Bobgram

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 29 December 2024

Happy New Year (mid-week)

Olde Lang Syne was written by Robbie Burns in 1788, one of the verses
reflects with melancholy on the various voyages done together (in the
past year), and the inverse of that is a joyful look ahead to the
voyages that may come our way in this coming year
An apt way to "toast" in the New Year

However, the seas "roared and swelled" almost every other month last
year
Here is a recap of the top six cyclones

MAY Cyclone Remal left 84 people dead in eastern India and Bangladesh
as one of the longest lasting such storms on record there.

JULY Category-5 Hurricane Beryl ravaged Grenada on July 1. It later
struck the Yucatan Peninsula and Texas coast as a much weaker storm.
At least 18 people were left dead in its wake.

SEPTEMBER Hurricane Helene killed 234 people and unleashed
catastrophic flooding in Florida, Georgia and North Carolina.

OCTOBER Helene was quickly followed in early October by Category-5
Hurricane Milton, which ravaged Florida as the second strongest ever
recorded in the Gulf of Mexico and the strongest worldwide for 2024.
Milton left 35 dead. . T

NOVEMBER The Philippines was ravaged by six consecutive typhoons in
less than a month, punctuated by Typhoon Man-yi.

DECEMBER Category-4 Cyclone Chido left hundreds dead as it devastated
the French territory of Mayotte in the Indian Ocean mid-December. It
then killed at least 42 others in Mozambique and Malawi.

TROPICS
That Low which was in the Coral Sea last weekend failed to deepen into
a named cyclone. However, the weather map shows that the South Pacific
Convergence zone remails active from northern Coral Sea to norther
Vanuatu. It also still carries a depression near Fiji, L1. This
depression is moving east. It is also ingesting dry southwest winds,
so not expected to develop. By mid-week another depression L2 is
expected west of Vanuatu and then hovering over the Vanuatu area until
next week. There is LOW chance this system might develop into a small
cyclone. Avoid Vanuatu/Fiji area this week.

WEATHER ZONES
The South Pacific Convergence zone is active and broad and extends
from New Guinea to Austral Islands spreading onto Society Islands at
times. Avoid.
The MJO is now fading and moving away, so SPCZ should relax over next
few weeks.

LOWS and HIGHS
Subtropical Low s L1 and L2 are expected to hover near Fiji and
Vanuatu this week.

Low L3 is expected to remain slow moving east of New Zealand,
maintaining mainly a SW flow over New Zealand and as far north as 30S
between NZ and Fiji. It may become multi centred and another Low from
the SW is expected to cross the South Island on Thursday.

HIGH H1 should spread from Tasmania into central Tasman Sea by
Wednesday and then fade in northern Tasman Sea. Another HIGH is
expected to spread into central Tasman Sea by Friday and then hover
there until next week.

Low L4 is expected to remain over inland Australia.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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Weathergram archive (with translator) is at
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>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 22 Dec

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 22 December 2024

Seasons Greetings

Sydney-Hobart 1998
A storm formed in Bass Strait during the Sydney-Hobart 1998.
Six sailors died, 70 were injured.
The weather maps as shown at
journals.ametsoc.org/view/journals/wefo/15/5/1520-0434_2000_015_0543_t
abdso_2_0_co_2.xm

The report of the court of Inquiry makes interesting reading
at
www.ussailing.org/wp-content/uploads/2018/01/Sydney-to-Hobart-Race-Cor
oners-Report-1998.pdf

With comments such as
"It's going to be a shit fight in Bass Strait" on page 68

This is a storm that changed the way marine forecasting is done.
From the Court of Inquiry report, recommendation Number 6 on page 21
(for Category One Yacht races) was as follows

6) THAT WEATHER FORECASTS WHICH ARE SPECIFICALLY PROVIDED FOR YACHT
RACING FLEETS CONTAIN:-(a) AS WELL AS THE AVERAGE WINDS EXPECTED, THE
MAXIMUM GUSTS OF WIND THAT ARE LIKELY TO OCCUR; AND (b) AS WELL AS THE
SIGNIFICANT WAVE HEIGHTS EXPECTED, THE MAXIMUM WAVE HEIGHTS THAT ARE
LIKELY TO BE ENCOUNTERED.

Ever since then all marine forecasts issued by the Bureau of
Meteorology in Australia carry a disclaimer:


As for this year's Sydney to Hobart starting on Thursday:
For starters there is expected to be an increasing Northeast wind
making for fast and furious conditions for the maxi Yachts. Then there
is potential for some nasty weather ahead for the majority of the over
100 vessel fleet. A change is being forecast on Friday which could
whip up testing conditions - including 35 plus knots of wind and 4m
seas in Bass Strait.

TROPICS
Hundreds were feared dead after the eye of Category-4 Cyclone Chida
made a direct hit on the impoverished French overseas territory of
Mayotte in the western Indian Ocean. Officials said 90% of the island
nation's buildings were destroyed. Chida went on to leave dozens dead
in Mozambique and neighbouring Malawi.

There is a convective complex in the Coral Sea which is forecast to
deepen on Monday and then weaken on Tuesday then swing off to the
southeast towards Raoul Island.

This system may briefly be named as a tropical cyclone.


WEATHER ZONES
The wind accumulation shows that mid-latitude Low L3 has more wind
than tropical Low L2. Subtropical Low L1 has strong NW winds on its
eastern side. The spot value off the Eden corner this week has a
maximum of 55kt for the Sydney-Hobart.

The South Pacific Convergence zone extends from PNG to South of Tahiti
and is very active this week thanks to an active MJO.

LOWS and HIGHS

Subtropical Low L1 is expected to form south of Niue on Monday out of
a thundery trough that crossed NZ this weekend.

Tropical Low L2 is expected to deepen in Coral Sea on Monday then
travel Se towards Raoul Island and weaken. It might briefly be named
as a tropical cyclone and is expected to bring strong winds and heavy
rain to Vanuatu mid-week.

Low L3 is expected to deepen off New South Wales on Monday and then
travel east along 40S, building a southerly swell over 6m in
mid-Tasman by mid-week. It should then cross central NZ on Boxing Day
and merge with L2 east of NZ continuing east along 40S into next week.
Avoid.

HIGH H1 should form off New South Wales mid -week and move into
central Tasman Sea following L3. It has strong NE winds on its western
side and is expected to be followed by a strong trough reaching Bass
strait early Friday, in time to affect the Sydney-Hobart fleet.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 15 Dec

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 15 December 2024

The incoming MJO

For a MJO forecast see www.cpc.ncep.noaa.gov/
The (bubbly) blue areas are associated with extra convection and the
(mellow) yellow areas are associated with supressed convection
So, this forecast indicates an increased risk for tropical cyclone
formation over the Pacific Ocean during the next two weeks

TROPICS
Cyclone Chido spun up over the Indian Ocean and then clipped the
northern tip of Madagascar at near Category-4 force.
This week there is a thundery westerly flow over the sea off Northern
Australia.
MJO is now travelling eastwards across Indonesia and northern
Australia

WEATHER ZONES

The wind accumulation shows a zone of green over most of the tropics,
good for sailing. However, there are some red windy areas across
Northern Australia and in the Coral Sea due to extra convection. Also,
there are strong winds around the lows near 30S and in

The South Pacific Convergence zone extends from the Solomon Islands to
Samoa to the Southern cooks and is intensifying. There is also extra
convection expected over the seas of Northern Australia and in the
Coral Sea. This can be attributed to the incoming MJO A Low is likely
to form in Coral Sea area around mid-next week.

We start the week with L1 995hPa SW of Rarotonga

High H1 is located to southeast of L1 and expected to move off to the
SE.

Then on Monday L2 is expected to form near 30S between Fiji and NZ.

By Mid-week L2 is expected to deepen to below 985 t NE of NZ and go
south, whilst L1 travels SW and is absorbed by L2

Also, by mid-week a Trough and Low L3 should form in south Tasman Sea
and then travel across South Island over the weekend,
followed by H2 early next week.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 8 Dec

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 8 December 2024

This stuttering LA NINA

The sea service temperatures in the eastern equatorial Pacific are
slightly cooler than normal and holding steady at around -0.4C
off-normal, but are NOT expected to cool far enough to produce a full
blown La Nina.

