Marine Weather and Tide Forecast for Suamico, WI

DISCUSSION
Issued at 1208 PM CDT Tue Oct 13 2026

The current surface analysis shows an area of low pressure moving east over northern Lower Michigan with a cold front extending southwest into the central Plains. Surface high pressure centered over the Dakotas is building eastward, driving a cold advection regime with brisk northwest winds and widespread cloud cover across northern Wisconsin. Upstream, a deep upper-level low is positioned over Nevada while shortwave energy ejects across the Central Rockies toward the Upper Midwest. Cold advection behind the front will keep conditions mostly cloudy and seasonably cool through Wednesday.

Light Rain And Lingering Stratus Through Wednesday: As weak shortwave energy ejects from the western CONUS trough this evening, a 20 percent chance of light rain showers will traverse central and northeast Wisconsin. A pronounced mid- level dry wedge between 5,000 and 8,000 feet will rainfall intensity, keeping NBM 90th percentile QPF under 0.05 inches area- wide. Low stratus will surge southward overnight into Wednesday morning, getting trapped beneath a persistent subsidence inversion. High pressure building into the region Wednesday will maintain mostly cloudy skies with daytime high temperatures ranging from the middle 50s to middle 60s.

Widespread Rain Thursday Into Thursday Night: Attention then shifts to an amplifying northern stream shortwave and associated surface low tracking northeast across the Great Lakes Thursday into Thursday night. Strong dynamic forcing and moisture transport with precipitable water values reaching 180 percent of normal will spread widespread light to moderate rain across the region after noon Thursday. NBM probabilistic guidance reflects high confidence in widespread measurable rain, showing a 40 to 60 percent probability of 24-hour QPF exceeding 0.50 inches. Rain will transition to scattered showers Thursday night before the primary low exits eastward early Friday morning.

Strong Friday Winds And Showers: Cold advection surges across the western Great Lakes Friday morning in the wake of the departing cyclone, dropping 850mb temperatures over western Lake Superior to near -5 degrees C. Steep low-level lapse rates and a tight surface pressure gradient will yield strong, gusty northwest winds, with NBM guidance indicating a 40 to 70 percent probability of gusts exceeding 40 mph. Over the Green Bay nearshore zones, confidence is increasing for gale-force wind gusts. Strong thermal instability over the lake waters will maintain scattered rain showers through Friday afternoon before surface high pressure builds in from the west.

Widespread Friday Night Freeze And Frost Risk: Canadian surface high pressure settling directly over Wisconsin Friday night will establish a very chilly airmass across the region beneath clearing skies and decoupling winds. Overnight minimum temperatures are forecast to plummet into the middle 20s to lower 30s across inland north- central and central Wisconsin, with mid-30s near the Lake Michigan shore. NBM probabilistic guidance displays high confidence in a widespread freeze, showing a 70 to 90 percent chance of minimum temperatures dropping below 32 degrees west of the Fox Valley. Rapid diurnal warming beneath full sunshine Saturday morning will quickly burn off widespread frost, with temperatures rebounding into the upper 50s and 60s for the weekend.

AVIATION
for 18Z TAF Issuance Issued at 1208 PM CDT Tue Oct 13 2026

As low pressure exits the region to the east, widespread MVFR and IFR ceilings prevail across the region. With cold advection occurring through the taf period, some minor improvements can be expected through the middle of the afternoon. There may be sufficient mixing for KGRB/KATW/KMTW to become VFR as the cloud mass on the southern periphery breaks up somewhat. Confidence on a return to VFR at those TAF sites is medium low.

A weak upper disturbance could bring widely scattered light showers to the region this evening (20% chance). Impacts to the TAF sits appear minimal.

Ceilings are expected to lower after midnight at all TAF sites.
Widespread IFR to MVFR ceilings are the expected through the end of the TAF period.

GRB WATCHES/WARNINGS/ADVISORIES
None.