textproduct: Sioux Falls

KEY MESSAGES

- Patchy fog, some locally dense, will continue mainly over southwest Minnesota through the mid morning hours. Use extra caution if driving in these area and be prepared for rapidly changing visibilities.

- Spotty light showers are expected this morning mainly over northwest Iowa. Showers and very isolated thunderstorms are likely tonight 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. Latest guidance suggests about a 40-70 percent chance for more than an inch of rain.

UPDATE

Issued at 326 AM CDT Fri Oct 30 2026

A surface high continues to slide towards the western Great Lakes allowing for winds to be slightly higher tonight than compared to last night. This should help limit widespread fog development, but since it will take a bit longer for winds to increase over southwest Minnesota, patches of fog have already developed there early this morning. We will continue to see fog in these areas (especially closer to the Highway 14 corridor of SW MN) through the morning commute. Fog has already been locally dense at times especially in and around the Marshall area, but widespread dense fog is not expected. Still, be prepared for quickly changing visibilities on the roads this morning and consider leaving extra time to get to your destination. Any fog should lift by 10 am.

Looking at radar across the region, showers and thunderstorms have developed mainly along and just north of the I-80 corridor in eastern Nebraska and western Iowa, with this activity lifting east-northeastward. Seeing a few weak returns developing north of this along the Highway 20 corridor, and we'll continue to see spotty showers here through this morning. Thunderstorms do look unlikely here given limited instability, so light showers are expected. As warm air advection slowly increases northward heading into later portions of the day today, so will the chance of showers. Perhaps a little more elevated instability late this afternoon into the overnight, thus can't rule out some weak thunderstorms. If a storm develops, the main difference it would bring would be locally higher rainfall amounts, but otherwise most of the showers today and tonight should remain on the lighter side. Outside of any showers, patchy drizzle with be possible as well.

We'll continue to see showers and isolated thunderstorms through the overnight hours tonight, with activity gradually lifting northeastward and moving out of the area heading through the morning hours on Saturday. A secondary wave moving across western South Dakota, albeit a bit of weaker one, may help keep some showers in the area through the day on Saturday. Even without the showers, low stratus will remain in place with soundings showing some shallow instability within this layer. This will allow for more patches of drizzle through the day Saturday, especially in the morning when the stratus deck will be closest to the surface.

Another system enters the picture Sunday night into Monday, with near universal agreement amongst guidance that we will get a decent rain with this. As such, NBM PoPs are already pushing 100%, which is also in line with the global 30.00Z ensembles. However, there is still some uncertainty regarding the track of the low and and where and when the heaviest rain sets up, so keep up to date with the latest forecast and be prepared for a rainy day on Monday!

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 /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 651 AM CDT Fri Oct 30 2026

Areas of fog, some locally dense, have developed over portions of southwest Minnesota mainly from KMML to KMWM this morning. This will continue to impact the area until the fog lifts by around 15z. MVFR stratus currently over eastern Nebraska will lift north across the area as the day progresses, continuing into tonight. Cigs will also gradually lower, with IFR conditions expected to return gradually from south to north tonight. Scattered showers with very isolated thunderstorms will increase in coverage this evening into the overnight hours, but confidence was not high enough in coverage of thunder to include mention in the TAFs at this time. Winds will be out of the east-southeast today, turning more southeasterly heading into tonight. Winds will be fairly light through the period, sustained around 5-10 kts.

FSD WATCHES/WARNINGS/ADVISORIES

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