textproduct: Duluth

KEY MESSAGES

- Snow and freezing drizzle will taper off this morning.

- The next clipper will arrive late this morning through the afternoon and will bring heavy snow to areas generally south of US-2.

- Winter Weather Headlines were extended north in Minnesota and the Winter Storm Warning in NW WI was expanded. End times from the I-35 corridor east were extended.

- A period of several hours of heavy snow with rates around 1 inch per hour is expected late this afternoon through this evening.

- Freezing drizzle may follow the snow early Wednesday morning.

- Cold temperatures and additional chances of precipitation are expected later this week into next week.

DISCUSSION

Issued at 418 AM CST Tue Dec 9 2025

SUMMARY OF HEADLINE CHANGES

- Winter Weather Advisory for portions of north-central and northeast Minnesota remains in effect until 6 AM today.

- Winter Weather Advisory for this afternoon and tonight was adjusted north to include Itasca, central St. Louis, and southern Lake county areas.

- Winter Storm Warning was expanded north in northeast Minnesota to include northern Cass, northern Aitkin, Carlton/South St. Louis counties.

- Winter Storm Warning timing for Pine and Carlton/South St. Louis counties was adjusted. Starts at 20Z today and ends at 12Z Wednesday.

- Winter Storm Warning for Burnett County was extended until 15Z Wednesday.

- Winter Storm Warning in northwest Wisconsin was expanded to include Douglas, Washburn, Sawyer, and Price Counties. Time was extended to 15Z Wednesday.

- Winter Weather Advisory for Bayfield, Ashland, and Iron counties was extended to 18Z Wednesday.

----------

The first of two clippers is departing the Northland this morning. As the higher altitude clouds depart, the lower altitude liquid droplet clouds remain. Therefore freezing drizzle has been observed after snow ended across much of the Northland. GOES-East night microphysics product reveals clear skies northeast of a line from near International Falls to near Two Harbors. Another area of low stratus was moving southeastward toward the Arrowhead and may provide another burst of freezing drizzle. Minor ice accumulations are possible from the freezing drizzle which may make roads, sidewalks, bridges, and elevated surfaces slippery. Otherwise look for conditions to improve for a time this morning before the second clipper arrives.

The big story with this forecast package is the second clipper system which will arrive from the west this afternoon and tonight. The system is fast moving with complicated dynamics and abundant moisture available from an atmospheric river which is impacting the Pacific Northwest. This forecast is definitely not easy and has a high potential to bust both to the low side of forecast snow amounts north of US-2 and to the high side south of US-2. The NAM solution is farther north today than yesterday morning while the global models have come into better alignment. Thaler QG omega is quite strong from all the models with an area of 20 to 30 mb/hr ascent this afternoon and tonight. Frontogenesis will be aligned generally along the same axis. NAM and GFS cross sections reveal an area of 8 to 12 microbar per second omega co-located with the strongest FGEN and ample moisture. Very efficient snow crystal growth is expected where those parameters intersect. Look for several hours of 0.5 to 1.5 inch per hour snow rates generally near and south of US-2. Those rates should move across central Minnesota between 3 and 6 pm and over northwest Wisconsin between 6 and 10 pm.

On the other hand, the global models are bringing in strong dry air advection on the north side of the low track which will likely eat into snow totals. The greatest impact to snow totals should be north of the zone of strongest ascent, mainly along and north of US-2. Snow amounts in those areas may end up several inches too high if there's enough dry air to limit snowfall to only a few hours. Grand Rapids to Duluth are right in the zone where there may be a tight gradient in snow amounts. If the strongest forcing develops just a little farther south (20 to 40 miles) the higher snow amounts will be in MPX's area.

High-res CAMs are pointing to a convergent band of snow developing over the western arm of Lake Superior early Wednesday morning. The convergence is subtle. As we saw this morning and a few weeks ago, the CAMs do an OK job catching onto these narrow and usually transient bands of convergence and subsequent snowfall. The consensus is for the band of snow to impact the Twin Ports from around 2 am until 4 or 5 am Wednesday. That would be after the main synoptic snow had ended. The additional snow accumulation from that band has the potential to boost the event snow totals at Duluth. The convergent band will continue to sweep southeastward during the morning adding to snow totals in northwest Wisconsin. Lake-effect snow may develop as winds turn northwesterly Wednesday morning which would allow light snow to persist over Bayfield, Ashland, and Iron counties through the morning.

