Marine Weather and Tide Forecast for Harbor Springs, MI

DISCUSSION
Issued at 111 PM EDT Mon Oct 12 2026

Pattern Synopsis/Forecast:

Yet another warm day across most of northern lower Michigan...
driving by southwest winds out ahead of a slow south moving cold front currently cutting across the tip of the mitt. Even despite quite a few clouds this morning, seeing widespread readings in the 60s and 70s for most south of the big bridge. Post-frontal east winds, thicker clouds, and even a few light showers are keeping eastern upper considerably cooler...with most areas up that way in the 50s.

Straits cold front will be temporarily halted on its journey south tonight as weak wave of low pressure rides east along it. More rapid southern movement of that cold front expected Tuesday afternoon as that low exits stage right. More northern stream influences the second half of this week into the weekend will return our temperatures to much more normal levels for the middle of October.

Primary Forecast Concerns:

Shower and thunderstorm evolution tonight/Tuesday, followed by temperature trends and addressing any additional shower potential for the rest of the period.

Details:

As mentioned, front will essentially stall across northern Michigan tonight into Tuesday morning as weak shortwave trough and attendant just as weak surface low ride east along it. Strongest surge of isentropic upglide/Fgen response and upper jet support looks to align across the tip of the mitt into eastern upper later tonight into early Tuesday. Expect showers to be more organized and widespread in that area, with showers more scattered the further south one goes. Enough elevated instability to promote some embedded thunderstorms as well, but definitely not expecting anything too intense (maybe some small hail under the most intense updrafts?). In general, looking at quarter to half inch rain totals for those northern areas...likely less to the south. Locally heavier totals up to and perhaps over an inch are possible, especially in areas that see some repeated thunderstorms. Welcome rains indeed, especially for those across eastern upper Michigan. Still very mild tonight, with perhaps some areas down near M-55 not getting out of the 60s (warmer than normal high temperatures). That stalling front will let southern areas warm up quite significantly again on Tuesday, with current thermal progs supporting temperatures again topping 70...especially south of M-72. Considerably cooler further north, with much of eastern upper likely stuck in the 50s.

Reality sets in a bit heading into later Tuesday and Wednesday as the front gets a boot south with passage of that surface low. While this will end the rain threat, northwest winds will continue to usher in cooler conditions, with highs by Wednesday much closer to were they should be in the 50s and 60s.

Guidance has come in much better agreement sending a rather sharp northern stream shortwave trough crossing the area Thursday night into Friday. Now, with that said, this wave is slated to exit much faster and does not look nearly as robust as some guidance was suggesting just yesterday. Forcing is rather impressive however, supporting good chances for showers by Thursday night, with quick hitting shot of some impressive cold air advection supporting lake showers on Friday. That cold air will support highs only topping out in the lower to middle 50s Friday.

Current trends support a mostly dry weekend and beginning of next week as large area of high pressure builds into and through the region. Still chilly on Saturday, with again highs mostly in the lower to middle 50s. Temperatures look to moderate Sunday and Monday in developing return flow, with current progs supporting highs back up into the 60s by Monday.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
Issued at 104 PM EDT Mon Oct 12 2026

LIFR at CIU, MVFR at PLN through the afternoon... VFR elsewhere.
Cold front moving through the region tonight into Tuesday.
Showers and thunderstorms seem a fair bet at CIU and PLN, with decreasing chances the farther south one goes. Rapidly changing conditions possible at TAF sites, including drops in visibility and wind shifts. CIGs to trend MVFR to IFR across the rest of the region, holding LIFR at CIU, perhaps leaking into PLN and APN later tonight. Showers to decrease in frequency through Tuesday morning, with flight category improvements eventually to follow just beyond the conclusion of the forecast period.

SW winds at TVC and mbL thru evening, more N and E winds at APN, PLN, and CIU. Varying wind directions anticipated later tonight into Tuesday morning as surface low pressure moves overhead... with a sharp turn NW with gusts 15-20kts anticipated late Tuesday morning into the afternoon.

APX WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory from 8 PM this evening to 8 AM EDT Tuesday for LHZ345>347.
Small Craft Advisory from 8 PM this evening to 8 AM EDT Tuesday for LMZ341-342.