textproduct: Duluth

KEY MESSAGES

- Arctic air this weekend will keep highs in the single digits to low teens with overnight lows below zero.

- Active weather next week with several clipper systems passing through the region. The Tuesday into Wednesday system currently looks to be the most impactful with the potential for heavy snowfall.

- Another round of arctic air late next week and weekend will push highs back down into the single digits to low teens with overnight lows below zero.

DISCUSSION

Issued at 220 PM CST Sat Dec 6 2025

Today - Sunday:

A strong arctic high pressure centered over Alberta today and into the Red River Valley on Sunday should keep mainly dry conditions and colder air over the region under primarily clear skies for most. There are a few exceptions to this, however. First, is some cloud cover from the Brainerd Lakes east into inland northwest Wisconsin through this evening on the northern fringe of a cloud shield associated with a low pressure system passing well to our south. Second, are some light snow showers downwind (i.e. southeast) of bigger inland lakes in Minnesota, especially near the International Border today through tonight. Third, are South Shore lake-effect snow showers due to the colder air over a relatively warm (around 40F) Lake Superior water surface. The South Shore lake-effect should linger into daytime Sunday before coming to an end in Ashland and Iron Counties Sunday evening as winds turn westerly and drier air cuts off lake-effect processes. Expect less than an inch of snow from the inland lake-effect snow showers in northern Minnesota and generally another 1" to locally 3" of very fluffy snow in eastern Ashland and northern Iron Counties for today through Sunday.

Temperatures will be well-below average today and Sunday, with highs both days in the single digits to teens and lows tonight and Sunday night for pretty much everywhere in the Northland. Some lows tonight in north-central and northeast Minnesota may even dip below -10F in areas where skies stay clear and winds remain very light to calm. This could set up overnight and early Sunday morning wind chills in the -10F to -25F range, lowest in the Arrowhead and Iron Range.

ACTIVE PATTERN NEXT WEEK:

Monday - Early Tuesday Clipper:

On Monday, the surface high pressure and main lobe of the arctic airmass will be sliding southeast of the Northland, setting up southerly return flow into the Northland and moderating temperatures with highs in the upper teens to mid 20s. Very light snow is possible late Sunday night into Monday morning as a weak 500 mb shortwave interacts with weak lift due to warm advection in a saturated dendritic growth zone. Snow amounts with this snow look minimal, with the best potential for measurable snow in the Brainerd Lakes to inland northwest Wisconsin (20-40% chance).

Then, there is good agreement amongst ensemble surface low tracks for the first in a series of Alberta Clippers to move through Northern Minnesota, albeit with a very slight southward shift relative to previous model runs. This would bring snow to much of the Northland starting Monday evening, peaking in coverage and intensity in the late evening and overnight, and then exiting the Northland to the east by mid to late Tuesday morning. Synoptic lift from divergence aloft and differential vorticity should aid in a small period of time in the late evening and early overnight hours when moderate to locally high snowfall rates would be supported. Areas generally along and north of US-2 in Minnesota and along the South Shore are the with the best potential for 2"+ of snow at 40- 70%, locally 80% along the North Shore. 4"+ probabilities have dropped off slightly, with 10-20% for the aforementioned areas and locally 20-30% along the North Shore.

Tuesday - Early Wednesday Clipper:

Quick on the heels of the first Clipper will be a second, stronger Alberta Clipper diving into Minnesota late Tuesday into early Wednesday. This system should be much deeper, with ensemble member forecasts of a surface low with a central pressure ranging from 977- 990 mb. The NAEFS MSLP forecast shows these pressures being near or at the minimum of the climatology for this time of year. This system's moisture will also have Pacific Northwest origins from a potent atmospheric river. Modification of the moisture as this system tracks into the Upper Midwest would put forecast PWAT values near the 90th percentile for the Northland relative to climatology for early December at around 0.50". The main difference between the 12Z suite and 00Z suite of global ensemble guidance has been a better clustering in the timing of the low pressure tracks through Minnesota and Wisconsin from Tuesday afternoon through Wednesday morning. There is still some room for the track of the center of this low pressure system to wobble as far north as northern Minnesota or as far south as northern Iowa late Tuesday afternoon/evening, but most of the ensemble tracks are through central Minnesota or the southern half of Minnesota. The exact track will play an important factor in where the heaviest snow falls and snowfall amounts for the Northland as strong frontogenetic banding on the northern side of the surface low and mid/upper-level synoptic support for strong lift (e.g. differential vorticity and divergence aloft) should drive periods of heavy snowfall rates (0.5-1" per hour), particularly late Tuesday afternoon and evening given the current forecast timing.

There should be a fairly sharp gradient on the northern side of this banded snow, so a shift of even tens of miles could drastically change which locations see the highest snowfall amounts. A more southerly low track across southern Minnesota/Wisconsin could mean much of northern Minnesota would only see lighter accumulations, while a low track across central Minnesota/Wisconsin would place more of the Northland in moderate to heavy snowfall potential with this system. Current probabilities for 2"+ of snow are 50-70% generally along and south of the Iron Range in Minnesota and for all of northwest Wisconsin. Meanwhile, 4"+ probabilities are 30-55% along and South of US-2 in Minnesota and for northwest Wisconsin and up to Silver Bay along the North Shore given initial wind trajectories off of Lake Superior adding in some lake/terrain enhancement. Higher snowfall thresholds tail off slowly, with 6"+ probabilities of 20-35% for the same areas as the 4"+ probabilities.

Late Next Week into Next Weekend:

While this second Clipper system will pull out of the area by Wednesday PM, there should be some lingering snow showers through much of the day along the South Shore. Global ensemble guidance then points to the active weather pattern and clipper train continuing late this week into next weekend as more Alberta Clippers slide somewhere across the Midwest on Thursday, Friday, and possibly next weekend. Still plenty of uncertainty regarding the late next week systems with regards to timing, tracks, and intensities. With that said, the there are some early indications that the Thursday system may track far enough south for its associated precipitation to completely miss the Northland.

One thing that is more certain for late next week into next weekend will be a return of another cold arctic airmass in the wake of the Tuesday/Wednesday Clipper. High temperatures will likely return to the single digits above zero to teens, with overnight lows below zero.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1125 AM CST Sat Dec 6 2025

Light lake-effect snow showers/SCT to BKN MVFR cloud bases persist downwind of the bigger inland lakes today, especially in far northern Minnesota as evidenced by satellite and observations. These clouds and possibly (10-20% chance) for very light snow could impact INL/HIB this afternoon and evening, though the current northwest wind direction has kept the coverage of MVFR ceilings and light snow east of those terminals. Farther south, BRD and HYR continue to see VFR ceilings around 3500-5000 ft this afternoon on the northern edge of a cloud shield associated with low pressure passing well to the south. Expect these ceilings to lift higher this evening, with some clearing of cloud cover tonight into Sunday morning.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 220 PM CST Sat Dec 6 2025

Northwest winds pick up, with gusts to 15-20 kt this evening into midday Sunday. Waves could approach 2-4 ft in the Outer Apostle Islands. No Small Craft Advisories are expected at the moment, but may be needed if winds and/or waves increase any further. Winds weaken and back to southwesterly Sunday evening and night.

Weather then becomes much more active for Monday into next week, with multiple clipper systems set to impact the region. The Tuesday into Wednesday system looks to be a prolific snow producer. Gusty southwest winds of 20-30 kt are forecast for Monday, and out of the northeast to north Tuesday night into Wednesday. There is also a 10-30% chance for gale- force winds Tuesday night into Wednesday morning for the Outer Apostle Islands and from Grand Marais to Grand Portage.

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.