textproduct: Marquette

KEY MESSAGES

- Warmer temperatures will result in daytime snow melt, which may refreeze overnight. This may result in ice or black ice and isolated hazardous roadways during the morning commutes today and Thursday morning.

- Northwest winds near 40 mph are possible near Lake Superior and in the Keweenaw Wednesday (~50% chance).

- A Gale Warning is in effect for much of Lake Superior late tonight through Wednesday for northwest 34-40 knot winds.

- Lake effect rain and snow showers are expected into Thursday with little to no impacts.

- A gradual warm up to above normal temperatures is expected by this weekend.

DISCUSSION

Issued at 155 AM EST Wed Nov 12 2025

Shortwave has been noted diving southeast along the northeastern lakeshores of Lake Superior on GOES Water Vapor imagery atop a surface trough/cold front that's extending south across Upper Michigan. Synoptic precip was largely limited mainly to Ontario or Lake Superior in Canadian waters from east of Keweenaw Point to near the Soo. Behind the front, lake effect showers have been noted on KMQT radar pressing into Alger and Luce counties and west of Marquette in the Michigamme Highlands. Webcams also show precip across the higher terrain of the Keweenaw and Gogebic Range. Some snow appears to be mixing into the lake effect rain showers, but accumulations haven't amounted to much given the mild surface and road temperatures being observed across the region. As the night progresses we could cool into the low 30s to upper 20s. Given the cloud cover though and temperature trends so far, this may be difficult to come by. Should this occur, yesterday's snow melt could refreeze on roadways, resulting in black ice for this morning's commute.

Across CONUS, mid-upper level ridging is observed stretching north across the western third with troughing across the eastern third. This places our forecast area in northwest flow aloft and at the mercy of any weak or low amplitude shortwaves caught in the flow. The first is the current shortwave migrating through the Upper Great Lakes. The second and weaker impulse comes late tonight into early Thursday morning with a similar track. With 850mb temps expected generally near -6C in this period, lake effect showers are expected to persist downwind of Lake Superior until surface ridging builds into the region from west to east tonight and Thursday. Shower activity will be confined mainly in the traditional northwest wind snowbelts today but will diminish across the west given an increased dry near surface layer and influence on the building ridge. Scattered shower activity should continue in the east through at least Thursday morning or early afternoon. Ptype during daytime hours will be rain or a mix of rain/snow but cooler temps overnight should allow snow showers to be more common. The lack of significant moisture though will make accumulations and impacts hard to come by.

With the punch of cold air advection bringing 850mb temps to near - 6C occuring this morning and coinciding with pressure rises and daytime mixing, breezy northwest winds should be expected today. 20- 30 mph gusts will be widespread, with gusts approaching 40 mph being common in the Keweenaw and near Lake Superior. Recent EC ensemble mean winds are pinged above 40kts by this afternoon, but model soundings and raw output from all other guidance packages aren't as aggressive. NBM probabilities for >40mph winds also only peak near 50%. Given this lack of consistency, opted not to issue a Wind Advisory, but will be worth monitoring through the day.

Ridging will keep the region dry Friday as a deepening low pressure migrates through northern Manitoba. The past 24 hours has provided a slightly better sense of when this system's cold front will swing through the region; between the EC/Canada/GFS deterministic packages, the front moves west to east through the region Saturday, with precip potential being maximized across the east half by afternoon given left exit region dynamics from an amplifying jetstreak at 300mb to the south. Strong cold air advection, potentially on the order of 20C in 24 hours, will make for breezy northwest winds Saturday night and Sunday while lake effect rain and snow showers press downwind into the traditional northwest wind snowbelt regions. High pressure will slowly build into the Great Lakes afterwards, but there's differing opinions on when it will be enough to end the lake effect. At this point, guidance suggests shower activity could linger into Monday or Tuesday.

The warming trend continues into this weekend. Expect each day Thursday through Saturday to be just a little warmer then the day prior, with highs peaking Saturday in the upper 40s to 50s. Overnight temperatures fall to or below freezing tonight and Thursday night, which may result in isolated pockets of hazardous driving for their follow on morning commutes due to black ice formation. Friday night, temperatures may remain above freezing for most of the forecast area (40-80% Friday night east to west per latest NBM run).

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1224 PM EST Wed Nov 12 2025

VFR conditions favored through the TAF period. Could be a few lake effect cumulus around 2.5-3kft for the early part of the afternoon. However, increased mixing and drier air will keep ceilings VFR. IWD is already seeing clear skies, with conditions at CMX and SAW clearing out tonight. The main impact to aviation interests will be gusty west to northwest winds. Gusts through the afternoon will reach 20-25 knots at SAW and IWD and 35 knots at CMX. This will result in a significant crosswind this afternoon for SAW. Winds diminish to around 10 knots tonight into Thursday, predominantly from the west.

MARINE

Issued at 155 AM EST Wed Nov 12 2025

Westerly and northwesterly flow have been observed on Lake Superior behind a front trough that moved through the region earlier. Cold air aloft has been filtering in while a tighter pressure gradient is in place. This is supporting winds of 25-35kts on the lake and by the lakeshores so far. Additional colder air will filter into the region this morning, which will help support more widespread gale potential in the waters surrounding the Keweenaw and eastern Lake Superior. Winds should mostly stay below 40 knots given the pressure rises accompanying the colder air isn't that strong. No changes were made to the inherited Gale Warning for central and eastern Lake Superior. In the western lake north and west of the Apostles, near 30kt winds should be expected, especially in the waters along the Arrowhead where downsloping/drainage winds may provide for localized gale force winds extending into the open lake. Winds will slowly lighten from west to east tonight, but gale force gusts should persist near and east of the Keweenaw at least into Thursday morning. By Thursday late evening, winds below 20kts are expected lake-wide.

Friday afternoon, another system will begin migrating eastward through Manitoba. Tighter pressure gradient and a low level jet ahead of the system's cold front will move over the region, which will help support increasing southerly flow through the frontal passage on Saturday. The strength of the 925mb LLJ differs among the various guidance packages, so its unclear how widespread gale potential will be Friday night across the north-central. By Saturday morning though, the airmass at 850mb is expected to be warmer than the lake surface, so any stronger elevated winds will be difficult to mix to the surface. Latest guidance suggests the cold front will swing through by Saturday afternoon, followed by a period of strong cold air advection (potentially 20C temperature drop at 850mb in 24 hours). At the same time, a stronger gradient is expected over the lake. While the degree of cold air advection and wind speeds are still a question, confidence in another gale event late Saturday into Sunday night is increasing. Latest GEFS and EC ensemble runs suggest 30-70% chance for gales while the NBM peaks near 50% east of the Keweenaw.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning until 7 PM EST /6 PM CST/ this evening for LSZ241- 242-263.

Gale Warning until 1 AM EST Thursday for LSZ243>251-264>267.

Lake Michigan... None.