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.
Compiled Sunday 28 November 2021
REVIEW OF THE LAST MONTH (November 2021)
Sea Surface temperature anomalies from http://www.ospo.noaa.gov/Products/ocean/sst/anomaly/index.html
Sea surface temperature in the eastern equatorial Pacific are showing the cool eddies of a LA NINA episode. This is surrounded by a C-shaped zone of warmth from north of Hawaii to Indonesia to south of Fiji. And there is now a warm zone from Madagascar to southwest of Australia.
To see how the annual weather cycle and the seasons are working out, we can check the average isobar maps for past 30 days and their anomaly from psl.noaa.gov/map/clim/glbcir.quick.shtml
Average isobars for past month (below)
Northern Europe is showing typical winter change with intensification of a High over China.
The southern hemisphere subtropical ridge is shifting south for the summer, most notably in the Australian bight.
Pressure anomolies for past month (below)
The anomaly map shows there are now fewer lows forming around Australia than last month.
Zooming into the NZ area
Last few weeks (below)
A month ago (above)
The main change in the past month has been the extension of the subtropical ridge southwards into the Australian Bight. Also, the 1010 isobar has shifted south and east from Indonesia to northern Australia and Samoa.
TROPICS
The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html
We are continuing with the typical November hiatus with no cyclones around at present.
Winter storm ARWEN has been bringing damage to UK with a northerly gale.
WEATHER ZONES
Weather Zones Mid-week GFS model showing isobars, winds, waves(magenta), Rain (Blue),
STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) and CAPE (in pink)
CAPE mid-week as seen by ECMWF and GFS from Predictwind.com, with vastly different ideas this week
SPCZ=South Pacific Convergence zone.
The SPCZ is stretching from PNG across Solomon Islands and northern Vanuatu to Samoa and Tuamotu Islands.
Rain Accumulation next five days from windy.com
HIGHS and LOWS
LOW L1 south of Tahiti is travelling SE and deepening, stealing the wind from the tropics and moving a convergence zone onto Tahiti by mid-week.
HIGH H1 east of NZ is moving east along 35to 40S west of L1.
LOW L2 in Tasman Sea is expected to travel across central NZ on Tuesday and then fade and get pushed off to the north.
LOW L3 is expected to develop around Tuvalu by mid-week and then travel southeast and deepen south of Southern Cooks by end of the week.
HIGH H2 is expected to move from Tasmania around southern NZ by mid-week and then go northeast, making a squash zone with L3
After L2 it looks Ok to sail westwards to Australia or southwards from Fiji to Opua until next trough arrives around Fri 10 Dec.
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If you would like more detail for your voyage, then check metbob.com to see what I offer.
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Weathergram archive (with translator) is at weathergram.blogspot.co.nz.
Contact is bob@metbob.com or txt 64277762212
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MetBob 
Hello, We love your service and used the weekly updates as we made our way from Panama to FP in 2020. We are now considering sailing from Tahiti to Panama. This route doesn’t show up on world cruising routes for obvious reasons but we need to get the boat back to the east coast of the US and are interested in this option. We are also considering Tahiti to Hawaii which would be a much longer route to get the boat back to the eastern US. We have a Lagoon 410 (catamaran) and would be looking for a weather router for the trip. Would you recomend the Tahiti to Panama route (north of the equator?) and be able to be our weather router should we take it. We would need to leave Tahiti in May due to visa issues. Any thoughts appreciated. Thanks, Jules Miller & Ken Johnson S/V Painkiller
Hi there Jules and Ken: I have routed a few yachts from Tahiti to Panama . There are usually some southerly winds along 2 to 5N so strategy is to go north from Tahiti to these then east to Panama , avoiding the ITCZ and counter currents. See
https://www.pitufa.at/oceanwinds/, adjust month at top right. Email me at bob@metbob.com closer to when about to depart. Bob