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

31 October 2021

Bob Blog 31 Oct

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 31 October 2021

REVIEW OF THE LAST MONTH (October 2021)
Sea surface temperature in the eastern equatorial Pacific are showing the
coolness of an incoming LA NINA episode. This is surrounded by a C-shaped
zone of warmth from north of Hawaii to Indonesia to south of French
Polynesia.

Average isobars for past month :Northern Europe is showing seasonal change
with intensification of a High around Siberia. There is a noticeable
weakening of the southern hemisphere subtropical ridge over Australia. The
anomaly map shows there have been lows forming over eastern Australia.

Zooming into the NZ area
The lowering of pressure about and east of Australia is REMARKABLE, as has
been the amount of damaging weather there during October.

TROPICS
WANDA is zigzagging across the North Atlantic.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ stretches from PNG to northern Vanuatu, to Samoa and drifting
between Tuamotu Islands and Society Islands. A passing trough is expected to
visit Fiji mid-week.

HIGHS and LOWS
High H1 should linger near 35S 140-160W until mid-week then move off to
east.
Low L1 southeast of the South Island is expected to move off to the
southeast, allowing a strong cold southerly onto southern NZ on Monday.
Low 2 is expected to deepen to northeast of North Island by end of Tuesday,
bringing a strong SE flow over the North Island on Wednesday and Thursday.
High H2 east of New South Wales tomorrow is expected to travel southeast
towards Chathams by mid-week, combining with L2 to strengthen SE flow over
North Island.
Avoid arriving in Northland on Wed/Thu this week and on Friday 12 Nov.

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

24 October 2021

Bob Blog 24 Oct

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 24 October 2021

A DOUBLE DIP LA NINA LIKELY
We had a LA NINA episode last summer, and it now looks likely we are heading
for another LA NINA episode this coming summer.
See
www.scoop.co.nz/stories/WO2110/S00220/pacific-likely-to-experience-double-di
p-la-nina-episode.htm
for more details.
During a LA NINA the trade winds are stronger than normal, feeding
sun-drenched warm water westwards. This also increases the upwelling around
the eastern equatorial pacific (EEP), so that sea surface temperatures are
cooler than normal there.
The South Pacific Convergence zone SPCZ is likely to shift to south and west
of normal, from Coral Sea to northern Tonga to southern Cooks.

Having two LA NINA episodes in a row (a "double-dip" LA NINA0 is unusual.

TROPICS
RICK is intensifying and expected to make landfall over west coast of Mexico
on local Monday.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ stretches from PNG to Tuvalu to Samoa and drifting from Society
Islands to Southern Cooks.
Good trade winds over South Pacific this week.

HIGHS and LOWS
Trough over northern NZ tonight should fade away on Monday.
High H1 has been lingering over Chathams area for a few days and should
travel slowly northeast this week.
Low L1 east of Tasmania is expected to travel east reaching central NZ by
Thursday then northeast across the North Island on Friday, following H1.
High H2 is expected to travel NE to east of South Island late in the week,
following L1.
High H3 is expected to travel east across the northern Tasman Sea from
Tuesday to Saturday.
Low L2 is expected to travel southeast over Tasmania on Friday.
Avoid arriving at Opua on Monday 1 Nov due passing trough followed by
southerlies, or on Wed 3/Thursday 4 Nov due possible strong easterly winds.

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

17 October 2021

Bob blog 17 Oct

Bob McDavitt: 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 17 October 2021

South Pacific coming Cyclone season Nov 2021 to April 2022.

During the past week NIWA and MetService of New Zealand, along with BoM from
Australia, issued a combined news release giving their outlook for the
coming South Pacific Cyclone season.

For details see tinyurl.com/SouthPacificOutlook2022

In summary, the agencies say there is a good chance that we will be having a
LA NINA episode during next six months. NOAA have already declared this to
have developed along with an 87% to continue into February 2022 (see
tinyurl.com/NCEPENSO).

Combine this with recent Sea surface temperature anomolies across the South
Pacific, and it is logical to forecast that the South Pacific Convergence
zone SPCZ is likely to be south and west of its normal position , enhancing
the cyclone risk for western countries and reducing the risk east of the
dateline.

From around 50 years of data, 6 analogue years with similar La Nina and Sea
surface temperature coupling were picked, Showing the first cyclones may
form around New Caledonia and Queensland coast, and later in the season the
zone from Queensland coast across the Coral Sea to between Vanuatu and Fiji
may be favoured.

Looking at atmospheric dynamics combining several models shows the outlook
for isobar anomolies from Jan to Mar 2022 Indicates lows are likely to
develop or deepen between New Caledonia and New Zealand.

And the forecast rain map for January to March shows the South Pacific
Convergence zone from Coral Sea to northern Tonga, with a finger towards
northern New Zealand.

