textproduct: Marquette

KEY MESSAGES

- A Clipper low passing through the region this weekend brings a period of light rain for most. Accumulations by Sunday morning are generally around a quarter inch for the south half and a third to a half inch for the north half.

- This Clipper will also bring gusty winds, initially out of the south tonight and then northwesterly Sunday. Chances of gales on eastern Lake Superior both ahead of and behind the Clipper are 40- 70%. The Gale Watch will be upgraded to a Gale Warning.

- Mostly dry forecast for next week. Gusty winds with a dry cold front on Tuesday may (~50% chance) exceed 30 mph.

DISCUSSION

Issued at 314 PM EDT Sat Oct 3 2026

Early afternoon GOES-East Day Cloud Phase RGB imagery shows a shallow midlevel cloud deck overspreading the UP with some glaciation over far western Lake Superior and northern Wisconsin that suggests that scattered precipitation is likely. This is supported by increased reflectivity returns from KDLH radar, though the shallow nature of these showers is evident by reflectivity returns from the KMQT radar being minimal to none. RAP analysis shows a tightening pressure gradient over the western end of Lake Superior as a 1010mb Clipper Low over the ND/MN/MB tri-point contrasts against 1028mb high pressure centered east of Georgian Bay. Disturbed weather ahead of the Clipper's cold front will arrive throughout the rest of today and overnight tonight. The mean HREF arrival of precipitation over the western UP is around 21Z, though a couple hours earlier is also reasonable as stray cells ahead of the front are showing up on radar. Rain arrives in the central UP around 00Z and in the east by 04Z tonight. By the time synoptic precip ends UP-wide around 12Z, mean HREF QPF totals are between a third and a half inch for the north half and around a quarter inch for the south half, which is a slightly wetter trend than previous runs. The precip will initially have to battle some surface dry air as current dewpoint depressions are as much as 20-25 degrees in some locations, but NAEFS vapor transport charts shows unseasonably high rates of moisture arriving in the region (top 10% of climatology), so by the time the main area of precipitation arrives tonight, the moisture present will be sufficient for that rainfall to occur.

Another aspect of the Clipper will be gusty winds. Both the strong gradient as well as significant pressure rises and falls will encourage strong wind gusts, first out of the south tonight and then out of the northwest in the Clipper's wake. In both wind direction regimes, the REFS shows chances of 30+ mph gusts near Lake Superior to be around 50% with 40-70% chances of 35 kt gales over the open waters of the lake.

Along with gusty winds, the brisk northwest flow will bring cool air aloft, with the NAM showing 850mb temperatures over eastern Lake Superior of around -3C over a lake that is between 10-14 C at the surface. The NAM resolves this with 50-150 J/kg of CAPE, enough to support some lake enhanced and lake effect precipitation in the east overnight Sunday into Monday morning, though the NBM shows precip ending later Monday morning as mid-upper 1020s mb high pressure expands across much of the central CONUS and the resulting subsidence puts an end to precip over the UP.

The 500mb pattern stagnates somewhat into next week as there is little in the way to perturb the persistent ridging over western North America and persistent troughing over eastern North America. This leaves the UP in continental northwesterly flow, keeping the forecast mostly dry, and while surface high pressure will allow for some radiational warming to above normal temperatures for Tuesday (NBM highs in the low 70s for the west), radiational cooling will also allow for temperatures to regularly fall into the 30s and sub- freezing overnight. The most impactful part of the forecast next week looks to be Tuesday, where a shortwave passing through northern Ontario will cause a Clipper Low to pass, though it will be too starved of moisture to cause precipitation. However, the mean wind gusts from the Euro ahead of the Clipper's cold front are above 30 mph, so the combination of warm, dry weather and gusty winds could cause fire weather concerns, especially as dry, fallen leaves increase the volatility of the ground fuels, although the current forecast is for RHs to remain above 40%, so the fire weather is not an immediate cause for alarm, but a forecast worth monitoring.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 742 PM EDT Sat Oct 3 2026

VFR conditions have returned to TAF sites for the time being. However, expect MVFR conditions to return by Sun 03Z followed by IFR conditions after Sun 06Z. Widespread rain showers in association with a Clipper system/cold front will continue to reduce cigs and visibilities. Meanwhile, strong southerly winds will veer to the northwest early tonight with gusts up to 25 kts at IWD and SAW and as high as 30 kts at CMX by tomorrow morning. Look for gradual improvement to VFR around mid to late morning tomorrow.

MARINE

Issued at 314 PM EDT Sat Oct 3 2026

A Clipper is forecast to pass north of Lake Superior this weekend, bringing along with it a cold front. Ahead of this front tonight will be rain showers and 40-70% chances of southerly gale force gusts in the east half of the lake and 20-40% chances for northern Lake Michigan. Wave heights build to 4-7 ft for both Lake Superior and Lake MI, with some waves north and northeast of Stannard Rock up to 8-9 ft. Sunday, winds swing to be out of the northwest, remaining at 40-70% chances of gales over the east half. Waves will remain steady until the afternoon before they pick up to 7-10 ft over eastern Lake Superior, 3-7 ft over western Lake Superior, and below 4 ft for northern Lake Michigan. Any gale force gusts will end around sunset Sunday, falling below 25 kt around sunrise Monday and falling below 20 kt Monday afternoon. Relief from gusty winds ends by midday Tuesday as a "dry Clipper" passes north of Lake Superior, bringing with it 20-30 kt gusts and a 10-20% chance of gales. The back half of next week settles into a westerly to northwesterly pattern with wind gusts around 20-25 kt.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning from 8 AM to 11 PM EDT Sunday for LSZ248-251-265- 267.

Gale Warning from 2 AM to 11 PM EDT Sunday for LSZ249-250-266.

Lake Michigan... None.