Hour — local time at the break, like every
time on this page.
Rating — how good the surf should be at
this hour, from 0 to 5 stars: the swell's size (a longer period counts as
bigger), its period and how well its direction fits this break, reduced by the
wind, the tide and a crossing second swell; above the size this break works up
to the stars fall, to none where it closes out. Stars round to the nearest half.
Verdict — the word for the star band:
poor under 2, fair 2 to 3, good 3 to 4, epic 4 and over, or too big, whatever
the stars, when the swell is beyond what this break or your level can take. A
break whose shoreline has not been surveyed is unrated, never scored low.
Wave height — the significant height of
the sea at this hour, the typical larger waves in open water, not the face at
the beach.
Period — the seconds between the waves
carrying most of the energy. At the same height, a longer period carries more
power.
Swell direction — the compass
direction the swell comes from, which the rating compares with the directions
that reach this break.
Swell trains — the model splits the sea
into up to three swells; their heights, largest first. One figure means one
train, a reading and not a gap.
Tide — the predicted height of the water
about mean sea level, and whether it is rising or falling, from EOT20.
Wind — measured against this break's
own shoreline: offshore blows from the land and grooms the wave, onshore blows
in from the sea, cross sits between; glassy is almost no wind.
Gust — the strongest gust the atmospheric
model expects at this hour. A gust well above the steady wind means a surface
that keeps changing.
Sky and air — the sky at this hour and the
air two metres above the ground. The air is not the water temperature.
Air — the air two metres above the ground.
With a wave model picked whose centre runs an air model it is that model’s;
otherwise the middle of the air models that reach this hour. Past ten days the
sky is not forecast, so the air stands without it.
Sea — the sea-surface temperature. With a
wave model picked whose centre runs a sea model it is that model’s; otherwise
the middle of the sea models that reach this hour, and where none does, the
dated OISST analysis. A forecast, like every other figure here.
Models for the air and the sea — how
many models the air comes from, and whether they agree: within 3° they agree,
wider apart they are split. With one model left, or one picked in the model
menu, there is nothing to compare, so agreement is not measured.
Rain — how hard it rains at this hour, in
millimetres per hour: a rate, not a chance of rain. Under 0.2 mm/h is not
printed.
Power — the wave power at this hour, in
kJ per metre of wave crest, from the height squared and the period: what
separates two hours of the same height.
Not forecast this far out — the sky, the
air, the rain and the gust come from the atmospheric model, which stops at ten
days. The sea, the wind, the tide and the rating carry on.
Burning Swell
Mossel Bay