textproduct: Marquette

KEY MESSAGES

- Temperatures drop back into the 60s on Thursday and cool to near seasonal normal values in the upper 50s to low 60s through the weekend. Frost and freeze concerns are likely from Thursday night onward.

- Breezy conditions are expected as winds shift out of the west- northwest Thursday and Friday. Gusts around 30mph are likely near Lake Superior from the Keweenaw east to Whitefish Point.

- Winds calm Saturday before a chance (10-30%) of gales for southeastern Lake Superior enters the forecast Sunday.

DISCUSSION

Issued at 308 PM EDT Wed Sep 30 2026

Current radar imagery indicates that this morning's precipitation has cleared out of the area. Visible satellite shows mid-level cloud cover also moving out of the U.P. as its associated system progresses eastward and is replaced with a relatively dry air mass. Cloud cover is expected to stick around this evening in the form of low-level cumulus clouds currently building in response to diurnal heating in the western U.P. as the cloud cover higher aloft leaves the area.

Tonight's low temperatures are expected to be warmer than average thanks to the cloud cover sticking around. Light southerly winds are expected across the U.P., which, combined with high RH from this morning's precipitation, could lead to the development of fog overnight. Thursday is expected to stay mostly cloudy and mainly dry. A prevailing zonal pattern is forecast across the area Thursday morning due to a combination of a 500mb longwave trough over central Canada and large-scale ridging over the SE CONUS. At the surface, a cold front associated with a low in Ontario is expected to move across the area Thursday morning, causing winds to increase and shift to northwesterly, daytime RH to drop, and skies to clear. Given the relatively warm lake surface and northwesterly winds, there is potential for a stray lake effect rain shower or two, however, any showers that reach the ground will be brief with minimal accumulation. Clear skies will result in below-average low temperatures Thursday night, resulting in a frost potential around 20-50% for the interior.

The cooling trend continues Friday, with seasonably cool highs in the upper 50s. Breezy conditions out of the northwest are expected throughout the day near the southeastern Lake Superior lakeshore, with gusts around 30mph. Lake effect showers may also return to the eastern U.P. on Friday, but will again remain spotty and light. Frost concerns return Friday night as lows reach the upper 20s to low 30s, about 8-10 degrees below average. Winds die down Friday night into Saturday as a surface high moves into the region, but are expected to return along with chances for precipitation Saturday night into Sunday as a weak clipper system progresses into southern Ontario. Precipitation totals are expected to remain low (around a 30% chance of 24-hour accumulations exceeding a tenth of an inch), however, chances for precipitation are widespread across the U.P. Sunday also brings the next best chance for gales, although a large amount of model uncertainty remains. The NBM's highest chances are around 30% off the coast of Luce County, with 15-20% in the rest of southeastern Lake Superior. The LREF is much less optimistic, with gale chances remaining out of the forecast entirely. Looking ahead to the start of next week, temperatures are expected to remain relatively cool through Tuesday.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 150 PM EDT Wed Sep 30 2026

Ceilings will continue to rise this afternoon, with VFR conditions expected for the late afternoon and evening at all terminals. Patchy fog is expected across the area tonight. IFR conditions are likely at KSAW overnight (60%) and possible at KCMX (30%), with conditions becoming VFR after sunrise. Northwesterly winds with gusts of 15 to 25 kts will develop during the day on Thursday.

MARINE

Issued at 308 PM EDT Wed Sep 30 2026

Lake Superior: Winds are currently southwesterly over the western arm of the lake at around 10kts and southerly over the eastern portion of the lake at around 5kts until a cold front progresses across the lake Thursday morning, causing winds to increase and shift to northwesterly. Wave heights will be 2-3ft across most of the lake, with the southeastern portion reaching 3-5ft heights. West- northwesterly flow around 15-20kts expands into areas west of the Keweenaw Thursday afternoon and overnight Friday. Wind speeds decrease to around 10kts for the western arm Friday, but are expected to increase to 20-30kts in the east. Friday night into Saturday, winds are expected to decrease in strength to around 10kts and shift to southerly as surface high pressure moves across the lake. Winds remain southerly Saturday night, then increase in speed and shift to west-northwesterly Sunday morning. Wind speeds could reach gale conditions in the southeast Sunday, however, there is still considerable uncertainty remaining in the forecast. If winds approaching gales remain in the forecast, wave height could reach up to 10ft in the southeast, with 4-8ft waves in the northeast and 1- 4ft waves in the western arm.

Northern Green Bay and northwestern Lake Michigan: This afternoon, expect southerly winds around 10-15kts, decreasing to 5-10kts and shifting westerly by the mid-morning Thursday. Winds remain around 10kts, but shift to northerly Thursday afternoon, with conditions remaining the same overnight. Wave heights will remain below 1ft in the bay and reach 3ft in NW Lake Michigan. Friday morning, northwesterly winds pick up to around 15kts before dropping to around 10kts Friday afternoon as a surface high moves into the area. Waves will remain between 1-2ft. Winds shift to southerly and decrease to around 5kts Friday night into Saturday morning, with calm waters expected. Saturday afternoon, southerly winds increase up to around 15kts with waves around 1-3ft. Overnight Saturday, winds shift once more to westerly and increase in speed up to around 15kts. By Sunday afternoon, winds are expected to be out of the northwest at around 15kts with waves around 2-3ft.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Beach Hazards Statement until 8 PM EDT this evening for MIZ014.

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