textproduct: Sioux Falls

KEY MESSAGES

- Showers and very isolated thunderstorms will be possible Friday night into Saturday morning, mainly near and east of Highway 81. Drizzle and spotty showers will be possible west of Highway 81.

- More widespread rain returns later Sunday night into Monday. The EC/GFS and Canadian ensembles suggest about a 40-70 percent for more than an inch of rain.

DISCUSSION

Issued at 104 PM CDT Thu Oct 29 2026

Weak ridging aloft moves through the area tonight into Friday. This will allow for an increase in south to southeast flow in the lower levels. Models soundings point towards some possible patchy fog again later tonight, but stratus should increase from south to north late tonight into Friday afternoon. So for now not anticipating widespread fog issues. Other than the increasing stratus through the day, Friday should mostly be dry. By afternoon into the evening a wave will rotate northward bringing slightly cooler temperatures aloft above the increasing low level moisture. This should bring some weak instability with maybe 200-500 J/kg CAPE and no real shear to speak of. This the expectation will be for mainly scattered showers with isolated thunderstorms. The better chances for showers and isolated thunderstorms should be near and east of I-29 with areas near and west of the James River possibly capped and seeing a better chance for drizzle with roughly the lowest 5000 feet saturated and weak lift moving through. For now rainfall amounts look light with some spotty tenth of an inch or so possible.

Saturday the challenge will be trying to break through a fairly deep stratus layer as weak upper level support gradually diminishes. For now expect cloud cover the linger and temperatures to not reach their full potential, likely topping out in the lower 60s in most locations. Still mild for this time of year.

Saturday night into Sunday expecting mainly dry conditions as saturation aloft diminishes and any weak instability is gone. Sunday will likely see a resurgence of stratus ahead of the next wave coming Sunday night into Monday. This should again keep high temperatures mostly in the lower 60s.

Sunday night will see a surge of warm air advection in the lower levels as low pressure deepens to the west southwest and an initial wave races by to the northeast. Would not be at all surprised if we see enough instability Sunday night into Monday morning to produce a few thunderstorms as the band of strong warm advection moves through. After this a few question marks on low pressure development. With the jet still pretty strong and southwest of the main trough, expect low pressure to deepen across KS/NE area, then lift east or northeast into Tuesday. The low pressure movement is fairly low confidence as the models are yet to agree upon how much jet energy wraps around to the east side of the low, but if enough does, we could see rainfall continue well into Tuesday. For now even on the backside of this system it is a bit too warm for snow, so thinking all rain.

If this system were to wrap up as much as the ECMWF suggests, a few snow showers would be possible Wednesday into Thursday, but not a lot of support from other models, so nothing more than something to keep an eye on.

As for precipitation amounts, the latest GEFS is still bullish bringing over an inch of rainfall to many locations, with a 50-60 percent chance in far southeast SD, northwest IA and northeast NE. The latest AI model information leaning towards the lower side on rainfall amounts which worked well with the rain event this past Monday when many models (lower and hi res) and ensembles were indicating a widespread 1-2.5" of rain and we saw something closer to 0.50 to 1.25 inch rainfall amounts.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1224 PM CDT Thu Oct 29 2026

VFR conditions are expected through much of the period. Late tonight and early Friday morning some patchy valley fog will be possible, possibly into the MVFR and IFR categories. Otherwise MVFR stratus will surge north to the Missouri River late tonight and closer to I-90 by the end of the TAF period.

FSD WATCHES/WARNINGS/ADVISORIES

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