textproduct: Duluth

KEY MESSAGES

- A system arrives for this evening through tomorrow bringing rain, snow, and possibly freezing drizzle to the region. Snowfall of 3 to 6 inches are possible from Koochiching County into northern St. Louis, and much of Lake and Cook Counties. Lake-effect/enhanced snowfall will lead to 3 to 6 inches of accumulation along the South Shore as well. A Winter Weather Advisory has been issued for these areas.

- Gusty southerly winds tonight to 30 to 40 mph will turn northwesterly Thursday with gusts to 40 to 55 mph during the late afternoon and into Thursday night. Higher gusts to 60 mph will be possible in parts of coastal Lake and Cook counties where a High Wind Watch is in effect.

- Temperatures warm tonight before dropping through the day Thursday and may lead to flash freeze conditions on roadways.

- Additional snow chances possible this weekend and into next week along with variable temperatures.

UPDATE

Issued at 805 PM CST Wed Dec 17 2025

We decided to upgrade most counties to a Winter Weather Advisory Thursday afternoon and evening. This is due to the combined effects of light snow, gusty winds (leading to some blowing snow), and quickly plummeting temperatures that may lead to flash freeze conditions (any lingering liquid water on surfaces may quickly freeze). This could lead to areas of reduced visibility and poor driving conditions on roadways and walkways for the Thursday afternoon commute.

DISCUSSION

Issued at 359 PM CST Wed Dec 17 2025

High pressure was centered over the mid-Mississippi Valley this afternoon and extended northward into the western Great Lakes. Low pressure was analyzed over southern Alberta with warm fronts extending into the Dakotas. A pressure gradient between this low and high was starting to tighten over the Upper Midwest with southerly winds starting to increase over the Red River Valley. Radar returns nearing 30 dBZ were located along and north of the Iron Range, but this activity likely wasn't reaching the ground with some very dry air near the surface. Heading into tonight, a warm front will lift in from the southwest set up along/near the International Border. As the lower levels moisten, precipitation will begin to reach the ground. This may be in the from of light freezing rain or freezing drizzle before temperatures warm and change that to over to rain or a rain/snow mix along and north of the International Border. Models have come into better agreement tracking the low along the International Border tonight into tomorrow morning.

The low will drag a cold front across the Northland late tonight into tomorrow morning, bringing more in the war of rain or rain/snow mix along and ahead of the front. A dry slot will then work across the region from west to east behind the front. With a loss of ice aloft in the dry slot, another chance of freezing drizzle will be seen, mainly from the Brainerd Lakes area eastward into the I-35 corridor and into northwest Wisconsin before snow showers on the backside of the low spread in from the west. These snow showers will then linger into Thursday night before ending. Given the strong winds (discussed below), convective nature of the showers, and fairly steep lapse rates, snow squalls will be possible during the afternoon hours. Lake-effect snow showers will then linger along the South Shore through sunrise Friday.

With all this said, snowfall amounts of 3 to 6 inches will be possible north of the Iron Range into the Arrowhead with a half inch to 3 inches along and south of the Iron Range. Lake-effect will lead to slightly higher totals across northern Bayfield, central Ashland and northern Iron counties with 3 to 6 inches possible with locally higher amounts. Confidence in any ice accumulation is low and only a glaze to a few hundredths is possible. Winter Weather Advisories have been issued for the higher snowfall areas along the International Border and along the South Shore.

With the surface low deepening to around 985mb as it crosses the region, gusty winds are expected to develop as well. The first round of winds will be this afternoon and into tonight from the south. Gusts up to 30 to 40 mph are expected as steep lapse rates mix down a strong low level jet ahead of the cold front. The snow ahead of the cold front will likely be heavy and wet given the temperatures around freezing. Combined with the breezy winds, trees and power lines will be at risk. Following the cold front, winds turn northwesterly and increase Thursday afternoon into Thursday night with widespread gusts to 35 to 45 mph expected. As temperatures cool behind the front, the snow will become lighter in consistency and become easier to blow around which will lead to pockets of reduced visibilities. Stronger wind gusts to 50 to 60 mph will be possible along the North Shore from around the Silver Bay area to Grand Portage during the evening and early overnight hours as strong cold air advection arrives setting up a katabatic setup. Given the higher gusts expected, a High Wind Watch has been issued for the North Shore coastal zones.

