textproduct: Marquette

KEY MESSAGES

- Highs in the upper 60s to mid-70s continue today and Tuesday.

- A few shortwave lows tracking through the Central CONUS could bring rain chances back into the U.P. late Tuesday into Thursday, followed by cooler and more seasonable temperatures.

- Marginal (~35 knot) west-northwest gales are possible (30-50% chance) along the southern Lake Superior shoreline from the Keweenaw to Whitefish Point on Thursday.

DISCUSSION

Issued at 125 PM EDT Mon Sep 28 2026

As high pressure ridging leaves the Upper Great Lakes this afternoon through tonight, expect mostly sunny skies across the area to allow highs to reach into the mid-70s across much of the area once again, allowing for pleasant early-Fall weather to complement the gorgeous Fall colors across the Yoop. Heading into the overnight hours, expect the mostly clear skies to continue, allowing the temperatures to tank down to the dewpoint once again and creating areas of fog; could see the need for a Dense Fog Advisory for portions of the interior U.P. tonight into Tuesday morning given that visibilities could become a quarter mile or less, but confidence on the timing of the fog and where it will be dense (quarter mile or less vis) at is too low at this point in time to issue Special Weather Statements or Dense Fog Advisories. Nevertheless, the greatest chances for dense fog do look to be in the east half tonight as some upper-level cloud cover begins to move into the western U.P. by the early morning hours; expect lows around 50 in the west to the 40s and potentially even mid-30s over the interior east tonight.

Attention then turns to troughing over the central CONUS on Tuesday that develops split flow, with one low moving through Canada towards Hudson Bay while another forms in the Southern Plains before lifting and dissipating northeastward towards the Mid-Atlantic/New England through the mid to late-week period. With this in mind, a preceding shortwave low lifts from the Northern Plains towards Hudson Bay on Tuesday, bringing upper-level cloud cover across the area. Nevertheless, expect another pleasantly warm Fall day on Tuesday, with the U.P. perhaps being set up with some light rain showers late Tuesday into Wednesday as the shortwave passes along the periphery of our area. While the 850mb LLJ increases up to 35 to 45 kts aloft Tuesday afternoon and evening with the passage of the shortwave low, no severe weather or even breezy conditions are expected as there will be very little to no instability to work with aloft and capping is expected just above the sfc due to subtle WAA creating a stable atmospheric profile in the lower levels. While the low that develops over the Southern Plains and lifts towards the Mid-Atlantic/New England could bring additional light rain showers to the area Wednesday into Thursday, more medium range guidance does suggest a more southerly track to the precipitation chances, with now only the south central and east perhaps seeing synoptic rainfall, if even that. That being said, once the cold sector moves through, expect winds to pick up from the west to northwest across the area late Wednesday night and Thursday; while the temperature advection and height rises do weaken with time on Thursday, we could see wind gusts of 30 to potentially even 40 mph along the Lake Superior shoreline on Thursday. In addition, the delta-Ts and winds over Lake Superior may be enough to kick-off some quick-hitting lake/upslope- induced light rain/drizzle showers over the northwest wind belts before ending by Thursday evening. Overall, rain totals continue to decrease with this event, with expected amounts now around a tenth to quarter inch for most of the west and north central. While the south central and east could see around half an inch of rainfall or more, only the area near Menominee now looks to receive an inch or more of rainfall, with the NBM now only showing up to a 50% chance of that happening.

Moving into the rest of the week into this upcoming weekend, expect more normal Fall temperatures as highs are projected to only rise up into the lower 60s during the afternoon hours from Thursday onward. With high pressure redeveloping over the Northern Plains for the latter portion of the week behind the troughing and potential rainfall, expect fairly pleasant Fall weather to continue until rain chances potentially return with a Clipper low this weekend. Given the fairly clear skies expected with the ridging moving through late this week, we may see some widespread frost develop over the interior areas Thursday and Friday nights; keep an eye on the forecast to see the latest updates.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 125 PM EDT Mon Sep 28 2026

VFR conditions with light winds are expected to continue through this evening. High-based cloud cover is expected to move into the area tonight, beginning with KIWD and progressing eastward overnight. Winds overnight will be light, shifting to southerly, and will pick up speed again around sunrise. Fog is possible for KCMX and KSAW after 03z, however there is uncertainty surrounding the extent of the densest fog. KCMX has a 25% chance of seeing MVFR conditions. KSAW has a better chance of reaching MVFR conditions (around 50%), with a lower chance (around 15%) of seeing IFR conditions. Given the lower chances for visibility impacts, KCMX remains at P6SM in the TAF, while KSAW visibilities have been dropped to 5SM with BR from 03z to 13z Tuesday.

MARINE

Issued at 125 PM EDT Mon Sep 28 2026

Lake Superior: Light winds of 20 kts or less continue the rest of this afternoon through tonight as high pressure ridging retreats to the east and troughing builds in from the Northern Plains. With a shortwave skirting our area to the northwest Tuesday and Tuesday night, expect southerly winds to increase to 20 to 25 kts over the lake, with gusts up to 30 kts being possible over the eastern open lake late in the day as a LLJ moves into the area. The winds do generally slacken to 20 kts or less by Wednesday behind the shortwave, but the eastern open lake may hang on to southerly 20 to 25 kt winds until Wednesday evening. As CAA moves into the area early Thursday through the rest of the day, expect winds to pickup from the west-northwest to 20 to 30 kts across the lake, with gales up to 35 kts possible along the southern shoreline from the Keweenaw to Whitefish Point (the current NBM has gales at ~35 kts or higher at 30 to 50% along the aforementioned area for Thursday). As ridging builds back in late this week, expect the winds to die down to 20 kts or less again by Thursday night/Friday morning and to remain that way through Saturday.

Northern Green Bay and northwestern Lake Michigan: Light winds of 15 kts or less hold the rest of today through tonight as high pressure ridging retreats to the east while troughing approaches from the west. Expect winds to pick up from the south and southwest to 15 to 20 kts by Tuesday as a shortwave passes by the area from the Northern Plains to Hudson Bay. The winds may increase to 20 to 30 kts by early Wednesday as a low over the Southern Plains dissipates and heads towards the Mid-Atlantic/New England. However, once it passes expect the winds to have a quick reprieve down to 15 kts or less Wednesday night/Thursday morning before picking back up to 15 to 20 kts from the northwest on Thursday via CAA. Expect the winds to slacken to 15 kts or less again by Thursday night and to remain light the rest of this week as ridging returns to the area.

MQT WATCHES/WARNINGS/ADVISORIES

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