textproduct: Sioux Falls

KEY MESSAGES

- A couple areas of storms are moving east-northeast this morning. Although severe risk has diminished, a stronger storm could produce wind gusts around 55 mph. Locally heavy rain and isolated flash flooding are also a concern.

- Additional scattered are possible Tuesday afternoon/evening. Severe risk is low and focused southeast of a Sloan to Cherokee line. The main threats remain quarter sized hail, wind gusts to 60 mph, and locally heavy rain.

- 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.

UPDATE

Issued at 219 AM CDT Tue Sep 8 2026

Continuing to see storms move across the area this morning, and watching the development continue in NE. Have seen steady downward trend over last hour or so with sporadic gusts around 50-55 mph. Storms appear to be elevated and tied more to the LLJ forcing now than earlier tonight. Expect periods of showers/storms to continue near and south of I-90 through the overnight hours as the next wave lifts out of NE and the LLJ remains over the area. Although storm motion is more progressive, high PWATs and still relatively deep warm layer support continued locally heavy rain. Will need to watch areas that have had multiple rounds of storms over the last few days. Temperatures thus far are remaining mild in the upper 60s to upper 70s this morning with wind gusts around 25-30 mph at times. Highs warm into the 80s.

Showers and storms linger through the day Tuesday with the surface cold front sagging south through the day and southwesterly flow aloft promoting waves through the pattern. Low end severe risk our far southeastern forecast area (southeast of Sloan to Cherokee) later this afternoon and evening. Anticipate that we'll struggle with destabilization due to morning convection and cloud debris, so any severe threat would be limited to a narrow window this afternoon and evening - likely a couple hour window between 3 and 8 PM (depending on if/how quickly we destabilize and where the surface boundary is). Shear may trail a bit behind any instability initially which would also limit the severe potential. 60 mph wind gusts, quarter sized hail, and brief heavy rain are the main threats. Storms should clear out through the evening hours, with a more seasonal night Tuesday night into Wednesday.

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 /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1215 AM CDT Tue Sep 8 2026

Main aviation concern through Tuesday night will be periods of showers and storms. One round of showers/storms is moving slowly to the east-northeast at the time of this discussion near the I-90 corridor and occasionally producing wind gusts around 45 knots. Also seeing some locally heavy rainfall as well. Some patchy MVFR and lower conditions have been observed with these storms.

Next area to watch is across NE, and will move into the area later in the overnight hours into Tuesday morning - these may be remain south of I-90. Another chance for convection returns to northwestern IA and adjacent portions of northern NE/far southeastern SD during the afternoon and evening. An isolated stronger storm may be possible. Convection may lead to MVFR and lower conditions.

Outside of convection, expect shifting wind direction through the period with a couple of boundaries in place. Synoptic non- thunderstorm winds at times gust around 20-25 knots. Light winds to end the period. VFR conditions prevail barring convection.

FSD WATCHES/WARNINGS/ADVISORIES

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