Yesterday I just happened to pick up a tide table for the Ventura
area (where our vacation single-wide is located) and noticed what I
was initially quite certain was a mistake. The tide table indicates
that the usual two tides (four tidal extrema) a day routine would be
disrupted this Friday (August 14, 2009.) On that day there the table
indicates no low tides at all and only one high tide in the late
afternoon. That is, the prediction is for just one half of "a tide"
on Friday. It turns out that the tide table is correct. The
following link to a graphical tide table shows how it works:
Notice that Friday happens to be one of the very rare days when the
lower high tide (in the wee hours) happens to be lower than the
higher low tide (at dawn). But compounding the rarity even further,
the previous low tide occurs at 11:23 PM on the 13th (37 minutes
before the 14th begins) and the next low tide occurs at 12:39 AM on
the 15th (39 minutes after the 14th ends.) The result is a single
tidal extremum at 4:19 PM on the 14th.