Bob Blog 7 Nov

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 07 November 2021

Note that FIJI is NOT changing to Daylight saving (had been planned 14 Nov
2021 to jan 16 2022). This was announced on 10 October However Microsoft may
not have enough time to implement this change in time, so if it affects you
and you have a device using Fiji time, then be aware that it may still
change to daylight saving on 14 Nov, and perhaps turn off "Adjust for
daylight saving automatically" in date and time settings.

Now that we are in the Cyclone season, interest is rising on when the first
cyclone may develop.

A good indicator to this is the MJO (Madden Julian oscillation). Named in
1971, when Roland Madden and Paul Julian discovered a pulse of extra energy
that travels east wards along the tropics from Indian Ocean to Pacific
Ocean. It is a regional scale coupling between atmospheric circulation and
tropical convection. It is known to increase the risk of cyclone formation
and can be tracked watching cloud and rain patterns.

A good site to see its extrapolated trend is
www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml, scroll down
to Ensemble map of the OLR (outgoing long wave radiation) anomolies. Here,
blue is bubbly and yellow is mellow. At present the next MJO is expected to
reach Papua New Guinea between 10 and 15 November and maybe weaken after
that. This is probably too early in the season to trigger anything.

These MJO pulses tend to be 4 to 6 weeks apart, so , with some hand-waving,
there is an indication of one around the end of December, and that is indeed
a time of moderate risk for cyclone formation.

Another site to check is the sophisticated modelling done by Meteo France as
shown on the New Caledonian weather web site at
www.meteo.nc/nouvelle-caledonie/cyclone/coin-des-experts. This shows the
results of a regression model using 2 predictors for the state of the MJO, 3
to measure ENSO and IOD, and one to measure the climatological seasonal
cycle.

This map shows that there is a slight increased risk of cyclone formation
around Western Australia between 21 and 27 November, but not by much.

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

WANDA is weakening and heading for Ireland. It is the end of this years
alphabet, and any more named features around North America this year will
come from a supplementary alphabet (from Adia to Will). There are potential
zones for formation west of Sumatra at 5N and 5S,

WEATHER ZONES
SPCZ=South Pacific Convergence zone.

The SPCZ is narrower than normal this week, mainly around Eastern Fiji and
Northern Tonga.
A convergence zone over French Polynesia is moving off to the east.
A trough between Fiji and east of New Zealand is expected to drift
eastwards.

HIGHS and LOWS
HIGH H1 was a blocking High last week at near 40S 160W and is expected to
weaken and go east this week.
LOW L1 has been trapped east of North Island for a few days and should peel
off to the southeast and east this week.
HIGH H2 west of South Island is expected to get south of Chathams by
mid-week then go east, followed by warm northerly flow over Tasman Sea and
NZ.
LOW L2 is forming off Sydney tonight and expected to deepen as it crosses
the Tasman Sea then go across the South Island by Friday, with associated
front crossing North Island and northern Tasman Sea on Saturday.
HIGH H3 should form over northern Tasman Sea later this week.
LOW L3 is expected to deepen off Sydney by Friday.
Avoid arriving in Northland on Sat/Sun 13/14 Nov
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If you would like more detail for your voyage, then check metbob.com to see
what I offer.
Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe
at bottom).
Weathergram archive (with translator) is at weathergram.blogspot.co.nz.
Contact is bob@metbob.com or txt 64277762212
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