Computer generated chart which is manually edited and generated twice a day from the 00Z and 12Z computer model runs. The forecast relies on guidance from the NOAA WaveWATCH III model. The peak period is the period (in seconds) of the dominant wave system derived from the wave energy spectrum. This can either be the locally generated `wind sea' (in cases with strong local winds) or swell that is generated elsewhere. Note that the peak period field is discontinuous. These discontinuities can represent locations where the energy associated with one wave system becomes dominant over another or may be the leading edge of a swell system or swell front. In reality many wave systems overlap at most locations and times. Arrows on the chart are the prevailing direction of propagation of the dominant wave system.
Areas of superstructure ice accretion, based on a specialized ice accretion model, are identified with a unique, internationally recognized, symbol. A bold line separates areas of moderate or greater from light or less. The areas of fast ice (ice attached to land) are shown with a scalloped edge when appropriate.