The cabability to forecast waves calls for weather data and significant amounts of area expertise in beach exposures and surf spots. Open ocean storms generate waves and weather forecasting gear and buoys realise this specific energy. Then it is up to the surf forecaster to build models for the swell, map out how much the swell will weaken, and finally ascertain size and quality at a particular surf area at a distinct spot in the near future.

To begin, blowing wind is the key ingredient in producing waves for surfing. High pressure systems are characterised by lighter, milder air packages and low pressure is characterised by more dense, cooler air packages. Air inside a high pressure system is attracted to low pressure systems producing blowing wind. A low pressure system will strengthen when it collides with a hot air mass making air spin more rapidly creating more wind. Swell are generated by wind blowing on the surface of the ocean. Breeze first produces tiny surf but the more wind spanning a larger distance causes larger surf to form. The most significant contributing factors to swell size and period are wind speed and fetch where fetch is considered the range the wind is blowing. The more substantial a wave grows, the greater surface area the blowing wind can grip the swell and supply power into it which makes it larger. The one thing stopping swells from increasing over and above a certain level is whitecapping which diminishes wave size and power.

As swells disseminate from the weather event, they begin to disperse and group together. Surf of similar sizes and pace group into sets of waves and journey collectively within the ocean. Next the surf will decay while it journeys far distances throughout the ocean. The nearer you are to a significant swell creating occurrence, the larger the surf you will see when it strikes the coast. As the swells travel great distances, you will observe a swell will clean up as waves spread away from each other and are not all stacked over each other.

Overall surf size is decided by a couple key elements, wave amplitude and the period of the wave. Wave amplitude is obvious as a swell may be 3 feet high in the open ocean. The period is the time it takes to go from trough to top to trough of a wave and is measured in seconds. The larger the period of the wave, the faster the wave will move plus the more deep ocean power the wave has as well. You might hear people who surf reference a long period wave of about twelve to fourteen seconds or larger as a groundswell and shorter period waves as wind swell. Groundswells with large periods will produce a more substantial breaking wave compared to a wave with a equivalent amplitude but a shorter period.

Waves break when they encounter shallow water and the base on the wave slows down enough that the top of the wave crumbles ahead falling over the bottom of the wave. The more swiftly the ocean bottom transitions from deep water to shallow, the faster and more heavily the surf will break. Bathymetry of the ocean bottom identifies structures that alter the depth of the water like sandbars, reefs, and shelves and bathymetry impacts how a wave breaks at a particular surf area.

To determine the surfing forecast, sophisticated information is gathered from organizations like NOAA. Models are developed that look at wind speed and direction together with distance of continual winds to determine wave amplitude, period, and the swell route leaving a weather event. These models will approximate the way the wave will propagate throughout the ocean to create a surf forecast. Then nearby individuals from surf reporting services will venture out to surf spots early in the day to capture the surf report taking a look at surf amplitude, form, and conditions.