Wouldn’t it be amazing to be able to forecast waves and catch the perfect one?
Keep your friend close, and your enemies closer. Whether you consider the waves as those friends letting you enjoy surfing, or as enemies you need to tame, it’s important to handle a couple of scientific notions about waves, both to better deal with them and to learn how to forecast them!
Wind is the key
Surfable waves wouldn’t exist without wind. They are created when wind touches the surface of the ocean, and are affected by local winds as well, although they lower their quality and make them unstable. In this case, the wave is called “sea”, and later becomes a “swell” when it continues on its own after the wind stops blowing.
Offshore winds, on the other side, push against the waves and make them longer and stronger, counterbalancing those first winds that generated them in the middle of the ocean.
Good waves are created by low-pressure systems, which have great wind speed. The friction between the winds gives energy to the waves: the longer (and larger) the winds blows, the bigger the waves!
From the sea to the shore
However, our waves have to travel a lot before reaching enthusiast surfers: they are affected by other variables, such as variances in the ocean floor, underwater currents, rainfall, tides, those offshore winds we mentioned before, and of course…gravity! Deeper waters create bigger waves, which will slow down and lose strength when reaching shallow waters: this is called shoaling, and results in the wave increasing its height, decreasing its speed and lengths, and having orbits become asymmetrical.
There’s a reason why pro surfers like Ace Cool had themselves dropped by a helicopter at Outside Pipeline: they were looking for big, strong, intense waves!
There are four parameters to “measure” a wave:
Wave height (from high trough to crest)
Wave period (time interval between arrival of consecutive crests at a stationary point)
Wave propagation direction
Wave length (from crest to crest)
The first three lead us to wave prediction and therefore surf forecasting. Many professionals publish their forecasting online and if you’re lucky enough to be in their same area you might benefit of their predicting skills, but learning to do it yourself is just a matter of training. There are many tools you can use: satellite images, atmospheric models, wave models. Some websites publish data about outer buoys and will teach you how to turn them into useful values.
A good advice is to spend time observing the spot you’re interested into: learn to know it and check which conditions usually lead to good or bad waves. Practice on your favourite spot trying to forecast weather and waves and check your outcomes: you’ll learn to adjust your deductions and you’ll sharpen your sixth sense!