textproduct: Marquette

KEY MESSAGES

- Lake effect rain showers become widespread this evening and transition to snow overnight.

- An extended period of lake effect snow is expected for tonight into Saturday. The most impactful periods look to be during the overnight and early morning hours, especially Thursday night into Friday.

- A Winter Weather Advisory goes into effect tonight for Baraga and Marquette Counties. Snowfall of 4-8" is expected for the tonight through Friday period over the higher terrain of Marquette and Alger counties with 1-3" elsewhere. There is a 40% chance for snowfall exceeding 12" west of Marquette CR510, 10+ miles north of US-41 and 10+ miles southwest of Big Bay.

- Temperatures rebound to unseasonably warm (upper 40s/low 50s) early next week.

DISCUSSION

Issued at 159 PM EST Wed Nov 11 2026

Early afternoon RAP analysis shows surface low pressure around 1010mb skirting south of the Great Lakes while 1028 mb is over northern Manitoba. Aloft, the 500 mb pattern consists of a strong ridge over the US Rockies to Canadian High Plains and a deep closed low over Quebec with a well-defined shortwave embedded over northern Ontario. This shortwave is going to pivot through the UP and Upper Great Lakes region over the next day, bringing a cold front and significant cold advection aloft for the region. With Lake Superior still at around 8 to 10 C and 850mb temperatures falling to -6 to -9 C by midnight tonight, lake effect rain and eventually snow will form. A Winter Weather Advisory will go into effect overnight tonight as the high terrain of Baraga and Marquette Counties is still expected to see 4"-8" of snow throughout the next 2-3 days.

The greatest impact period starts overnight tonight as in addition to the aforementioned cooling temperatures aloft causing lake effect precip, surface temperatures will also fall sub-freezing. The main challenges with this forecast are temperatures, snow ratios, precip intensity (QPF) and the resulting accumulations when combining the QPF and snow ratios. While the current forecast of 4-8" above 1000' elevation (or about 400-600 ft above Lake Superior and higher) is still on the lower end of traditional criteria for a 48 hour span, the wet/slushy nature of the snow (at least initially) and expected occasional moderate-to-heavy rates (0.5-1.0+"/hr) support the first advisory of the 2026-27 winter season. Near the Lake Superior shoreline, warm flow onshore from an above-freezing Lake Superior will result in generally less than an inch of accumulation (including the city of Marquette). The best chance to see any accumulations there would be Thursday night when the 850mb temps fall to near -9C (REFS mean). Impacts to the area roads will be greatest during the overnight hours tonight and Thursday night, though periods of heavier snow during the daylight hours will still be impactful.

For temperatures, the NBM continues to forecast much too cold for overnight temperatures as its bias-correction has been trained on recent stretches of cool, clear nights. This results in it having temperatures falling into the mid 20s over the interior and even below freezing at the immediate lakeshore tonight and Thursday night. This seems to be an unlikely scenario given the strong onshore flow from a warm lake, cloud cover, precipitation processes releasing latent heat, and only marginally cold 850mb temps of -6 to -10C. Overall thinking is that temperatures will remain above freezing overnight near the Lake Superior shoreline and much of the eastern U.P. tonight with slightly cooler temperatures Thursday night falling to right around freezing.

SLRs also look quite a bit overdone in the NBM with 16:1 by Friday including over the Great Lakes. This again would be an unlikely scenario given the warmer low levels and warm ground temperatures (mid 40s) ongoing. Similar thermal profiles to last week's high terrain lake effect snowfall yielded between 5:1 and 7:1 SLR. These values seem reasonable for tonight into Thursday, then approaching 10:1 Thursday night as cooling continues. A locally developed temperature-to-SLR curve matches up well with this for areas away from the lake with very low SLRs. Have bumped up SLRs some as REFS soundings interior from the Great Lakes do show inversion heights to around 8kft and saturation into the lower end of the DGZ, which would support periods of above 10:1 SLRs (without the above context of warmer temperatures, etc).

While confidence is high in achieving a low end advisory scenario, confidence is low with regards to higher end scenarios. While the coarse resolution models (LREF members) are producing a mean QPF of around one third to two thirds of an inch, the hi-res models such as the REFS members are much more aggressive with a mean QPF over the high terrain of Marquette and Baraga counties of over an inch. The 75th percentile of the REFS (a "reasonable high-end solution") paints a bullseye of nearly 1.75" in the high terrain at the Baraga/Marquette County line. Even with lower end SLRs, this would yield warning criteria snowfall of 12-16" or more. REFS probabilities for 12"+ over the advisory period are in the 30-40% range for the highest terrain (well away from any US/MI highways in the McCormick Wilderness area). The area of strongest convergence will determine if these high-end scenarios are able to be realized. If convergent bands can reside over the same location for much of the next couple days, higher snow totals would be realized, but if those bands waver and wobble, the snow would be spread out over a wider area. As the global 500mb map still has notable spread in how the shortwaves aloft pivoting around the eastern North America closed low will look even by late Friday, confidence is low in the placement and residence time of these bands, so will continue to monitor trends. Current probabilities for moderate snowfall rates (0.5-1.0"/hr) are around 80% with a 30% chance for heavy snowfall rates (1"+/hr).

LES should diminish Saturday, confined mainly to northern Marquette County and Alger County during the morning hours with a few lingering rain/snow showers into the afternoon, though as is typical with LES events, wouldn't be surprised if LE showers linger longer than guidance suggests. As ridging aloft moves over the Plains, high pressure will keep Sunday through Tuesday mostly dry with temperatures warming into the 40s and eventually back into the upper 40s to lower 50s.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 615 PM EST Wed Nov 11 2026

Expect generally MVFR to occasionally IFR conditions over the terminals tonight through Thursday as rain transitions to lake effect snow showers this evening over the north wind snow belts. Could see some vis and cig drops to LIFR conditions in the heaviest snow bands (up to 20% chance); the greatest snowfall rates are looking to occur over SAW tonight into Thursday given the help of upslope flow and localized convergence of the winds, although its also possible for a few hours at CMX too given some Lake Nipigon help. Expect gusty N'rly winds throughout the period, and VFR conditions from time to time are possible (10-40% throughout the next 24 hours for each hour); however, don't expect VFR conditions to last long if they occur due to the lake effect snowfall.

MARINE

Issued at 159 PM EST Wed Nov 11 2026

A cold front has brought a wind shift to the north and gusty winds to around 25 knots. A few gale force gusts tonight cannot be ruled out (isolated pockets of 20-40% probabilities), but confidence and duration are too low for any Gale Warning. Additional minor disturbances aloft will keep gusty (but sub-gale) winds in the eastern half of Lake Superior through Friday evening. This will drive waves of up to 5 ft on Lake Michigan and 4-8 ft on Lake Superior by Thursday morning (highest in the nearshore waters from Au Train Bay to Big Bay). Waves fall below 4 ft Friday afternoon for all except the east half of Lake Superior, with waves falling below 4 ft in the east Saturday afternoon. High pressure will keep winds mostly below 20 kt and waves mostly 2 ft or less through the first half of next week.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory from 10 PM this evening to noon EST Friday for MIZ004-005.

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