Bob Blog 1 Jan 2017

WEATHERGRAM
YOTREPS
Compiled Sun 01 January 2017

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.

Auld Lang Syne says welcome to the New Year, and to fresh beginnings.

In hindsight, during Dec 2016 the Subtropical ridge in the South Pacific
slightly further south than normal and more intense than normal in the Tasman
Sea (and around Madagascar). The Subtropical ridge in the northern hemisphere
has been stronger and further north than normal too. These are traits of the La
Nina weather pattern, and in recent weeks the ENSO/SOI values have been slightly
positive, showing a weak la Nina. West Australia has had lower than normal
pressures, thanks to the Monsoonal Low which started out as Yvette.

Average isobars for the past 30 days and their anomaly may be seen at
www.esrl.noaa.gov/psd/map/images/fnl/slp_30b.fnl.html

Last 30 days of rainfall, and its anomaly, are seen at TRMM
trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html

Tropical cyclone NOCK TEN brought extensive wind and rain damage to Philippines
during Christmas and Boxing Days

The Tropics are quiet at present. Be watchful in the Coral Sea area as that may
be where a tropical depression may appear by end of this week.
Rain maps show that activity is on the increase in the Coral sea area.
see trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is active and consists of several discrete convergence zones spanning the
entire South Pacific.
The accumulated rainfall forecast map from windyty.com shows a wet week ahead
almost everywhere, but New Caledonia may escape.
Active SPCZ extends from east of Solomons/Rotuma to Tonga /Niue tonight and is
expected to drift south or southwest slowly over Fiji and weaken next few days.
Another Convergence is likely to take over in the Coral Se area by the end of
the week.

Subtropical ridge (STR)
The slow-moving ridge located to NE of NZ is expected to linger there this week.
The next HIGH is expected to travel east across Tasmania on Tuesday and then
northeast across the Tasman Sea reaching northern NZ on Friday where it weakens
into a ridge that merges with the one already to NE of North island.
Another High is expected to travel east across the Tasmania area into South
Tasman sea on Friday/Saturday.

Tasman Sea/NZ Area troughs.
Trough travelling across North Island tonight and Monday. Another trough is
expected to follow on Tuesday afternoon/night, and deepen into a low east of NZ
on Wednesday. Avoid the southerly winds and swells of this. Another trough is
likely over the North Island late Friday/Saturday followed by SW winds.

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