BoM data from late November shows a plume of expected predictions from
several models, but only a few of them break the -0.8C threshold, and
most show a relaxing of conditions after end of January.

It now seems likely that this LA NINA event is a weak one and is
having minimal impact on weather as compared to previous episodes.

TROPICS
FENGAL tracked across Sri Lanka and Southern India last week.

No cyclones are around at present.

MJO is now travelling eastwards across Indonesia and northern
Australia.

WEATHER ZONES
The wind accumulation shows a couple of windy fronts near North
Island, NZ, this week and windy conditions generally south of 40S. The
tropics look OK except for strong winds and heavy around Niue and
Southern Cooks associated with a tropical depression late in the week.

The South Pacific Convergence zone extends from Northern Vanuatu to
north of Samoa to an active region over Southern Cooks Tropical Low L2
is expected to deepen and travel SE of southern cooks by end of week.
Another low L3 may form over New Caledonia area late in the week and
travel southeast crossing North Island around Sunday 15 Dec.

When the MJO starts arriving over north Australia and into the Pacific
over the next few weeks, more active tropical weather is likely.

HIGHS and LOWS

This is a good week for a NW steering field on our weather features.

HIGH H1 may stay quasi stationary well to southeast of Tahiti. The
HIGH H2 east of NZ should travel southeast well east of NZ this week.

The trough crossing NZ tonight and Monday is expected to peel off to
the southeast next few days.

Low L1 should travel off the heat trough over central Australia and
form near Lord Howe by Wednesday then travel weaken into a trough
crossing NZ on Thursday.

HIGH H3 should be over Aussie Bight by Wednesday and into central
Tasman Sea/ Southern NZ area by Saturday.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 1 Dec

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 1 December 2024

A review of last month's weather

Here is a link to a YouTube clip giving an animated loop of the
isobars and streamlines in the South Pacific for the last month at
youtu.be/O1igNpEvKxs

November was dominated by large HIGHS travelling east across the South
Pacific. Some going around northern NZ maintaining a zone of light
winds near 30south, and some going around southern or central NZ.
Between the Highs there were troughs, with cloud bands that lingered
in a frontal graveyard near 20 to 30 South.

Over Australia front often acted like an atmospheric river taking
moisture from far north to central areas.

The Kuroshio current continues to feed warm seas across the North
pacific,

And the weaker cool tongue along the Pacific equator is a sign that
the incoming La Nina.

Average isobars for past month are at
www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html

The subtropical ridge in the Southern hemisphere has strengthened and
shifted south.
An interesting hollow of low pressure is sitting over the
warmer-than-normal waters around the Aleutian Islands in the North
pacific.

The anomaly pressure pattern for November shows the dominant HIGH over
NZ.
North America has become a breeding ground for lows.
Locally, The northern 1015 line is drifting south across Australia.
The 1020 isobar has expanded.

TROPICS
FENGAL formed over the Bay of Bengal near Sri Lanka and is bringing
locally heavy rain and strong winds to India's Tamil Nadu and Andhra
Pradesh states. EROBYN is in south-central Indian Ocean

WEATHER ZONES
The wind accumulation shows the light wind zone along 30 to 35S for
the subtropical ridge. North of that are the trade winds, with a
squash zone near 20 to 25S south of Fiji and Tonga associated with a
small low L1. South of the subtropical ridge are the strong winds of
the disturbed westerlies.

The South Pacific Convergence zone extends from Solomons to Samoa to
northern Cooks. Associated convergence zones extends from New
Caledonia to Fiji across part of Tonga to Niue and then off to the
southeast.

The MJO is moving across the Indian Ocean this week, and that means
the SPCZ should remain quiet this week. However, it is likely to
activate between mid and late December.

HIGHS and LOWS

HIGH H1 east of NZ is moving off to the east

Tropical trough/low L1 id expected to form south of Fiji on Monday and
travel slowly southwest on Wednesday and then to the southeast and
fade. There is a zone off light winds on the north side of L1.

Low L2 is crossing Tasmania on Tuesday and NZ on Thursday and Friday,
followed by H2.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 24 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 24 November 2024

NIWA'S climate outlook for next three months for South Pacific

FROM A NEUTRAL NOVEMBER TO A LA NINA IN DECEMBER
These notes come from NIWA at their web site at
https://niwa.co.nz/climate-and-weather/island-climate-update
Quote >>>>>
There is a 60% chance that La Niña will develop by January 2025. Tropical Pacific trade winds will continue to push the ocean in a La Niña-like direction during December.
As of 19 November, the traditional 30-day Niño 1+2 Index anomaly was -0.12˚C, within the neutral range. The 30-day NINO3.4 Index anomaly (in the central equatorial Pacific) was -0.22˚C, also in the neutral range.
An alternative measure of central Pacific SSTs, called the relative oceanic Niño Index, has had an average anomaly of –0.84˚C over the last 30 days (to 19 November) and is more aligned with La Niña-like oceanic conditions.
The Southern Oscillation Index (SOI) was in the neutral range during September-November (+0.1), while the November value was -0.1 (in the neutral range), a decrease since last month.
The subsurface equatorial Pacific continues to be 2˚C to 4˚C cooler than average just below the surface in the east of the basin.
Above average upper oceanic heat content continues in western parts of the Pacific basin. The West Pacific Warm Pool is continuing to become more unusually warm, which is also reflective of the potential development of La Niña.
The South Pacific Convergence Zone was located slightly south of its climatological normal position during November.
During December-February, model guidance favours an enhancement in convective forcing over the western Pacific and Maritime Continent, consistent with a developing La Niña. This may lead to enhanced rainfall for some countries such as Palau, Federated States of Micronesia, Marshall Islands, and southern Papua New Guinea east to Fiji
Tropical cyclone season continues through April 2025. While no activity is forecast in the short-term, it is important to remain vigilant and prepared as tropical cyclone season is now underway.
End quote>>>>>>>>>>>>>>>>>
A LA NINA episode shifts the South Pacific convergence zone southwards, as shown in the expected rainfall map for the next few months

This shows the wettest area in the southern hemisphere, a proxy for the heart of the South Pacific Convergence zone, to be New Caledonia and south Vanuatu to Fiji.
So, the "juiciest" latitudes are likely to be between 15 and 20S, and cyclones forming in that latitude belt might not have enough time to mature before leaving the tropics.

TROPICS

Finally, the recent brush of cyclones seems to have come to an end.
Recently, at least 10 people died in storm-related accidents in the northern Philippines as Typhoon Man-yi became the sixth consecutive tropical system to hit the country in less than a month. Man-yi was also one of four November cyclones to exist simultaneously in the western Pacific—the first such occurrence since records began in 1951. • Tropical Storm Sara left at least four people dead from flash flooding across Nicaragua and Honduras. • Former Category-4 Cyclone Bheki skirted Mauritius and Réunion as a tropical storm.

The MJO, which boosts tropical activity is expected to make its way across northern Australia in early December and then into the Pacific by mid-December. This is likely to increase the risk of cyclone formation.
For a Time -Longitude prognosis from https://www.cpc.ncep.noaa.gov/



WEATHER ZONES
The wind accumulation shows a calm zone near northern New Zealand associated with the subtropical ridge. Also, it shows windy zones associated with lows L1, L2 and L3.
The South Pacific Convergence zone has a northern branch which extends from Solomons to Samoa to Northern Cooks, and a southern branch associated with Low L1 south of Tahiti and Low L2 near Fiji.
HIGHS and LOWS
HIGH H1 is staying quasi stationary near 40S well to southeast of Tahiti., with a subtropical Low L1 on its western shoulder.
HIGH H2 is up and down in strength and is quasi stationary to northeast of NZ with a strong ridge into the Tasman Sea. This should keep troughs away from northern NZ this week. It has a Low L2 on its NW shoulder forming near Fiji mid-week. As L2 come south its will be pushed by upper winds towards the west.
Low L3 I expected to cross the Aussie bight during the week and end up this weekend as a trough in South Tasman Sea.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram

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.

