Boisterous conditions which caused the Lake Express ferry to cancel a trip on Friday are holding on in Chicago. At 1030 Saturday Chicago had 19 knot winds from the ESE. To the north and to the west winds rapidly drop off. On the Wisconsin shore Milwaukee has 9 knots while on the Michigan shore Muskegon has only 4 knots. The southern lake weather buoy located mid lake off Milwaukee shows 11 knots.

Barometric pressures range from 1027 MB at Chicago to 1030 MB at Muskegon and Mackinac Island. The forecasted high has come to Lake Michigan meaning the Chicago breeze is an aberration. This high will control the weather to Monday. Forecasts going forward are still in the 5-10 knot range.

How best to deal with this situation? Sometimes around the edge of the high you can find breeze. Since the high stretches hundreds of miles inland from Lake Michigan you simply can’t do this.

When thre is a 10 degree difference between water and air temperature often you can find a sea breeze. The warm air rises above the land allowing the cooler air to blow in from sea. This is not likely in the south half of the lake but will become increasingly possible as the fleet sails north.

Perhaps the best situation for those wishing to play the shore is an onshore breeze developed by the pressure gradient. In the case of this race winds are expected to switch to the SW. This will be an onshore breeze on the Michigan shore. From Sunday on the Michigan shore could be the best place to be with good temperature differentials and an onshore breeze. Essentially the sea breeze and gradient breeze blow the same way, combining and accelerating.

Conversely on the Illinois and Wisconsin shore this will be an offshore breeze. This tends to diminish any sea breeze affect. I can’t see the west shore being a windy area.

While the start maybe fast things will get slower and less clear as you sail north. For now it appears to be a race that will be sailed largely in Michigan waters. You need not sail straight to the shore, but from Sunday on the shore maybe your only friend wind-wise.

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