Good afternoon everyone! We are working in the very beginnings of our complex winter storm across portions of SD and NE, though it is in the form of patchy light rain/drizzle at this time. Additional precipitation is expected to surge from the southwest as time goes on this evening into tonight with many at first experiencing a mixed bag of light freezing rain and rain showers before locations further west across western SD/NE gradually transition to snow as colder air works into the region. Also to note, areas of fog/mist will increase in coverage through the remainder of the day. More on this below.
As we progress through the evening into the nighttime hours, mist/fog issues will become more prevalent once again across a majority of SD and the southwestern half of MN. These will be the areas to watch for widespread freezing mist/drizzle/fog given temperatures will be right at or slightly below freezing. Slick spots will be possible as some of the water molecules in the fog may freeze on contact with its surroundings. Do note that the model may be a tad overdone with the fog (darker shadings) and depicting mist/drizzle as fog.
Here’s a look at the current winter storm alerts across the area: Winter Storm Warnings are in effect across the southern half of SD into northern/central NE and far southwestern MN/far northwestern IA. We are targeting these areas to receive significant snow accumulations before all is set and done. Winter Storm Watches remain in effect for northern IA given the uncertainty that continues with this storm system. However, with time we expect these to transition to either Winter Weather Advisories or Winter Storm Warnings. There are also newly issued Winter Weather Advisories for additional portions of southern MN.
Simulated radar through 6am CST Saturday: The storm system develops over the southern Plains and strengthens rapidly as it lifts into the area this evening into tonight. This means we will witness a mix of rain/freezing rain possible as early as 9/10pm CST in south-central/southeastern SD and northern NE before also spreading eastward with this mixed bag of precipitation into northern IA overnight. To the south, rain coverage will increase (some of it heavy) overnight in the eastern half of NE into IA. We’ll see a changeover to snow from west to east overnight with most of western SD into western NE seeing snow by 6am CST tomorrow. Rain in eastern SD into northern IA and far southern MN will continue to mix with freezing rain at times, allowing for a light icing on elevated objects and untreated pavement.
Simulated radar from 6am CST Saturday through 12am CST Monday: Rains gradually transition to snow across eastern SD through Saturday morning and early afternoon with the same being said for eastern NE as well. Northwestern IA and southern MN will take a bit longer as those areas see the transition to snow early tomorrow afternoon. However, a heavy band of snow will setup in southern/southeastern SD, southern MN and northern NE Saturday afternoon and evening related to an area of frontogenesis (development of a boundary that aids in lift). Rain showers will still be occurring for a good portion of IA during this timespan as the snowband shifts north into southern MN. However, as we head into Saturday night the low pressure system will slowly work eastward with colder air wrapping in, allowing for a transition to snow showers across IA while snows remain persistent across NE, the southern two-thirds of SD and southern MN. Combined with wind gusts of 30-40mph+, near-blizzard conditions are possible especially tomorrow afternoon and night. The low pressure center will meander slowly eastward Sunday, which will help to pull the snows eastward with time and steadily weaken the snow coverage. However, snow showers will remain likely for most of NE, IA, and far southern MN even into Sunday evening.
Here’s a simulation of the temperatures through the duration of the event. Temperatures will start out marginal (low to mid 30s) for most tonight into the day Saturday, allowing for a heavy, wet snow that then freezes as colder air works into the region Saturday night into Sunday. The heavy, wet snow will weigh trees and power lines down, with power outages possible. Snow will more easily accumulate into Sunday with the falling temperatures (well into the 20s), but the frontogenesis Saturday will allow for heavy banding and quick accumulations as well.
Here’s the latest thinking regarding snowfall amounts through Sunday: Confidence remains lower still in eastern SD, IA and far southern NE given model discrepancies and how quickly rains can transition to snow, especially in IA. Note, the gradient in eastern SD could be quite strong with a short distance between nearly a foot of snow and less than 1″ creating the lower confidence. We are still targeting north-central NE to receive the brunt of this storm where a band of 12-18″+ is likely. Localized pockets of 2 feet of snow can’t be ruled out in this region. This will be a memorable storm given its slow-moving nature. Travel in some areas will be near impossible.
As stated previously, expect gusty winds Saturday into Saturday night with gusts over 30mph (locally 40+). These winds will gradually taper down to 25-30mph gusts late Saturday night through Sunday. Blowing/drifting snow should be anticipated, especially in SD, southern MN, NE and northwestern IA given greater snow coverage and strong winds.
Total precipitation through Sunday: Given consistent banding, liquid exceeding 2″ will be likely in northern/northeastern NE while rainfall amounts over 1″ is expected in central/eastern IA. Notice the sharp gradient in northern SD and central MN (the reason for the sharp cutoff in snow totals).
If you have any questions do not hesitate to reach out! Have a great evening!