textproduct: Duluth

KEY MESSAGES

- A large system moving north will bring rain then snow to the Northland starting tonight through Wednesday. Windy conditions and possibly some blowing snow will accompany it.

- Enhanced snowfall is expected from a potent FGEN band over the Arrowhead, a gravity wave over far northwestern Wisconsin, and lake effect snow along the South Shore.

- Light lake effect snow will linger across the South Shore into the weekend, and another system over the latter half of the weekend may bring another round of snow.

DISCUSSION

Issued at 232 PM CST Mon Nov 24 2025

We have an interesting pattern set up for the next few days. Two troughs, one in the Southern Plains and one moving across the Pacific Northwest will work together to bring an impactful system to the Northland through Wednesday. The southern system is helping to bring warm, moist air northward and will be a major source of moisture for this system. As the southern trough moves north, it will be somewhat "absorbed" into the overall flow, but the northern trough will be close behind and will provide the forcing for when the system moves over the Northland. At the surface, the associated surface lows will work together to create one large overall system throughout the eastern half of CONUS.

One surface low currently near eastern SD/NE and western IA is slowly moving north, producing light to moderate rain showers. Onset time of precipitation has slowed due to fighting dry air to the north, and will take a bit to fully saturate the vertical column. However, we are expecting rain to start reaching the ground early Tuesday morning across northwest Wisconsin. Meanwhile, a second surface low associated with that northern trough will move east across the Northern Plains, already contributing to some snow across ND and will bring light snow to northwest and north central MN early Tuesday morning as well. These two systems will combine as they move through the area, and precipitation types will remain divided with snow across the Iron Range and Borderlands with rain elsewhere across northwestern Wisconsin. In between will be the transition zone from the Brainerd Lakes region to the Twin Ports and up the North Shore throughout Tuesday morning. The line of rain switching to snow will move southeast throughout the day as cold air is advected from the north.

As we head into Tuesday evening, a band of frontogenesis combined with strong forcing and divergence will create a band of enhanced snowfall in the TROWAL region of the now-combined system. Where exactly this band will fall remains uncertain, but confidence is high (80%) that it will fall somewhere in the Arrowhead and/or far northwest Wisconsin. Additionally, as flow begins to turn to the northwest, CAMS are showing a potential for a gravity wave to set up over Douglas/Bayfield counties, which could lead to over an inch per hour rates at times in localized areas.

A break in the snowfall may be seen in our southern line of WI counties as the dry line moves east just to our south. The exact track of the dry line should stay largely to the south, so a break in precipitation should be brief.

Early Wednesday morning, as winds shift further to the northwest, lake effect snow will begin over northwest Wisconsin. Since we have had temperatures averaging above normal for the last few weeks, Lake Superior water temperature is still in the 40s. With the CAA, the air mass will be much colder than the water, which will enhance the lake effect snow further along with sufficient mid level lapse rates (5-7 C/km) increasing throughout the morning (7-9 C/km). Snowfall across the region will begin to exit Wednesday morning, but lake effect snow will continue for Ashland and Iron counties through Wednesday and into the latter half of the week.

Overall, a majority of the area will see 6"+ except for far north central Minnesota and central Wisconsin. Areas under the TROWAL could see up to a foot of snow, and the gravity wave/lake enhancement across the South Shore counties will lead to 10-15 for most, with bullseyes of 20"+ in northern Iron County. Therefore, with the additional nudge that travel will be heightened from the Thanksgiving holiday, have opted to include most of our area in a new Winter Storm Warning starting at various start times over Tuesday. Koochiching and the bottom tier of our Wisconsin counties are under a Winter Weather Advisory. However, the Wisconsin counties may need to be upgraded if the snow gradient continues to move further south.

Winds throughout the system will be strong as well, increasing initially from the northeast before backing to the northwest. Gusts up to 35 mph are expected, especially on Wednesday, which could lead to any snow that hasn't already compacted to be blown around. A cool down is also expected behind the system, where we will have temperatures below freezing for the rest of the forecast period. High temperatures will be in the twenties and possibly even the teens by next week.

There is the potential for another system to bring light snow next weekend, but global model discrepancies in the path of the system makes it difficult to conclude anything concrete on whether there will even be any precipitation.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1201 PM CST Tue Nov 25 2025

VFR conditions prevail across northeastern Minnesota early this morning with conditions ranging from VFR to LIFR across northwestern Wisconsin. As a storm system begins to work in this morning, conditions are expected to deteriorate with ceilings falling to MVFR to IFR or lower. As rain, snow, and mix activity spreads in through the day Tuesday, VSBYs are expected to fall to MVFR or lower with IFR VSBYs prevailing after sunset Tuesday when the heaviest snow is expected at the terminals. The exception will be INL which will be on the northern edge of the system and will see less snow. Snow will be heavy and wet today into this evening, but colder air moving in will start to increase the snow ratio late Tuesday evening. Winds will pick up later this afternoon with gusts to 20 to 25 knots expected into Tuesday night.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 232 PM CST Mon Nov 24 2025

A deepening low pressure will move across the Upper Great Lakes Tuesday into Wednesday resulting in Gale-force winds over Lake Superior. Northeast winds increase late tonight into Tuesday leading to building waves through the day Tuesday. By Tuesday evening the low center will be just south of Duluth, and as it tracks east- northeast towards the Upper Peninsula of Michigan, winds across western Lake Superior will increase and become more northerly Tuesday night, out of the northwest by daybreak Wednesday. Northwest winds of 25-30 knots with gale-force gusts to 40 knots Wednesday evening. On Wednesday evening, winds will start weakening as the low exits and an area of high pressure builds in from the west. The probability for gale-force gusts (34+ knots) is 80-100 percent, greatest for the north shore north of Grand Marais. Storm-force gusts over western Lake Superior are less likely, with around a 10 percent chance for Storm-force (48+ knots) gusts north of Grand Marais.

Beyond the storm, northwest winds linger through the rest of the week into the weekend at 10-15 knots Thursday, then less than 10 knots Friday, Saturday, and Sunday.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Winter Weather Advisory from 6 AM Tuesday to noon CST Wednesday for MNZ010. Winter Storm Warning from noon Tuesday to midnight CST Wednesday night for MNZ011-012-019>021-037. Winter Storm Warning from 6 AM Tuesday to noon CST Wednesday for MNZ018-025-026-033>036. Winter Storm Warning from 6 PM Tuesday to 6 PM CST Wednesday for MNZ038. WI...Winter Storm Warning from 6 PM Tuesday to midnight CST Wednesday night for WIZ001-002. Winter Storm Warning from 6 PM Tuesday to 6 AM CST Thursday for WIZ003-004. Winter Weather Advisory from 6 PM Tuesday to 6 PM CST Wednesday for WIZ006>009. MARINE...Gale Watch from Tuesday evening through late Wednesday night for LSZ121-140>148-150.