textproduct: Sioux Falls

KEY MESSAGES

A strong system is expected for this evening and overnight as winds strengthen out of the northwest with gusts up to 50-60 mph expected. Isolated higher gusts are expected as well. Patchy blowing and drifting snow is expected, resulting in reduced visibilities. Light snow is also expected mainly across southwest Minnesota and adjacent parts of southeast South Dakota and northwest Iowa. Further reduction in visibility down to a quarter of a mile or less is expected in falling snow.

- A High Wind Warning has been issued for the entire area and is in effect from this evening through the overnight hours. A Winter Weather Advisory has been issued for all of southwest Minnesota and adjacent parts of southeast South Dakota and northwest Iowa. The Advisory is in effect from 9 pm this evening to 4 am Wednesday morning.

- Chances for precipitation will persist into the weekend, with Wednesday night through Thursday and Friday night having the highest probabilities for accumulating precipitation. Mixed precipitation is likely (50-70%) for the chance for Wednesday night through Thursday system, including the potential for light ice accumulations.

- A much colder airmass looks to persist through the weekend. Near Advisory level winds chills may be possible Saturday night.

DISCUSSION

Issued at 311 PM CST Tue Dec 9 2025

Light rain continues to push through the forecast area this afternoon. While mainly rain, a few sites have reported light snow at times. Accumulations are expected to be light on the order of a about a tenth of an inch or less. While quite benign in terms of immediate impact, this rain, along with high temperatures warming to mid 30s for the majority of the area, has resulted in uncertainty regarding how blowable the snowpack will be this evening and night. The rain and warm temperatures are also melting the snowpack as well. Any chance for rain will come to an end during the late afternoon and evening hours. As chances for rain dwindle as a cold front pushes through the forecast area late this afternoon and evening. A strong shot of cold air advection (CAA) will accompany the passing cold front. The front will turn winds to more northwesterly in its wake and will ramp up the strength of the winds. Very strong winds are expected with gusts mainly up to 50-60 mph with isolated higher gusts above 60 mph expected. These strong winds will persist through the evening hours and into the overnight timeframe before beginning to weaken during the early morning hours. These strong winds will result in patchy blowing and drifting snow as well.

The second component to this system is snow showers developing in the post frontal, cold air overnight. The best low level moisture along with steepening low level lapse rates looks to be just enough to generate a hint of instability. This will result in snow showers instead of a broad area of stratiform precipitation. These snow showers look to reside mainly across southwest Minnesota and adjacent portions of southeast South Dakota and northwest Iowa. Any chance for snow showers looks to come to an end before daybreak. While patchy blowing and drifting snow is expected, any falling snow combined with the wind will make for very low visibilities falling down to a quarter of a mile or less. These combinations of factors has resulted in a change to headlines for the area. Have converted the Winter Storm Watch to a High Wind Warning and issued a Winter Weather Advisory for southwest Minnesota and adjacent parts of southeast South Dakota and northwest Iowa. Have made these changes because confidence is not high enough in Blizzard conditions being met given how the current rain and warm temperatures will modify the current snow pack.

Winds will be weakening into the morning hours on Wednesday before going light come the late afternoon hours thanks to incoming surface high pressure. This high will result in a break in active weather but keep conditions cool with highs only warming to low 20s to low 30s. However, this break in the action will be brief as the next chance for precipitation returns to the area thanks to another clipper system pushing through the Northern Plains. Any chance for precipitation looks to begin Wednesday evening and persist through the day on Thursday. A baroclinic zone looks to remain situated just east of the Rocky Mountains. As this wave pushes into the area, it will strengthen the thermal gradient and strengthen WAA ahead of the boundary to it's northeast. This will drive the precipitation chances though this looks to be a mixed precipitation event. The strong WAA aloft looks to warm 850 mb temperatures near to above freezing mainly along a Huron, South Dakota to Sioux Falls, South Dakota, to Storm Lake, Iowa line. Surface temperatures look to fall near to below zero near to east of this line. This mixed precipitation is possible in the forms of freezing rain, sleet, and snow. Both the GFS and Euro ensembles support this as they show 50-70% chance for freezing rain, sleet, and snow. Latest ensembles show support for some ice accumulations with their probabilities up to a 20-50% chance for a light glaze of ice along and southwest of the previously mentioned line. In terms of snow, the same ensembles show a 30-60% chance for snowfall totals to exceed an inch along and northeast of the previously mentioned line. Have stuck with the NBM at this time but trends will be monitored with this system as the location of where precipitation sets up can still change.

