Marine Weather and Tide Forecast for Harrisville, MI

DISCUSSION
Issued at 254 AM EDT Sun Oct 11 2026

Pattern Synopsis:

Low-amplitude midlevel ridging continues to remain settled over the northwoods with closed midlevel low pressure over the Mississippi/Ohio Valley today tied to the remnants of Isaias. This ridging will support enough subsidence aloft to keep conditions dry for our CWA through Monday while low-level warm air advection keeps our temperatures well above normal for early October. At the same time, a disheveled wave develops surface low pressure lee of the Canadian Rockies and pushes moisture toward the Great Lakes Region late Monday night. Subsequent rainfall will slowly progress across Northern Michigan through Tuesday with most areas likely observing QPF amounts of a quarter inch or less.

Surface high pressure builds on the backside of Tuesday's frontal boundary with a northerly cP air mass influence. Temperatures return to normal for the remainder of the forecast period with highs in the 50s for most areas accompanied by surface high pressure centered over Ontario/Manitoba. Only chance of rainfall beyond the midweek remains around the Friday timeframe as long range ensembles depict a weak clipper system digging across the Great Lakes Region, but impacts associated with rainfall amounts remain low at this time.

Forecast Details:

Today and Monday: Beautiful fall conditions with summer-like temperatures continue today as aforementioned subsidence with troughing to our south supports dry weather with highs in the 70s for most areas. Some alto and cirrostratus cloud cover will build across the northern lower as the remnants of Isaias progress across the Southern Great Lakes Region. Same conditions continue for Monday with temperatures remaining slightly cooler due to the approaching weak frontal boundary to our northwest. Nevertheless, widespread highs in the 60s and 70s will persist before fall like temperatures return through the remainder of the forecast period.

Tuesday through Saturday Outlook: Well advertised rainfall will commence Monday night across eastern upper before slowly making its way across northern lower. Latest model soundings depict deeper and warmer saturated profiles attached to subtropical moisture over the American Southwest. Latest guidance keeps QPF totals around a quarter inch or less for most areas, but some localized areas could observe higher amounts in excess of a half inch as the center of low pressure crosses the Northern Lower. The rest of the week remains rather quiet as high pressure builds to our north accompanied by highs turning back to normal (50s). Low precipitation chances remain in the forecast as long-range ensembles depict a clipper developing over Alberta and digging across the Midwest around the Friday timeframe. At this time, guidance keeps most rainfall during the day, so the threat of any different p-type moving into the forecast remains low as we head into mid October.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/
Issued at 254 AM EDT Sun Oct 11 2026

VFR is expected to continue through the entirety of the TAF period.
Winds continue to subside today while remaining from the south, gusting into the low teens. Mid and high level As and Cs spread from the south across KMBL, KTVC, KAPN, and KPLN today as the remnants of Isaias progress toward the northeast. Some low IFR CIGs develop near KCIU late overnight, but confidence of it being observed at the TAF site remains low.

APX WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory until 6 AM EDT early this morning for LHZ345>349.
Small Craft Advisory until 6 AM EDT early this morning for LMZ323-341-342-344>346.
Small Craft Advisory until 6 AM EDT early this morning for LSZ321-322.