textproduct: Sioux Falls

KEY MESSAGES

- Breezy to strong southerly winds are expected today with gusts between 30-40 mph expected for most areas. Slightly stronger winds will be possible across the Buffalo Ridge in southwestern MN.

- A conditional chance for stronger storms is expected this afternoon and evening mainly east of I-29. While all hazards remain possible, 2 inch hail and damaging winds up to 70 mph will be the primary threats.

- A pattern shift will lead to cooler conditions over the weekend with highs mainly in upper 60s to 70s. Periodic rain chances will continue into the new week.

UPDATE

Issued at 330 AM CDT Fri Sep 11 2026

Not many significant changes on the weather front with the main focus being on the breezy to strong winds today and the potential for severe weather this afternoon/evening. Starting with the winds, southerly surface winds should increase just after daybreak as the surface pressure gradient tightens ahead of an approaching cold front. This will lead to wind gusts recurringly in the 30-40 mph range for most areas throughout the day. Still thinking that a pocket of stronger winds (40-50 mph) will develop along the eastern side of Coteau Des Prairies as mixing deepens and the 850mb to 925mb LLJ strengthens. With this being further agreed upon by short-range guidance, decided to pull the trigger on a Wind Advisory from 7 am to 7 pm on the Buffalo Ridge in southwestern MN. Should see surface winds gradually weaken after the front progresses through the area this evening.

Otherwise, the focus continues to be on the severe weather chances for the second half of the day. Still thinking our chances for anything stronger will be conditionally dependent on if we can break through the weakening cap. With diurnal heating, the best chances will likely occur be between 5pm to 10pm mainly east of I-29. IF this occurs, isolated to scattered updrafts could quickly become severe with access to between 1500-2000 J/kg of CAPE and 30-40 kts of bulk shear. While all hazards will be possible, steep mid-level lapse rates and inverted "V" sounding profiles will favor up to 2 inch hail and damaging wind gusts up to 70 mph. Though confidence is low, if a discrete supercell can anchor to the surface front; an isolated tornado can't rule out. Lastly, should see most of this activity exit our area around midnight with the cold frontal passage.

DISCUSSION

Issued at 145 PM CDT Thu Sep 10 2026

This afternoon will be dry and breezy with gusts 25-35 mph, mostly clear skies, and highs in the upper 70s to 80s. Dew points will be lower this afternoon at around 60 or less. Overall a pleasant day is in store. Overnight lows will be in the mid to upper 60s with the breezy winds continuing into Friday.

Friday will be another warm day with highs in the 80s for most of the CWA, and the low 90s west of the James River Valley. Throughout the day a narrow plume of Theta-E air will advect in from the south, along and east of Highway 81. Instability will increase along and east of the plume with MUCAPE values climbing to 1500-2000 J/kg. Modest mid-level lapse rates around 7+ deg C/km will align well with the plume of instability. Bulk shear will be 35-40 kts. With clockwise curved hodographs this set up is marginal to slightly favorable for all modes of severe weather. This is also outlined in the SPC Day 2 outlook with a Slight Risk (level 2 of 5) for severe weather. However, a few items of uncertainty keep confidence in convection initiation and coverage low. Probably the most important factor is despite the moisture advection model soundings remain dry through most of the column for areas west of I-29. Forcing is on the strong side in the form of the upper trough and surface low/cold front, but without moisture not much is going to happen besides some cumulus clouds. East of I-29 moisture return flow is better, however the environment will be strongly capped. As the whole system progresses east through the evening and into the overnight the airmass slowly saturates. But by this point the forcing should be along our eastern CWA border if not into central Iowa. In this scenario we will get very little if any convection. This is the most likely scenario at this time.

The other scenario is the better moisture return drifts farther west. Then as the system passes through we could see saturation occur sooner, and thus convection begin earlier east of Highway 81 between 4 and 7 pm, and along and east of the I-29 corridor roughly between 7 pm and 10 pm. Storms would track east and be out of the CWA roughly between midnight and 3 am Saturday. The final scenario is we are able to lift off the 850-700 mb layer and scattered strong to severe storms could develop. All this to say a very conditional environment will be in place with risks for large hail and damaging wind gusts. Though the risk is low, a tornado cannot be ruled out.

Behind the cold front overnight lows will cool into the 50s and low 60s over northwest Iowa. Through the morning hours a few isolated elevated showers are possible. Winds will become northerly and light during the day. Mid-level temperatures will fall into the teens C and at the surface highs will be slightly below average for this time of year, in the low 70s north of I-90 and the mid to upper 70s to the south. Much drier air will advect in from the north bringing dew points down to the 40s to mid 50s. Saturday will be a pleasant taste of fall.

Early Sunday morning the flow aloft becomes mostly zonal and high pressure builds in at the surface. Modest moisture return on southeast winds and WAA ahead of an approaching low amplitude wave may be enough to trigger light scattered showers and thunderstorms by the late morning to early afternoon. These are not expected to be severe but could bring rain to a larger portion of the region. Sunday evening into the overnight a strong upper trough swings through northwest of the region. An associated surface low ejects out of Colorado onto the central Plains and accelerates northeast into our CWA. Though many details are unclear at this time, some storms could be strong to severe Sunday night into Monday morning. Storms may linger into the afternoon.

Northwest flow aloft is expected for the first half of next week. At the surface highs will be closer to seasonal averages, in the 70s. Another round of storms is possible mid-week.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 634 AM CDT Fri Sep 11 2026

VFR conditions will prevail this TAF period. Besides some high level cirrus, a strengthening LLJ will lead to a few hours of LLWS at all of our TAF sites. Otherwise, a breezier day will continue with increasing southerly surface winds producing wind gusts between 30-40 mph throughout the day. Lastly, there's some low confidence (30% or less) in isolated showers and storms east of I-29 this afternoon and evening. However, confidence isn't high enough yet in placement to include in the TAFs at this time.

FSD WATCHES/WARNINGS/ADVISORIES

SD...None. MN...Wind Advisory until 7 PM CDT this evening for MNZ071-072-080- 081-089-090-097. IA...None. NE...None.