Every surfer who's used any computer generated surf forecast regularly in the past ten years or so has learnt one fairly obvious fact: forecasts can change and the further you look into the future the more likely this is to happen.
You know the story, you spot a new swell right at the end of the seven day forecast and cross your fingers, as it draws closer the forecast updates and it either sticks around, changes, or sometimes even disappears completely. You know this and we know this, but magicseaweed is the first and only free surf forecast service to now try to put some science to this phenomena.
We run 20 different swell models all using slightly different starting conditions to predict future wind and swell. When the atmosphere is generally stable and easy to predict by the model these different models will tend to show similar information, when the situation is very changable they'll show a spread of possibilities. This gives you a good guide, at a glance, to the likelihood of the forecast changing. Clicking this column allows Pro users to see every one of the 20 variations to also see what else could happen.
You'll see, as you expect, probabilities ranging from 100% in the near term to as low as 5% 10 days out. Do bear in mind we don't have a crystal ball, we're the first and only surf forecasting company to give you some idea of the chances of the forecast changing, but this in itself is just a prediction! The swell models can be 100% confident in a particular scenario but that isn't the same as an absolute certainty of the future.