textproduct: Marquette

KEY MESSAGES

- General weather pattern of Clippers followed by lake effect snow continues for the next week, perhaps beyond.

- Gusty NW winds this morning will help reduce visibility within snow showers and will cause some blowing and drifting snow. A few brief gale force gusts are possible (~50%) over the east half of Lake Superior this morning.

- Cooler than normal temperatures, with highs in the teens to 20s and lows as low as the negative single digits (particularly Monday AM).

DISCUSSION

Issued at 443 AM EST Sat Dec 6 2025

Early morning KMQT radar returns show a number of NW/SE-oriented bands of snowfall. Some of the bands have penetrated impressively far inland over the interior central UP, though CAMs show that bands will retreat to the more typical NW wind LES belts. Lake Superior remains around 5 C despite the constant cool air over the lake, and 850mb temperatures will remain 50-90% likely to be in the negative double digits of degrees C throughout the entire forecast period, so thermodynamic support for LES will be present throughout, regardless of wind direction. Aloft, expansive and stubborn ridging off the CA coast contrasts expansive and stubborn troughing over Hudson Bay, with the resulting flow in between those features being northwest flow over much of the CONUS. With neither longwave feature in a hurry to move or deform any time soon, forcing for the sensible weather over the UP well into mid December will come from two sources: ridge-riding shortwaves that pass through the Canadian Rockies and spawn Alberta Clippers, and embedded shortwaves within the Hudson Bay trough that send periodic cold fronts/surface troughs over the UP. Except for the strongest of these features, the synoptic forcing will be generally too weak to provide impactful winter weather for the UP. However, the cold air and cyclonic surface flow in the wake of each disturbance will bring enhanced LES setups periodically which depending on the available moisture, inversion heights, and DGZ depth, may be worth consideration for winter impacts.

Today, LES potential will be limited by a drying near-surface layer, shallow inversion heights (5 kft or less), and limited DGZ depth/moisture. HREF chances of 1"/6hr is only around 30% in the strongest bands over the east, so no Winter Weather Advisory will be necessary. Still, with winds up to 35 mph mixing down to the surface (per KP59 and KCMX ASOS obs), some reduced visibility has been observed even in the "weaker" bands and some blowing/drifting snow may be observed, so some extra care may be needed for the morning commute. As the pressure gradient relaxes today, expect winds to relax in kind and become more westerly.

Tonight into Sunday, a confluence of one of each of the aforementioned types of shortwaves is forecast to occur over the Midwest, sending a weak surface low well south of the UP. CAMs bring 15-30% chances of some system snow for the southern half of Menominee County, but even the 95th percentile of the HREF only shows an inch of snowfall for that area. Of perhaps more impact will be the cool northwesterly flow behind the shortwave supporting further LES. The HREF shows chances of 48-hour snow totals exceeding 6 inches to be around 30-50% for the Munising, Grand Marais, and Tahquamenon Falls areas, though as the snow will be falling at a slow pace over an extended time period, no headline is anticipated to be issued.

To kick off the work week, high pressure moving south of the region will help decrease the coverage and intensity of LES with one notable exception: a weak shortwave will help cause some localized convergence which could bring some relatively rare SW-wind LES off of Lake Michigan to Schoolcraft County east of Manistique and Luce County south of M-28. This feature may bear some monitoring for brief travel disturbances along the US-2 and M-28 corridors, though uncertainty still exists in regards to the details of such a mesoscale feature beyond 48 hours out.

Attention then turns to a pair of clipper lows: a weak one around 1006mb approaching the western UP overnight Monday into Tuesday and then a much stronger one below 990mb Tuesday night into Wednesday. Chances of a widespread 1+" of snow are high with the first feature (~70%), though the ceiling of impacts is low as the chances of over 2" is only 20-40%. The second feature has similar probabilities to deliver a safe floor of an inch of snowfall, but the ceiling is higher, with around 20% chances of 4+" of snow by midday Wednesday along the MI/WI state line.

Ensemble spread then grows in the details of the pattern evolution, but little broad-scale changes in the weather pattern are expected until at least mid-December, perhaps longer. Long-duration cool continental NW flow aloft will help keep temperatures cooler than normal, with NBM highs generally in the teens to 20s and lows in the teens near the shores to single digits above and occasionally below 0. The coolest temperatures will come in the interior west where breaks in the clouds can allow for efficient radiational cooling to occur. One such example will be Monday morning, where clearing skies in the interior west allow for NBM lows to fall to around -6 for Iron County. Mercifully, the coolest temperatures also line up with high pressure and thus the weakest winds, so wind chill concerns are low.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 614 AM EST Sat Dec 6 2025

MVFR/IFR flight restrictions to continue at both IWD and CMX through this afternoon as weak disturbances produce light snow showers. IWD could see a brief return to VFR late this afternoon, but that may a bit too optimistic as ceilings again look to lower to MVFR tonight. At SAW, though, mainly VFR conditions are expected through the forecast period as any snowfall will be lighter. Meanwhile, strong northwesterly winds with gusts to 25 to 30 kts at CMX could result in blowing snow and thus additional visibility impacts at times.

MARINE

Issued at 443 AM EST Sat Dec 6 2025

A few brief NWerly gale force gusts are possible (~50%) in the east half of the lake this morning, but a relaxing pressure gradient with approaching high pressure will allow for gusts to fall to 20 kt or below by this afternoon. A disturbance aloft will help focus NW winds tonight into Sunday morning, with NW gusts to 25-30 kt for Sunday before high pressure once again relaxes the gusts below 20 kt for Sunday night. A pair of Clipper Lows passing through the Great Lakes in the first half of next week will bring gusts up to 30 kt, first out of the southwest Monday PM, then out of the northeast to north Wednesday AM. Chances of prolonged gales with these Clippers is currently around 20%, though the chances of more isolated, brief gale force gusts is higher (~40%). Not much change in the weather pattern is expected well into the middle of the month, with occasional Clippers bringing chances for low-end gales, and the combination of long-duration NWerly winds and cool air mass will cause occasional moderate freezing spray.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... None. Lake Michigan... None.