textproduct: Sioux Falls

KEY MESSAGES

- Isolated severe storms will be possible this afternoon over parts of southwest MN and northwest IA, especially along and east of Highway-60.

- Near critical to critical fire weather concerns are expected this afternoon and evening especially across most southeastern SD and parts of southwestern MN. Avoid any outdoor burning!

- A return to more seasonable temperatures with highs in the mid 50s to lower 60s is expected Friday through the middle of next week.

- A very good chance (30%-60%) for showers and thunderstorms returns Sunday into Monday. Some locally heavier rain will be possible.

UPDATE

Issued at 436 AM CDT Thu Apr 23 2026

Taking a look across the area, low to mid-level clouds continue to filter in ahead of our next wave. With the passage of a lingering outflow boundary, we're starting to see a few scattered showers develop across the area this morning. While pockets of light to moderate rain will be possible, severe weather is not expected. Shifting gears here, the main changes with the 00z to 06z runs of guidance are: 1. The progression of the cold front has sped up quite a bit from yesterday's guidance.

2. Because of this, our window for stronger storms has shifted to earlier and farther southeastwards.

3. RH values have trended drier behind the cold front by this afternoon.

4. More critical fire weather concerns are now expected along and west of I-29.

The last two bullets will be discussed further in the fire weather section. As for the severe weather concerns, we're starting to run into some uncertainty. As mentioned above, the cold front's progression has trended faster than initially expected. As a result, instead of things kicking off between 3-10 pm; its now starting to look like the window will be between 12pm-6pm. The main questions that we have are how quickly will this morning's stratus push out of our area and how quickly will we erode the cap depicted in soundings. Both answers will vary depending on which model you choose. While that uncertainty continues, the target area continues to be areas east of I-29, more specifically along and east of a Sioux City, IA to Marshall, MN line. If and when storms do develop, stronger storms could produce large hail up to half dollar size and damaging wind gusts up to 60 mph. With this in mind, we're still outlooked in a Day 1 Slight (Level 2 of 5). Lastly, the ingredients (CAPE/ML Shear) align nicely in northwestern IA so that would be where my attention would be focused.

DISCUSSION

Issued at 109 PM CDT Wed Apr 22 2026

Strong winds will continue into the evening, but the lower humidities will diminish around sunset. It should be noted however that fairly strong southerly flow will continue through the night. Otherwise, a cluster of showers and thunderstorms will become likely in central SD later this evening into the overnight hours. With 1000-1500 J/kg CAPE potential and some drier low levels hail to the size of half dollars and wind gusts to 65mph will be possible. These storms should be confined to areas west of the James River and possibly mainly closer to the Missouri River in central SD. The weak mid and upper level wave associated with this development drifts east through the night, but instability wanes towards I-29, so expect any stronger storms to generally weaken as they head east late tonight into early Thursday morning.

The late tonight and early morning activity will diminish through the morning, but given the amount of clouds left behind as well as the progression of the pre-frontal trough, the threat for severe weather seems pretty limited for Thursday afternoon and likely shifted a bit east. For now, the best chance for isolated severe storms will be mid to late afternoon and mainly east of a Marshall to Sioux City line. If we can break out of the cloud cover and warm enough, there will be about 1000 J/kg CAPE with about 30 knots of shear so the potential for half dollar hail and 60 mph winds will exist.

Friday looks cool and dry with winds remaining mostly below 15 to 20 mph, so not too bad of a day. Highs mainly in the 60s.

On Saturday, low pressure to the northwest will drift east but not move very much, as jet energy wraps around the southern edge into the area. Saturday into Sunday a southern stream jet will also spread into the Central Plains and bring additional upper level support to the area. What this means is that from roughly Saturday into early Monday the area will see periods of moderate to strong mid level warm advection, which will bring periodic chances for showers and thunderstorms. The strongest period of lift appears to arrive on Sunday but for now the various models focus is all over the place so confidence is a bit low on the exact location of the more organized showers and storms. Of note the canadian ensemble and euro ensemble indicate most of the area will see a 60-90 percent chance for a half an inch or more of rain while the GEFS indicates something similar, just to the southeast of the area. Probabilities of an inch or more are running about 30-40 percent. Long story short, will need to watch trends to see if we can really get some meaningful rainfall in the area.

Low pressure wraps up to the north Tuesday into Wednesday, leaving the area in faster west to northwest flow and likely mostly dry conditions. There will be some spotty chances for showers and thunderstorms but for now that looks like a very isolated threat. Temperatures will be near the seasonal normals.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1259 AM CDT Thu Apr 23 2026

Taking a look across the area early this morning, there are some high based thunderstorms mainly in north central South Dakota, with a second area of weaker storms in northern Nebraska. These storms will miss the area for the most part, the exception being near KHON. However, confidence of getting thunder near or at the airport was only high enough for a PROB30 group at this time. All this activity is associated with an eastward moving dryline, and a few areas of rain will continue to develop through the rest of tonight into this morning, but thunder looks unlikely at KFSD and KSUX for at least this early morning round. As we head into the late morning/early afternoon, a broken line of showers and storms looks to develop over parts of northwest Iowa in southwest Minnesota and quickly push eastward through the afternoon. It's looking likely the chance of thunder with this activity will remain east of KFSD, but things are a bit more uncertain down by KSUX. Guidance is split on whether or not storms develop in and around KSUX or just to the east. A PROB30 group for -TSRA appears sufficient at this time until confidence grows in where these storms develop.

An area of stratus is currently located over eastern Nebraska and southwest Iowa. This area will lift north and lower as we head into the early morning hours, bringing MVFR ceilings mainly near and east of I-29. Locally IFR ceilings will be possible with this activity mainly over parts of northwest Iowa and southern Minnesota after sunrise and into the early afternoon hours. Overall, these lower ceilings will gradually push east throughout the morning into the afternoon.

Winds stay gusty through the period and will gradually turn west southwesterly as the dryline pushes eastward through this morning. A cold front will then move across the area from northwest to southeast this afternoon and evening, turning winds to the northwest to end the period. Wind will remain gusty to 35 kts through sunrise, decreasing slightly during the daytime morning hours before increasing again behind the cold front.

FIRE WEATHER

Issued at 436 AM CDT Thu Apr 23 2026

Fire Weather: Looking into the fire weather side of things, near critical to critical concerns are expected this afternoon/evening. Similar to yesterday, surface winds will be on the breezier side as the SPG tightens ahead and behind the previously mentioned front. Not only will this help gradually shift our surface winds from southerly this morning to more westerly this afternoon then more northwesterly this evening, we'll also see an uptick in speeds directly behind the front with wind gusts between 30-40 mph expected. This along with deeper mixing will help transport warmer and drier air to the surface leading to relative humidity values in the 12-20 percent range. With all this in mind and collaboration with our neighboring offices, a Red Flag Warning has been issued for most of southeastern SD and portions of southwestern MN. Lastly, make sure to avoid any outdoor burning as the conditions could help a fire quickly spread out of control!

FSD WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning from 1 PM this afternoon to 8 PM CDT this evening for SDZ039-040-054>056-060>062-065>069. Red Flag Warning from 11 AM this morning to 5 PM CDT this afternoon for SDZ038-050-052-053-057>059-063-064. MN...Red Flag Warning from 1 PM this afternoon to 8 PM CDT this evening for MNZ071-072-097. IA...None. NE...None.