Bob Blog 15 Oct

Bob Blog 15 Oct
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 15 Oct 2023

The Cyclone Outlook for the coming season:

Gilbert Walker was an applied mathematician at the University of Cambridge
when he became director-general of observatories in India in 1904. While
there, he studied the characteristics of the Indian Ocean monsoon, the
failure of whose rains had brought severe famine to the country in 1899.
Analysing vast amounts of weather data from India and the rest of the world,
over the next fifteen years he published the first descriptions of the great
seesaw oscillation of atmospheric pressure between the Indian and Pacific
Ocean, and its correlation to temperature and rainfall patterns across much
of the Earth's tropical regions, including India. One of his identified
oscillations has been named the Southern Oscillation and Walker worked with
the Indian Meteorological Department studying the link between the monsoon
and Southern Oscillation phenomenon. He was made a Companion of the Order of
the Star of India in 1911.


Image shows a normal Walker circulation as a conceptual zone of rising air
over Australia and sinking air over Peru. aloo shows a reversed Walker as it
is now during an El Nino event with sinking air over Australia (dry) (see
Oceanreview.com))

The Walker circulation over the Indian ocean is known as the Indian Ocean
Diopole. This is having a positive phase at present, also bringing sinking
dry air over Australia. (from study iq.com).

Thanks to the combination of an El Nino and a positive Indian Dipole,
Australia is being dealt dry sinking air from both the Pacific and the
Indian Oceans. Australia's Bureau of Met have issued their Cyclone outlook
for the coming season with the summary:

Below average number of tropical cyclones is likely for Australia in 2023-24

And in New Zealand the combined resources of NIWA and MetService have issued
a map of expected cyclone numbers:

Using analogue years 73/73,83/83,02/03,04/05, and09/10 and going for reduced
risk near Australia, normal to elevated risk between Tuvalu and Tahiti, and
elevated risk for Vanuatu, Fiji and Northern Cooks.
See://niwa.co.nz/sites/niwa.co.nz/files/tc_outlook_2023-24.pdf

TROPICS

SEAN is travelling to the northwest across he North Atlantic.

WEATHER ZONES
The South Pacific Convergence zone is expected to stay north from Solomons
to northern Vanuatu to Tuvalu. There is expected to be a passing trough over
Southern Cooks and Tahiti around mid-week helping Island -hopping from
Tahiti to Tuamotu Islands.

HIGHS and LOWS
HIGH H1 east of NZ is expected to travel slowly eastwards along 35 to 40S.

LOW L1 is expected to roll in from SW of Tasmania and go NE and deepen in
the Tasman Sea on Tuesday. Associated warm front should stall around
northern NZ on Wednesday and Thursday with strong NE to E winds. Low is then
expected to weaken into a trough reaching Fiji and Tonga over the weekend.

Low L3 is expected to deepen over northern Vanuatu next week and maybe
travel SW into Coral Sea. Avoid this next 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).
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Contact is bob@metbob.com or text 64277762212.
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