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

16 January 2010

BOBGRAM7 issued 17 Jan 2010

Issued 17 Jan 2010
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.

A weakening MJO or Madden Julian Oscillation of extra convection is
making its way eastwards into the Papua New Guinea region this week.
This may well help feed the LOWS that are forming in the Coral Sea. One
of these LOWS may move southwest wards across Solomons on Fri 22, deepen
in the Coral Sea on Sat 23 and possibly make landfall onto northern
Queensland on Sun 24 Jan. Avoid.

The South Pacific Convergence zone SPCZ in the past week has been active
as a zone from around Tokelau to Northern cooks and French Polynesia,
and another zone the Coral ea to New Caledonia. There was a low that
took rain to south of Southern Cooks, but also a large very dry area
over Fiji and Tonga, stretching to Vanuatu and Samoa. Activity is very
intense between Solomons and the Equator-connecting to the ITCZ
International Tropical Convergence zone--- this is where a zone of
equatorial westerly winds is busy brewing boisterous bubbly clouds.

There is a subtropical high near 40S 150W are to south of French
Polynesia with a weak subtropical ridge towards the Kermadecs at the
start of the week but that is fading.
Tasman Sea area is predisposed to low pressure this week, blocking the
start of a new subtropical ridge, but one should form across northern
Tasman Sea and last from 21 to 24 Jan

Continuing unsettled: Those damp cold southerlies we mentioned in the
last weathergram brought some minor wind damage to parts of Wellington
Next LOW is expected to deepen a lot in mid/south Tasman Sea Mon to wed
18 to 20 Jan and then weaken as it crosses central NZ from Thursday to
Saturday. Most of its wind and rain is wrapped up with its fronts,
crossing North island on Wednesday/Thursday, but the LOW is also likely
to be followed by a strong and showery southwest flow on Friday and
Saturday 22-23 Jan. Plan around it.

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