Bobgram 3 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 Sunday 3 November 2024

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 at youtu.be/H1hRtFYQbvQ

The main pattern for October was a procession of HIGHS travelling east along around 25 to 35S followed by a trough or two, sometime three with disturbed westerly wind south of 40S. Early in the month a low was blocked in the Tasman Sea so that rain clouds were held in place with a fetch of moist air from the subtropics onto Dunedin, producing severe flooding.


Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
The Kuroshio current is feeding warm seas across the North pacific,
And the weaker cool tongue along the Pacific equator is a sign that the incoming La Nina.

Average isobars for past month From http://www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html
The subtropical ridge in the Southern hemisphere has weakened and is starting to drift south.

Pressure anomalies for past month

The anomaly pressure pattern for October shows lows in the southern hemisphere breeding in the south Indian Ocean and around southern South America.

The northern 1015 line is drifting south across Australia.
The 1020 isobar has shrunk.

TROPICS
Super Typhoon Kong-rey killed at least one person as it slammed into Taiwan with winds of up to 125 mph as a Category-3 tropical cyclone. It was the largest such storm to hit the island since Typhoon Herb in 1996.

* Late reports from the Philippines say floods and mudslides from Tropical Storm Trami killed at least 136 people before the storm later doused central Vietnam.

* Cyclone Dana uprooted trees, snapped power lines and caused local flooding as it made landfall in India's Odisha and West Bengal states.

PATTY is heading for Portugal

WEATHER ZONES

The wind accumulation shows the light wind area in north Tasman Sea from Brisbane to Auckland and several windy zones around the low south of Tahiti in the coming

The South Pacific Convergence zone extends from Solomons to Fiji/Samoa and then southeast to Southern Cook Islands. It is expected to shift south across Tonga between Wednesday and Friday.

The MJO is reforming in the Indian Ocean this week, and that means the SPCZ should weaken over the week or two. However, it starts off this week as a strong and broad feature.

HIGHS and LOWS

Front that travelled east past NZ on Saturday is expected to mix cold air with most warm air and form a LOW L1 south of Niue and east of NZ by Monday. L1 then deepens and moves slowly east. Accompanying trough is expected to travel east from Cooks to Tahiti.

HIGH H1 is moving over NZ early this week and then travelling east along 35S following L1.

It is followed by a moist NW flow in the Tasman Sea. The trough following this NW flow is expected to cross Northland on Sun 10 November, and then the models differ over the details.

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