Minerva reefs

The Minerva reefs are found two days sailing southwest of Tongatapu,
or a quarter of the way to New Zealand. They are a popular staging
ground for yachts, a place to stay while waiting for the weather to be
agreeable for sailing on to New Zealand. As I write this there are a
dozen vessels waiting in the North Minerva reef. It has the added
attraction of being around 23:40degress south, so it is just south of
the Tropic of Capricorn (23 degrees 26 minute 22 seconds south), and
so it "outside the tropics".

On the Flotsam page of Gulf harbour Radio
www.ghradio.co.nz/flotsam.html is an article written by Rich and
Michelle on SV Pogeyan. This amazing article describes what they have
learned over many visits and weeks exploring both North and South
Minerva. Rich has given me permission to share some of the article
with you here, and I recommend that you go to the Gulf harbour radio
web site to read the rest.

Republic of Minerva Ruins

The Wikipedia article for Minerva Reefs provides a summary the
misguided attempt by Michael Oliver (born Moses Olitsky) to create his
own idea of a Libertarian paradise at Minerva North reef. For an
in-depth account of the whole strange affair, see "How to Rule Your
Own Country" by Harry Hobbs. In 1971, Oliver's shell company, called
Ocean Life Research Foundation, transported barges of sand from Fiji
with the goal of raising 2000 acres above the high tide line. After
building some concrete structures and covering 7 acres with sand, they
ran out of money AND attracted the attention of the neighbouring
Pacific Island nations - especially Tonga. Within a year, Tonga
destroyed all the work and built their own "permanent structure above
the tide line". At that point Tonga declared the reefs to be their
territory. Some of the sand appears to remain at the Southwest corner
of the reef and forms large sand bars that dry out at low tide.
There's also a building foundation and several huge chunks of concrete
that appear to be the result of the Tongan demolition work.


TROPICS
A seemingly never-ending parade of powerful typhoons continued to
batter the northern Philippines for a second consecutive month, with
Yinxing and Toraji being closely followed by Category-4 Usagi.
Strengthening Tropical Storm Man-yi to the east was predicted to
strike with hurricane force during the following weekend. The cyclones
have flooded villages and caused extensive damage to homes and
infrastructure and have killed at least 151 people.

SARA is about to cross the Yucatan peninsular.

BHEKI is in the South Indian Ocean

The MJO, which boosts tropical activity is also in the Indian Ocean
this week.



WEATHER ZONES


The wind accumulation shows a calm zone in the North Tasman Sea,
showing the main position of the subtropical ridge. Further north
there is a squash zone of enhanced trade winds in the Coral Sea and
around Vanuatu.

The South Pacific Convergence zone extends from Solomons to Samoa and
then southeast to Southern Cook Islands. It occasionally shifts south
across Fiji and Tonga.

A Low is expected to form near 25S 140W on the SPCZ and then deepen as
it goes south.

The MJO is now in the Indian Ocean, and that means the SPCZ is rather
weak for a while the week or two. However, SPCZ is expected to shift
south over Tonga this weekend and maybe form a tropical Low there
around 20 November, perhaps.

HIGHS and LOWS

There is a Low L1 forming on Monday between Fiji and NZ and this
should move off to the southeast to east of NZ. This system maintains
southerly winds between Fiji and NZ until Wednesday. Avoid.

HIGH H1 over southern NZ is expected to travel off to the east along
45S allowing L1 to drift south along its western side. Then L2 can
travel eastwards across NZ on Thursday

HIGH H2 is expected to travel slowly Northeast across the Tasman
reaching northern NZ this weekend.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram

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 November 2024

COP29

The 29th session of the Conference of the Parties to the United
Nations Framework Convention on Climate Change is being held from11 to
22 November at BAKU Stadium in Azerbaijan.

COP meetings are where governments assess global efforts to advance
the Paris Agreement attempting to limit global warming to 1.5°C as
informed by the latest science. At COPs, world leaders come together
to measure progress and negotiate the best ways to address climate
change. There are now 198 Parties (197 countries plus the European
Union) to the Convention, constituting near universal membership.
A graph at carbonbrief.org shows that the world leaders have a tough
job, since the past 13 months have all been above that 1.5degree
threshold.
Considering the downpours that the northern hemisphere has been
delivering over recent weeks it seems that the atmosphere seems to
have access to extra energy to feed the storms.


TROPICS


Typhoon Kong-rey drenched coastal areas of East China and southern
Japan after leaving two people dead in Taiwan. In its wake are TORAJI
and MAN-YI
• The far northern Philippines was lashed by Category-3 Typhoon
Yinxing, which was the third such storm to strike Luzon Island in less
than a month.
• Jamaica, the Cayman Islands and western Cuba were lashed by
strengthening Hurricane Rafael,
*Tropical Storm Patty formed briefly near the Azores.

WEATHER ZONE
The wind accumulation shows calm zones along 30 to 35S, showing the
main position of the subtropical ridge. Further north there is a
squash zone of enhanced trade winds from the Cooks to Tonga along
around 18S. Avoid.
The South Pacific Convergence zone extends from Solomons to Samoa and
then southeast to Southern Cook Islands. It occasionally shifts south
across Fiji and Tonga.
The MJO is now in the Indian Ocean, and that means the SPCZ should
weaken over the week or two. However, SPCZ is expected to shift south
over Tonga this weekend and maybe form a tropical Low there around 20
November, perhaps.
HIGHS and LOWS
There is a Low L1 east of NZ and well south of Tahiti moving slowly
off to the SE
There is a left-over trough south of 30S and northeast of Northland
tonight.
This lingers there as a HIGH H1 now in the Tasman Sea travels east
across central New Zealand this week and then off to the northeast.
Heat trough over inland Australia is expected to form a deepening LOW
L2off Sydney on Tuesday and this should then travel southeast across
southern NZ late in the week, bringing another dose of heavy rain to
Southern Alps.
Between H1 and L2 a strong NE flow should form south of 30S with a
warm front crossing Northland on Friday and Saturday. Avoid.
There maybe a LOW forming near Northland after that front bring
unsettled weather there early next week. This is still uncertain but
might be worth avoiding getting south of 30S to NZ from 17 to 18
November.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 3 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 3 November 2024

A review of last month's weather

Here is a link to a YouTube clip giving an animated loop of the isobars and streamlines in the South Pacific for the last month at youtu.be/H1hRtFYQbvQ

The main pattern for October was a procession of HIGHS travelling east along around 25 to 35S followed by a trough or two, sometime three with disturbed westerly wind south of 40S. Early in the month a low was blocked in the Tasman Sea so that rain clouds were held in place with a fetch of moist air from the subtropics onto Dunedin, producing severe flooding.


Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
The Kuroshio current is feeding warm seas across the North pacific,
And the weaker cool tongue along the Pacific equator is a sign that the incoming La Nina.

Average isobars for past month From http://www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html
The subtropical ridge in the Southern hemisphere has weakened and is starting to drift south.

Pressure anomalies for past month

The anomaly pressure pattern for October shows lows in the southern hemisphere breeding in the south Indian Ocean and around southern South America.

The northern 1015 line is drifting south across Australia.
The 1020 isobar has shrunk.

TROPICS
Super Typhoon Kong-rey killed at least one person as it slammed into Taiwan with winds of up to 125 mph as a Category-3 tropical cyclone. It was the largest such storm to hit the island since Typhoon Herb in 1996.

* Late reports from the Philippines say floods and mudslides from Tropical Storm Trami killed at least 136 people before the storm later doused central Vietnam.

* Cyclone Dana uprooted trees, snapped power lines and caused local flooding as it made landfall in India's Odisha and West Bengal states.

PATTY is heading for Portugal

WEATHER ZONES

The wind accumulation shows the light wind area in north Tasman Sea from Brisbane to Auckland and several windy zones around the low south of Tahiti in the coming

The South Pacific Convergence zone extends from Solomons to Fiji/Samoa and then southeast to Southern Cook Islands. It is expected to shift south across Tonga between Wednesday and Friday.

The MJO is reforming in the Indian Ocean this week, and that means the SPCZ should weaken over the week or two. However, it starts off this week as a strong and broad feature.

HIGHS and LOWS

Front that travelled east past NZ on Saturday is expected to mix cold air with most warm air and form a LOW L1 south of Niue and east of NZ by Monday. L1 then deepens and moves slowly east. Accompanying trough is expected to travel east from Cooks to Tahiti.

