textproduct: Duluth

KEY MESSAGES

- Another warm day on tap today with highs 5 to 20 degrees above normal.

- A messy wintry system will arrive this weekend, with all precipitation types on the table. Snow and ice amounts will be low and are far from certain. See below for details.

- An active weather pattern and a roller coaster of temperatures will continue into next week, bringing additional chances for light messy wintry precipitation.

DISCUSSION

Issued at 347 AM CDT Fri Mar 20 2026

Overview...

The Northland remains under a baroclinic zone beneath a progressive northwest flow pattern aloft. (Baroclinicity is a "notable" horizontal temperature gradient through some portion of the atmosphere.) This pattern will support vacillating temperatures from day to day and frequent chances for light mixed wintry precipitation over the next week.

Early this morning and today...

Low pressure centered over the Minnesota Arrowhead early this morning will propagate southeastward into Upper Michigan by 12Z. An area of low stratus stretched from northwest Minnesota eastward across the Arrowhead and will continue to advect south- southeast through mid-morning. Similar to the past few days, the higher sun angle and thin cloud layer will allow adequate surface heating to mix out the clouds by mid to late morning. Another batch low stratus is upstream over far northwest Ontario and eastern Manitoba which may move into the region later this morning. That area of clouds should mix out as well.

Areas of fog early this morning will dissipate as winds veer northwesterly with the low pulling away. Partly to mostly sunny skies today will allow for temperatures to climb 5 to 20 degrees above normal with highs in the low 40s in the eastern Arrowhead to the upper 50s in central Minnesota. Northwest Wisconsin will see middle 40s to middle 50s. The heating will continue to cause ripening of the snow pack across the region.

Tonight and Saturday...

The additional low-level moisture will support patchy areas of fog tonight. Surface winds ahead of an approaching clipper may keep the boundary layer mixed and limit fog development. Forecasting fog development has been difficult the past several days and tonight promises to be no different.

An area of low pressure is forecast to move southeastward across the region Saturday. Precipitation is forecast to begin over far northern Minnesota into the Arrowhead tonight in response to height falls and isentropic lift ahead of the surface low pressure system. Forecast thermal profiles reveal a deep warm nose aloft which creates uncertainty in precipitation types. A wintry mix of rain, freezing rain, and snow are all possible. There is some good news. Precipitation amounts regardless of type will be low with this system and there will be limited travel impacts.

Model profiles show a variety of possibilities and are also dependent on location. northern Lake County and most of Cook County have the best chance of snow or freezing rain. The chance of rain increases farther south and west. Snow and freezing rain chances dwindle in favor of rain by late morning through the afternoon. Precipitation chances overall will diminish Saturday night from west to east. Potential ice accumulation is greatest along the high terrain of the North Shore where there's a 10-20% chance of up to a tenth of an inch of ice accumulation. The odds of seeing any ice in northeast Minnesota range from as high as 80% in the high terrain north of Grand Marais to 60% to Isabella and Silver Bay to 40% at Two Harbors to 10-20% near Duluth.

We have low confidence in snow amounts as well. The warm temperatures will have a significant affect on snow density and accumulation. The 20.00Z model suite is trending warmer than the previous forecast data. As such the snow accumulations diminished with this forecast though they might go back up if the system wobbles south again. High terrain along the North Shore could see 1 to 2 inches with the highest amounts in the high terrain between Grand Marais and Grand Portage. Those snow amounts dwindle to a dusting near Duluth and Virginia.

Saturday night through Sunday night...

Colder air will advance into the Northland as the low pressure system departs Saturday night. There is a 10-30% chance of lingering light precipitation Saturday night which should fall as snow. High temperatures on Sunday will be near to slightly below normal in the upper 20s to around 40 degrees. Stubborn light precipitation chances of 10-20% dwell over the Arrowhead and portions of northwest Wisconsin through Sunday night with negligible additional accumulation expected.

Monday through next week...

The wavy pattern persists through next week. Temperatures trend a little warmer on Monday. Another shortwave trough will propagate through the Canadian Prairies and northern Ontario Monday night into early Tuesday. Warm air advection ahead of that wave will bring a 10-30% chance of a mix of rain and snow to the Northland.

A more potent system may move through the region Wednesday and Thursday and bring another round of wintry mixed precipitation.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 545 AM CDT Fri Mar 20 2026

Two batches of low stratus are the main challenge over the next few hours. One area of stratus was over BRD, DLH, and HYR and the other over northwest Ontario. Both areas of stratus will continue to move southward through 17Z. Expect the clouds to scatter out in response to diurnal heating by late this morning. The southward trajectory will mean clouds will clear DLH, BRD, and HYR before they scatter out. The stratus over Ontario is a bit more challenging. As of 1030Z it appears that stratus will reach INL between 12Z and 13Z. If it stays together, it will arrive at HIB around 17Z. Otherwise expect VFR conditions and northwest winds today. Another clipper will move into the region tonight and Saturday. Winds will become southerly which may give rise to areas of fog including BRD and HYR. INL will see ceilings return after 21.06Z and precipitation chances increase. Confidence in precip types is low due to the position of the low-level freezing forecast to be near the terminal. I opted for a mix of freezing rain and snow. If temperatures are warm enough rain and snow would be the appropriate mix. If temperatures aloft are warmer, rain and freezing rain would be the result. For the moment I leaned toward the more impactful conditions in the PROB30 group.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 347 AM CDT Fri Mar 20 2026

Relatively quiet conditions are expected until Saturday. A fast- moving low pressure system will pass southeastward across the region Saturday and Saturday evening. Winds will be from the east and gradually strengthen on Saturday. Wind gusts will increase to 15 to 30 knots by early Sunday morning with waves building to 3 to 8 feet. The highest waves will be from the Outer Apostle Islands to Saxon Harbor. There is a 10-30% chance of low end gales to around 35 knots near Grand Marais and Grand Portage Saturday night and early Sunday morning. Winds will gradually weaken while remaining northeasterly Sunday into Sunday evening. Gusty winds return Monday night and early Tuesday morning near Grand Marais. A stronger low pressure system late next week could bring widespread hazardous conditions and gales to western Lake Superior Wednesday night through Friday.

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...None.