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

02 July 2017

bob blog 2 July

WEATHERGRAM
YOTREPS
Compiled Sun 2 July 2017

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.

That was a long blog last week, so here's a nitty-gritty one this week

The Tropics
This week it's Japan's turn for a tropical storm with TC NANMADOL approaching from the southwest.

The last week's rain map
from trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
shows an enhancement in the rain south of the equator in the Indian Ocean, around the coast in China, and about the Solomon Islands, and a decrease in intensity in the Intertropical convergence zone ITCZ.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ stretches as an almost continuous band from Papua New Guinea/Solomons to around Tuvalu/Tokelau. It is expected to stay put this week. The convergence zone over the Society Islands in French Polynesia today is expected to fade away between Society Group and Tuamotu group.

Subtropical ridge (STR)
HIGH that is in the North Tasman Sea on Monday is expected to cross northern NZ on Tuesday and then fade between NZ and Tonga between Wednesday and Friday.
A ridge is expected to remain in the north Tasman sea all week, but next HIGH to the west is NOT expected until next week over eastern Australia tonight is expected to spread into the Tasman Sea by mid-week and then onto central NZ around Thursday and further east this weekend.

Australia to New Caledonia:
May be Ok on a Monday departure, after that the ridge between Brisbane and New Caledonia offers a barrier of light winds for the remainder of the week.

Departing northern NZ to the north or east for the tropics:
An upper trough is crossing the North Island tonight and Monday with squally conditions, so best to stay put Monday.
Best day to escape between weather systems is Tuesday.
Even then there may be some strong winds on Thursday ahead of the next trough from the SW, with 3 occasionally 4 metres swells. These troughy conditions are expected to last until early next week.

French Polynesia to the west:
There is a convergence zone lurking to north of Society Islands on local Sunday, the best day of this week to go west this week is on local Monday in the trade winds that follow that convergence zone.
A passing trough is likely to reach Palmerston Island by around local Thursday followed by northerly winds as another trough lurks off to west of Palmerston Island.
If you would like more detail for your voyage, then check metbob.com to see what I offer.

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See my website http://www.metbob.com for more information
Feedback to bob@metbob.com or txt 6427 7762212
Weathergram text only (and translator) is at weathergram.blogspot.co.nz.
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