textproduct: Duluth

KEY MESSAGES

- Patchy freezing fog and rime ice on the North Shore into tonight.

- Light snow accumulations up to one inch along the Canadian border tonight.

- Gusty northwest winds on Tuesday.

- Messy winter storm with mixed precipitation possible for Christmas and Friday, with the potential for travel impacts.

UPDATE

Issued at 805 PM CST Mon Dec 22 2025

Bumped up wind gusts slightly along the North Shore due to an increasing signal in high resolution weather models for wind gusts in excess of 35 mph Tuesday morning into early afternoon. The reason for this increase is due to a combination of a tight pressure gradient in the wake of a passing cold front and cold advection behind the front pooling up colder air against the higher terrain of the North Shore that should then accelerate winds downslope into lower terrain. The potential for persistent gusts of 45+ mph remains below 50% with this update, so have held off on any Wind Advisory issuance. However, if this wind gust signal continues to increase, a Wind Advisory may be needed.

DISCUSSION

Issued at 223 PM CST Mon Dec 22 2025

Moisture advection off Lake Superior continues to create areas of freezing fog and rime ice on trees and elevated surfaces along the higher terrain of the North Shore. Webcams indicate lowered visibilities in the Sawtooth Mountains, and these conditions are expected to persist through the evening. A shift in the wind direction tonight will eventually help clear these obstructions as a clipper system moves across the region from the west.

This clipper system has trended slightly further north in recent model runs, meaning the bulk of the accumulating snow will be confined to areas right along the Canadian border. Total snow accumulations through Tuesday morning are expected to be between one quarter of an inch and one inch for the Borderlands. While some high-resolution models have hinted at a window for mixed precipitation or freezing drizzle, the probability has dropped significantly, and the forecast currently favors primarily light snow for the northernmost counties.

Behind the departing clipper, a tighter pressure gradient will develop on Tuesday morning, leading to a period of brisk northwest winds. Gusts between 25 and 35 mph are possible, particularly along the North Shore where downslope enhancement can occur. A warming trend then takes hold for Wednesday and Thursday as an upper-level ridge builds over the central United States. Afternoon high temperatures will likely reach the mid- twenties to low thirties across much of the Northland. A weak disturbance may pass through on Wednesday morning, though most precipitation is currently projected to fall over the open waters of Lake Superior and toward the Upper Peninsula of Michigan.

Attention remains focused on a potentially impactful and messy weather system arriving late on Christmas Day and continuing through Friday. A push of warm air aloft will likely create a melting layer, introducing the threat of multiple precipitation types including rain, freezing rain, and heavy wet snow. Significant uncertainty remains regarding the exact track of this system, which will dictate where the heaviest accumulations and most dangerous ice potential occur. Despite PWATs projected to be in the 99th percentile, current indications suggest that while snow amounts may be light for much of the region. The Arrowhead, however, could see higher totals due to terrain and lake enhancement. Another clipper system may follow closely behind this storm for the weekend, potentially bringing additional mixed precipitation to the Northland. Uncertainty in this system is very high and will depend on how the Christmas system develops. Global models show the following system also not having a lot of moisture, which will limit accumulations.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1136 PM CST Mon Dec 22 2025

Mostly VFR conditions early this morning (except at INL) should steadily become MVFR with some patchy IFR ceilings possible through the morning. At INL, MVFR conditions are expected to persist. Gusty northwest winds will affect all terminals through this morning and then calm through the afternoon while conditions return to VFR.

MARINE

Issued at 805 PM CST Mon Dec 22 2025

There is an increasing signal in higher resolution weather models for very gusty northwest winds developing along the North Shore within a few miles of the shoreline in the wake of a passing cold front Tuesday morning into early afternoon, with some enhancement due to downslope flow off of the higher terrain of the North Shore. This has increased confidence for gale- force wind gusts to 50-60% from Silver Bay to Grand Portage where a Gale Watch has been issued. The remainder of the forecast for the nearshore zones of western Lake Superior remains unchanged.

Previous Discussion: An easterly wind of 10 to 15 knots will persist through this evening with waves of 1 to 2 feet. Winds will turn southwest after midnight and then northwest by Tuesday morning. Strong northwest winds are expected Tuesday with gusts up to 30 knots, and potentially up to 35 knots near Grand Marais. Small Craft Advisories are in effect for all nearshore zones. Waves will build to 3 to 5 feet in the Apostle Islands on Tuesday before subsiding Tuesday night.

For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...Small Craft Advisory from 6 AM to 4 PM CST Tuesday for LSZ121- 143>148-150. Small Craft Advisory from 6 AM to 9 AM CST Tuesday for LSZ140>142. Gale Watch from 9 AM CST Tuesday through Tuesday afternoon for LSZ140>142.