Bob Blog 27 Nov

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 November 2022

LIGHTNING
Last week, between 16 - 25 November, the Aotearoa / New Zealand region saw
91,349 lightning strikes (Source: MetService), with around a 1/3 of those
situated over the land. All regions of the country have experienced
significant lightning activity, however of all the regions around the
country, the Waikato Region takes 1st place with 4,255 lightning strikes
over the period, followed by Westland (3,114) and Hawke's Bay (2,970).
Dunedin had the lowest recorded number of strikes, with 42 recorded over the
9-day period.

Lightning is the most damaging weather hazard for yachts. When you
anticipate it, the standard recommendation is to put some hand-held nav
instruments in the gally oven for protection for the duration, so if the
yacht is hit and losses its electrics, not all is lost.

When we have unstable air in the chimney of a shower cloud, rising water
droplets bash into sinking ice crystals and all that rubbing together rips
off electrons that float to the top, leaving an accumulating positive charge
at cloud base. Lightning occurs when the air between two electrically
charged regions can no longer keep them apart. The average discharge is
several gigajoules.

To put this in context, between the 9 days between 16-25th November
approximately the same amount of energy was discharged into the atmosphere
(or ground) as that either generated by the New Zealand National Grid or
consumed within all industry sectors in New Zealand (Source:
https://www.mbie.govt.nz/building-and-energy/energy-and-natural-resources/en
ergy-statistics-and-modelling/energy-statistics/electricity-statistics/)


TROPICS
The latest cyclone activity report is at zoom. earth and
tropic.ssec.wisc.edu and Tropical Cyclone Potential is from
www.ssd.noaa.gov/PS/TROP/TCFP/index.html

There are no named storms at present. There is a zone of potential
development in the China Sea.

WEATHER ZONES
South Pacific Convergence zone SPCZ
The SPCZ is somewhat quiet from Solomons to north of Fiji, then has an
active convergence zone/trough over southeastern parts of French Polynesia.

HIGHS and LOWS
HIGH H1 has been south of French Polynesia for a while is this week expected
to go off to the northeast.

HIGH H2 now between Fiji and NZ is expected to travel east along 30S.

HIGH H3 should stay slow-moving in the south Tasman Sea this week, and move
onto NZ at end of the week, breaking the spell of wet weather

LOW L1 formed over Wairarapa today, cancelling the Wellington Santa parade,
and is expected to travel off to the east southeast.

LOW L2 is forming around New Caledonia area and expected to deepen as it
travels southeast

LOW L3 should travel east across the south Tasman Sea.

LOW L4 is expected to deepen off Bundaberg and travel across the north
Tasman Sea late this week.

So, things are busy this week in the South Pacific, and changeable, but NZ
looks good for arrival from 3 to 6 December.

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If you would like more detail for your voyage, then check metbob.com to see
what I offer.
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metbob.wordpress.com (subscribe/unsubscribe at bottom).
Weathergram archive (with translator) is at weathergram.blogspot.co.nz.
Contact is bob@metbob.com or txt 64277762212
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