textproduct: Marquette

KEY MESSAGES

- Patchy fog is possible again tonight, mainly across the eastern UP.

- Mostly dry weather through Saturday, then chances (30-50%) for light rain return Saturday night and continue into Sunday.

- A period of cooler weather is expected early next week as colder air pushes south across the region.

DISCUSSION

Issued at 241 PM EDT Fri Oct 23 2026

Afternoon RAP analysis features midlevel ridging extending from the Great Lakes through the Southern Plains, with troughing over the Intermountain West. At the surface, high pressure is centered over the St. Lawrence Seaway, extending ridging westward into the UP, with a surface low moving into the Northern Plains. Skies have been able to clear across most of our forecast area, though Day-Cloud Phase RGB still shows some fog and low stratus near the Lake Michigan shorelines and over far western Lake Superior. Amid light southerly flow, temperatures have been able to climb well into the 60s and even low 70s over the far western UP (warmest in the southerly downsloping spots), while areas further eastward are peaking in the lower 60s. The Lake Michigan shorelines are struggling to get out of the 50s, but if we can finally see some clearing this afternoon, temperatures may be able to climb a couple more degrees.

Tonight, the western low makes its way into Manitoba, with increasing south-southwest flow aloft and strengthening warm air advection into the UP. This brings an increase in cloud cover and perhaps some spotty showers to the western UP, though little to no accumulations are expected. Temperatures under cloudy skies only fall back into the mid 50s, while to the east, under partly cloudy skies, temperatures fall back into the mid to upper 40s. Some patchy fog is not out of the question across the eastern UP, but increasing winds and cloud cover should limit the extent of dense fog compared to previous nights.

Southerly winds turn breezy Saturday, gusting to around 20-25mph for most of the area and in excess of 30mph over the higher terrain of the north-central UP and the downsloping areas near Superior. Temperatures stay elevated, peaking in the mid 60s to mid 70s over the western half of the UP and in the lower 60s over the east courtesy of flow off of Lake Michigan. Expect otherwise dry and mostly cloudy weather for the daytime hours, then chances for spotty rain showers return Saturday night as a cold front sweeps through. Rain lingers in the eastern UP into Sunday morning while the front exits eastward. Widespread totals of 0.10in or less are expected, though a few spots may be able to see slightly higher totals (20-30% chance for up to 0.15in). Winds turn westerly behind the front with cooler, near-normal temps peaking in the upper 40s to low 60s, coldest northwest and warmest south-central. Expect more breaks in the clouds into the afternoon as drier air works in, with soundings supporting a good dewpoint drop at least across the western UP. Dewpoints fall into the lower 20s and even upper teens over the interior-western UP, supporting minimum RH as low as 25-35%. Higher minimum RH in the upper 30s to mid 60s is expected in the Keweenaw and east. Winds look to remain under 15 mph at this time where RH is lowest (only a 10-30% chance for wind gusts exceeding 20 mph coupled with RH below 30%), limiting fire weather concerns. Will continue to monitor this period.

High pressure passes east over Ontario and the Great lakes Monday and Tuesday. Then flow aloft turns zonal, allowing for multiple shortwave troughs to track east next week into the following weekend. Guidance begins to struggle to resolve this pattern already by Tuesday night, but this likely sends a low pressure system just to the northwest of the Great Lakes mid to late next week. The shortwaves, low pressure system, and late week colder airmass yielding sufficient delta-Ts for lake effect precip keeps PoPs in most of the extended forecast. Otherwise, temps return near normal in the wake of the cold front on Sunday peaking in the 40s to low 50s Monday and Tuesday. Temps Monday night settle into the 20s to mid 30s, coldest interior west. Southerly flow returning for Wednesday and Thursday warm temps into the 50s with lows in the 30s and 40s.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 230 PM EDT Fri Oct 23 2026

VFR conditions have returned to all TAF sites this afternoon and will be the main flight category for the duration of the TAF period. Therefore, main impacts will be focused on winds/LLWS threat, mainly at IWD and CMX in the Sat 10-16Z time frame as a 40 kt low level jet skims western Upper Michigan. Left LLWS mention out of SAW at this time, but may need to be added with any deviations in future forecast runs. At the surface, southerly wind gusts of 25 to 30 kts will simultaneously impact IWD and CMX as well.

MARINE

Issued at 241 PM EDT Fri Oct 23 2026

Lake Superior: Winds remain light across the western arm of the lake this afternoon, currently coming in out of the east to northeast. Meanwhile, southerly winds over the eastern half of the lake continue to gust as high as 20kts, yielding waves as high as 3ft. Winds across the entirety of the lake increase out of the south tonight through Saturday morning. Widespread gusts to 20-30kts are expected, though there is a 10-30% chance of gales to 35 kts over the eastern half of the lake. Waves increase to 3-6ft across the lake, highest over the east half. Given the warm southerly flow creating stronger stability, opted to hold off on any Gale Watch for this marginal event. Winds briefly slacken Saturday night, then pick up out of the west behind a cold front Sunday; expect gusts to increase to around 15-30kts, strongest near the Keweenaw. Winds gradually decrease into Monday while veering northerly, and remain below 20kts across most of the lake Tuesday. The exception will be towards the Duluth harbor, where NE gust to around 20kts will be possible.

Northern Lake Michigan and northern Green Bay: Southerly winds remain below 20kts through tonight, but then gusts pick up to around 20-25kts by Saturday afternoon with wave heights increasing to around 3-5ft across northern Lake Michigan and 2-4ft in the bay. Winds fall back below 20kts into Sunday while shifting to the west, with wave heights falling below a foot in the bay and to around 1- 2ft over northern Lake Michigan. Light winds persist into early next week, turning northerly Monday and then easterly Tuesday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... None. Lake Michigan... Dense Fog Advisory until 4 PM EDT this afternoon for LMZ248- 250.