MSW Beta Forecast: Changes

We’ve made some fairly significant changes to the layout of your forecast page and added some new details, all in a new beta test version. It’s still a work in progress with details to be finalised but now is the time to email us your feedback. First things first though the forecast hasn’t changed! Every time we make the slightest change to this page we get told that it’s now much more/less accurate than before but we can promise that the computer model that works out the swell heading towards your local beach hasn’t changed at all for this update (and very rarely has in previous updates). However we’ve added a load of improvements to the layout and design and some critical new information to the forecast.

Breaking Wave Height Forecast

MSW has always brought you incoming swell heights, as the swell enters shallow water a number of factors influence it’s transformation into breaking waves (there are a lot more details here). Your new forecast, for the first time, attempts to give an actual breaking wave face height range on the beach using widely accepted algorithms to predict wave shoaling behaviour.

What it does do?

  • Adjust for height, period and direction of incoming swell.
  • Assume a standard distribution of wave heights to give a realistic range of sizes.

What it doesn’t do?

  • Adjust for tide – some spots will be very tide sensitive and can go from flat to surfable in just a couple of hours on the same swell.
  • Adjust for every element of local bathymetry. Local obstructions, refraction and seabed slope dependent on tide will all play a part in the final breaking wave height. You’ll still need to use a bit of local knowledge to dial this for your nearest beach.
  • Adjust for the effect of wind – onshore winds can cause waves to break earlier before they reach their maximum height for example.
  • Take account of a maximum realistic height for your spot. Some spots will start to ‘max out’ or break on an outer bank or reef beyond a certain size. We’ll show the largest theoretical wave range but won’t allow for this for each specific spot.

Multiple Swells

There can be (and often are) more than one separate swell sending waves towards the beach at any given time. Our previous forecast showed only the one most likely to make the largest waves, with a breakdown of all swells available on a┬áseparate┬átab. Our new page shows all swells on the main page – vitally important to best understanding your local break.