Bobgram 23 Nov

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 23 Nov 2025

Where are we with an incoming LA NINA?
Recent weather maps have had a typical LA NINA look to them…


The atmospheric SOI values are trending upwards as seen at from www.longpaddock.qld.gov.au/soi/

The international Research Institute have the following predictions for El Nino, Lal Nina or neutral scenarios… at iri.columbia.edu
and according to them: although La Nina has strong probability now, this quickly fades.

Status of La Niña declarations
• United States: The U.S. CPC declared La Niña is present as of October 2025, based on sea surface temperatures in the central equatorial Pacific being at least 0.5∘𝐶 below average for three consecutive months, along with corresponding atmospheric changes.
• Australia: The BoM has not yet declared La Niña and considers the current state to be neutral. They require more intense and prolonged ocean cooling before declaring an event, and their models predict a weak and short-lived event.
• New Zealand: Earth Sciences New Zealand (formerly NIWA) reports an 80% probability of La Niña conditions from November 2025 to January 2026.



TROPICS
Tropical Storm Fina visited Darwin last night and today and became the earliest such tropical cyclone to strike Australia since Cyclone Alessia hit on 21 November 2013.
The Latitude /Time diagram from CPC the Climate Prediction centre shows a pulse of blue coloured extra-convection travelling eastwards into the Pacific after lingering over northern Australia for the past two weeks. This is an MJO and it is expected to move over the Coral sea area in the next two weeks and fade near 180 in early to mid-December.

WEATHER ZONES
Rain accumulation this week from Windy.com shows well defined and increasingly active SPCZ expanding southwards onto Fiji.
Also, a zone of heavy rain associated with a Low L1 south of Tonga

Wind accumulation from windy.com shows windy westerlies in the Tasman Sea and associated with a Low L1 south of Tonga. Also a zone of intense wind with Cyclone FINA.

LOWS and HIGHS
HIGH H1 east of NZ over 1020 is quasi stationary and expected to shift to the southwest this week., leaving a lingering ridge across the North Island and back to the NW towards New Caledonia and the Coral Sea. From this ridge a new HIGH is expected between New Caledonia and NZ by the end of the week.
Low L1 has formed south of Fiji and is expected to travel to the southeast across the Kermadecs this week. near 40S 160W with a rim of enhanced winds (squash zone) on its northern to western edge.
Low L2 is east of Sydney tonight and expected to travel southeast across the South Island later this week.
Low L3 is south of Perth tonight and expected to travel East-southeast and cross Tasmania region on Wednesday

Cyclone FINA should continue going southwest along the coast and fade as it goes inland.
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