HIGH H1 is moving over NZ early this week and then travelling east along 35S following L1.

It is followed by a moist NW flow in the Tasman Sea. The trough following this NW flow is expected to cross Northland on Sun 10 November, and then the models differ over the details.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 27 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 27October 2024

Palolo Rising

Mid last week on24 October, on the last quarter of the October moon,
the tides are just right for the palolo coral warms to break off their
eggs and sperm sacs so that they float out of the coral reefs in a
swarm to fertilize their new generation. Several Pacific Islands
gather in the early morning in their lagoons to gather a feast of this
caviar,

Even though this annual delicacy could have been made available for
the CHOGM 2024 dinner in Samos this weekend, it didn't feature.

A little bird tells me that King Charles III enjoyed seasonal produce
throughout the meal, set to include a salad of marinated local
vegetables with lopa beans, carrot, and watercress hummus.

The King and Queen dined on line-caught red snapper, wilted laupele,
breadfruit fondants, and confit tomatoes. For dessert, attendees to
the dinner had coconut jam cheesecake, fresh mango, and papaya, along
with Samoan vanilla ice creams.

WATHER ZONES

A MJO event is now moving into the Pacific and boosting the ITCZ near
Micronesia. One yacht at 3S on the north coast of New Ireland has
witnessed two occasions of equatorial westerly winds that, around
25kt. These have NOT been picked up by the models.

The South Pacific convergence zone SPCZ extends from Solomons to
Northern Vanuatu and a boost of squally showers is expected to form
over Vanuatu on Tuesday and then travel southeast to the Minerva area
on Wednesday then further southeast and may form a low near 40S on
Thursday .

HIGH H1 is moved over northern NZ late last week, followed by a front
this weekend. This system is moving steadily off to the east past this
week, and the lows over southern NZ and moving off to the south.
leaving a disturbed westerly flow over northern NZ.

A new LowL1 is expected to travel quickly along 50S to be near central
NZ by Tuesday night with associated trough crossing Northland. Avoid.

Later in the week HIGH H2 I expected to travel east across the Tasman
Sea along 30S producing a large calm area, not good for sailing. And
next weekend this may be followed by another HIGH H3along 30S. So
early next week when H3 departs to the east there may be a good
pattern from getting from the tropics to NZ in the northerly on the
back of a HIGH.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 20 Oct 2024

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 20October 2024

The Greening of Antarctica
Antarctic Peninsula is greening at an increasing rate , mainly due to
the growth of mosses
As seen at www.nature.com/articles/s41561-024-01564-5


TROPICS
My normal sources are out of date today, so this is a snatch from
Windy.com (thanks) showing Nadine over southern Mexico and Oscar to
northeast of Cuba.

WATHER ZONES

The wind accumulation shows several zones of strong wind this week
from L1 and L3 .
Also some nice green areas west of New Caledonia and between Fiji and
New Zealand.

A MJO event is expected to move into the Pacific over the next few
weeks. This MIGHT help trigger a cyclone near Philippines (there is a
depression there mow), but us probably too early in y=the season to
trigger a cyclone in the South Pacific. The next MJO evet is due
around early to mid-December so that maybe delays the start of our
cyclone season.

The South Pacific Convergence zone is building and expected to send a
dose of squally showers to northern Vanuatu on Wednesday, Fuji on
Thursday and Tonga on Friday. However, the activity stays mainly aloft
this week, unlike the activity last week which formed a low L1 last
few days near Minerva. This low is now travelling off the SE, allowing
the HIGH H1 in the south Tasman Sea to spread onto northern NZ by
mid-week and then move off to the east after Thursday.

The Low L2 now stalled near Lord Howe Island is losing its upper
support and is expected to travel NE and fade away.

It has "stolen" the isobars wets of New Caledonia, making a large lull
zone there, but this should be replaced by SW winds on the back side
of L2.

Low L3 os currently over the hot interior of Australia and expected to
eek its way across the coast and into the Tasman se on Thursday,
creating a southerly buster along the east coast (avoid).

L3 is expected to deepen as it crosses central or southern NZ between
Friday and Sunday. Just in time to ruin our long holiday weekend.
Associated FRONT expected to cross Northland around Friday night
(avoid arriving in Northland then) ,in time to interfere with our
COASTAL CLASSIC yacht race from Auckland to bay of Islands.

This race may well be bigger than usual this year since Team NZ won
again the Americas Cup last night.

After L3 moves off around Mon 28 oct, a new HIGH H3 is expected to
follow it across Tasman Sea and onto NZ. This may keep the next trough
away until around 31 Oct /

.

Travelling to Australia: Avoid L3 and its southerly buster on Thursday
and Friday.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 13 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 13 October 2024

Southwest Pacific Tropical Cyclone Outlook – October 2024

The NIWA and MetService assessment of tropical cyclone activity
indicates six to 10 named TCs could occur in the Southwest Pacific
from November 2024-April 2025.

The NIWA and MetService assessment of tropical cyclone (TC) activity
for the coming season indicates normal to below normal activity.
(Tropical cyclones are categorised in strength from 1 to 5, with 5
being most intense. Tropical cyclones that reach category 3 or higher
are classified as severe, with mean (10 minute) wind speeds of at
least 119 km/h.)
Six to 10 named TCs could occur in the Southwest Pacific from November
2024-April 2025. The long-term average number of named TCs per season
is around nine.
TCs have a significant impact across the Southwest Pacific, with the
season starting in November and lasting through April. For the coming
season, significant differences are expected between the western and
eastern halves of the basin.
The risk of impact from a TC is expected to be higher near the Coral
Sea, Solomon Islands, and Papua New Guinea, as illustrated in the
following map. Normal to reduced risk is anticipated in the central
and eastern part of the basin.


Watch the NIWA video at youtu.be/Jdy9lJ2tOv4

Tropical cyclone outlook summary for New Zealand

On average, at least one ex-TC passes within 550 km of New Zealand
each year. This season, the risk is considered normal-elevated.
If an ex-TC tracks close to the country, there is a near-equal
probability of it tracking to the east or west of the North Island
based on historical climate data.
Two out of five analogue years considered in this outlook had at least
one ex-TC passing within 550 km of the country.
Analogue years suggest that a decaying ex-TC entering the New Zealand
region could affect maritime and coastal areas around the North
Island, but an interaction with the South Island cannot be ruled out.
El Niño-Southern Oscillation outlook

As of early October 2024, sea surface temperatures across the eastern
and central equatorial Pacific Ocean are below average and close to La
Niña thresholds.
Atmospheric circulation patterns related to ENSO over French Polynesia
and northern Australia indicate neutral ENSO conditions as of early
October 2024.
Oceanic and atmospheric forecasts for ENSO suggest La Niña, of
weak-to-moderate intensity, has a 60-70% chance of emerging by
December 2024. La Niña conditions, should they develop, are likely to
persist through the back half of the TC season in February-April.

TROPICS
Hurricane Milton pummelled Florida's central Gulf Coast as a
Category-3 storm and the fifth hurricane to make landfall in the U.S.
this year. The storm brought storm surges, wind damage and record
rainfall.

• Hurricanes Kirk and Leslie churned the open Atlantic Ocean.

• Typhoon Krathon left two people dead after striking southern Taiwan.

• Tropical Storm Ancha formed in the Indian Ocean out of season (South
Indian Ocean cyclone season nominally open mid-November).

WATHER ZONES

The wind accumulation shows several zones of strong wind this week,
which cruising yachts should avoid this week

The South Pacific Convergence zone is building and shifting southward
across Vanuatu next few days. It is expected to form a Low L3 near
Tanna late on Wednesday and this Low should then travel quickly
southeast to be around 1004 over Minerva on Thursday and then quickly
away. AVOID. Associated trough should cross Tonga on local Thursday
with gusty northly winds.

Travelling to Australia: There is a small squash zone of 25kt SE winds
in the Coral Sea around Tuesday maybe Wednesday, and a south to
southeast wind change from a passing trough at Brisbane around
Thursday, otherwise it looks OK.

HIGHS and LOWS

HIGH H1 has been blocking movement and remains near 35S to south of
Tahiti.

