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Bob McDavitt's ideas for sailing weather around the South pacific

08 February 2015

Bob Blog

WEATHERGRAM
YOTREPS
Issued 8 February 2015
Bob McDavitts ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world

A quick and short blog this evening as I was driving from Wellington to
Auckland today and had to fix a puncture along the way, replacement tyre was
a space-saver and they upset the wheel balance and reduce a cars maximum
controllable speed (on good roads) to 80kph  an interesting speed for me to
attempt on the Auckland motorways).

TROPICAL TOPICS
Cyclone OLA faded in the north Tasman last week but its clouds brought some
much needed rain to northern NZ on Wednesday 4 Feb.
At present there is a named cyclone in the NW Pacific called HIGOS heading
for the area north of Guam and weakening.
And TC FUNDI in the Indian Ocean which may bring gales to an area south of
Madagascar on Monday (local).
The weekly rain maps over the past week show the track of OLAs rain onto
northern NZ and the recent downpours in Madagascar.
Comparing this with the previous weeks map shows a DROP in the top
intensity of tropical rainfall, but a greater spread in area.
Weekly rain signatures are seen at
http://trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is expected to weaken further and split into a northern and a southern
zone. Spreading the convergence like this only weakens its ability to gang
together the thunderstorms into cyclones, and so we should have a cyclone
free weekunusual at this time of the year.

STR= Sub-tropical Ridge
The blocking of January has been replaced by mobile and strong Highs in
February  with increasingly noticeable troughs in-between.
The HIGH that is crossing Tasmania on Monday should travel east onto
southern NZ on local Tues/Wed and then east along 45S.
Next HIGH is expected to travel SE from the Aussie Bight on Thu 12 Feb and
skirt around the south of NZ, at 47 to 50S on Fri/Sat 13/14 Feb and then
travel east along 45S.
With the STR so far south, there are likely to be strong SE winds likely
this week between 25 and 35S building easterly swells to over 3 metres
especially in the zone north of the migratory Highs.

Over NZ/Tasman
Between the migratory Highs there are cold fronts/troughs with brief SW
changes - one on Monday(local) and one on Thursday/Friday (local); these
travel NE but are expected to fade over southern North Island (as they move
away from their upper support).

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe.
My website is at metbob.com
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