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 7 December 2025
Ozone hole
The ozone hole over Antarctica closed on 1 December-- the earliest
disappearance since 2019 and the smallest overall in five years, according
to Copernicus, Europe's climate-monitoring program.
The hole formed in mid-August and remained between 5.8 and 7.7 million
square miles through September and October, with a peak at 8.14 million
square miles, well below the peak of 10 million square miles measured in
2023. Then it had a rapid decline thru November.
As seen at atmosphere.copernicus.eu/monitoring-ozone-layer


Australia is having a heatwave:
Today's Fire spread index as shown on windy.com reveals the large area of
extreme risk around Australia. Today's passing front on the east coast has
cold southerly winds. clashing with hot moist northerly winds, triggering
lightning and strong winds that are spreading wildfires. A whole
neighbourhood of houses near Lake Mcquarie was burnt down this afternoon.

TROPICS

Tonight: there are no named storms, but there is a tropical depression over
the Philippines and a sizable depression southeast of French Polynesia
moving off to the southeast.

A positive phase of the MJO is starting to travel eastwards into the Pacific
and should reach Fiji around 17 December. In the diagram below from Bureau
of Meteorology, jade colours are extra convection, and brown colours are
less than normal convection.

The seas around Vanuatu are already warm enough to turn a tropical low into
a tropical cyclone. I think small tropical lows may form in the Vanuatu
area around Fri 12 December and Friday 19 December. Maybe.
In the past few weeks.
. Unusually powerful Cyclone Ditwah left at least 474 people dead from
flooding and mudslides in Sri Lanka's "largest" natural disaster on record.
The storm later moved northward into India, causing additional damage and
deaths.
. Relatively weak and exceptionally rare Cyclone Senyar and its remnants
caused devastating flooding and landslides to northern Sumatra and the Malay
Peninsula. More than 1,000 people perished in Indonesia, Malaysia and parts
of Thailand.
WEATHER ZONES
Weather Zones Mid-week GFS model showing isobars, winds, waves (purple),
rain (red), MT (Monsoonal trough), STR (Subtropical Ridge), SPCZ (South
Pacific Convergence Zone) CZ (Convergence Zone)

Rain accumulation this week from Windy.com above shows well defined SPCZ
mainly in the north but heavy rain visiting Vanuatu at times. Tropical low
L1 may form between Fiji and Minerva on Monday and then travel south.
Another Tropical low L2 is expected form near Vanuatu by end of Friday.
Avoid.

Wind accumulation from windy.com above shows windy areas associated with a
tropical low L1 mainly in a squash zone between L1 and the High east of NZ.
Next weekend there may be extra winds around Vanuatu as tropical Low L2
might form.

HIGH H1 is quasi-stationary to northeast of NZ and is expected to shift
south this week.

Low L1 is expected to form between Fiji and Minera on Monday and deepen as
it travels south-southeast to Chatham Islands next week.
HIGH H2 is expected to travel east along 37-38S from Aussie Bight to central
Tasman Sea.
Low L2 is expected to form near Vanuatu around 12 to 15 December and may
deepen as it crosses southern parts of Fiji next weekend.

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