Low L1 is crossing central NZ on Monday then expected to travel east
along about 40S.

A High currently in the central Tasman Sea is expected to travel NE
and fade near Norfolk Island

Low L2 is expected to form well offshore of Sydney on Monday then
travel NE following a High, and then fade away on Friday., leaving a
lull of light winds over New Caledonia for the weekend.

HIGH H2 is expected to travel into the South Tasman Sea 1032 by late
Tuesday then travel onto central NZ, maintaining an easterly flow
between Northland and the tropics this weekend and early next week.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bob Blog 6 October

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 6 October 2024

A review of last month's weather
Here is a link to a YouTube clip giving an animated loop of the
isobars and streamlines in the South Pacific for the last month at
youtu.be/aB6kMuWLNKQ

The main pattern for September was a migratory HIGH travelling east
along around 25 to 35S followed by a trough or two, sometime three
with disturbed westerly wind south of 40S.


The tropics in the South Pacific were quiet.

Sea Surface temperature anomalies from psl.noaa.gov/map/clam/sst.shtml

The Kuroshio current is now retesting after crossing the entire north
pacific last month.
Will someone show the latest North Atlantic Sea surface map to the
candidates for US leader
as one of them seems to think this month's cyclones are abnormally
late.

And the weaker cool tongue along the Pacific equator os a sign that
the incoming La Nina is stuttering.

Average isobars for past month

During September the Monsoon spread east across Asia.
Being an equinoctial month the subtropical ridges in both hemispheres
strengthened.

Pressure anomalies for past month (below)
The anomaly pressure pattern for September shows ridging over the
North Sea and troughing over South America, a total reversal of last
month.
The southern 1015 line has stayed from about Tasmania to Gisborne.
The northern 1015 line has shifted to south of Darwin. a sign that
winter is over there.

TROPICS
Around 200 people perished in flooding and other storm-related
disasters as Hurricane Helene ravaged Florida and other parts of the
southeastern United States. .

Hurricane John caused at least five deaths as it made a second
landfall in Mexico's Guerrero state.

. Hurricanes Isaac and Joyce, and Tropical Storm Kirk, churned the
Atlantic.

.LESLIE is in mid Atlantic and MILTON ins in the Gulf of Mexico.

. Typhoon Krathon lashed Taiwan.

. Typhoon Jebi skirted northeastern Japan.

. ANCHA is the first named storm in the southern hemisphere after the
equinox (the South Indian Ocean cyclone season has a nominal start of
15 November0.

WEATHER ZONES
The wind accumulation shows the light wind area associated with H1 and
some weak squash zone around the Cook Islands, along with gaps between
them
It also shows lots of wind NE of NZ later this week from L2, but a gap
of OK winds emanating north from Northland, NZ.

The South Pacific Convergence zone is sitting over Solomon Islands and
extends to Rotuma and Samoa and then to the southeast across Southern
Cooks. A trough and low L2 tis expected to form over Vanuatu on
Thursday and then travel SE to be pass by eastern North Island on
Friday /Saturday 11/12 Oct. Avoid.

Travelling to Australia: Looks OK this week, but for a southerly
change at Brisbane on Wednesday, and another over the weekend and
southerly swells to 3m as north as 25S on Monday 14 Oct. SPCZ might
start shifting south next week across Vanuatu.

HIGHS and LOWS

HIGH H1 has been blocking movement and remains near 35S to south of
Tahiti.

Low L1 is zipping quickly along 50S passing by southern NZ on
Wednesday. NZ has a showery NW flow on Monday/Tuesday, a squally
Wednesday, a southerly flow for Thursday then mainly sunny with a
passing High H2 over centre of NZ by Friday.

L2 forms between Norfolk and Raoul near 30S on Friday and deepens and
it passes by eastern North Island on Saturday. Avoid.

For New Caledonia: The trough associated with L2 is expected to bring
a southerly change late Tuesday. The HIGH H2 moving along 30S into the
Tasman Sea after L2 is expected to develop a squash zone of strong SE
winds near New Caledonia and in the Coral Sea from Wednesday to
Saturday. Avoid.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bob Blog 29 Sep

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 229 September 2024

Getting to New Zealand from the tropics during the disturbed
westerlies of Sprong

Over the next month or two the yachts that have been enjoying the
tropics take on the migration to NZ or Australia to avoid the cyclone
season that nominally starts on 1 November.

It so happens that spring is the time of the year when the Antarctic
circle experiences sunlight after six dark months. Just as dawn is the
oldest time of the day, so it is that equinox is the coldest time of
the year for the Antarctic .
t is the temperature difference between tropics and pole which powers
the strength of the disturbed westerlies, and this is strongest at the
equinox, hence ethe expression 'equinoctial gales'.

To give a measure of these gales here are the wind roses at 39S 160E
in mid Tasman Sea from https://www.pitufa.at/oceanwinds/ a useful
resource showing monthly averaged winds around the seas of this planet
as measured by scatterometers on satellites.
The bulges to the west in September turning to Southwest by November.

In comparison , the wind rose for March (when the temperature
difference is at its weakest) shows less wind and no bulges.

I have mentioned before that when approaching the 'roaring 40s' from
the tropics are producing disturbed westerlies , we often have a
series slow moving Highs travelling east along around 30S and a
procession of faster moving troughs , some with lows, travelling
southeast along around 40 to 45S. In this pattern sometimes the best
strategy is to deliberately encounter a passing trough at around 33 to
35S so as to arrange arrival in NZ "between trough"

=======================

The routing advice I give may be considered as being an independent
opinion which maybe uses tools which you are not using in your own
weather studies.

I load my expeditionmarine.com program with weather data from the
ECMEF and GFS global models , the new ECMWF AIFS ( using AI) , and the
unified mode, also with ocean data such as sea, swell and currents
from Mercator. This data is merged .

One tool I use is to ask my software to produce a table , for example
for voyages from

Minerva to Opua calculating one departure per day for the days we have
data

for a yacht with up to 6kt sailing boat speed,

that gives (in UTC) the time each voyage takes (the longer this is the
riskier it is).

that avoids swell over 3m, head winds over 15ktt and tail winds over
25kt (a comfortable enough setting)

Highlighting the next "sailing window"

and clearly showing which stays we may just as well stay put.


This way the estimated trip time is a QUICK PROXY that measures the
risk of that voyage. Yes other paths may be more comfortable and
other paths again may be less risky.

In this table the colours are simply assigned to help differentiate
the paths when drawn on a map and are otherwise meaningless.

Ina few days the tables show a trend and usually the trend is the
thing to watch for timing departure ( rather than an analysis
paralysis each day)..

As to the data . Clearly all model data becomes distorted Ina few days
the tables show a trend and usually the trend is the thing to watch
for timing departure rather than overly analysing each day. The
arithmetic of chaos unravels the signal the further it goes into the
future. Usually the idea shown gets unreliable beyond 7 days unless
there is a trend. The data I have covers the next 14 days , but any
finishing date beyond that is just an artifact of numerology.

Another , more time intensive, tool is to calculate the voyage profile
of individual voyage . Here is one for example:

Voyage profile

min 25%ile med 75%ILE max


wind true 4 10 13 14
20 avg kt

apparent 6 9 11 12
18 avg kt

angle true 40 91 122 131
156 avg deg

apparent 31 64 100 110
144 avg deg

Boat 2.3 4.70 4.90 5.35
6 kt

swell 1.3 1.4 1.5 1.7
2 sig m

Baro 0 1013 1014 1015
1016 hPa

beat beam aft

<50 TWA >150 deg

<10kt 9% 18% 0% 27%

TWS 0% 64% 9% 73%

>20kt 0% 0% 0% 0%

Totals 9% 82% 9%

AWA apparent wind angle


<10kt 18% 27% 0% 45%

AWS 0% 55% 0% 55%

>20kt 0% 0% 0% 0%

Totals 18% 82% 0%

If we have two voyages then these voyage profiles help to
differentiate between them .

Another tool is a simple graph of forecast wind and sweel .



