I live on the Gold Coast and often go night fishing after work in the local rivers. I often notice the wind drops at sunset, and stays very comfortable for fishing. But sometimes it stays blowing all night, like last night, and presumably tonight. Can anyone tell me how to better fine tune our predictions for a calm night? Im used to looking at seabreeze, the 4 day HP Bom chart, and BOM observations. Should I start factoring in sea surface temps or humidity in my decisions? Is it a simple as whenever there is a Low in play, the wind will stay up?
The main reason the breeze drops off around dark is that kite / wind surfers stop putting their coin in the wind machines
Also, (take Debbie out of this) if its the onshore breeze that normally drops off around dark it could be the land is cooling and therefore the air over the land doesn't rise as fast therefore the air over the ocean doesn't get dragged in to replace the rising hot air.
On shore sea breezes usually are created by the difference between land mass temperature and ocean surface temp, not by pressure systems (which is what XDeb is and has been doing)
And on a totally clear day / sky with no haze or sea mist the onshore breeze will be stronger and more constant, I believe this is because the air is denser and also the colder the air the denser it is verses hot air.
My 5 cents worth,
On a hot day I've found the wind comes or picks up stronger late in the afternoon as temps drop around 27/28 deg, tonight was exactly that, I always kite in the afternoon to late afternoon, winds at a premium, some spots go cross off late on before filtering out
You've got to distinguish between a seabreeze and a gradient wind.
A onshore seabreeze is driven by the heat of the sun and will drop soon after sunset. It always comes from a specific direction in any location. In the Southern hemisphere, if you stand on the shore looking seaward, it will come from about 45 degrees to your left; moving further left as it gets stronger later in the afternoon. [This can be mucked up by unusual shoreline formations and in bays and harbours you need to be thinking in terms of the bigger coastline]
The gradient wind is driven by the weather systems. The closer the isobars on the weather map, the stronger the wind and it persists 24 hours. A cyclone is just a very intense example. But gradient winds can come from the same direction as a seabreeze (depending on the location of the high or low pressure system.
On the right day it is the case that the seabreeze overrides the gradient wind (actually the gradient wind is still flowing above it), so when the seabreeze dies, the gradient returns, but if the isobars are far enough apart, there may not be much of it.
