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

02 February 2014

BOBGRAM issued 2 Feb 2014

Issued 02 February 2014

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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

SOI The Southern Oscillation Index SOI (30 day running mean) sums up the
weather pattern over the South Pacific as one number. It is based on the
standardized difference in the barometer readings between Tahiti and Darwin.
SOI has jumped into possible La Nina territory over the past few weeks.
Its 30-day running mean was plus 1.30 on 1 Feb.

The combination of a new moon and a perigean moon is bringing King Tides
around the worldand this is causing damage in the UK where it has been
combined with strong onshore winds. The high water of a King tide of Feb
CE2014 is an initial indicator of what rising sea levels may add to the
average tide by CE2100. There need to be local corrections applied due to
rising and falling landmasses and maybe a shift of the sea-level surface
around the planet by then, but sceptics who ignore these signs do so at the
risk of their grandchildrens welfare. Its up to international politicians
to respond on our behalf; the IPCC can only point out to all the signs of
where we are going.

Islands such as those in Tuvalu and Kiribati are especially vulnerable at
the time of the King tide. Luckily there was nothing much extra from the
weather this time round.

Why was TC JUNE followed by TC DYLAN????.. well we have TWO warning centres
in this part of the world. Fiji looks after 160E and eastwards and is the
South Pacific Basin (and named TC JUNE), Australia looks after 160E and
westwards, the Australian Basin (and their names are up to DYLAN).

Cyclone DYLAN was too large in size and unable to develop to it full
possible potential before it went inland across the Townsville area last
Thursday. It did bring some minor wind and storm-surge damage and some
much-needed rain, but didn't break the central Queensland drought. Would
have been more damaging if it stayed offshore and deepened a few days then
went onshore with the peak of the King Tides, but no one in their right mind
would want to see that!. Phew, it missed.

The Australia Monsoonal trough is in its peak at present, and expected to
drift south this week. A Low is likely to form inland over northern
Australia by Monday and then drift west  It is likely to develop into a
tropical cyclone when it drifts onto the sea over NW Australia early next
week around 10 or 11 Feb. Avoid.

The next tropical feature in the South Pacific is already forming in the
Coral Sea just west of Vanuatu. This is expected to deepen into a possible
cyclone by Tuesday and track southwards to west of New Caledonia on
Wednesday and then unravel in the central Tasman Sea. However it is expected
to inject moisture and lower-density air into the eastern side of a low from
the Southern Ocean  the one that is expected to cross Tasmania on sat/Sun
8/9 Feb. This difference in density between the west and east side of this
Low is likely to aid further deepening of this feature as it crosses the
South Tasman Sea and sideswipes southern NZ next week. Avoid.


South Pacific Convergence Zone SPCZ
This is very active in the Coral Sea at present and expected to form a Low
by Tuesday that tracks south to west of New Caledonia on Wednesday and then
unravels in the Tasman Sea.

Sub-tropical Ridge STR
The HIGH in the Tasman Sea is expected to make a rare crossing of central NZ
on Monday (=height of summer conditions) and then wander off to the NE of
the North Island on Tuesday and then to east of NZ along 35S for the rest of
the week.

New Zealand area
Ridgey and summery. A trough is likely to cross NZ on Tue 4/wed 5 Feb and
then a HIGH crossing Tasmania on Tue 4 Feb is expected to cross central and
Southern NZ on Thu 6 Feb (Waitangi Day, a public holiday in NZ) to Sun 9
Feb. So most of NZ gets a ridgey week at last and enjoys summer- However
Northland gets a lot of easterly wind and swell  surf up East coast.
This is the week that air temperatures normally reach their maximum of the
year in NZ, and indeed this seems to be the case for 2014. Next week the
downward drift starts all the way to the depths of winter.

See my yotpak at for terms used.
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