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

21 March 2009

BOBGRAM7 issued 22 March 2009

Issued 22 MAR 2009
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas come from
the patterned world of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

The equinox was at 1144UTC last Friday. Weather systems around the
equinox are special; some say they set the pattern for the next few
months. Well, the cooler-than-normal sea temperatures along the Pacific
Equator are now slowly returning to normal, so the seasonal outlook is
that this LA NINA will weaken away over the next few months.

KEN came from that unorganised convection around the Cooks, and came and
went harmlessly enough. That LOW near New Caledonia today is the one
that EC was picking would form in the Coral Sea, and it seems to be
moving out the tropics without much drama (so far, anyway).

The South Pacific Convergence Zone SPCZ remains active over northern
Australia, and in the Coral Sea. There is a weak
Madden-Julian-Oscillation MJO arriving over the Coral Sea this week -
this is a tropical oscillation that tends to increase the SPCZ. It
looks as though this will be a week with low pressure areas forming in
the Coral Sea, extending as far as Vanuatu at times. These lows will
need watching and maybe worth avoiding.

The Low that is near New Caledonia on Sunday is forecast to be between
Norfolk and Kermadecs on Monday wandering to the SE, and helping another
low now east of NZ to deepen near 40S 160 to 150W on Tuesday and

There is a secondary branch of the SPCZ along around 10S between
Tuvalu/Tokelau /Northern Cooks and Marquesas. This is typical of the
twinning that occurs near the equinox and is somewhat associated with
the ITCZ along 5 degrees N.

There is a Southerly over NZ to start the darker half of the year,
reminding us : just one fortnight of NZDT left.

HIGH 1018 over Tasman Sea/South Island should build to 1025 over North
Island on Wednesday (good fishing) and then weaken away to a thin ridge
near 30S by Friday. North of this high there will be a squash zone
between 30 and 20S initially in the North Tasman Sea/southern Coral
Sea-and gradually expanding eastwards with the high to get east of 180
by Friday and for the weekend. Avoid the squash zone.

For NZ there will be a interlude between highs with a frontal trough
over the South island on Thursday and the North Island on Friday,
followed by a mediocre southwest flow getting over NZ by the end of the
28/29 March weekend.

Next HIGH is likely to be in the central Tasman Sea by Mon 30th March,
along with another LOW in the Coral Sea - again I say: avoid the squash
zone in-between.

The terms used are more fully explained in the METSERVICE Yacht Pack.
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