Surf forecastin’ USA

Catching a choice wave is epic. So is conducting a large-scale experiment still regarded as field-changing 50 years later.

Walter Munk, professor emeritus at Scripps Institute of Oceanography, pioneered the use of power spectra in describing wave behavior in his seminal paper with Frank Snodgrass and others in 1966.

Munk and Snodgrass’ experiment traced waves generated by winter storms in the Southern Hemisphere at six stations spaced thousands of miles throughout the Pacific Ocean. Twice-daily wave records were analyzed to yield energy spectra at each station as a function of frequency and time. ‘It so clearly explains the physics and maths of traveling waves, and the way they did the experiment was a perfect example of the scientific method,’ says Graeme Rae, chief scientist at Surfline , a California company that provides live and predicted ocean weather information for surfers and other ocean users.

Additionally, Munk’s 1949 algorithm on wave shoaling, or the increase in waves’ heights as they travel from deep to shallow water, remains one of the best prediction tools in the field.

While the science of surf forecasting is rooted in Munk’s work, more precise forecasting has resulted from several decades spent finding out what makes different locations produce the best waves.

Surfline employs a team of meteorologists who analyze models and observations to forecast surfing conditions around the world—including surf height and winds. A recent technological advance, HD cameras, provide a clear picture of ocean patterns anywhere in the world.

‘The difference from regular weather forecasting is that we are forecasting for a very, very niche market,’ says Rae. Surfline aims to weed out erroneous information produced by models and predict the best possible locations, since most of Surfline’s users are already knowledgeable and their lifestyle rides on the accuracy of the forecasting work.

Surfers are not the only ‘niche market’ to benefit from Surfline’s work. The Buoyweather feature provides a more general forecast for boaters, sailors, and the oil and gas industry, along with tools to acquire data and build your own forecast. And Fishtrack uses subsets of data to help anglers predict where the fish will be.

‘One of our larger markets is in southern California,’ says Surfline meteorologist Mark Willis. ‘If I wanted to know where to go surfing in north Orange County, the first thing would be to check the specific forecast.’ This forecast correlates models with observations from webcams and buoy data because, according to Willis, ‘it’s hard to predict what happens in the future if you don’t know what’s going on now.’

Surfline meteorologists run their own version of the publicly available WAVEWATCH III ocean wave model, but incorporate realtime observations, and adjust forecasts accordingly. The biggest adjustment is to analyze how deepwater waves interact with bathymetry, or underwater topography, to produce surf heights around the world. ‘This is pure modeling, but also a bit of art,’ says Rae.

When meteorologists detect anomalies in the models, they must adapt their forecasts and observations. A recent development allows Surfline to provide more detailed spot forecasts for surf heights around the world. An algorithm that combines observed surf heights and winds can predict whether good surfing waves will occur in a specific location.

With a background in ocean engineering, Rae began his surf science career teaching university in Florida, where he launched a small website to show surf heights. To his dismay, his surfing students would use the data to figure out when to skip class. Willis grew up as a surfer and meteorologist on the east coast—where good forecasting is needed because conditions change so rapidly—and joined Surfline.

It is no wonder that Willis and Rae are excited for upcoming work with Munk to verify anew some of his studies from the 1960s. And the fact that the ‘father of surf reports’ will re-analyze this work years later is a testament to the rigors of surf science then and now.

That’s something for which the surfing community is no doubt grateful as the (northern hemisphere) summer season approaches.