textproduct: Sioux Falls

KEY MESSAGES

- A couple of supercells will be possible west of the James River late this afternoon through early evening. IF a storm can develop, a tornado or two, ping pong ball sized hail and wind gusts to 70 mph are all possible.

- Additional scattered and possibly severe storms are possible from late evening into the early overnight hours. The main threats will be half dollar sized hail and wind gusts to 65 mph.

- Quiet but continued warm conditions are expected for the rest of the work week with the next better chance for precipitation Saturday night into Sunday.

DISCUSSION

Issued at 103 PM CDT Mon Sep 7 2026

Elevated showers and thunderstorms will continue to move northeast through central SD into the afternoon. Locally heavy rain and wind gusts to 50 mph will be the main threats.

Otherwise, showers and thunderstorms will likely be hard to come by this afternoon as strong capping is in place. The exception may be in central SD closer to increasing southwest flow aloft and slightly stronger surface heating. If these storms can develop, CAPE around 2000 J/kg as well as about 40 knots of deep layer shear as well as decent turning from southeast to southwest in the lowest km. This will support all modes of severe weather with an isolated tornado, hail to ping pong ball and wind gusts to 70 mph. Unless the models are completely incorrect in handling the capping inversion, the chance for this very late afternoon and early evening convection will be confined to areas west of the James River. One other negative is the ongoing convection in central SD, which appears to be taking a bite out of the daytime heating.

Farther east the threat will be more likely from about 8 pm to 2 am as storms could become more rooted in a stronger LLJ with increasing southwest flow aloft. This lay lead to a cluster of stronger updrafts with half dollar sized hail, wind gusts to 60 mph and pockets of heavy rain the main threats.

Instability lingers through late tonight into early Tuesday morning as upper level support slowly moves through. Confidence is low on additional stronger convection, but with potentially 1000-1500 J/kg of instability some isolated stronger storms will be possible. For now the threat of heavy rain like the past couple of days looks pretty low as storms should be more progressive.

Instability is slow to shift southeast through the day on Tuesday and should result in additional showers and potentially stronger thunderstorms Tuesday afternoon. The better chance for this will likely be south of a Yankton to Jackson MN line, with the better chance from about 3 pm to 8 pm.

A stronger westerly jet aloft settles into the area Wednesday into Thursday, with a fast moving trough expected to move through Thursday night into Friday. This pattern should support dry conditions on Wednesday and Thursday with a chance for showers and thunderstorms late Thursday night, but more into Friday. Depending upon the timing of the front with this wave on Friday, highs could climb into the 90s in a few locations before a fairly strong shot of cooler air moves in for next weekend where highs in the 70s are more likely. Saturday night into Sunday will see a decent chance for showers and thunderstorms as models are fairly agreeable with a wave moving through, just not so much with the exact timing.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 633 PM CDT Mon Sep 7 2026

Latest radar and satellite imagery shows remaining showers in and around KBKX pushing off to the northeast early this evening. At the same time, thunderstorms are developing southwest of KAGZ. These thunderstorms will continue to push off to the northeast through the rest of the evening hours. Will watch convective trends but the coverage of thunderstorms could also increase as well. Have kept PROB30/TEMPO groups in KFSD and KSUX's TAFs through most of the overnight hours. Lowered ceilings and visibilities are expected within the storms, potentially down to MVFR levels. Some of these storms could be strong to severe with large hail and damaging winds as the main hazards. Chances for storms looks to wane into tomorrow morning though showers may persist through the morning and into the afternoon timeframe. A cold front will be pushing through the forecast area tomorrow, turning winds to out of the northwest in its wake. This same front looks to develop another round of thunderstorms across northwest Iowa towards the end of the period tomorrow afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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