textproduct: Duluth

KEY MESSAGES

- Unseasonably warm weather Monday with increasing clouds and maybe a little rain late-afternoon.

- A wintry system will bring rain starting around Monday evening into Tuesday, changing to snow Tuesday afternoon and evening and ending for most places by Wednesday evening. Accumulating snow and blustery winds are likely for many places.

- Lake-effect snow is expected to increase in northern Iron County Wednesday and Wednesday night, then taper off going into Thursday evening. Heavy snow amounts are possible.

- Cold temperatures are expected from Wednesday onward.

- Another impactful winter system may affect the upper Midwest this weekend, which could cause post-Thanksgiving travel impacts.

DISCUSSION

Issued at 257 PM CST Sun Nov 23 2025

Some warm air advection today is fueling clouds for much of the region this afternoon. We might see a little clearing up north tonight into Monday, but otherwise we will probably have at least some clouds around.

On Monday, we start to see influences from our incoming storm system from the south. Models continue to back off on the start time of rain in our region. It is quite possible that we remain completely dry on Monday and don't see the initial round of rain arriving from the south until sometime later Monday night, probably in northwest Wisconsin. In fact, pretty much all of the synoptic forcing for that looks like it will be largely confined to Wisconsin, so most of northeast Minnesota might even stay dry until precipitation starts associated with the second west-to-east tracking low that will pass through Tuesday and Wednesday. At this point, it looks like this second low will essentially overtake the first on Tuesday, tying in with the deformation rain band and spreading moisture through a TROWAL westward to the north and northwest quadrants of what will become one stronger low once they merge.

While models had waffled quite a bit from Friday to Saturday, they are showing more consistency into today regarding an area of strong vertical ascent ahead of the upper level low, which will pass through the region Tuesday afternoon and night. This is what we are watching for the potential for accumulating snow. There have been some high QPF amounts in global ensemble members that I still hesitate at buying into at face value. We should see a ~6 hour period where the strong vertical ascent could produce some efficient dendrite growth and snowfall rates that could be in the 0.5 to 1 inch per hour area (maybe even locally higher briefly). But, the low will be passing through fairly swiftly, so duration of heavy snow rates will be a limiting factor in producing very high QPF and thus snowfall amounts. Snow-to- liquid ratios are also in question as we will be starting with wet/heavy snow in the evening as cold air advection develops behind the low's passage and temperatures start to fall below freezing. Snow-to-liquid ratios should be pretty low initially, then gradually increase into the evening and overnight. In the heart of the heaviest snow during the evening, we should definitely have saturation through the DGZ and some pretty efficient dendrite production (i.e. big snowflakes that can accumulate quickly). But, this isn't the most efficient-looking thermal profile I've seen, and SLRs will probably be closer to 10-15:1...maybe a smidge higher. Lingering wraparound light snow into Wednesday morning may approach the "light and fluffy" consistency, and with wind gusts increasing to around 25-35 mph and temperatures staying below freezing, some blowing snow may occur. I'm not as concerned about ptype issues Tuesday afternoon and evening since most of the precipitation will be moving in coincidentally around sunset, and a fairly smooth transition from rain to snow seems likely. Areas around the Brainerd Lakes are maybe the most uncertain for snowfall amounts relative to ptype issues. If it stays warm enough with the onset of this precipitation in the afternoon, there could be a bit more rain there before it eventually transitions to snow, which could eat into amounts a bit.

Despite there still being a fair amount of forecast uncertainty, there are some pieces that appear to be coming together. For example, most ensembles have a swath of precipitation associated with this second and overtaking low tracking somewhere through our CWA. There is even a bit of clustering going on with total QPF amounts around 0.5 to 0.6" at Duluth and Brainerd per SREF plumes (though there are still plenty of outliers). This gives a bit of increasing confidence that this area of precipitation may pass through the Brainerd Lakes to Duluth and into western Lake Superior areas. There is now a lot less clustering (and thus higher uncertainty) up north towards International Falls. There are plenty of ensemble members that take the main axis of precipitation through the Iron Range or into northwest Wisconsin, so still plenty of change that could still happen, but at least we're starting to see somewhat of a trend starting to emerge.

