Followers

Translator

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

28 November 2021

Bob Blog 28 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 28 November 2021
REVIEW OF THE LAST MONTH (November 2021)

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

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.
The anomaly map shows there are now fewer lows forming around Australia than last month.
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
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
SPCZ=South Pacific Convergence zone.
The SPCZ is stretching from PNG across Solomon Islands and northern Vanuatu to Samoa and Tuamotu Islands.
a
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for your voyage, then check metbob.com to see what I offer.
Or Facebook at /www.facebook.com/metbobnz/
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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

21 November 2021

Bob Blog 21 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 21 November 2021

In the illustrated edition at
metbob.wordpress.com/2021/11/21/bob-blog-21-nov/ there are to screen shots
of EUMETSAT satellite imagery showing long lines of patterned cumulus,
chaotic cumulonimbus, and speckled squalls.

TROPICS
We are continuing with the typical mid-November hiatus with no cyclones
around at present.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is stretching from PNG across Solomon Islands and northern Vanuatu
to Samoa.
A convergence zone over French Polynesia by mid-week is expected to move
towards Niue late in the week.

HIGHS and LOWS
LOW L1 south of Rarotonga 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 faster than L1.
LOW L2 just south of Noumea tonight is expected to travel southeast to east
of NZ and then go east following the L1/H1 combo.
LOW L3 is just west of South Island tonight and expected to cross NZ on
Monday and then move off to the east southeast.
HIGH H2 is expected to move from Tasmania to central NZ by mid-week and then
go northeast, allowing LOW L4 to spread from inland Australia to Tasman
Sea/southern NZ by end of the week.
After L2 it looks Ok to sail westwards to Australia or southwards from Fiji
to Opua until around Wed 1 Dec.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for your voyage, then check metbob.com to see
what I offer.
Or Facebook at /www.facebook.com/metbobnz/
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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

14 November 2021

Bob Blog 14 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 14 November 2021

NZ immigration has reduced the required managed hotel isolation Q time from
14 days to 7 days for those flying in , and to 10 days for yachts with
time-spent-at-sea counting, so this will help those sailing into NZ from
overseas.
Tomorrow the South Indian Cyclone season nominally starts and lasts until 30
April 2022.
Last Wednesday the equatorial westerly winds in the Indian Ocean helped
produce a twinning of lows near 10degrees north and 10 degrees south

The Flooding of Australia
It has only taken a week and one muggy and windy low to bring wind and rain
affecting half of Australia as reported here
www.9news.com.au/national/weather-forecast-australia-eastern-states-brace-fo
r-second-day-of-heavy-rain-with-potential-of-more-flooding-and-hail/e61b0587
-f468-4334-b820-710b8645dec1

the Low broke many rainfall records, even Alice Springs got over 100mm in a
day, Perth got a double monthly average rainfall in one day and top weekly
accumulation was 440mm at Samuel Hill in coastal Queensland,

TROPICS
We are having the typical mid -November hiatus with no cyclones around at
present.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is stretching from PNG across Solomon Islands and northern Vanuatu
to Samoa.
A convergence zone over French Polynesia is expected to fade by mid-week.
A low, L3, is likely to form between New Caledonia and Fiji by Saturday and
then travel southeast to be east of the North Island by Monday 22 Nov.
Looks Ok to sail to NZ from the tropics this week or next week, but avoid
L3.

HIGHS and LOWS
HIGH H1 between Fiji and NZ is moving east along 32S.
LOW L1 980 in south Tasman Sea-the one that flooded much of Australia - is
travelling ESE across the south of NZ, making a zone of strong westerly
winds over NZ until Tuesday turning SW on Wednesday and Thursday.
HIGH H2 is expected to form east of New South Wales on Wednesday and then
travel east across the North Island on Friday.
LOW L2 is expected to be in the Australia Bite by mid-week, cross Tasmania
on Thursday and turn into a trough reaching the Tasman Sea to South Island
by Saturday.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for your voyage, then check metbob.com to see
what I offer.
Or Facebook at /www.facebook.com/metbobnz/
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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

07 November 2021

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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Blog Archive