Tuesday update: Weekend winter storm will pack a punch in Minnesota

Rain, freezing rain, sleet and heavy snow are likely when a storm system that is expected to pack a punch engulfs Minnesota Friday through Sunday. 

The National Weather Service is still hesitant to discuss totals, but is saying accumulations are likely. It probably won't be until Thursday before it has confidence in what types of precipitation will fall in specific locations, and how much of it piles up. 

"Heavy precipitation and mixed precipitation are expected. The location of the heaviest precipitation and precipitation type remains uncertain," the NWS Twin Cities announced Tuesday morning. 

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According to the NWS Duluth, the Northland could be on the cold side of the storm and wind up with a "prolonged period of snow from late Friday afternoon through Sunday Night."

As meteorologist Sven Sundgaard pointed out in Monday's update, what will be critical are the temperatures in the layer of the atmosphere where the precipitation develops. Temps in that area need to be below freezing (32 degrees) to form snow, while temps above freezing in that layer will result in sleet or rain. 

As of now, the storm track – based on what the models are showing – would deliver accumulating snow to central and northern Minnesota and mostly rain and mixed precipitation to the Twin Cities and southern Minnesota. 

Let's go through some of the key components of what the models are showing, all while understanding that these models are updated multiple times every day, so changes should be expected. We'll get formal snowfall and freezing rain forecasts from the National Weather Service later this week. 

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What the European model is showing

The first graphic is how much liquid precipitation the model is forecasting through the weekend, with the vast majority of it falling Friday-Sunday. This model shows the heaviest amounts – up to 1.5 inches of liquid – falling on a southwest to northeast line through the heart of Minnesota. 

The second graphic shows how much snow could fall at a 10:1 ratio, meaning 10 inches of snow for every 1 inch of liquid. You can see that the Euro is projecting accumulating snow under the heaviest area of precipitation. Again, this is going to change so the amounts the map shows aren't that reliable right now. 

The third graphic shows a generalized view of what types of precipitation could fall and where they could fall. The four quadrants show rain (green), freezing rain (pink), snow (purple) and sleet (orange). 

What the American (GFS) model is showing

The American model is pushing out more precipitation than the European model, and what quite a bit as it shows upwards of 2 inches of liquid being dumped by this storm. 

It's similar to the European model, however, in showing the heaviest snow in central and northeastern Minnesota, with lower amounts to the south (where more rain and mixed precipitation could fall). 

The third graphic shows a generalized view of what types of precipitation could fall and where they could fall. The four quadrants show rain (green), freezing rain (pink), snow (purple) and sleet (orange). 

What the Canadian (GEM) model is showing

Similar story from the Canadian model compared to the European and American models, but it has the heaviest precipitation from the Twin Cities into north-central Wisconsin. 

The Canadian model is also keeping snowfall totals lower in Minnesota (and refined to the northern half of the state) while really dumping along and near the South Shore of Lake Superior. 

The third graphic shows a generalized view of what types of precipitation could fall and where they could fall. The four quadrants show rain (green), freezing rain (pink), snow (purple) and sleet (orange). This would bring a bit of everything to the Twin Cities.