Marine Weather and Tide Forecast for Fennville, MI

DISCUSSION
Issued at 142 PM EDT Sun May 17 2026

- Severe threat with possible tornadoes remains through mid evening

All of the ingredients remain in place for a possible severe event late this afternoon and evening for our area north of I-96. As mentioned earlier, we are concerned with an MCV over Wisconsin that looks to interact with a warm front that is draped over the heart of the forecast area. As of 17z/1 pm EDT, the front extended from near the Muskegon/Oceana county border, to Newaygo and Mecosta counties, to just south of Alma.

The MCV over Wisconsin is already producing severe weather with Severe Thunderstorm Warnings and Tornado Warning there.
Extrapolating this line of storms has it hitting Oceana and Mason Counties near Little and Big Sable Points around 4 pm. This trajectory looks very favorable for interacting with the front. The MCV will help to bump the Effective Deep Layer Shear values up to around 50 knots, right near the front where plenty of low level shear is present.

The threat looks to be through about 00-01z/8-9 PM EDT before the MCV moves out. This is likely to give the area a lull in the shower/storm activity for much of tonight.

- Periodic showers/storms possibly strong to severe through Tuesday

The sequence of events is a bit uncertain then for Monday through Tuesday as multiple rounds of storms will be associated with the main sfc front and waves along it. What we do know is that we should be in the warm sector from Monday through at least early Tuesday. We could see the leftovers of a line of storms come in from our WSW very late tonight and Monday. This then would potentially affect additional development of convection, or subdue it with other convection that would try to form. We are thinking that the main threats Monday would be wind and hail. We do not have good low level shear present on Monday to support any tornado threat.

One signal we do have for a better bet of convection will be late Monday night into Tuesday. This would the development of convection to our WSW, and try to bring it in here Tuesday morning. Then, depending on that convection, we will have the potential for frontal convection Tuesday afternoon and evening. The evolution of that will depend on how much early morning convection would affect the area, and limit destabilization ahead of the front. The air mass ahead of the front could be favorable for severe with sufficient destabilization, and 40-50 knots of deep layer shear. Low level shear is also favorable with a 45 knot low level jet core over the area.

- Much quieter and seasonable mid-late week

All of the rain should be out of the area by midnight Tuesday night/Wednesday morning. High pressure will build in at the sfc. We see a couple of short waves try to clip the area, but they look like they will stay just far enough north to not affect the area. The sfc ridge will funnel dry air in from the NE through Friday. A weak short wave approaches on Saturday, but it will not have much of any moisture to work with. There could be maybe a weak shower on Saturday, but for the most part the area should stay dry. Highs will start out in the 50s on Wednesday, and warm to the 70s by Fri/Sat.
with return flow starting to develop.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
Issued at 747 PM EDT Sun May 17 2026

Overall VFR conditions will dominate the pattern for most of the TAF sites over the next 24 hours. However there are several aviation threats through that timeframe. Any storms that have occurred in Michigan have been well north of any of our TAF sites.
A weak line out ahead of the incoming system could bring some weak showers/storms between 08Z to 13Z. This could affect MKG and possible GRR. However, those will weaken as they come on shore so have them covered with a Prob30.

The next concern remains LLWS. A frontal pattern will move in overnight bringing a strong LLJ that will affect all TAF sites.
Winds will remain gusty upwards of 25 to 35 kts at the surface for most, if not all, TAF sites overnight. However the LLJ is expected to be around 240 at 45Kts. The LLWS is expected between 05Z and 13Z.
Winds will then mix out with gusts at the surface upwards of 35 kts.

Another round of convection will be possible tomorrow afternoon.
The latest models have the front stalled. The line is moving northward so there is a strong signal for widespread storms to affect the TAF sites after 18Z. Given timing questions have PROB30 groups to account for the storms.
IFR cigs and vsbys are possible in storms, especially since some of those storms could be strong to severe.

MARINE
Issued at 142 PM EDT Sun May 17 2026

We are going to expand the current Small Craft Advisory further south to our border with IWX at St. Joseph. Plan views of winds indicate that the strongest and most consistent winds will remain north of Holland. However, there is enough wind on and off south of Holland to necessitate the SCA down there. Right now we have it going through Monday evening at 8 pm, but it will likely need to be extended at some point through the Tuesday frontal passage.

Once the winds come down after the frontal passage on Tuesday afternoon, headlines will likely not be needed for the rest of the week.

GRR WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory from 11 PM this evening to 8 PM EDT Monday for LMZ846>849.