For QPF and snow amounts, I mentioned that some ensemble members have had some high QPF amounts that I am not so sure about. My main concern is the fairly quick movement of this low Tuesday evening and night, so while some higher amounts are certainly possible, I'm leaning towards the mean and favoring totals in the 0.5 to 0.7" ballpark with locally higher amounts for QPF. Translating this to snow amounts, given the variable SLRs, most places are likely to see advisory-level snowfall amounts and several 6"+ totals are certainly possible if some of those higher ensemble members come out to be correct.

All of that above was focused on the main synoptic forcing, but we also have lake-effect to talk about. As snow starts to end Wednesday morning for most places, the South Shore will "clear up stormy" as snowfall rates start to ramp up Wednesday. Strong cold air advection will develop, initially enhancing the synoptic snow along the South Shore Wednesday, then translating to mainly pure lake-effect going into Wednesday afternoon and night. Lake-to-850 hPa temperature differences should be around 15 to 20 degrees celsius, which should be very favorable for heavy lake-effect snow. The caveat may be wind direction, which may become slightly more west than north Wednesday afternoon and evening, which may confine the heaviest bands to northwest Iron County. But there and then, wind shear should be pretty minimal and copious over-lake instability could easily result into some 1-2" per hour snowfall rates. There's still some variation among ensemble members for total QPF, but most are over an inch and with SLRs likely to be >15:1, I think the snow should fall heavy and accumulate easily. This is the place that I actually lean on the higher end of QPF from ensemble solutions. Latest NBM probabilities for 12"+ of snow are ~90% and are around 60-70% for 18"+ of snow. This, in my opinion, may be a smidge high, but still the potential is there for significant amounts of lake-effect snow.

Winter Storm Watch Rationale: With confidence increasing on this upcoming system, we have decided to issue Winter Storm Watches for much of the region. We are looking at current forecast snowfall amounts that are a little above and below the usual 6" storm total threshold for considering a watch. We decided to be generous in coverage of these for several reasons: 1) This is the first accumulating snow for much of the region, 2) It is happening during pre-Thanksgiving holiday travel, 3) Storm track may change a bit, and we want to have watches out for areas where we are reasonably confident that the heaviest amounts could fall, and 4) There is still uncertainty and potential for higher amounts to occur should some of the higher QPF solutions among ensembles ring true. Confidence is about 50% for most places, except higher along the South Shore. It is likely that several areas under a watch may end up with an advisory and not a warning, but we want to "watch" all of these areas until we can narrow down places where conditions may warrant a warning.

There may be a few lingering light snow showers on Thanksgiving and lingering lake-effect along the South Shore, but by and large, snow should be tapering off. The main story thereafter is that it's going to be cold! Whatever snow falls is going to stick around.

The weather pattern will remain active, and there is potential for a large winter storm to impact some parts of the upper Midwest going into the weekend. There may be even more that follow with a southwest-to-northeast oriented storm track setting up. At this time, it looks like storm tracks are generally favoring areas southeast of the Northland, but these tracks could certainly shift. At the very least, those with travel plans to/from places southeast of here should keep a close eye on the the forecast.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1149 PM CST Sun Nov 23 2025

VFR cloud cover will persist through much of the period. Some MVFR ceilings may work into HYR after sunrise Monday, but will likely return to VFR by early afternoon. Surface winds will remain light through the period. A low level jet will move east through the early morning hours and bring low level wind shear to all terminals except BRD. This will end by 10z.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 257 PM CST Sun Nov 23 2025

Winds are expected to shift to southwesterly overnight and become a bit blustery with gusts up to 20 kt. Localized and brief gusts to 25 kt can't be ruled out around the outer Apostle Islands, but confidence is not high enough to issue a headline at this time.

Winds briefly decrease on Monday before switching to northeasterly ahead of a low pressure system Monday night. Winds are then expected to increase into Tuesday. Widespread gusts to around 25 to 30 kt. Gales are possible (up to 40% chance) late Tuesday night through Wednesday night. Gusty winds will decrease slightly thereafter, but likely remain strong with gusts to 20 to 30 kt through early Friday morning. Small Craft Advisories are likely to be needed, and Gale Warnings may be needed. Through this time, rain changing to snow is expected 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 Storm Watch from Tuesday morning through Wednesday morning for MNZ010-018-025-026-033>036. Winter Storm Watch from Tuesday afternoon through Wednesday evening for MNZ011-012-019>021-037. WI...Winter Storm Watch from Tuesday evening through Wednesday evening for WIZ001-002. Winter Storm Watch from Tuesday evening through late Wednesday night for WIZ003-004. MARINE...None.