textproduct: Sioux Falls

KEY MESSAGES

- A wintry mix begins tonight and continues into Saturday afternoon.

- Light elevated and bridge icing will be possible along and north of I-90. Snow totals of a dusting to a couple inches will be possible along Highway 14.

- Isolated to scattered thunderstorms will be possible in NW Iowa Friday morning after 7am through 11am. Small hail most likely, but a very isolated quarter report possible.

- Wrap around snow Saturday morning along with occasional gusty conditions may bring brief slick roads.

- Dry, but cooler than normal temperatures return into next week.

UPDATE

Issued at 705 AM CDT Fri Apr 3 2026

Northeast flow has allowed slightly lower dew points and temperatures to filter into the area early this morning. This could allow for a broader area of light icing from I-90 to perhaps as far south as the Highway 18 corridor before surface temperatures rebound back above freezing later this morning. Morning commuters should be prepared for scattered slick spots, especially on elevated areas such as bridge decks and other untreated surfaces.

Issued at 1244 AM CDT Fri Apr 3 2026

The forecast remains largely on track for a late winter storm system to impact the region. The tricky part is still the precipitation types (p-type) at the surface. Soundings indicate a typical mixed precipitation set up with a warm layer atop a cold surface layer hovering around freezing. The depth and duration of the warm layer varies widely from location to location and will have a huge impact on accumulations. For areas north of I-90, surface temperatures are expected to fall below freezing for the fastest, which will mean the most likely p-type at onset will be freezing rain/drizzle to ice pellets. As the system progresses east over the next 24 hours CAA will eventually cool the warm layer and surface temperatures to below freezing. At this point there will be a transition to sleet, and eventually snow. Another snag to be on the look out for is soundings indicate intermittent loss of saturation in the DGZ, which could result in transitions from snow to freezing drizzle and back. For areas south of I-90 light rain is the most likely p-type at onset. Again, the intermittent loss of saturation could result in periods of drizzle to freezing drizzle and back as temperatures decrease. Rain totals will be light, between 0.05" to 0.20".

While the whole region may see at least some freezing rain/drizzle, the areas most likely to see accumulating ice on surfaces are north of I-90. Potentially impactful accumulation of 0.10" to 0.20" of ice lie along a rough line from Wessington Springs in South Dakota east to Jeffers Minnesota and north. Snow totals have held steady with 1- 3 inches possible along and north of a line from Chamberlain to De Smet. South of there generally less than an inch with amounts decreasing as you head south. Considering all this the current Winter Weather Advisory looks to be in good shape. There is also the question of road temperatures. Yesterday we saw most frozen precipitation melting and only accumulating on elevated surfaces such as bridges and road signs. The same will likely be true today during daylight hours. After sunset surface temperatures fall rapidly below freezing. Wet roadways and sidewalks may become slippery. Precipitation pushes northeast through the overnight Friday and cease from west to east through Saturday afternoon afternoon.

One final item to keep a watch on for Friday is the chance for isolated to scattered thunderstorms over northwest Iowa mid to late Friday morning. Elevated instability between roughly 500-1000 J/kg MUCAPE, lapse rates around 7 C/km, and weak shear of around 25 kts could work with strong WAA ahead of an approaching warm front to produce thunderstorms. Main threat would be small hail, though a few stronger storms could produce hail to the size of a quarter.

DISCUSSION

Issued at 152 PM CDT Thu Apr 2 2026

THIS AFTERNOON: We're continuing to watch this initial shortwave move east of the CWA early this afternoon. Weak isentropic downglide will bring end end to the precipitation in most locations, with reports of minor elevated icing reported over portions of SW Minnesota and the I-29 corridor of eastern SD. MRMS radial freezing rain accumulations also support this, with fairly localized 0.10" totals through the Ridge areas. While a low probability, patchy drizzle or freezing drizzle may still develop this afternoon. Temperature remain near or above freezing in most areas.

TONIGHT: Winds will turn light and variable later this evening as surface ridging slides east. Latest short term guidance keeps extensive cloud cover through the region which may keep temperature a bit warmer than the NBM initially suggested. We'll have to watch the impacts of a colder NE wind out of central MN that could bring in minor surface cold advection by daybreak. A deeper upper trough moving into the Central Rockies will spread scattered through northern Nebraska and central South Dakota by midnight. Additional scattered showers will develop southeast into northern Iowa by daybreak within a corridor of modest low-lvl warm advection from the SE. Temperatures will be critical to surface impacts, with some shift northward in warmer temperatures reducing icing south of I-90.

FRIDAY: Two things to watch on Friday. First will be eastward spread of showers through the Tri-State area after daybreak. Latest soundings continue to show a favored trend towards partial to full melting of falling hydrometeors, pushing favorite p-types towards rain and sleet. Surface temperatures will be critical once again, though as we've seen today, warm road and ground temperatures are preventing much in the way of icing on roads (except for bridges). Most icing is likely to remain on elevated cooled surfaces. At this time, icing is more likely north of I-90, with meaningful icing along Highway 14 into SW Minnesota. Should colder air deepen into central South Dakota early Friday, a quick 1-3" of snow could fall along a line from Chamberlain to Huron. Will issue a winter weather advisory for portions of the CWA north of I-90. Later forecasts will need to closely monitor the temperatures into the overnight for any potential adjustments to icing.

The second thing to watch is a narrow corridor of elevated instability rooted at the 800 mb layer that could approach 1000 J/KG. The intensification of focused warm advection and a sharp convergence zone could lead to isolated to scattered thunderstorms moving through NW Iowa and into southern Minnesota by mid-morning. Effective shear is minimal, but with freezing levels between 9-10K ft AGL, small hail to isolated quarter hail could be possible.

FRIDAY NIGHT: As the upper trough moves into the Dakotas and continues to deepen, an expansive dry slot will move through the Tri- State area, potentially shutting off precipitation or converting it over to drizzle. Latest guidance continues to show the potential for light snow to pivot around the upper trough into Saturday morning, through guidance has backed off on the southward extend of this precipitation today.

SATURDAY: We'll see stronger cold advection move through the area Saturday as the trough crosses into MN/WI. Some questions about potential for a few convective snow showers remain for Saturday afternoon, though soundings do no seem to be as aggressive with lapse rates by the afternoon. Nevertheless, afternoon gusts to 30 to 35 mph may be possible.

SUNDAY-WEDNESDAY: Mostly quiet conditions are expected well into next week as mid-lvl heights gradually rise over the West Coast. Temperatures through Monday will be colder than normal as Canadian high pressure drains into the Plains. A quick flip around to gusty southerly winds is expected Tuesday afternoon but thankfully after widespread precipitation fire weather risks will be much lower. A brief surge of warm air aloft arrives on Wednesday and may provide our only chance of exceeding normal this week. Precipitation chances rise again by Thursday.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 705 AM CDT Fri Apr 3 2026

Widespread MVFR to IFR conditions with a wintry mix of precipitation types will impact the region through this period. The bulk of the precipitation will be today, with a dry slot lifting north into the area late afternoon and evening. After sunset, most areas will transition to light snow, but the daytime hours could see some ice accretion, especially north of I-90.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Winter Weather Advisory until 7 AM CDT Saturday for SDZ038>040- 052>058. MN...Winter Weather Advisory until 7 AM CDT Saturday for MNZ071-072- 080-081-097. IA...None. NE...None.