textproduct: Sioux Falls

KEY MESSAGES

- A significant southward shift has occured in the latest modeling for tomorrow snow. While some light snow is still on the tap for tomorrow, amounts have come down considerably. Now, up to 3 inches of snow is possible, highest along the highway-20 corridor.

- The Winter Weather Advisory has been trimmed to now only including Clay and Union counties in South Dakota, Dixon and Dakota counties in Nebraska, and Plymouth, Cherokee, Buene Vista, Woodbury, and Ida counties in northwest Iowa. The time of the Advisory has changed to noon on Thursday through midnight.

UPDATE

Issued at 1050 PM CST Wed Feb 18 2026

Latest 18z and 00z guidance has come in with a significant shift to the south in the snow for tomorrow. Currently looks like snow will begin during the late morning to early afternoon hours and may have a convective component to it. The snow will expand in coverage but looks to stay along and south of highway-20. If some of the furthest south solutions were to verify, then just about no snow would fall anywhere in the area. This appears to be due to the models coming into better consensus on how they are handling an internal potential vorticity (PV) anomaly. This PV anomaly will set up a deformation zone, strengthening the frontal forcing and enhancing snowfall. But, with the models having a better grip on this PV anomaly, the trends are to push the boundary southwards. There remains some instability above the frontal zone, increasing confidence that this will be a tight frontal band. With the bulk of the snow now falling generally south of the area, have trimmed a significant portion of the Advisory, now only including Clay and Union counties in South Dakota, Dixon and Dakota counties in Nebraska, and Plymouth, Cherokee, Buena Vista, Woodbury, and Ida counties in northwest Iowa. Up to 3 inches of snow is possible in the Advisory. Have also changed the timing of the Advisory, now keeping it in effect from noon on Thursday through midnight. Patchy blowing snow is also possible given the breezy winds in place. Will still watch trends through the night as additional shifts back to the north is possible.

DISCUSSION

Issued at 305 PM CST Wed Feb 18 2026

Winds will continue to slowly diminish through the late afternoon and evening, but outdoor burning should continue to be avoided as relative humidity values are below 25% especially near Highway-20 where a critical fire danger remains. This fire danger will diminish tonight as winds lighten and relative humidity values recover. Temperatures drop to the upper teens to low 20s tonight, coldest over south-central South Dakota and Highway-14 wherever snow fell today. Attention now turns to our next storm system, which is discussed below.

A low pressure system will move across the central Plains through the day tomorrow and then pivot northeastwards towards the Great Lakes tomorrow night. Snow associated with this system will move into south-central South Dakota around daybreak and continue pushing eastward through tomorrow morning. The snow will reach the Highway-20 corridor in far northeast Nebraska and northwest Iowa by the afternoon and continuing lifting northeastward from there. The snow will gradually pull away to our east through tomorrow night. It's currently looking like the greatest snowfall totals will be along the Missouri River Valley into northwest Iowa, where a broad 2-5 inches of snow can be expected. This was enough to warrant issuing a Winter Weather Advisory starting at 6 am tomorrow for areas west of the Sioux City metro and then starting at noon along and east of there. Guidance continues to suggest that a narrow band of heavier snow will likely develop either over parts of the area or just south and east of us. The location of this band is where the greatest uncertainty lies with this forecast, but if it does set-up over our area, then a narrow stripe of 5-7+" will certainly be possible. The area to watch for these higher totals will be from roughly along and south of a Sioux City to Spencer line. If certainty grows as to where this narrower band sets up, then upgrades to Winter Storm Warnings will be possible. Either way, breezy conditions when even light snow is falling will reduce visibility to less than one mile at times, so be sure to use extra caution on the roads. Winds don't look to be as strong as what we've seen today, but could still gust as high as 40 mph in south-central South Dakota. Winds will be a bit lighter farther east, gusting up to 30 mph along and east of I-29. This will mean the strongest winds will be offset from the heaviest snow potential tomorrow afternoon/evening, but trends will be monitored closely because if winds look to be a bit stronger over northwest Iowa than currently expected, then brief near- whiteout to whiteout conditions will be possible. Snowfall totals will decrease quickly with northern extent as dry air tries to wrap around the north-side of the system and frontal forcing becomes weaker. This will lead to snowfall amounts as far north as the I-90 corridor to be generally less than inch, except for those areas along I-90 that are also east of Highway-75 in southwest Minnesota where up to 2 inches are possible.

Colder temperatures settle in this weekend, with highs in the 20s and 30s Friday through Sunday and morning lows returning to the single digits by Saturday morning. Quiet weather looks likely into early next week, with our next system to deal with likely not moving in until mid-week, though confidence is low on details with this.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1050 PM CST Wed Feb 18 2026

Mainly VFR conditions begin the TAF period. Some MVFR stratus persists along portions of highway-14 late this evening. Though latest trends are showing this stratus pushing towards KFSD. Have decided to amened KFSD's TAF to include mention of this incoming stratus. Trends in this MVFR stratus will be monitored through the night. Marginally breezy winds are expected to persist through the overnight hours while turning northerly. More expansive low level stratus will develop by tomorrow morning. This stratus is expected to sit at predominately MVFR levels with pockets of IFR possible. Some snow remains possible for mainly highway-20 tomorrow afternoon. Have kept PROB30 groups in KSUX's TAF but latest trends keep the snow generally south of KSUX. WIll keep an eye on trends in the snow through the night as additional shifts in the track of the snow remain possible.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Winter Weather Advisory from noon Thursday to 6 AM CST Friday for SDZ071. Winter Weather Advisory from 6 AM Thursday to midnight CST Thursday night for SDZ070. Winter Weather Advisory from 6 AM to noon CST Thursday for SDZ050-063-068-069. MN...None. IA...Winter Weather Advisory from midnight Thursday night to 6 AM CST Friday for IAZ002-003-012>014. Winter Weather Advisory from noon Thursday to 6 AM CST Friday for IAZ020>022-031-032. NE...Winter Weather Advisory from noon Thursday to 6 AM CST Friday for NEZ014. Winter Weather Advisory from 6 AM Thursday to midnight CST Thursday night for NEZ013.