textproduct: Sioux Falls

KEY MESSAGES

- Cooler conditions will continue through today then more seasonable temperatures return over the weekend into next week with limited precipitation chances.

- Widespread fog could return tonight. Locally dense patches could lead to visibilities less than one mile.

DISCUSSION

Issued at 240 PM CST Fri Nov 6 2026

Low level stratus has begun to thin, becoming scattered to few this afternoon as slightly warmer, light winds aloft erode it from the top down. This evening and overnight an upper trough will pass through central Canada toward the Great Lakes region. This will drag a diffuse surface boundary and narrow band of slightly higher moisture through the region. Weak instability and WAA in the moist layer will likely result in low stratus formation after midnight tonight. Subsiding air aloft will work to lower the stratus to very near the surface. At the same time cooling surface temperatures approach the dew points and patchy dense fog may also form. The combination of low stratus/fog could result in visibility decreasing to 1 mile or less at times. REFS guidance indicates a medium probability of 50-70% in low visibility through mid-morning Saturday. There is a very low probability (<15%) of freezing fog, mostly north of I-90 where temperatures are projected to fall to or just below freezing. This could result in scattered slippery spots on roads. Please use caution and be prepared for rapidly changing road conditions. South of I-90 lows are expected to be in the low to mid 30s. There is some uncertainty with overnight lows due to uncertainty in stratus coverage and thickness. If it is very thin temperatures could be a degree or two colder than forecasted.

Clouds slowly dissipate Saturday morning as light but warmer south- southwesterly winds flow into the region. By Saturday afternoon partly to mostly sunny skies are expected as highs climb into the mid 50s to low 60s. Late Saturday afternoon into the evening a surface low located just southwest of the Hudson Bay will drag a cold front through the upper Plains. This will turn winds northwest for the overnight hours. Lows will fall to the mid to upper 30s. An upper ridge moves over the Plains during the day Sunday, turning winds to the south by the afternoon. Highs will climb into the 50s and low 60s.

Monday and through the middle of next week the pattern aloft will be "wavy". However, lack of moisture at the surface and midlevels keep the forecast dry. Highs will be warmest Monday in the low to mid 60s. Temperatures Tuesday through Thursday will be cooler in the 50s, but still above average for this time of year (upper 40s). Wednesday night into Thursday bring the next chance for precipitation, but details are vague at this time.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1219 PM CST Fri Nov 6 2026

A mix of VFR to MVFR ceilings across the region as weak, slightly warmer westerly winds aloft work to erode stratus from the top down. Clouds may become scattered to few briefly this afternoon. However, the ceilings will remain low as subsiding air aloft pushes the stratus layer toward the surface. This evening and overnight a diffuse surface boundary and thin band of moisture will advect across the region. This will work to expand a thin layer of very low stratus to fog across the CWA. Ceilings are expected to lower during this time to IFR down to LIFR. Ensemble guidance indicates a medium probability (50-70%) of visibility falling to 1 mile or less at times after midnight through mid-Saturday morning. Similar to this afternoon weak, slightly warmer air flowing over the top of the stratus will work to gradually scour out the stratus through the end of the period.

Winds during this time will be out of the south and light, becoming light and variable overnight.

FSD WATCHES/WARNINGS/ADVISORIES

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