A low pressure system with its cold front and upper level trough will move out of the Northern Plains and across the upper Midwest from Friday into Saturday morning. Large scale lift will accompany this system, while a rich supply of moisture will also be in place out ahead of this system, the result from this should be for a round of rain and some thunderstorms which will move SW-NE across the Northland from late Friday afternoon or Friday evening into early Saturday morning. Unfortunately this system looks fairly progressive, so although it might rain heavily in some areas, the rain probably won’t last too long in any given area.
Rainfall amounts have increased a bit in the Northland compared to 24 hours ago, with a chance of widespread 0.50-1″ rain totals in northeast Minnesota (highest amounts across northern Minnesota) With around a quarter to half inch of rain in most of northwest Wisconsin, except in far eastern areas where generally <0.25″ of rain is forecast.
Note: Rainfall totals over the Greenwood fire (outlined in dark red) could reach a half inch or so, with the rain falling late Friday night-early Saturday morning.
As for the timing of the rain late this week, it looks to be from late Friday afternoon to early Saturday morning, with rain moving from southwest to northeast.
Here’s the 18z NAM 3km model simulated radar forecast valid from 7 AM Friday to 1 AM Saturday.
Note: Rain chances in Duluth and Superior hold off until late Friday night (probably after Midnight) the way it looks now.
An upper level ridge will remain over the Northland into early Friday, but a trough over the western U.S. will be moving ENE which will help knock down the ridge over our area by late Friday.
500mb heights will lower as that western trough moves across the upper Midwest late this week.
Goes-16 water vapor loop from Wednesday, August 18, 2021 showing our late week system which is currently affecting the Rockies, looks impressive!