There is also a potential to see a period of freezing drizzle Wednesday morning as the upper-level moisture advects east faster than the low-level moisture, a scenario similar to this morning. If the freezing drizzle develops and persists, headlines may need additional extensions tomorrow morning.

In the end snow amounts have ticked up a little bit with this forecast. We now have a swath of 5-7 inches from Cass County to Price County. For the Twin Ports, Cloquet and areas south along I-35 have the greatest potential for higher end amounts. Duluth may only see 4-6 inches. There are some challenges in where the enhanced upward vertical motion will develop. One of the models keeps Duluth largely out of the snow!

We extended the headlines for this afternoon and Wednesday north one tier of counties in Minnesota and extended the Winter Storm Warning east into Wisconsin. Since Ashland, Bayfield, and Iron counties have higher snow thresholds for a warning, we left them in an advisory. We also added a few hours to the Carlton/South St. Louis, Pine, Burnett warning. The I-35 corridor is now until 6 AM Wednesday and Burnett is 15Z along with the rest of the NW WI counties in the warning. We extended the Advisory for NW WI until 18Z to account for additional light snow and lake effect Wednesday morning.

Attention then turns to the latter portion of the week. Another clipper is forecast to pass to our south Thursday and early Friday. The passage of that low pressure system will reinvigorate the cold air advection over the Northland for Friday into the weekend. By Saturday we may see highs straddling zero. Cold weather headlines may be needed later this week into the weekend. The cold air will bring another chance of light snow Friday. The clipper parade persists into next week with another shot of snow Sunday night and Monday. Some models are indicating a warming trend Tuesday and Wednesday which would see temps above normal.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 546 AM CST Tue Dec 9 2025

Areas of freezing drizzle and flurries persist this morning and are expected to dissipate by late morning. GOES-East night microphysics imagery reveals an area of potential freezing drizzle which persists for several hours after snow ends. Ceilings may briefly improve to MVFR before the next clipper arrives late this morning into the afternoon. At the moment I think that's unlikely. That system will bring IFR/LIFR ceilings and visibility. High snow rates of 0.5 to 1.5 inches per hour are expected from 21Z to around 00Z at BRD. There could be a period of freezing drizzle after snow ends.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 428 AM CST Tue Dec 9 2025

Another fast-moving clipper will pass to the south of the lake Tuesday afternoon through Wednesday afternoon. Winds will back northeasterly and strengthen Tuesday evening and will become hazardous for small craft once again. Gales of 35 to 40 knots are forecast from Taconite Harbor to Grand Portage where a Gale Warning is in effect. Small Craft Advisories go into effect at 10 pm tonight for the remainder of the waters. Wind gusts of 25 to 30 knots are expected. Waves will build to 3 to 10 feet over the southwest arm and along the waters of the South Shore. As the clipper departs on Wednesday winds will back northwesterly and diminish. Small Craft Advisories will likely be needed for portions of the North Shore from late Wednesday morning through Wednesday evening. Cold air moving over the high terrain will likely lead to katabatic winds from Silver Bay to Grand Portage. Wind and waves will then relax for Thursday before increasing again on Friday.

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 until 6 AM CST early this morning for MNZ010>012-018>021-026. Winter Weather Advisory from noon today to 3 AM CST Wednesday for MNZ018>020-026. Winter Storm Warning from noon today to 3 AM CST Wednesday for MNZ025-033>036. Winter Storm Warning from 2 PM this afternoon to 9 AM CST Wednesday for MNZ037-038. WI...Winter Storm Warning from 3 PM this afternoon to 9 AM CST Wednesday for WIZ001-006>009. Winter Weather Advisory from 3 PM this afternoon to noon CST Wednesday for WIZ002>004. MARINE...Small Craft Advisory from 10 PM this evening to 10 AM CST Wednesday for LSZ121-142>148-150. Gale Warning from 10 PM this evening to 10 AM CST Wednesday for LSZ140-141.