textproduct: Sioux Falls

KEY MESSAGES

- Scattered shower with isolated thunderstorms will be possible by Wednesday afternoon and evening. However, severe weather is not expected.

- Unseasonably warm temperatures and dry conditions combined with breezy southwest winds will lead to elevated to near- critical fire danger especially across southeastern SD. Additional concerns will be possible by Friday. However, increase rain chances could temper concerns.

- A pattern shift will lead to a brief cool down over the weekend. While this could be accompanied by precipitation chances (30%-40%) mainly on Friday, there is some potential for multiple types so make to monitor your local forecast.

UPDATE

Issued at 910 PM CDT Tue Apr 14 2026

Taking a look across the area, not much has changed from the initial discussion below. The area of scattered showers has slightly expanded with the line now extending from roughly Wagner, SD to Marshall, MN. However, with soundings continuing to show pockets of drier air; accumulations have been minimal if any. From here, we'll likely see this area of activity fester over the next couple hours before dissipating with the absence of diurnal heating. Looking into tonight, could see some additional development across areas along and south of U.S. Highway-20 as another weak wave interacts with the stationary boundary just southeast of our area. Nonetheless, with weakening instability; not expecting much besides some scattered light to moderate showers at times through daybreak on Wednesday.

Heading into Wednesday, the main focus continues to be on the severe risk from the late afternoon to evening hours. Still thinking the area of focus will across northwestern IA and more specifically our far southeastern zones (Woodbury, Cherokee, Clay, Buena Vista, and Ida counties) as this is probably where the better shear (40-50kts) and instability (300-800 J/kg) will be collocated for our area. However, with 18z-00z guidance supporting another shift southeastwards; confidence continues to decrease in the severe weather potential for our area. Looking further into things, looks like the overall system slightly shifted eastwards pushing the axis of the strongest activity eastwards as well. With this in mind, not expected any stronger activity in our area. However, scattered showers with isolated thunderstorms could progress through the area for a short-time (4-8pm) before pushing into northcentral IA.

DISCUSSION

Issued at 233 PM CDT Tue Apr 14 2026

Radar is picking up on a stripe of showers extending from roughly Marshall, MN to Gregory, SD this afternoon, but most of this will not be reaching the ground due high cloud heights and dry air beneath said clouds. Scattered showers and storms will continue to develop off to our south and west over the next hour or so where the greater surface moisture is. Can't entirely rule out an elevated thunderstorm over northwest Iowa as soundings show a few hundred J/kg of CAPE lifted from around 750 mb this afternoon, but likely not enough for severe weather. However, small hail would be possible with mid level lapse rates around 7-7.5 C/km and 50-60 kts of 0-6 km bulk shear if a thunderstorm can develop.

A boundary will be lifting northward across the region late tonight into Wednesday morning. The NAMNest is the fastest with this boundary arrival, bringing in storms to the Highway 20 corridor just before sunrise Wednesday, but this remains an outlier. What's more likely to occur is showers and storms not developing until the afternoon as the boundary continues drifting northward and instability increases due to daytime heating. Isolated strong to severe storms will be possible given mid level lapse rates greater than 8 C/km and bulk shear in the 45-55 kt range. The main threat with any of these afternoon storms would be large hail up to ping pong ball in size followed by damaging wind gusts to 60 mph. If we do get morning showers or storms tomorrow, then that may limit the ability for the atmosphere to recover in the afternoon, thus less afternoon instability. The best chance of an isolated severe storm Wednesday afternoon will be roughly along and east of a Spencer to Sioux City line. Any storms will push east of the area heading into Wednesday evening as the surface low and upper wave move out of the area.

We are dry for Thursday, but this may come with the potential for critical fire danger in parts of the area. Southwesterly winds look to return for areas mainly along and west of I-29, which will help drop relative humidity values down to 25% and below Thursday afternoon. With temperatures in the 80s and winds gusting to 25 to 30 mph, a very high fire danger can be expected for most of the area. Uncertainty remains on how strong the winds will get and how far east these stronger winds make it, and if the grasses are starting to green up enough to prevent more widespread fire weather concerns. With that, held off on fire weather headlines for now until certainty grows.

The main western US trough that has been helping to send all these impulses across the area over the past couple of days will finally move eastward heading into Friday, pushing a strong cold front into the area. Ahead of the front, warm and moister air will be favorable for thunderstorms, some of which could be strong to severe mainly east of I-29. Timing of the cold front will play a role in how much coverage of storms can be expected, with a faster passage meaning a lower threat and a slower passage leading to a greater threat of stronger storms. One thing is for more certain is the colder air that will follow this system, with lows expected to drop below freezing for most of the area by Saturday morning. This means some rain with this system may at least briefly turn to snow as the precipitation exits the area, but confidence is very low on this potential. Either way, expect much cooler temperatures heading into the Friday night through Sunday morning time frame. After this push of colder air, ridging aloft looks to return and thus a quick warming trend looks possible into early next week.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 644 PM CDT Tue Apr 14 2026

Mainly VFR conditions with occasional MVFR vsbys will be possible this TAF period. Taking a look across the area, a few scattered showers continue to progress through areas east of I-29 this afternoon. Could see additional showers and potentially thunderstorms develop near KSUX and the U.S. Highway-20 corridor overnight. With this in mind, decided to add a PROB30 group for the increasing potential of MVFR vsbys with the developing activity. Otherwise, lighter winds will continue for the duration of the TAF period.

FSD WATCHES/WARNINGS/ADVISORIES

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