Bobgram

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 01 Feb 2026

A review of last month's weather
Here is a link to a YouTube clip giving an animated loop of the isobars and
streamlines
For the month of January is at youtu.be/dF205bOjbXI

Australia heatwaves continue with daily records over 48C last week.
New Zealand had damaging rains on Wed 21/Thursday 22 January


The 500hPa heights and anomalies shows that prolonged upper low over Tasman
sea late in the month
From http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_sh_anim.shtml

Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml

The La Nina cool waters over eastern equatorial Pacific continue to relax.
The marine heat wave to northeast of New Zealand has intensified and spread
further east. Its northern edge is now touching Tongs.

Average isobars for past month From
http://www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html
There is now a monsoonal low over central Australia. The subtropical ridge
in January is well south, much the same as in December. The colour scheme
for January is slightly different.
The low pressure band over the Aleutian Islands has deepened.
The anomaly pressure pattern for December shows the large low breeding area
over New Zealand and now also over Australia.
And the 1010hPa isobar in the South Pacific has drifted south.

TROPICS
. Former Tropical storm Luana strengthened and maintained its appearance for
around 400 miles a sit moved inland across Australia.
. Tropical storm Ewetse caused little impact when it passed over
Madagascar.
. Tropical cyclone Fytia is now moving Southeast away from Madagascar
. An unnamed tropical Low skirted near New Caledonia last week,
weakened by disruptive winds aloft.

WEATHER ZONES

Rain accumulation this week from Windy.com above shows a well -defined
South Pacific convergence. Intense rain associated with Tropical low L1 is
expected over Tonga next few days.
Wind accumulation from windy.com above shows bursts of wind associated with
Lows L1 and L2.

Highs and LOWS

A tropical Low L1 near Tonga is expected to linger in the Niue area for a
few days and then move south to southeast. This Low may help remove a lot of
energy from the SPCZ.
A trough is forecast to cross New Zealand on Monday and Tuesday is expected
to develop a low L2 passing across Cook Strait on Tuesday night. L2 then
moves off to the east, faster than L1. They might merge late in the week.
HIGH H1 well to southeast of Tahiti is expected to move off to the east.
HIGH H2 is forecast to cross Tasmania on Monday and then central New Zealand
on Thursday with some of it lingering over north Tasman until Sunday.
Another tropical cyclone may brew off the northwest coast of Australia late
this week.



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