Marine Weather and Tide Forecast for Grand Haven, MI

UPDATE
Issued at 905 PM EDT Sun Apr 20 2025

Earlier batch of showers which passed north of a Kalamazoo to St Johns line has exited and only isolated showers remain at this time. Pops ramp up again overnight into early Monday as the remnants of the squall line currently in wrn IL passes through.
Intensity of that line will decrease by the time it gets here but numerous to widespread showers and a few tstms should survive as negatively tilted upper trough and sfc occlusion swing through the region.

DISCUSSION
Issued at 254 PM EDT Sun Apr 20 2025

- Several opportunities for showers/storms

Low pressure over southeast Kansas will continue to move north to Wisconsin by Monday morning. Regional radar shows showers and isolated thunderstorms moving across northern IL attm. CAMs show isolated showers moving over the western cwa late this afternoon becoming more numerous tonight, along with scattered storms; a decent short wave accompanies the warm front moving north. Instability isn't all that great though...a couple of hundred joules, but probably enough to generate a few storms; severe storms are not expected.

Rain chances will decrease Monday behind the front as the low moves northeast toward Quebec.

Rain chances briefly increase again Tuesday night into Wednesday as the next warm front moves across the cwa.

Quasi zonal flow develops mid week with rising heights, which means warmer temperatures, but also a parade of minor short waves.

Chances of showers/storms will increase again Thursday night and Friday as low pressure develops over the Missouri Valley and moves toward Wisconsin. Showers/storms near the warm front and again with the cold front will create an unsettled end of the week.

- End of week warmup

As the upper heights rise toward the latter half of the week, temperatures will climb through the 60s Wednesday and into the 70s Thursday and Friday. The cool off behind the cold front Friday will only drop highs into the 60s Saturday and Sunday.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
Issued at 814 PM EDT Sun Apr 20 2025

Increasing challenges for aviation later tonight after 04Z with LLWS, showers with temporary reductions in visibility, and a chance of thunderstorms. MVFR ceilings arrive with a cold front between 11-13 Z, with southeast winds shifting southwest. MVFR ceilings should stick around much of the day, along with gusts 30-35 knots.

MARINE
Issued at 254 PM EDT Sun Apr 20 2025

We've added a small craft advisory for this evening through Monday night and a gale warning Monday. As the low moves north tonight, the pressure gradient will tighten and winds will increase. If the water temperature was warmer, we'd probably have gone with a gale warning tonight. However, due to the cold water temperatures, a substantial inversion will exist tonight and the stronger winds will likely ride over the top of the inversion.

As the cold front plows into the region Monday, those stronger winds will have an easier time mixing to the surface and a gale warning is needed.

GRR WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT Monday for LMZ844>849.
Gale Warning from 8 AM to 8 PM EDT Monday for LMZ844>849.