textproduct: Sioux Falls

KEY MESSAGES

- Scattered showers and a few thunderstorms are likely tonight. An isolated strong to severe storm is possible mainly near and west of the James River, with damaging wind gusts up to 65 mph the main threat.

- Isolated severe storms are again possible Thursday afternoon over parts of southwest MN and northwest IA, especially along and east of Highway-60.

- 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 854 PM CDT Wed Apr 22 2026

Allowed the Red Flag Warning to expire at 8 pm as planned as relative humidity recovers. It will only recover gradually over the next couple of hours, so expect an elevated fire danger to continue this evening as winds remain elevated. By midnight, relative humidity values will be well above critical levels area-wide.

Attention then turns to the chance for storms overnight. Storms are currently ongoing near a dryline over western South Dakota, aided by an upper low moving across eastern Montana. These storms will be lifting northward, but as the dryline nudges eastward tonight, additional showers and storms look to develop as a 50-55 kt southerly low level jet cranks up over our area. This will lead to around 500-1000 J/kg of CAPE tonight, with instability gradually decreasing into the early morning hours and with eastward extent. The main concern with any thunderstorm would be damaging wind gusts up to 65 mph as there will be ample dry air underneath the clouds that will help mix down stronger gusts. With the dry sub cloud layer, will also need to keep an eye out for any outflow boundaries from any storm, as these could also bring stronger wind gusts as well. The best chance of severe weather will be near and west of the James River. Mid level lapse rates will be quite steep, on the order of 8-9 C/km; however, with limited instability and weak bulk shear, updrafts will likely have trouble sustaining themselves and thus only small hail looks possible at this time.

Otherwise it will be a warm night tonight with lows in the 50s and 60s. Winds look to diminish somewhat towards daybreak, but still remain on the breezy side with gusts to 20-30 mph during the morning commute Thursday.

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 ec 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 /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 640 PM CDT Wed Apr 22 2026

VFR conditions begin the TAF period. Strong southerly winds persist across the area with gusts up to 30-40 knots. These winds will slowly weaken through the overnight hours. As the same time, some showers and thunderstorms are possible tonight, mainly around KHON initially. These same showers and storms look to push eastwards though on a weakening trend. MVFR/IFR ceilings look to develop across locations east of the James River tonight as well. These low ceilings will persist through the morning hours before exiting the area during the afternoon hours tomorrow. Winds on Thursday will be turning westerly while remaining breezy through the day. Another round of showers and thunderstorms looks to develop tomorrow afternoon. Some uncertainty remains regarding where these storms develop. As of now, locations along and east of a KMJQ to KSUX line have the highest odds of seeing showers and storms. These showers and storms will finish out the TAF period.

FSD WATCHES/WARNINGS/ADVISORIES

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