Friday looks to continue the trends of a brief break in the action before another round of precipitation passes through the area. With a cold airmass in place, highs on Friday will only warm to the teens to 20s. Breezy northwest winds will result in cold wind chills down to the positive and negative single digits. With a prevailing northwest flow pattern aloft, another chance for precipitation looks to come Friday night through Saturday morning. The ensembles show near 100% probabilities that this chance for precipitation will be all snow. Amounts are uncertain at this time given how the best WAA is just south and west of the forecast area. Will keep an eye on this system over the coming days.

Aside from precipitation chances, high temperatures remain quite cold across the area with highs only warming to the single digits to up to barely touching the teens along the Missouri River Valley. Sunday will be bit warmer with highs warming to the single digits and 20s. Saturday night looks to be the coldest night with bitterly cold lows falling down to the negative single digits and teens. This will also result in quite cold wind chills across the area as well.

Next Monday and Tuesday look to be quiet with highs rebounding to the 20s and 30s.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1118 AM CST Tue Dec 9 2025

Light rain will continue to move southeast through the CWA early this afternoon. We'll continue to watch the progression of a strong frontal boundary moving southeast later this afternoon, which will begin bringing 40+ knots gusts into early evening and falling temperatures.

The arrival of a secondary cold front late this evening will lead to even higher surges of wind over 50 knots, along with widespread MVFR to IFR ceilings. Big questions remain on the potential for blowing snow and then the development of horizontal convective rolls after midnight. Should the snowpack be able to be lofted, it will reduce visibilities quickly. For now, will suggest a persistent MVFR visibility with a lower probabilities of 1 mile or lower visibility based on HREF guidance through the core of the peak winds. These will need to be monitored and amended as needed over the upcoming 18 hours.

Ceilings will gradually improve and winds will weaken Wednesday morning.

FSD WATCHES/WARNINGS/ADVISORIES

SD...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday for SDZ040-055-056-062-066-067-069>071. Winter Storm Watch Wednesday morning for SDZ038>040-052>056- 058>062-064>071. Winter Weather Advisory from 9 PM this evening to 4 AM CST Wednesday for SDZ040-056. Winter Storm Watch until 6 PM CST this evening for SDZ038>040- 052>056-058>062-064>066-068-069. High Wind Warning until 3 AM CST Wednesday for SDZ038-039- 052>054-058>061-064-065-068. High Wind Warning until 3 AM CST Wednesday for SDZ050-057-063. MN...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday for MNZ071-097-098. Winter Storm Watch Wednesday morning for MNZ071-072-080-081- 089-090-097-098. High Wind Warning from 9 PM this evening to 6 AM CST Wednesday for MNZ072-080-081-089-090. Winter Weather Advisory from 9 PM this evening to 4 AM CST Wednesday for MNZ071-072-080-081-089-090-097-098. Winter Storm Watch until 6 PM CST this evening for MNZ071-072- 097. IA...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday for IAZ001-012-020-031. Winter Storm Watch Wednesday morning for IAZ001>003-012>014- 020>022-031-032. High Wind Warning from 9 PM this evening to 6 AM CST Wednesday for IAZ002-003-013-014-021-022-032. Winter Weather Advisory from 9 PM this evening to 4 AM CST Wednesday for IAZ002-003-014. NE...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday for NEZ013-014. Winter Storm Watch Wednesday morning for NEZ013-014.