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

29 May 2016

Bob Blog 29 May 2016

WEATHERGRAM

YOTREPS

Issued 29 May 2016

 

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.

 

The Tropics

Tropical Storm Bonnie, the first of the year to threaten the United States, stalled in the Atlantic before strengthening slightly today.

 

Rain maps for the past fortnight from trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif show a drop in the rain over the Bay of Bengal, so maybe the Monsoon is stuttering. Not much change over the Pacific.

 

WEATHER ZONES

SPCZ=South Pacific Convergence zone.

SPCZ is expected to remain draped from PNG across to the Tokelau/Samoa area, with a touch over northern Cooks.

A new convergence zone is expected to build in the Coral Sea this week and move on Vanuatu on 6-7-8 June.

 

STR= Sub-tropical Ridge

The next HIGH travelling east off Tasmania on Monday is expected to build over the central Tasman Sea from Tuesday to Friday and then cross NZ on Sat-Sun-Mon.

 

Voyage Outlooks:

 

Panama to Galapagos:

Light to moderate southerly winds around Panama this week, so not a good week to depart.

Also the ITCZ seems to be active and squally at times between 8N and 5N, so another week when its better to stay put.

 

Travelling to Marquesas:

Winds near Isla Isabela are expected to be moderate southerly this week so departure any day is OK. May as well get best from the current by going to 4S then west to 135W and then direct. And around Marquesas Islands expect moderate easterly winds from local Monday.

 

Tahiti to the west

The SPCZ may affect Tuamotu area until local Tuesday (and after Thursday) but should remain clear from the Tahiti area this week. Looks like a good week for steady SE winds for sailing west towards Niue and Tonga. One proviso on this is that the outlook is for a trough to move onto the Tonga area around 09/10 June UTC.

 

Between NZ and the tropics

After two weeks of disturbed westerly pattern with active troughs, it looks like there should be a pattern change over NZ this week as , finally, a HIGH moves across Tasman Sea and then onto NZ on sat Sun Mon 4-5-6 June, our Queen’s Birthday Holiday. Yippee!

 

There are still a few days to go with disturbed SW winds over Northland. One more trough embedded in the SW flow is expected to deepen into a Low that may travel NE across the North Island on early Wednesday local, preceded by strong westerly winds on early Tuesday and followed by strong SE winds on Wednesday night.

 

So that means the next good looking departure is THURDAY, local, in quiet southerly winds.

 

There is the option of a good enough departure late on Tuesday, using the lighter winds near the middle of that passing LOW to sail with, but it rather tricky as the real world is delivering an outcome somewhat different for the ideas from the models.

 

Than Annual Auckland to Fiji yacht race starts on Saturday. This year it is ANZ Sail Fiji 2016, see sailfiji.co.nz/. Early indications is that the fleet are likely to encounter a front around mid-next week 8 June and the northerly winds ahead of this will slow them down, and may thwart any race record this year.

 

Between Australia and New Caledonia

There are easterly winds east of 160E this week. Best departure is Monday, but even that will need to tack a lot.

A series of troughs are likely to cross the Brisbane area from Wed to Sunday, so may as well stay put and maybe look at a departure Monday/Tuesday 6/7 June.

 

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See my yotpak at boatbooks.co.nz/weather.html for terms used.

See my website http://www.metbob.com for information on tailor-made voyage forecasts

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