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

15 November 2015

Bob Blog 15 Nov



Issued 15 November 2015

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.


Equatorial Twin tropical lows

There are no tropical cyclones at present, but two tropical lows are twinning near 170E.

In the north is 95W and this is expected to peel off to the west and then recurve before reaching Philippines.

And 93P in the south should travel south across Vanuatu this week then turn into a trough that is expected to reach Fiji to Minerva by Friday and maybe Tonga on Saturday. 


Weekly rain maps at show build ups of convection around India and in the South Pacific to north of Fiji.



SPCZ=South Pacific Convergence zone.

The main part of the SPCZ is expected to linger from PNG to Vanuatu and from Tuvalu to Samoa.  There is also likely to be some squally rain with the low /trough associated with 93P.


STR= Sub-tropical Ridge

The STR is stronger this week than last week with large slow-moving highs.

  One to NE of NZ on Sunday is expected to travel along 30S. Another is crossing Tasmania on Sunday night local and cross the Tasman Sea on Monday Tuesday, then NZ on Wednesday, and off to the NE of NZ from Thursday.


Over NZ/Tasman:

A weakening front is expected to cross northern NZ on Monday followed by a SW flow on Tuesday. Next front is expected to cross northern NZ on Friday followed by a weak ridge on Saturday and another front on Sunday 22 Nov. 


Travelling Tahiti to Marquesas. 

Easterly winds.   Active convergence zone with squally showers lies in-between.  


Between Tropics and NZ:

OK for departing from Fiji/Tonga early in the week, so long as you arrange arrival in NZ to avoid the front and SW winds expected on 22/23 Nov. 

After around Tuesday, take into account the track of that tropical low over Vanuatu. 

Its trough is expected to reach Fiji to Minerva by Friday, and the NE winds and squally showers that precede this trough may reach Fiji to Minerva by late Thursday.


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