A low pressure system is expected to bring widespread precipitation to the Northland from Wednesday night into Friday, but a lot of this precipitation looks to be in the form of rain as there will be a lack of cold air initially, but eventually we should get enough cold air to move in which will cause the rain to mix with and change over to snow sometime Thursday or Friday, but at the moment this doesn’t look like it’ll be a major snow event/winter storm for northeast Minnesota and northwest Wisconsin.
Around an inch or more of precipitation is possible across the Northland late this week, and if all of this were to fall as snow, then we’d be looking at around 12″ or more of snow accumulation, but that is highly unlikely to happen the way it looks now.
Computer models are in good agreement on a large scale trough moving out of the Rockies and into the Plains later this week, but the models continue to disagree on how strong this trough will be, and on a potential track of an upper level low along with a surface low for late this week.
Upper level trough on Wednesday (highlighted in black)
There is some potential for the upper level trough to slow down and become negatively tilted while deepening further on Thursday with a closed low possibly developing somewhere from the Dakotas to Minnesota.
Upper level low and trough covers the western Great Lakes on Friday but begins to slowly move away from the Northland.
An animation on how an upper level low/trough evolves from Wednesday morning to Friday evening per 12z European Ensemble model.
Notice the green colors appearing across the Plains and upper Midwest later this week, this is a sign of a deepening upper level trough.
Here’s my forecast for the late week system, but I’m pretty sure will see a few changes to this forecast over the next few days.
Low pressure initially over the Western High Plains Wednesday morning tracks east to southeast, reaching southern Minnesota Thursday morning before lifting northeast toward central Upper Michigan by Friday morning.
Precipitation associated with this system is forecast to move into the Northland Wednesday afternoon or Wednesday night with additional precipitation occurring Thursday into Friday, although precipitation may begin to diminish on Friday depending on how quick the low moves through.
As for precipitation types — Temperatures from the surface to aloft look warm enough for rain in northeast Minnesota and northwest Wisconsin Wednesday night through most of the day Thursday, however, enough cooling may occur for the rain to mix with or change to snow in western and far northern areas (north and west of Duluth) during the day Thursday.
Eventually we should see colder air work into the entire Northland causing rain to turn over to snow Thursday night into Friday, but a lot of this snow looks to be on the light side as the deeper moisture pulls away from our area before the change over from rain to snow takes place.
At the moment, I think the greatest chances for 2″ or more of snow in the Northland will be over northwest portions of the area, from roughly Walker to Bigfork to International Falls and points west, with the highest chances for seeing accumulating snow occurring from Thursday afternoon into Friday morning.
As for the Duluth-Superior area: Mostly rain with the system for late this week. Rain develops Wednesday night and continues into Thursday. Rain mixes with and changes to some snow Thursday night or Friday, with a chance for a trace to an inch of snow accumulation in the Twin Ports.