TROPICS
ISAAC and JOYCE are in the North Atlantic and Jebi and Krathon are in
the NW Pacific

Tropical Storm Pulasan brought unprecedented flooding rains to areas
of western Japan still recovering from a devastating quake that killed
at least 236 people on New Year's Day. . Hurricane Helene raked parts
of Florida as it roared ashore in the panhandle. . Hurricane John
killed at least three people in mudslides across southwester

WEATHER ZONES

The South Pacific Convergence zone is sitting over Solomon Islands and
northern Coral Sea and extends to Tuvalu and Tokelau then southeast to
Southern Cooks.

There is a squash zone of strong winds and rough seas between Tahiti
and Tonga mid -week.

HIGHS and LOWS

Low L1 is moving east well south of Tahiti and may form a secondary
near 43S.

HIGH H1 over NZ on Monday the expected to travel off to the east, with
a squash zone of enhanced trade winds on its northern side mid-week.

Low L2 is an east coast low near Brisbane on Monday and expected to
turn into a north-south trough over NZ on Wednesday. Associated trough
may affect New Caledonia and Vanuatu rather weakly on Tuesday. The
trough then moves on to the east, as a secondary low forms in the
Tasman Sea. This low may well bother NZ next week.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bob Blog 22Sep

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 22 September 2024

The Ozone layer

Spring is also the Antarctic ozone hole season,

During the southern winter the Southern Polar Vortex was highly
disrupted and consequently the 2024 ozone hole development began
relatively late.. The evolution of the 2024 ozone hole so far is
similar to that observed in 2022, as shown in the chart above.

There was a larger than normal Ozone hole in 2023.. it also lasted
longer than normal. This is thought to be a consequence of the extra
water vapour in the stratosphere from the explosive volcanic=c
eruption in Tonga in January 2022 with a plume of 53km up into the
atmosphere.

The Ozone hole is formed when direct sunlight shines into the polar
atmosphere. During the dark of winter chemical pollutants such as CFC
build in intensity , and when the sunlight returns the UV reacts with
these pollutants o deplete ozone and build the ozone hole.

However, when the polar vortex is weak, a sit was at times last
winter, with higher temperatures and slower winds than usual in the
stratosphere, the ozone depletion process is weaker, leading to ozone
columns above 220 dobson units (DU), the threshold value used to
define the Antarctic ozone hole.

According to an analysis by NASA's Earth Observatory, Antarctica
experienced two rare sudden stratospheric warming events in July and
August 2024 when temperatures in the stratosphere jumped 15ºC and 17ºC
respectively.

As a result, the southern hemisphere polar vortex was elongated and
with weakened winds, as opposed to the circular, cold and fast winds
conditions that favour ozone depletion, seen for example in 2023.

Instead of the typical behaviour, the ozone hole this year didn't
develop until the end of August.

More can be found at www.facebook.com/watch?v=1056948995791531

TROPICS
There are no named storms tonight. Remnants of Typhoon Yagi took
another 226 lives in Myanmar. • Typhoon Bebinca lashed Shanghai with
the highest winds and heaviest rains since Typhoon Gloria struck in
1949. Weaker Tropical Storm Pulasan took a more southerly course days
later. • Tropical Storm Lleana drenched southern Baja California,
while Tropical Storm Gordon churned the central Atlantic Ocean.

WEATHER ZONES
The South Pacific Convergence zone is sitting over Solomon Islands and
extends to Tuvalu and Tokelau then southeast to Southern Cooks.
Another convergence zone or trough is sitting over southern parts of
French Polynesia.

The wind accumulation map shows the trade winds may get strong at
times thru the Fiji passages around the Niua Islands in northern Tonga
and about southern parts of French Polynesia (avoid), and Coral Sea
may be OK enough for sailing westwards.
This map shows the average position of the light winds of the
subtropical ridge near 25S and the extent of the disturbed westerlies.
A small trough is expected to form off Sydney around Thursday/Friday
(avoid) and deepen as it crosses the Tasman and reaches NZ around 3 /4
October.

HIGHS and LOWS

HIGH H1 remains slow moving well south of Tahiti.

Over New Zealand a trough is crossing on Monday/Tuesday deepening into
L1 travelling off to the SE.
A brief ridge with H2 is expected on Wednesday,
then another broad trough on Thursday and Friday followed by the
ridge of H3 over the weekend.

It looks OK to depart from the tropics and get to NZ, so long as you
avoid the rough stuff near NZ on 26/27 September, and maybe 3 and 4
October.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

BoB Blog 15 Sep

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 15 September 2024

The climate influencers

A quick review of the trends in the parameters we use to watch the main seasonal weather influencers. Thanks to bom.gov.au/climate

The Pacific

From the Pacific Ocean comes the ENSO (El Nino Southern Oscillation) parameters. La Lina is the name given to the period when sea surface temperature SST over the eastern equatorial Pacific is below normal.

In the atmosphere we monitor ENSO = El Nino/Southern Oscillation and its impact on the weather map by using. the Southern Oscillation Index SOI (30 day running mean). This is based on the standardized difference in the barometer readings between Tahiti and Darwin, in other words it counts the average number of isobars between them on the weather map. When the index stays above 7 (on the scale shown here) for more than a month we call it an LA NINA event.
This is showing that after neutral territory during winter , The SOI is no indicating a swing towards La Nina.

The Ocean:

The parameter used from the ocean is based on the sea surface temperatures in the equatorial eastern Pacific and called the NINO 3.4 SST anomaly.
International research Institute IRI have compiled the predictions for all the models as shown here from iri.columbia.edu. The consensus is that according to the Dynamic models there may be a weak LA NINA from October to February.

Expected impact in the South Pacific

The cooler than normal lounge of surface water across the east equatorial Pacific tends to nudge the South Pacific Convergence zone southwards. This makes the trade winds stronger than normal and shifts the subtropical ridge southwards. In spring this concentrates the disturbed westerly winds of the roaring forties. In summer the path taken by migratory Highs from south of Australia is across the Tasman Sea and along 40S, encouraging a northeast flow onto northern NZ. The peak cyclone prone area hugs Vanuatu.

However, each La Nina event is different and even a strong event only explains around 20% of the observed weather variance.

Tropics

The MJO Maden Julian Oscillation is the name given to a measurable increase in intensity that travels eastwards around the planet around once a month mainly along the Intertropical convergence Zone and affects tropical weather.

A good diagram of its current intensity and expected future for the next few weeks is at

www.cpc.ncep.noaa.gov/ --- in these maps BLUE is extra cloudiness associated with MJO and yellow is extra sunshine.

It is likely that with the MJO recently over Indonesia, it may have been associated with formation of Cyclone YAGI. MJO is expected to move east into the pacific Ocean over next few weeks and fade way.

Southern Ocean

For the Southern Ocean comes the SAM parameter (Southern Annular Mode). This measures the strength of the polar vortex, a ring of westerly winds circulating around Antarctica between 50 to 60S. When positive, polar outbreaks are few, and when SAM is negative polar outbreaks are encouraged.

After a long negative period, a few months ago, SAM is now positive, but is expected to drop over the next weeks. This is consistent with the snowy southerlies expected over SE Australia and South Island this week.

Rounding up the Climate Dogs

Agriculture Victoria have compiled some animated cartoons explaining six seasonal weather parameters as dogs with different characteristics see

agriculture.vic.gov.au/climate-and-weather/understanding-weather-climate-and-forecasting/the-climatedogs-the-six-drivers-that-influence-victorias-climate

and watch six climate docs: Ridgy, Eastie, ENSO, Indy, Sam and MoJo strut their stuff.

TROPICS
Around 200 people were killed in flash floods and mudslides triggered by Typhoon Yagi, which swept from South China's Hainan Island to northern Vietnam. Yagi was the most powerful storm the region had seen in decades. * Tropical Storm Bebinca is forecast to become a powerful typhoon before striking the Chinese coast near Shanghai this week. * Louisiana and parts of coastal Texas were battered by Hurricane Francine, which later caused flooding across the lower Mississippi Valley

WEATHER ZONES

The South Pacific Convergence zone is sitting over Solomon Islands and extends to Rotuma and Samoa and then to the southeast across Southern Cooks. A passing trough tonight west of Fiji is expected to travel east across Tonga and Niue early in the week and reach Southern Cook and Tahiti late in the week. This trough is expected to be accompanied by a lull and some squalls and followed by a day or two of SW swells.

