION

Issued at 200 PM CDT Sat Oct 24 2026

Currents & Tonight: Another dreary day continues! Taking a look across the area, a brief break continues this afternoon as drier and cooler air filters in behind a cold front. This along with breezy northwesterly surface winds with gust between 25-35 mph has led to quite the chilly feel this afternoon with highs sitting in the upper 40s to mid 50s west of I-29 and the 60s to low 70s east of I-29. Expect temperature to continue their gradual decline from here. Otherwise, the intermittent showers resume from late afternoon onwards as southwest flow aloft helps additional pieces of energy lift through areas mainly west of I-29 through Sunday morning with mainly light accumulations. Lastly, given the increased cloud cover overnight thinking temperatures won't decrease as fast nor as far as the NBM thinks (mid 30s to low 40s). With this in mind, decided blend in some CONSshort into our MinTs slightly nudge up overnight temperatures into the low to upper 40s

Sunday-Monday: Looking into Sunday, another wet and dreary day is ahead as a subtle 850mb front stalls across our area roughly along a Wagner to Sioux Falls to Windom, MN line. With broad southwesterly flow firmly in place aloft, additional pieces of lift (dPVA) will stream into the warm air advective (WAA) regime along and northwest of this near-surface feature spurring intermittent showers throughout the day within the left exit region of the coupled jet. While mostly light accumulation are expected during this period, should see an uptick in coverage from late Sunday evening into Monday as additional lift arrives and WAA strengthen ahead of the inverted trough axis. Looking aloft, most guidance has the base of the mid-level trough gradually lifting into the Nebraska Pan handle by Monday morning then central and eastern SD by Monday afternoon/evening. While there some questions remains on where the heaviest accumulations set up, its worth nothing that NBM QPF has taken a noticeable northwest shift towards the better dynamics which are west of I-29.

As such, still thinking most areas receive accumulating rainfall through Monday. However, currently thinking the axis of 1+ inches sets up somewhere west of a Yankton to Sioux Falls to Slayton, MN line with the heaviest accumulations west of Highway 281. Everywhere east of this line could be affected by a bit more dry air leading to accumulations of a 0.50" of an inch or less. While not a drought buster, this system will provide beneficial rainfall for parts of the area over a 24-36 hour period. With this in mind, the flood concerns are minimal though some ponding will be possible in some urban and low lying areas. Lastly, expect the cooler conditions to persist for both days given the increasing rain chances with daily highs sitting in the mid 40s to mid 50s north of I-90 and low 50s to low 60s south of I-90.

Tuesday Onwards: Heading into the extended period, quieter conditions will temporarily return for the first half of Tuesday. However, additional showers could develop by Tuesday afternoon along and east of I-29 as a cold front swings through. From here, the quieter conditions should persist through at least Friday as solutions in long-range guidance begins to diverge. Lastly, expect daily highs to remain mainly in the 60s to low 70s with the warmest conditions across northwestern IA.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 635 PM CDT Sat Oct 24 2026

Light rain remains across the area early this evening, mainly along a KBKX to KMDS to KAGZ line. Ceilings remain a mix between VFR and MVFR with visibilities VFR as well. More persistent rain across northern Nebraska will push northeastwards along this line this evening, potentially making it into the KFSD area. Rain looks to wind down to drizzle to perhaps light showers through the night before another round of more persistent rain develops for Sunday morning. Ceilings and visibilities look to fall to MVFR levels in the second round of rain. The second round of rain will push to the northern and western fringes of the forecast are by tomorrow afternoon, leaving mostly dry conditions for the rest of the TAF period.

Winds will remain light out of the north through the night before veering to out of the northeast and strengthening up to about 10 knots be Sunday afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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