Marine Weather and Tide Forecast for Marquette, MI

SHORT TERM /THROUGH TONIGHT/
Issued at 322 PM EDT Fri Apr 25 2025

RAP analysis and GOES satellite imagery reveal the Upper Great Lakes placed underneath the right entrance region of a departing upper level jet streak with a weak sfc low reflected across southern lower Michigan, stretching back into the OH River Valley. This has brought soupy weather to the UP today with widespread light rain and patchy dense fog across the north-central tier. Through the rest of tonight and into Saturday morning, the aforementioned weak sfc low continues east into the Lower Lakes, briefing tightening the area pressure gradient and upticking northerly winds across the east-central. This should help to clear out locally dense fog seen around the Marquette/Alger area. Moist sfc conditions and lessening winds just before daybreak may help redevelop fog across the east half.
Meanwhile, a building ridge noses into the western UP overnight, introducing ~1030 mb high pressure which becomes solidly atop Lake Superior by tomorrow morning. With it, a much drier airmass will clear out skies and make way for a pleasant weekend.

LONG TERM /SATURDAY THROUGH FRIDAY/
Issued at 348 PM EDT Fri Apr 25 2025

Drier conditions move in on Saturday as high pressure pushes through the area this weekend. While warm air advection will begin Saturday, antecedent cool air and weakening northerly flow at the surface will keep temperatures a little bit on the cooler side of normal on Saturday; expect highs to only get into the lower 50s in the interior west and south central, even despite the mostly sunny skies by the afternoon hours. Remnant lake effect cloud cover over the north central and east, in addition to the northerly flow, is expected to keep highs in the 40s along Lake Superior in the north central and in most of the east. We could see RHs dip down to 30% in the afternoon over the interior west. However, given the recent rainfall and snowmelt, cool-ish temperatures, and light winds, fire weather concerns are limited at this time over there. Going into Saturday night, expect some high-level clouds to begin advecting into the area as a low pressure begins to develop over the Northern Plains. However, even with weak warm air advection continuing over the area, with the mostly clear skies overhead, expect the temperatures to tank, particularly over the interior east where winds are expected to be lightest; we could see lows easily get into the upper to mid 20s in the interior east. As for the west, increasing southerly winds late look to keep temperatures warmer; in the downslopes near Lake Superior along Gogebic and Ontonagon counties, we could see low temperatures struggle to even get into the upper 30s due to the warming created by the downslope winds.

Moving into Sunday, cloud cover moves over the rest of the area, with rain showers potentially beginning over the western U.P. late in the day. While we could see RHs drop down into the lower 30 percents again in the interior east, given the cloud cover overhead, expect conditions at the surface to be a little more moist on Sunday in comparison to Sunday for most of the area. As the low over the Northern Plains lifts into northern Minnesota, model guidance continues to have good convergence on the mid-level trough evolution. In addition, the most recent GFS seems to be much more in- line with the Euro in regards to the surface low, bringing it now through western Lake Superior Monday evening. In response to the more northerly track of the surface low, ensemble guidance has responded by increasing the risk of severe weather across our area late Monday into Tuesday morning as the warm sector of the low is projected to move through the area. With MUCAPE increasing to 1 to 2 thousand J/kg, 0-6 km bulk shear around 30 to 50 knots (fueled by a jet streak bringing PWATs above 1" into the area), we could see severe hail move through the U.P. Monday evening and overnight.
While the severe threat will be lessened during the overnight hours, given that we will be in the warm sector ahead of the low's cold front Monday night, some embedded energy aloft and strong shearing could very well allow strong to severe thunderstorms to continue across the region until the cold front moves through Tuesday morning. With cloud cover remaining over us throughout the day Monday via the warm front moving over us, no surface-based CAPE is projected; thus, tornadoes are not expected for our area. However, with convection being elevated in nature and strong shear keeping mesocyclones going, we could see severe hail across our area , with severe thunderstorm winds being a possibility too (albeit with a lower possibility of occurrence); currently, the SPC shows the U.P under a 15% chance for severe weather late Monday through Monday night. With showers and storms continuing over the area Monday into Tuesday morning, some training of convection may occur. Taking this into account, and ensemble guidance showing PWATs increasing up to around the 95th percentile modeled climatology, there is a non-zero chance that we could see some flash flooding across the area late Monday into Tuesday morning, particularly over the western U.P.
where guidance is highlighting higher QPF returns (WPC also shows a 5% chance for flash flooding for late Monday over the western U.P.).
As the cold front of the low pushes through on Tuesday morning, expect a progressive end to the rainfall from the northwest to southeast. We could see a quick transition over to some snowfall at the end, but with temperatures still being above freezing, nothing should stick. We could see some more river rises in response to the rainfall into the middle of next week though, particularly if this is a soaking rainfall event.

The active weather pattern continues into the latter half of next week, with drier weather on Wednesday being replaced by more rainfall over the area sometime late next week. Expect the temperatures to be fairly seasonable from Wednesday onwards.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 1219 AM EDT Sat Apr 26 2025

High pressure will gradually build into the region tonight, resulting in all sites trending toward VFR conditions. MVFR ceilings will still be possible early in the period tonight at KCMX and through the night at KSAW. Additionally, MVFR visibilities will also be possible at KSAW. Winds will be mainly northerly, with gusts to 20kts possible Saturday at KSAW.

MARINE
Issued at 400 PM EDT Fri Apr 25 2025

Light winds of around 20 knots or less this afternoon increase to northerly winds of 20 to 25 knots tonight over the eastern half of the lake as a shot of cold air advection moves through the area.
Winds weaken back down to 20 knots or less again by Saturday as high pressure moves through the lake this weekend. The winds remain light until a low lifting from the Northern Plains approaches on Monday.
As it does so, some thunderstorms could move into the western lake Monday afternoon, followed by the eastern half Monday evening; with the track of the surface low now going further north through western Lake Superior on Monday night, some of the storms could be strong to severe ahead of the low's passing Monday and Monday night, with severe hail being the primary threat; severe winds are a secondary threat and will be dependent on if they can make it to the surface.
If the winds can, the erratic and strong winds could make sailing dangerous underneath the thunderstorms. Ahead of the low's passage, expect winds to increase from the southeast and south to 20 to 30 knots over the eastern half of the lake Monday afternoon and evening. Behind the low's passage, expect winds to pick up from the northwest and north, potentially gusting up to gales of 35 knots over the north central and eastern lake on Tuesday. As high pressure moves back in on Wednesday, expect the winds to diminish back down to 20 knots or less again by Wednesday morning, continuing throughout the rest of the day.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.