Bob McDavitt's ideas for sailing weather around the South pacific

12 February 2017

Bob Blog 12 Feb 2017

Compiled Sun 12 February 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.

Lisa Blair has now crossed the dateline in her Around Antarctic adventure.
Her campaign still needs funding so if you would like to make a small donation
to help then please do so at

The tropics
A MJO (Madden Julian Oscillation) of increased convection is moving into the
South Pacific last week and this week. Two large and very active tropical
depressions TD 10F and TD 11F have been the result, near New Caledonia and Fiji,
and they are now weakening. The South Pacific convergence zone now has mostly NW
winds on its northern side as seen at

There is a distict lack of trade wind southeasterlies. I think one of the
factors why these depressions did not deepen into tropical cyclones was to do
with stronger winds aloft, so that they had their tops knocked off.
Nevertheless, they have been wet enough to flood rivers in Fiji (Nadi, Lautoka,
Rakiraki and Tavua). Queens road flooded near Nadi, see

Meanwhile there has been a heat wave over eastern Australia: Sydney airport,
near the sea, breaching 40C over past two days, and Penrith, a few miles inland,
breaching 45C. Should return to normal temperatures over next few days in a S/SW
change. The February graphs can be seen on Weather Underground at and

And in the Indian Ocean TC CARLOS is finally weakening after travelling mostly
southwards to east of Madagascar.

Activity in the tropics is increasing over N of Australia, and across the South
Pacific, and remains weak elsewhere.
Rain for the past fortnight may be seen at

SPCZ=South Pacific Convergence zone.
SPCZ is showing signs of increasing intensity over Coral Sea/New
Caledonia/Vanuatu area and another branch from Samoa to Southern Cooks.
Depressions are likely near New Caledonia /Vanuatu and Southern Cooks and in
Coral Sea by mid-week. Any of these depressions has the risk of deepening into
a tropical cyclone, and the one near New Caledonia is the most likely.

Subtropical ridge (STR)
The High north of NZ tonight is travelling east along 25 to 30S.
Next HIGH is expected to travel east along 40S into central Tasman Sea by
Wednesday then to east of South Island leaving a cell to west of central NZ on
Wed to Saturday.
This High may linger to east of NZ all next week as well, maintaining an
easterly flow onto northern NZ.

Tasman Sea/NZ Area troughs.
Low is deepening tonight and Monday to east of Canterbury but should quickly
travel SE away from NZ and towards Lisa Blair. Another trough is likely to cross
NZ on Tuesday.
Then, a High is expected to linger over central NZ for a week or so.
Mind you, this does mean that northern NZ is likely to get easterly wind sea and
swell for a week or so.
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