Bob Blog 27 June

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 June

A Time -Longitude plot of South Pacific rainfall.

The ENSO (El Nino/Southern Oscillation) continues neutral, The MJO (Madden
Julian Oscillation) is currently weak. And SAM (the southern Annular mode)
is about to dive negative around 10 July, encouraging a polar outbreak. In
this blog I wish to share with you an interesting way to visualize the
weather. In my illustrated edition is a graph concentrating on the zone
between 10 South and 25 South (which is where the South Pacific Convergence
zone lives), and showing time from March 1 to June 24 going downwards, and
longitude from 160E in the left to 130West (Pitcairn Island) in the right.
Wet events show as dark blobs.
It shows:

1) Weather is mix of pattern and chaos. Rain events are around six days
apart, but this rhythm keeps changing.

2) Rain events tend to drift eastwards across the South Pacific, and take
around a week to get from Noumea to Tahiti
-This is due to the stronger westerly winds aloft.

3) March and April had ample rainfall, but May and June had long dry period,
especially around French Polynesia.

TROPICS
ENRIUE is expected to remain offshore of Mexico west coast, and should fade
before getting near Cabot San Lucas. CHAMPI is east of Japan and going
northeast. There is still a moderate zone of potential development off the
southwest of Mexico, and in the equatorial Atlantic.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is expected to be about average stretching from Solomon Islands to
Samoa to Southern Cooks.
A trough over New Caledonia on Monday is expected to travel east and reach
Fiji/Tonga by mid-week and over the Southern Cooks by the local weekend.
A LOW is expected to form on local Friday near 30S on this trough and deepen
as it travels off to the southeast.

Subtropical ridge (STR)
HIGH 1030 to northeast of NZ is travelling east along 3OS.
HIGH 1034 is expected to form east of Bass Strait by Tuesday and travel east
across central NZ on Thursday.
This is likely to bring a squash zone of enhanced SE winds between NZ and
New Caledonia by Wednesday. Avoid.

Aussie/Tasman/NZ troughs
DEEP LOW 960 near 60 South is travelling east to south of NZ. Associated
cold front is expected to travel over South Island on Monday and North
Island on Tuesday followed by a SIGNIFICANTLY COLD southerly. Avoid
departing from North Island for tropics on Tuesday.
bob@metbob.com