In summary, the expected number of cyclones over the South Pacific is
between 9 and 12, slightly above normal:

A passing MJO (Madden Julian Oscillation = burst of tropical convection that
travels eastwards from Indian Ocean to Pacific Ocean around once a month) is
likely to provide us with times when risk of cyclone formation may peak.

TROPICS
NAMTHEUN is weakening over the open ocean in the far north Pacific.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ stretches from PNG to Tuvalu to Samoa and may visit Tahiti this
week.
Active trough over southern Cooks is expected to linger near Tahiti from
mid-week and form L2 that should go off to the SE
Active trough is expected to form over New Caledonia from Mid-week and
develop L4 near 40S/New Zealand.

HIGHS and LOWS
L1 about southern NZ tonight and associated trough over North Island
travelling off to the southeast followed by a west to southwest flow.
High1 east of NZ is expected to travel off to the east along 40S by
mid-week.
L3 is expected to travel northeast out of the Southern Ocean to 35S in the
wake of H1.
High2 should reach South Tasman Sea by Wednesday and travel east along 45S
to be near Chathams by the weekend.
After Wednesday, L4 complicates trans-Tasman travel, and L4 and H2 should
produce a NE flow between Fiji and NZ.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

10 October 2021

Bob Blog 10 Oct

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 10 October 2021

Bureau of Meteorology outlook for coming cyclone season around Australia
From tcoutlook.com/australia/latest-outlook/
Predictors
Recently ENSO has been neutral. Models are now indicating a 67% to 87%
chance of a LA NINA episode from Nov 2021 to Jan 2022neutral conditions. La
Nina typically results in increased cyclone activity in Australia and in the
South Pacific west of the dateline.

In spite of this, the Long-Range Tropical Cyclone Outlook for Australia
(TCO-AU) suggests near-normal cyclone activity around Australia for the Nov
2021 to April 2022 period, with between 8 and 13 cyclones.

TROPICS
TC LIONROCK has been crossing the China Sea and may make landfall onto north
part of Vietnam. KOMPASU has formed east of Manila and is expected to affect
northern Philippines. NAMTHEUN has formed around Micronesia and is expected
to curve off to the northeast.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is less active but more spread out than last week.
Active trough between Fiji and Samoa on local Monday is expected reach
Southern Cooks by local Tuesday with Low L1 near 25S and this then moves off
to the southeast leaving a large lull in its wake.

HIGHS and LOWS
High1 north of NZ on Monday is expected to travel northeast to 25S and then
east maintaining a lull in the wake of L1.
Low L2 is expected to form south of NZ in a trough crossing the South Island
on Monday and then deepen to 980 east of South Island on Tuesday/Wednesday
feeding polar chilled southerly winds onto NZ, then moving off to the east.
High H2 should follow L2 and then travel NE of NZ by Saturday, providing
good conditions for arriving in Opua early next week.
Low L3 is expected to travel east across Bass Strait and into the southern
Tasman by the end of the week.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

03 October 2021

Bob Blog 3 Oct

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 03 October 2021

REVIEW OF THE LAST MONTH (September 2021)
Sea surface temperature continue to get cooler than normal around the
eastern equatorial Pacific, and that's a hint to a possible LA NINA episode
for the coming cyclone season. A warm pool is starting to build in the
central South Pacific and that may help to tug the South Pacific Convergence
zone eastwards towards French Polynesia.
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
It's up and down: In the Pacific the northern subtropical ridge has
weakened, and the southern subtropical ridge has intensified near south
America. The southern subtropical ridge has intensified in the Indian Ocean
and weakened in the Atlantic.
The anomaly map shows more HIGHS east of r NZ and lower pressures along 50S
from south of NZ all the way to south of Africa, and that increases the
westerly flow along 45 to 50S.
The drop in pressure over inland Asia is interesting.
Zooming into the NZ area shows the 1015 line shifting south over northern
Australia and north over NZ, indicating spring is in the air with lulls in
the wind over Timor Sea and increased westerly winds over NZ.

TROPICS
There are still some areas of high potential for formation around
Philippines. TC SAM and VICTOR are in the North Atlantic, and SHAEEN-GU is
about to make landfall on northern Somalia.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ is more active than last week especially from Vanuatu to Fiji until
midweek and then from Solomons to Samoa and over French Polynesia by the
weekend.

HIGHS and LOWS
High1 to east of NZ is expected to travel east along 35S maintaining a good
SE flow between Tahiti and Tonga until mid-week.
Trof1 is expected to cross New Zealand on Monday and move off the southeast.

Low1 is expected to form off Sydney by late Monday and travel SSE to south
of NZ late in the week followed by another trough reaching NZ by Saturday
and a more active Low by Mon 11 Oct.
Low2 is expected to form south of Tahiti late in the week and move off to
the south
Trough2 is expected to cross the northern Tasman Sea on Tuesday. New
Caledonia on Wednesday and Tonga on Friday, leading in High2.
High2 is travelling east across Australia along 30S and should cross the
Tasman Sea along 30 to 35S from Wednesday reaching northern NZ by the
weekend.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

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