As if this system wasn't complex enough already, cold arctic air will pour into the Northland behind the front starting in the hours before sunrise. This will likely lead to highs occurring during the early morning hours across parts of northern Minnesota and before noon elsewhere with temperatures falling throughout the day. As temperatures drop below freezing, a flash freeze may occur on area roadways which may lead to a period of slick conditions. Temperatures will drop into the single digits and teens below zero for Friday morning with some single digits above zero across parts of northwest Wisconsin. With winds slowly diminishing during this time, wind chills in the teens and 20s below zero.

High pressure will quickly move through for Friday with another clipper moving through the Upper Midwest for Friday night into Saturday. Light snow will be possible with this system with accumulations up to an inch or two being possible, highest in northern and eastern areas. The pattern remains active into next week with another clipper possible in the Monday-Tuesday time frame. Temperatures during this time will be quite variable. Highs will reach into the teens and 20s above zero for Friday and Saturday before falling into the teens and single digits above zero for Sunday. A quick warmup is expected Monday with highs in the 20s and low 30s before falling back down below freezing by midweek. Sunday morning looks to be the coldest morning of the latter half of the forecast period with lows in the single digits and low teens below zero with wind chills in the teens and 20s below zero.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1203 AM CST Thu Dec 18 2025

A strong clipper was centered near GFK as of 18.05Z and will move across northern Minnesota to western Lake Superior by 18.18Z. Temperatures at the surface were generally above freezing at the terminals as of 18.05Z (except for CKC and TWM in the Arrowhead). The first round of precipitation fell as rain with a few snowflakes mixing in. After this first round of precip temperatures aloft will remain too warm for snow for at least the next several hours with rain, drizzle, or freezing drizzle being the main precip type. Eventually there will be a change to all snow as temperatures cool later this morning. LLWS will remain a concern early this morning. HYR will keep the LLWS risk the longest with winds aloft weakening between 18.09Z and 18.12Z. Winds will strengthen and turn northwesterly this morning into early afternoon. The combination of strong winds and snow will reduce visibility to IFR or LIFR at times. There is also a risk for snow squalls today which could result in brief periods of whiteout conditions at the terminals. Winds will weaken after 19.00Z. Sporadic light snow showers will persist as long as clouds remain at the terminals.

MARINE

Issued at 711 PM CST Wed Dec 17 2025

Update to issue a Heavy Freeze Spray Warning for the South Shore on Thursday night as very cold air moves in with gale- force wind gusts. No other changes from previous discussion.

PREVIOUS DISCUSSION:

Gusty winds with gales are expected into this evening with southerly flow ahead of an incoming clipper system. Expect wind gusts around 20 to 30 kt for all nearshore waters, except gales around 35 to 40 kt in the Outer Apostle Islands towards Saxon Harbor tonight. Wave heights increase to 4 to 8 ft, especially along the North Shore tonight but also the Outer Apostle Islands.

As the clipper passes through to the north, winds will decrease slightly and briefly Tuesday morning as winds veer to the northwest with a strong cold front passing through. Winds increase very quickly Thursday afternoon and evening, with gales expected for all nearshore waters. There is a 30-60% chance for some storm force gusts 50 kt or more along the North Shore Thursday afternoon and overnight. Winds will then decrease everywhere on Friday. Heavy freezing spray is also expected going into Thursday night as very cold air moves into the region behind the cold front. Gale Warnings and Small Craft Advisories are in effect.

Another clipper Friday afternoon through Saturday may bring more strong south to southwest winds. Gusts in the 20 to 30 kt range are possible, and some gales for parts of the North Shore may develop as well. Winds switch to northwesterly Saturday into Saturday night, and strong winds may persist then as well.

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 9 AM this morning to midnight CST tonight for MNZ018>020-025-026-033>038. High Wind Watch from this evening through late tonight for MNZ020-021. Winter Weather Advisory until midnight CST tonight for MNZ010- 011. Winter Weather Advisory until 4 AM CST Friday for MNZ012-021. WI...Winter Weather Advisory from noon today to midnight CST tonight for WIZ001-006>008. Winter Weather Advisory from noon today to 6 AM CST Friday for WIZ002>004. MARINE...Small Craft Advisory until 2 PM CST this afternoon for LSZ121- 140>147. Gale Warning from 2 PM this afternoon to 4 AM CST Friday for LSZ121-140>148-150. Heavy Freezing Spray Warning from 6 PM this evening to 4 AM CST Friday for LSZ121-145>148-150. Winter Weather Advisory from 9 AM this morning to midnight CST tonight for LSZ142. High Wind Watch from this evening through late tonight for LSZ142. Gale Warning until 4 AM CST early this morning for LSZ148-150.