textproduct: Duluth

KEY MESSAGES

- Arctic air remains in play for today. With Cold Weather Advisories continuing until late Sunday Morning

- Light lake effect snow showers continue for the South Shore until Sunday afternoon. Most will see a half inch or less. But northern Iron County can expect an additional 2-4 inches.

- Warmth returns Tuesday with highs soaring into the 30s and 40s.

- Widespread precipitation chances currently don't return until late Wednesday into Thursday.

DISCUSSION

Issued at 320 AM CST Sat Dec 13 2025

Current Conditions/Sunday:

An arctic air mass continues to spread in from the Canadian Prairies today as an upper level low swings across northern Lake Superior. The 00Z sounding at INL revealed an 850mb temperature of -21C. For context, when compared to sounding climatology that value is below the tenth percentile. This mass of cold air will lead to highs likely not breaching out of the subzero digits for most of the Northland. Northwesterly winds will still be a bit breezy during the day but not nearly as strong as yesterday due to the pressure gradient weakening as the high encroaches. The cold northwest flow will lead to continued light snow for the South Shore. Most locations will see an additional half inch. But, northern Iron could see an additional 2-4 inches. Can't fully rule out some snow on the MN side as well. The departing upper level low still has a decent fetch of moisture wrapping around it. Combine this over any inland lakes that aren't frozen will yield some light snow showers. And if we manage to generate enough low clouds we may see some anthropogenic snow at times. Overall, any snow accumulations on the MN side will be minimal.

Sunday will be another cold start. Although not nearly as cold as we are this morning. The arctic high moves into the Red River Valley which will lead to weakening winds across the region. Furthermore, the sector with the coldest air will have departed to the southeast. That being said, wind chills in the morning will still be in the -20s to -30s. No changes to the current Cold Weather Advisory.

Early Week Bounce Back:

The arctic high pressure weakens and drifts off to the southeast on Monday allowing for temperatures to recover back into the 20s. Temperatures continue their upswing as a warm front crosses through the Northland on Tuesday. Highs will soar back into the 30s and 40s as southerly winds stream through the region. These warmer temperatures look to persist through Wednesday before a cold front will bring us back down to climotological norms.

Precipitation chances:

Models don't have a strong consensus on the overall pattern as we head into the mid and late week timeframe. Cluster analysis maintains the zonal flow over the region through mid week but then has hints of a trough digging into the Northland for Thursday. The zonal flow initially may bring some quick hitting chances across our far north late Tuesday into Wednesday as a low pressure glides across Ontario. But the NBM does not seem to be to thrilled at this prospect as it is producing less than a 15% chance of precipitation. It's focus seems to be on the the midweek system where ensembles are pinging on another stout Alberta Clipper moving across the Upper Midwest. Low tracks still remain all over the place and will have a great impact on our precipitation type. A more northernly track may lead to a wintry mix for portions of the region on Thursday. Based on the source region, this system could also siphon off some Pacific Northwest moisture from the atmospheric river spilling into the region. Still a ways out, but something to keep an eye on in future forecasts.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 525 AM CST Sat Dec 13 2025

Arctic air has set up residency over the Northland this morning making it difficult to pick out clouds due little temperatures difference between them and the ground. But given the northwest flow and the occasional ob showing very isolated MVFR/IFR ceilings, one can gather that some streamers off of inland lakes still persist. Through the day model soundings support the development of some diurnal cumulus, which may be SCT to BKN at times. Additionally, expect some wind gusts out of the northwest, but not nearly as strong as yesterday's winds.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 320 AM CST Sat Dec 13 2025

Gusty northwest winds have arrived across western Lake Superior and they are here to stay for most of the weekend. The Heavy Freezing Spray Warning has been extended for the Outer Apostle Islands as waves will take some time to subside. The Gale warning for the North Shore has been cut short and replaced with a Small Craft Advisory. There is a brief window this evening where a few gales may be observed along the North Shore but the confidence is not high enough to hoist another warning at this time. In general, the winds are expected to start tapering down after midnight across all the near shore waters. However, there is only a brief lull in the enhanced winds for the Lake. Southwesterly winds are expected to increase late Sunday with a few gales possible along the North Shore once again.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Cold Weather Advisory until 10 AM CST Sunday for MNZ010>012- 018>021-025-026-033>038. WI...Cold Weather Advisory until 10 AM CST Sunday for WIZ001>004- 006>009. MARINE...Small Craft Advisory until 4 AM CST Sunday for LSZ121-140>148- 150. Heavy Freezing Spray Warning until 6 AM CST early this morning for LSZ146. Heavy Freezing Spray Warning until 6 PM CST this evening for LSZ147-150.