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

10 June 2012

BOBGRAM issued 10 June 2012

WEATHERGRAM
YOTREPS
Issued 10 June 2012
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.
The Southern Oscillation Index or SOI is becoming more negative. It was near zero at -0.14 on 27 May and was -0.56 on 10 June.
Indian Monsoon seems to be weakening at present. It is on time for India's west coast but behind time along their East Coast.
In the South Pacific, the Convergence Zone SPCZ is active across Solomons to Coral Sea and northern Vanuatu, and a second branch is sitting from Northern Tonga to Southern and central French Polynesia.
A new LOW is rapidly deepening off the Brisbane coast this evening and has already dropped below 1000hPa, feeding off a jet stream and the East Australian Current EAC. This Low is expected to drop to 987hpa by late Tues UTC (early Wednesday local time) between Lord Howe and Noumea. Avoid. It should then gradually weaken and slowly pick up speed as it travels east then southeast passing by Kermadecs at around 990 hPa on Friday.
SUBTROPICAL RIDGE STR
A weak high cell is likely to form at around 27S between NZ and Fiji on Monday and this should then wander east for remainder of the week.
The High over the Tasmania area tonight is expected to hover over southern Tasman Sea this week and cross the South Island on Sat 16 June.
NZ /Tasman Sea troughs
The High stuck in the south Tasman Sea is working in concert with a large area of low pressure east and southeast of NZ to shovel polar chilled air onto the eastern coast of NZ, in a series of fronts, between Monday and Wednesday, with each colder than the previous. Swell from the south should peak around Monday.
Departing from NZ for the tropics:
It is probably a good idea to let that LOW go first. So, at this stage, Friday or Saturday 15/16 June may be Ok days for departure.
The terms used are more fully explained in the METSERVICE Yacht Pack.
More info at http://weathergram.blogspot.com and http://www.metbob.com
Feedback to bob@metbob.com

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