The tables show the WAVEWATCH III predictions of significant wave height, peak period, and direction of propagation for four points on the Moroccan Atlantic coast: Larache, Casablanca, Safi, and Agadir. The predictions are for 6-hour steps from 6 January at 0000 UTC to 8 January at 1200 UTC (60 hours).
For the night of 6 January and morning of 7 January, the WW111 model predicts significant wave height values of 6 to 7 m. These values are high. But what’s remarkable are the period values, which are approaching 18 s. The height of long-period swell increases significantly as they shoal and break in shallow water. Depending on the beach steepness, 7 m waves with an 18 s period can easily be 10 m high when they break.
These waves are extremely powerful. Remember the power of a wave is proportional to its period times the significant wave height squared (P=0,4 * Hs² * T (kW per m)).
Here’s the same output in graph form. You can see the predicted evolution of the waves’ characteristics at the four locations.