HIGHS and LOWS

HIGH H1 remains slow moving well south of Tahiti.

A broad trough with many parts is crossing NZ area on Monday and Tuesday then is expected to deepen into a Low L1 near Chatham Islands. This maintains a cold strong southerly flow over NZ on Wednesday followed by a period of disturbed westerlies for the remainder of the week.

HIGH H2 is expected to travel across Australia and then from mid-week go east along 25S across northern Tasman Sea as a disturbed westerly flow spreads onto NZ

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, then check metbob.com to see what I offer.
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Bobgram 8 Sep

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 8 September 2024

The disturbed westerlies of spring

The annual climate of Hs (Significant wave height) around the planet
follows the seasons with a winter peak and summer minimum. As seen at
www.researchgate.net/figure/Climatological-distributions-of-the-averag
ed-Hs-MAS-significant-wave-height-simulated-by_fig3_370153387

However, in springtime there is the disturbed westerly pattern .

Since mid-August we have been having several examples of the weather
pattern termed "disturbed westerlies". On the weather map over
Australia /NZ and the South Pacific (south of the subtropical ridge)
we usually have a High and ridge followed by a Low and trough then
another High and so forth.

As we approach the equinox, the sun dawns again around the Antarctic
circle. Just as the coldest time of the day is around dawn, so it is
that the coldest time of the year around Antarctica is around the
equinox. This then is the time of the year when there is the strongest
temperature difference (delta T) between tropics and pole in the
southern hemisphere. And it is simple physics that the stronger the
delta T the stronger the wind speed and hence the higher the swells.

With the stronger delta T the weather pattern in the midlatitudes
turns more topsy-turvy, and instead of the High -low-High-low parade
there may be three or four troughs between the highs. This is the
pattern called "disturbed westerlies"

This year the disturbed westerlies seem to have come early as the NW
winds from Australia bump into the southerlies from the Southern
Ocean. The extra friction has been producing extra static and extra
lightning in the Tasman Sea. This is consistent with an incoming La
Nina, and if that happens then there may be an early end to these
disturbed westerlies, maybe during November.

I asked Chat GPT to write a sonnet about disturbed westerlies.

The Winds of Spring in Tasman's Rolling Tide

When westerlies, disturbed, sweep through the sea,
They bring the breath of storms to ocean's flow,
As winds twist in wild uncertainty,
And the light of spring begins to grow

From warmer lands the northern breezes fly,
While polar chills rush in to clash and churn,
These winds contend beneath the shifting sky,
When orbit of earth and season steadily turn.

Across the Tasman waters swirl and rise,
Restless westerlies their course ignite,
A dance of air and sea before our eyes,
In spring's embrace, both fury and delight.

So: sailors watch these winds with cautious eyes,
For springtime's song is sung in stormy skies.

Not bad, but I had to edit some bits, Chat GPT came up with Spring's
dimming light????

TROPICS
We are having a lull at present after a busy period. Typhoon Shanshan
left seven people dead and around 130 others injured as one of the
strongest storms to hit Japan in decades. . Downpours in the northern
Philippines triggered by Tropical Storm Yagi killed at least 14 people
in landslides, floods and swollen rivers. Tropical Storm Asna spun up
over the Arabian Sea.

WEATHER ZONES
The South Pacific Convergence zone is sitting over Solomon Islands and
extends to Samoa and then to the southeast across Southern Cooks. This
zone has been producing small squally lows that bring over40kt for
between a few hours and a few days. Avoid.

HIGHS and LOWS

HIGH H1 is moving steadily east along 30 to 35S off to east of NZ.

Low L1 belongs to a trough that is crossing NZ on Monday then moving
off to the east followed by H2 on Wednesday

Low L2 is expected to belong to a trough that crosses NZ on Friday,
followed by a "disturbed westerly flow" which blurs the details of
next week.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 1 Sep 2024

Bob Blog 1 Sep
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 1 September 2024
A review of last month's weather
Here is a link to a YouTube clip giving an animated loop of the
isobars and streamlines in the South Pacific for the last month at
youtu.be/h0FhIw4kZzs

The main pattern for August was a migratory HIGH travelling east along
around 25 to 35S followed by a trough or two, sometime three with
disturbed westerly wind south of 40S.

The tropics in the South Pacific were quiet.

The Kuroshio current has spread out into the north Pacific. The
equatorial Atlantic remains warmer than normal. The cool seas of a LA
NINA are spreading westwards from Galapagos to the dateline along the
equator.

During August the Monsoon spread east across Asia.
and the subtropical ridge in northern hemisphere weakened.
An equatorial trough developed in the mid Pacific.
The anomaly pressure pattern for August shows ridging over North
America,
Higher than expected pressures accompanying the Asian Monsoon,
and lower pressures than normal in the southern roaring 40s but for
high pressures around South America.

The roaring 40s have travelled northwards onto the South Island.
The 1015 line has shifted from near Campbell Island to near
Christchurch.

TROPICS
Powerful Typhoon Shanshan lashed Japan's southernmost islands with up
to Category-4 force before the weakened storm later caused damage and
severe flooding to Kyushu Island. . Hawaii's Big Island received flash
flooding and some wind damage from Hurricane Hone, which passed just
to the south. ASNA is near Yemen.

WEATHER ZONES
The South Pacific Convergence zone is sitting over Solomon Islands and
extends to Rotuma and Samoa and then to the southeast across Southern
Cooks. A trough and low L1 to south of Southern Cooks are moving a
windy rain band southward, followed by a lull in the trade winds.
Mostly OK this week for sailing to the west.

HIGHS and LOWS

HIGH H1 has been blocking movement south of Tahiti.

Low L2 is a secondary travelling quickly eastwards along around 45 to
50 S. Associated trough is expected to bring a cold southerly change
to NZ on Tuesday/Wednesday. It's primary Low is in the Southern Ocean.
Following that trough there is expected to be a burst of southwest
swell to over 5 significant metre sin the Tasman Sea. This should
travel north with 3+ m swells reaching Fiji on Thursday. Avoid. Low
L1.

For New Caledonia: The trough associated with L2 is expected to bring
a southerly change late Tuesday. The HIGH H2 moving along 30S into the
Tasman Sea after L2 is expected to develop a squash zone of strong SE
winds near New Caledonia and in the Coral Sea from Wednesday to
Saturday. Avoid.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 25 Aug

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 Sunday25 August 2024

ATLANTICCYCLONE SEASON - why so quiet?

At the start of this year's cyclone season a few months a go the
initial outlook was for a busy and active season with between 17 and
25 named storms. Now we are approaching the half-way mark and there
have only been 5 named storms. What gives?

Well, BERYL (June 28-July 11) had lots of cyclone energy, so the
accumulated cyclone energy graph shows we are having an active season.

Accumulated cyclone energy (ACE) this season has been historically
high despite the perceived slow start to the season. Thanks to (Kim
Wood/University of Arizona at kouya.has.arizona.edu/tropics/index.html

Also the current pause in Atlantic cyclone activity may be related to
what is called an ATLANTIC NINA or cooling of the seas surface due to
a zone of stronger trade winds triggering marked upwelling as show
near 1 in the Sea surface anomaly map

The cooling in the Eastern Equatorial Pacific indicates a trend
towards LA NINA. We are NOT there yet, and the pace of cooling has
recently stalled.

Maybe in September this cooling pace will resume, also there may be a
flurry of North Atlantic cyclones.

TROPICS

. A near miss on eastern Japan by Category-4 Typhoon Ampil spared the
region notable damage. . After making a direct hit on Bermuda with
Category-2 force, Hurricane Ernesto brushed Newfoundland and was
predicted to bring heavy rain and high winds to Ireland, the U.K. and
parts of Western Europe.

. Gilma reached hurricane force, moving westward over the Pacific
Ocean.

WEATHER ZONES
The South Pacific Convergence zone is increasing in width and
intensity and stretches from Solomon Islands to Tokelau /Samoa.
Another convergence zone over Fiji Sunday night a d Tonga on Monday os
associated with a Low L1 which should form south of Tonga on Monday
and then trave ESE during the week as a weak trough. The strong winds
and large swells which bothered Fresch Polynesia last week due to a
squash zone are expected to relax enough to allow travel westwards
from local TUESDAY. t

HIGHS and LOWS
This coming week should see a steady procession of HIGHs and LOWs
eastwards in the mid-latitudes.

