Bob Blog 27 Aug

Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.
Compiled Sunday 27 August 2023

A BLUE PERIGIAN MOON
The full moon on Thursday 31 August is the second full moon this month.
Many think the second full moon in a calendar month is called a 'blue'
moon,
perhaps because that is the colour it was given in some calendar.
But further research, such as this article
skyandtelescope.org/observing/once-in-a-blue-moon/
reveals that the origin is obscure.
This full moon is also a SUPERMOON coinciding with the monthly perigee.
It will be ~360.000km from earth and it only gets this close around three
times per year.
Of course, a closer moon means more extreme tides (both low and high).
Also, there is a lag between the perigee and the largest "king tide" of few
days.

tides.niwa.co.nz shows the tide heights plus and minus a few weeks around
this full moon for Opua in NZ (a reasonably well-behaved tidal spot with a
range ~2m) and from Karori rock near Cook strait and near a tide nodal point
(Amphidromic point) with a tide range of less than a metre (see illustrated
edition).

In its State of the Climate in the South-West Pacific 2022 report, the World
Meteorological Organization (WMO) said water levels were rising about 4 mm
per year in some South Pacific areas, slightly above the global mean rate,
so those sailing around the South Pacific should be aware of the King tides
this coming weekend

TROPICS
It has been a busy week for cyclones and tropical depressions.
HILLARY swamped LA and SanDiego. HAROLD brought rain to southern Texas.
FRANKLIN brought heavy rain to Hispaniola.
EMILY and GERT had brief lives in the central North Atlantic. SAOLA visited
Philippines and DAMRAY affected Japan.

WEATHER ZONES
The South Pacific Convergence zone is expected to intensify this week
between Solomons and Vanuatu and drift south and form a LOW L1 near New
Caledonia by mid-week Wednesday. Fresh trade winds over Tonga and the Cooks.
A lingering lull about French Polynesia this week

HIGHS and LOWS
Low L1 near New Caledonia by mid-week expected to deepen and travel SE
towards northern NZ.
HIGH H1 1031 in South Tasman Sea travelling east across NZ mid-week. Avoid
squash zone between H1 and L1.
Low and trough L3 expected to travel NE from Southern Ocean to south Tasman
Sea by end of week.

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If you would like more details about your voyage, then check metbob.com to
see what I offer.
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at bottom).
Weathergram archive (with translator) is at weathergram.blogspot.co.nz.
Contact is bob@metbob.com or txt +64 277762212
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