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 02 Nov 2025
A review of last month's weather
Here is a link to a YouTube clip giving an animated loop of the isobars and
streamlines in the South Pacific for the last month youtu.be/F-RXc9_fBFE
It was very zonal month, with trade winds in the tropics, a well
identified subtropical ridge near 25 to 30S and disturbed westerlies south
of 35S. Lows crossed NZ on 4, 23 and 27 October. The 23 OCT Low was special,
at 958hPa near Invercargill, so 40hPa of isobars between Auckland and
Invercargill. The speed of the movement of the low itself was added to the
wind over southland and some anemometers measured over 200 kph.
The Low on 23 October :


The 500hPa heights and anomalies shows these Lows.
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 North Pacific "blob" is still there, but there is now some colder
surface water north of Korea. The equatorial Pacific is slightly cooler,
and Coral Sea is noticeably warmer.

TROPICS

Tonight there is 1 named storms, KALMAEGI crossing the Philippines.

In the past few weeks.
. Super Hurricane Melissa ravaged western Jamaica as the most powerful storm
ever to strike the country. Melissa then weakened before pounding Cuba, the
Bahamas and Bermuda.
. India's central Bay of Bengal coast was drenched by Tropical Storm Montha.
. Tropical Storm Sonia formed in the eastern Pacific.

WEATHER ZONES

Rain accumulation this week from Windy.com below shows well defined SPCZ
mainly in the north but visiting Fiji and Tonga and connected to a low form
the tropics labelled L3.

Wind accumulation from windy.com above shows even winds in the tropics, a
well- defined subtropical ridge over Coral sea to Auckland, and winds around
a Low L3 between Fiji and Minerva plus along 30S just north of NZ.

LOWS and HIGHS
Low L1 well southeast of NZ is expected to move slowly over Southern Ocean
as HIGH H1 now just NE of Auckland travels ENE along 35 to 30S.
Low L2 is expected to stall over Tasmania/Victoria area until after the
Tuesday Melbourne Cup and then to travel SE to southern Tasman as High H3
zips around its northside and crosses central NZ this weekend. Then L2 may
stall over whole of NZ early next week.
Low L3 is expected to form over Tonga area by midweek and then maybe partly
go west and partly go east. Central pressure around 1010 so rather weak
but may breed squalls,
Low L4 from the tropics is expected to deepen intensely over Perth area
mid-week then shoot off to the southeast where it may merge with L2 over NZ
next week.
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