HIGH H1 gave French Polynesia a squash zone for the last few days and
is now moving off to the south relaxing the pressure gradient.

HIGH H2 is expected to travel east along 25S, into north Tasman Sea

Further south a disturbed westerly flow should bring passing fronts to
Aotearoa NZ especially on Tuesday and Thursday/Friday then Sunday and
again on following Tuesday. Avoid arriving those days.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 18 Aug

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 Sunday18 August 2024

POLAR VOTEX
The southern polar vortex is a ring of wind swirling over Antarctica
and this has been wobbling more than normal recently.

Our polar vortex is rather untidy, with a sheath of cold air extending
north into the Tasman Sea/South Island area, and another extending as
far north as 30S near Southern Cooks.
In July there was a SSW or sudden stratospheric warming event. This
was caused by a large-scale atmospheric wave, called a Rossby wave,
that was pushed up from below until it "broke" on top of the polar
vortex, causing the downwelling of a layer of air and thus a warming
of a large zone in the stratosphere. A SSW is a rare event -- last
three known events occurred in 2002,2010 and 2019. They disrupt the
polar vortex and encourage outbreaks .
SAM the Southern Annular Mode is a parameter we use to measure the
strength of the polar vortex. When SAM is negative the Polar vortex is
weak and allows polar outbreaks. I have access to AAO (The AntArctic
Oscillation) and use this as a proxy for SAM and it shows a long weak
period of the Polar vortex during July and August, but it is now near
normal and the forecast is for it to become positive in next few
weeks, retuning the Polar Vortex's health.
May be


TROPICS
Parts of northern Japan received record rainfall from Typhoon Maria. .
Maria was followed by Typhoon Ampil, which skirted the coast near
Tokyo and is now moving off to the northeast. . Tropical Storm
SonTinh dissipated near Japan's northernmost islands. . The Windward
Islands and Puerto Rico were raked and flooded by strengthening
Hurricane ERNESTO


WEATHER ZONES
The South Pacific Convergence zone is increasing in width and
intensity and stretches from Solomon Islands to Tokelau to Suwarrow.
A weak passing trough is crossing New Caledonia tonight and Tonga on
local Tuesday then fading sway.

HIGHS and LOWS
This coming week should see a steady procession of HIGHs and LOWs
eastwards in the mid-latitudes. The trough associated with Low L1 is
travelling east across Aotearoa NZ tonight and Monday, followed by a
cold southerly outbreak on Tuesday.
HIGH H2 is expected to cross Aotearoa NZ on Wednesday followed by the
trough associated with L2 on Friday and Saturday.
During the weekend on 24/25 August a trough is expected to stall
between NZ and Fiji and deepen into Low which may affect voyages next
week. So be aware of that and update accordingly.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 11 August

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 11 August 2024

The AMAZON as a measure of Climate change

A recent NATURE article
www.nature.com/articles/s41598-024-58782-5#citeas
offers data that can, visually anyway, show what maybe the impact of
global climate change over the past century and its increasing impact
over the past 20 years.

Showing he height of the Amazon level has been measured at MANUS near
the centre of the Amazon for over100 years.
This shows the annual cycle and also a possible sunspot cycle.
I've added the red and green trend arrows to the article's data graph
shown in my illustrated edition.
The article concentrates on the increasing annual cycle and links the
record breaking drought on 23 Oct 2023 to the EL NINO then rampant and
also to the generally warmer than normal Pacific Ocean.

A REGIONAL DROUGHT is affecting the New Zealand Hydro lakes
NIWA (NZ) say that during the month of July 2024 "mean sea level air
pressure (MSLP) was higher than normal over and to the south of
Aotearoa New Zealand. This was associated with more south-easterly
winds than normal. A large and slow-moving high pressure system was
present over New Zealand for much of July, leading to an extended
period of fine and settled weather, and regular heavy frosts for
inland areas. The strength of the high pressure peaked on 10 July,
when Ranfurly registered a MSLP of 1046.5 hPa - this is mainland New
Zealand's highest MSLP measurement on record."

This drop in input into the hydro lakes was enough to almost triple
the spot price of electricity in the past month.

The Higher pressures in July around Aotearoa New Zealand were just a
regional impact .

TROPICS
When DEBBY made landfall over Florida, it brought some unprecedented
flooding. . Then there were four named storms churning the Pacific at
the same time off Mexico and this is the highest number for the region
in 50 years. Only Carlotta lived long enough to travel significantly
westward toward Hawaii.

Tonight MARIA is making landfall over northern Japan, and there are 3
tropical depressions with one following Maria, one in the NE Pacific
and one in the Atlantic.

WEATHER ZONES
The South Pacific Convergence zone is increasing in width and
intensity and stretches from Solomon Islands to Tokelau to Suwarrow. A
passing trough is expected over Southern Cooks late in the week..

HIGHS and LOWS
Low L1 is travelling northeast on Monday to east of NZ bringing a
showery southerly flow.

From Tuesday to Thursday HIGH H1 should travel NE across northern NZ.,
a good time to arrive. Then this HIGH should travel east along 30S
with a small squash zone of stronger easterly winds crossing Niue ,
for example, on local Thursday/Friday.

Low L2 should start forming in Coral Sea from Tuesday and deepen off
Brisbane from Thursday then travel southeast across NZ on Saturday
preceded by strong NE winds, accompanied by heavy rain and followed by
southerly winds. AVOID arriving in NZ as this FRONT passes.

The models are in disagreement for next week's Tasman Sea pattern, so
seek updates for that.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bobgram 4 August

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 4 August 2024

A review of last month's weather
Here is a link to a YouTube clip giving an animated loop of the isobars and streamlines in the South Pacific for the last month at youtu.be/alCjq_vMeqM
An interesting period of weather occurred when a LOW was blocked in the Tasman Sea from 14 to 24 July under a closed low aloft. As in June there was a dose of rapid cyclogenesis between 19 and 20 July.

The tropics in the South Pacific were quiet.

Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
The Kuroshio current has spread out into the north Pacific. The equatorial Atlantic remains warmer than normal. The cool seas of an El Nino are spreading westwards from Galapagos to the dateline along the equator. A buildup of cold water - melted ice is showing around the Aleutians.

Average isobars for past month as at www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html
During July the Monsoon spread east across Asia and the subtropical ridge in northern hemisphere intensifies.

Pressure anomalies for past month (below)
The anomaly pressure pattern for July shows a relaxing away of the negative anomalies that were over North America and Australia. South America has built up large positive anomalies.
Around Suth Pacific : Not much change, but the low anomalies in the Tasman have faded.

TROPICS
Typhoon Gaemi weakened to a tropical storm as it made landfall on South China's Fujian coast. Even as a weakened storm, Gaemi's remnants had enough power to kill 22 people in disastrous flooding and mudslides across a wide area of China and parts of North Korea. In total, Typhoon Gaemi was responsible for at least 77 deaths over a two-week period. * Tropical Storm Bud formed briefly

Tonight we have DANIEL and CARLOTTA in the NE Pacific plus two tropical depressions. In the North Atlantic DEBBY is heading for Florida's panhandle.

WEATHER ZONES
The South Pacific Convergence zone is sitting over the northern Coral Sea and extends to Tuvalu and Tokelau to Suwarrow. There is a passing tough travelling east from Tonga to Southern Cooks this week, and maybe a squash zone of strong SE winds near Niue from 10 to 15 August.

HIGHS and LOWS
Low L1 was just north of Northland tonight and is expected to travel east along around 33S this week, with its northern extension bringing a slack passing trough to the zone between Tonga and Tahiti.

HIGH H1 is rather weak and expected to move southeast across NZ on Wednesday then fade away.

Low L2 is expected to form in mid-Taman by Tuesday and cross NZ area as a broad trough on Thursday and Friday.

HIGH H2 is expected to build in the Tasman Sea along 35S later in the week and poke a tongue of high pressure along 30S east of the dateline next week, causing a squash zone further north between 10 and 15 August. Avoid.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about 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 text 64277762212.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>