Coastal & Offshore Wave
CDIP's coastal wave height forecasts are actually the combined result of
two wave models:
The NOAA/NCEP implementation of the Wavewatch III wave model for deep
water regions (depth > 300m). The Wavewatch III model is a wind-wave
generation and propagation model. That is, the global wave forecasts
are made based on global surface wind forecasts.
The Coastal Data Information Program's implementation of a spectral
refraction-diffraction wave model for shallow water (10m < depth < 300m).
It models the effect of bathymetry on waves as they
travel from deep water towards the coast. This implementation is slightly
different than the swell version. We also include the propagation
(but not generation) of shorter period local seas based on input from the Wavewatch
Offshore Wave Height Plot This is the plot displayed
at the top of the page. It shows forecasted significant
wave heights from the NOAA/NCEP Wavewatch III model for the two deep water sites
off California used in the coastal wave models.
The plot is designed to provide a quick look at whether there is a big deep
water wave event on the horizon that may impact the coastline. The
storm threshold line of approximately 13 ft. is based on historical
storms in southern California, although
forecasts of offshore waves exceeding this threshold do not necessarily
mean damaging coastal waves will occur.
Coastal Wave Height Plot This plot is
similar to CDIP's real-time swell predictions of alongcoast wave height.
It is a plot of the model results along the 10m depth contour. They are
not breaking wave heights; generally, the 10m depth contour is outside the
Nevertheless, it does provide an idea of how much wave energy is reaching
the coast relative to other locations. Higher wave energy generally leads
to higher water levels and wave runup at the adjacent shore.
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