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

19 July 2008

BOBGRAM7 issued 20 July 2007

WEATHERGRAM
YOTREPS
Issued 20 July 2008 NZST
Bob McDavitt's ideas for South Pacific sailing weather.
(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).

TROPICS
The South Pacific Convergence Zone is hugging 10 South latitude from
Solomons to southern Tuvalu/Wallis - Futuna to Samoa, and is indistinct
further east, in the region between Southern Cooks and French Polynesia.
There are Northeast to easterly winds on its northern side and southwest
winds on its southern side.
Not much variation in this theme this week, except for a development
between Queensland and New Caledonia-a LOW is expected to form offshore
of Queensland on Wednesday 23 July. EC model picks this low to go east
past New Caledonia on Fri 25 July then southeast past Raoul Island over
the weekend. GFS model picks that the low may deepen to 985 hPa near
Norfolk Island around 12ooUTC Friday 25 July and then skirt past NE
parts of NZ over the weekend. There will be a gale force squash zone of
easterly winds on the southern side of this low, so AVOID, please.


MID LAITUDES
The best day of the week for sailing around NZ will be Monday 21 July as
a weak ridge passes by.

A LOW deepening to below 970 hPa to east of Tasmania on 21/22 July has
its cold front crossing NZ on 22 July followed by the LOW and its
squalls on 22/23 July and then a strong cold southerly flow on 23/24/35
July in time for that LOW from near Queensland to do a fly-by over the
weekend. So it's too unsettled for any voyaging to or from NZ from Tues
22 until at least the end of the month.

A HIGH in the Aussie Bight on Monday is expected to move east across
Victoria on 22/23/24 July and into South Tasman Sea and south of NZ on
24/25 July. This HIGH feeds cold southerly winds onto NZ, and there will
be a squash zone of enhanced easterly winds on its northern side
interacting with that low from the Queensland coast.

NOTE: I am on leave until 28 July but will be checking my email this
weekend 26/27 July.

The terms used here are more fully explained in the METSERVICE Yacht
Pack. Feedback to bob.mcdavitt@metservice.com

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