The Friday setup resembles a winter pattern more than a typical September scenario, though such events can occur occasionally. High pressure over Ontario channels dry air southward on breezy northeast winds, while low pressure over Nebraska moves east-southeast, pulling abundant moisture northward ahead of the system.
The boundary between rain and dry conditions on the north side of Friday’s system will likely be quite sharp. While Duluth may see a few showers, especially Friday afternoon, the heaviest rainfall is expected to remain well south of the Twin Ports.
Here’s a look at the blended model rainfall forecast through late Friday night. This model has trended noticeably drier on the north side of this system today, which aligns with what some have been indicating for Friday’s system over the past few days.
RAP model radar forecast valid from 7 AM to 10 PM on Friday.
Expect breezy easterly winds near Lake Superior, including the Twin Ports area, on Friday, with gusts reaching 15 to 30 mph.
A robust mid- and upper-level system continues to move across the northwest U.S. today, accompanied by a broad plume of moisture stretching from the southwestern U.S. through the Rockies and into the northern Plains.
Goes-19 water vapor loop from Thursday, September 17, 2026, covering 11:25 AM to 5:15 PM CT.
Friday’s rainy system, which will impact parts of the Upper Midwest, is currently organizing over the western High Plains and moving into South Dakota today.
MRMS radar loop from Thursday, September 17, 2026, covering 2:30 PM to 5:30 PM CT.
Duluth officially reached 70 degrees today, Thursday, September 17, 2026, marking the first 70-degree day since September 11.
Expect a noticeable drop in temperatures in Duluth on Friday, with highs remaining mostly in the 50s.
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