Marine Weather and Tide Forecast for Manitowoc, WI

DISCUSSION
Issued at 135 AM CDT Sat Apr 18 2026

A strong CAA regime has set up over the forecast area early this morning in the wake of a strong cold front. Temperatures across the area have fallen 20-30 degrees behind the front with most areas now in the middle 30s to 40s. Scattered shower activity is also trending down behind the front early this morning. For today cool and mostly dry conditions are expected, however, with upper level troughing linger over the area and nearly dry adiabatic low level lapse rates scattered instability showers/flurries are possible (20-40%) late this morning through the afternoon. Localized precipitation amounts of a few hundreths up to a tenth of an inch are possible, mainly across northern WI. Temperatures today will be seasonally cool with highs only reaching the upper 30s to 40s and overnight lows falling into the 20s to low 30s across the forecast area.

With lingering troughing over the area Sunday another round of instability showers/flurries will be possible (20-30% chance) mainly across central to east-central WI. Precipitation amounts should again remain generally less than a tenth of an inch across the region. The cool temperatures also stick around through the end of the weekend with highs again in the middle 30s to 40s Sunday.

Ensemble upper-level flow fields support a ridge building over the upper Great Lakes through the first half of next week bring a much needed proloned dry stretch. Temperatures are also expected to gradually warm through next week. Long range ensembles favor next Thursday into Friday for the next round of widespread showers and thunderstorms. Synoptically an upper trough is forecast to dig into the northern Plains spurring on an area of surface cyclogenesis.
along the US/Canadian border. This would place much of our forecast area in the warm sector making stronger thunderstorms possible Thursday night into Friday. NCAR AI convective hazards forecast is already painting 5-15% probs across much of WI during this time.

AVIATION
for 12Z TAF Issuance Issued at 634 AM CDT Sat Apr 18 2026

Blanket of MVFR status has developed over the region overnight. As the cold air advection continues to bring drier air into the region this morning expect status to start scattering out. This trend is already occurring upstream over northwest WI. With the linger troughing over the region scatter pop-up rain and snow showers will be possible late this morning through this afternoon across much the region, however, expect aviation impacts to be minimal.

Northwest winds will continue to be breezy today with frequent gusts of 20-25 kts and peak gusts around 30 kts.

HYDROLOGY
Issued at 135 AM CDT Sat Apr 18 2026

MRMS 24-hr QPE shows a narrow swath of 2-3" of rainfall from northwest Wood Co. to southern Langlade Co. with lesser amounts of 0.25-0.75" across the rest of the forecast area. This will likely lead to brief rises on rivers in central WI, mainly the Wisconsin River. A small area of these higher end totals did fall in the northern extend of the Wolf River basin which will slightly delay the eventual crest and recession of the major flooding that continues along the Wold River at New London and Shiocton. Additionally the Menominee river will remain in minor to major flood stage through this weekend due to recent rainfall and continued snowmelt in Upper Michigan. If you live near a river or stream, continue to monitor the latest hydro forecasts and Flood Warnings from the National Weather Service in Green Bay.

GRB WATCHES/WARNINGS/ADVISORIES
None.