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Swellinfo Wave Maps Explained

Posted: Friday Mar 20, 2009     By: Swellinfo     Category: Swellinfo

Explaining how to use one of the more useful tools on Swellinfo

On Swellinfo, there is an abundance of resources to use in order to peer into the crystal ball of upcoming surf. This article explains how to interpret and get the most out of the Swellinfo wave maps.

Below you will find the live wave maps for Ocean City, MD.

Swell Height - There is quite a bit of information within these wave maps. First, of course we get a spatial representation of the open ocean deep water wave heights. Well, what exactly does this mean? The deep water wave heights are the significant wave heights (calculated as highest 1/3 of all waves) before the wave starts to interact with the seafloor.
This height can often be misleading, since there can be a large contrast between a 3ft swell @ 5 seconds as compared to a 3ft swell at 18 seconds. So, it is always a good idea to also look at the wave periods, either through the wave period maps or the swell table/timeline.

Swell Direction - Swell direction is shown on the wave maps with white arrows pointing in the direction the swell is moving towards. This is the Dominant Swell Direction, so it is good to keep in mind there is usually more than one swell influencing a region at one time (use the swell table/timeline to recognize multiple swells).

Winds - The wind is shown on the wave maps with wind barbs. Wind barbs are a common meteorological symbol that shows both the wind speed and direction. The wind barb points in the direction the wind is from. There are two lines to represent the wind speed, a long line and a short line. The long line represents 10kts and the short line, represents 5kts. So, 2 long lines, equals 20kts. 2 long lines and 1 short line, equals 25kts, etc...

Nearshore wave maps - The Swellinfo nearshore models (Southern California, Oahu, Maui, and Puerto Rico) display slightly different wave maps, where the wind barbs are displayed along the coastline. Also, the dominant offshore swells are displayed in text over the land.

Wave Map Navigation - By default the surf forecast pages will display the most zoomed in wave map for your region. Often times, it is good to get a zoomed out look to see where swell is developing and coming from. You can easily zoom in and out, and pan to different regions, by mousing over the arrow buttons on the top left of the wave maps. If you are zoomed out, you can simply click on the desired region. To navigate through the forecast hours, you can either click the play buttons (top right), or click and drag the yellow forecast cursor over the timeline hours.

Overall, the Swellinfo wave maps are really an outstanding resource to use to easily get a glance at developing storms, swell arrival times, swell direction, and coastal/open ocean wind - all on one easy to use map.

Please also take a look at the Swellinfo Wave Map video tutorial in the Swellinfo Tutorial Section.