Bob Blog 26 May
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 26 MAY 2024
FASTSEAS -> gpx file -> Navionics
Windy.com has become a popular source for viewing weather files.
Registered members are given the option to do "Distance and Planning"
via a right click in a browser.
FastSeas.com is a web-based subscription application which uses this
feature to produce an easy to use and configure weather router and
passage planning/viewing too. It will calculate the fastest route from
A to B using the GFS weather forecast and oceanic currents. You can
configure the performance of your vessel and your comfort thresholds.
FastSeas allows routing via email and short message satellite
communications such as Zoea, Spot and Bivy Stick devices.
FastSeas can produce a gpx file of the optimum route. This can then be
transferred to a chart plotter.
Here is a link to a YouTube explanation of how to use FastSeas and
import the path into a Navionics program running on an iPad (or any
tablet with GPS).
https://www.youtube.com/watch?v=jbCQStHYphY&t=340s
or directly into a RayMarine chart plotter
https://www.youtube.com/watch?v=rz06aQXmwcI&t=202s
And here is an interview with its inventor, Jeremy Waters
https://www.youtube.com/watch?v=EtMXnny-RMA
FastSeas Basic allows five route calculations per month at no charge,
or a full subscription for US$10 per month or US$45 per 6months or
US$60 per year.
TROPICS
Tropical Storm Ialy skirted the coast of Kenya and far southern
Somalia after forming in the Seychelles, unusually far north off
Africa for such a storm.
EWINAR is brewing in the Philippines and expected to take the coastal
route northeast to eats of Japan .
REMAL is expected to make landfall over Bangladesh
The active part of a MJO oscillation is moving into the Pacific over
the next few weeks.
WEATHER ZONES
The South Pacific Convergence zone is active in a long line from New
Guinea, across northern Vanuatu, Fiji,
Tonga and then to south of Southern Cooks. It is expected to drift
northwards and may be along 11S by next week.
HIGHS and LOWS
Aotearoa/NZ starts the week in a SW flow. A small low L1 in this flow
is expected to cross the North Island on Tuesday
and then travel northeast and deepen east of Gisborne on Wednesday
and then move off to the SE.
HIGH H1 over NSW tonight is expected to move into central Tasman by
Wednesday,
then travel east along 37S from New Zealand to south of Tonga by
Sunday.
SQUASH ZONE is expected between Thursday and Sunday/perhaps Monday 3
June on the north side of this High,
mainly between Fiji and Aitutaki, but also over Tonga. The squash zone
is aligned with the SPCZ for a few days. Avoid.
Panama to Marquesas:
Light winds for starters. Squally doldrums from Panama to 2N, intense
between 6N and 4N.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
26 May 2024
19 May 2024
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 19 MAY 2024
Chilly Chile
The world's oceans have been absorbing so much heat in the past year
that May 2023 to May 2024 has broken the record with the highest
measured "World Sea Surface temperature" on record for a whole
contiguous year (https://climatereanalyzer.org/clim/sst_daily/)
Along with this record areas north of the equator have recently
suffered from the hottest weather ever recorded.
Despite all this, residents of Santiago, Chile, are suffering from the
longest Southern Hemisphere cold snap on record during autumn. "Since
1950 onwards, i.e., in the last 74 years, we have not had such an
intense cold spell in May, said University of Santiago climatologist
Raul Cordero.
Scientists have been researching the cooling ocean around the south of
South America for a while. It has been called "the most important
unanswered question in climate science".
"It's about 1 degree Celsius, it's not a lot but recall that the
planet has been warming, now, more than one degree, so it's a huge
departure from what the rest of the planet is doing."
One theory is that the "cold tongue" is melt water from Antarctica's
rapidly disappearing icepack. Maybe this melt water is being
transported by winds and ocean currents. Much of the cold water comes
from directly south of New Zealand.
So as the cool pool accumulates around Chile, a corresponding warm
pool accumulates further west, near Aotearoa/ New Zealand. At this
stage we do not know the implications for our future weather.
TROPICS
Cyclone Ialy is travelling northwards and may make landfall in
Somalia.
The place of greatest potential for formation this week is skirting
the equator around New Guinea.
WEATHER ZONES
The South Pacific Convergence zone is active over New Guinea and from
Solomon Islands to southern Vanuatu, to south of Fiji.
A passing trough is expected to travel east-wards across Tonga
mid-week.
HIGHS and LOWS
HIGH H1 south of French Polynesia has been producing a squash zone of
enhanced wind
and swell near 20 to 25S last few days and as it moves off conditions
are relaxing.
LOW L1 is well east of NZ at present and expected to travel SE to
south of H1.
Low L2 is expected to deepen in the Tasman Sea on Monday and travel
east
across the North Island on Tuesday then go off to the east and
southeast.
It is followed by a southerly flow for a few days. Avoid.
High H2 is expected to cross Tasmania late in the week and then move
into southern Tasman Sea.
Panama to Marquesas:
Light winds for starters. Squally doldrums from 6N to 2N, intense
between 5N and 3N.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Disclaimer: Weather is a mix of pattern and chaos; these ideas are
from the patterned world.
Compiled Sunday 19 MAY 2024
Chilly Chile
The world's oceans have been absorbing so much heat in the past year
that May 2023 to May 2024 has broken the record with the highest
measured "World Sea Surface temperature" on record for a whole
contiguous year (https://climatereanalyzer.org/clim/sst_daily/)
Along with this record areas north of the equator have recently
suffered from the hottest weather ever recorded.
Despite all this, residents of Santiago, Chile, are suffering from the
longest Southern Hemisphere cold snap on record during autumn. "Since
1950 onwards, i.e., in the last 74 years, we have not had such an
intense cold spell in May, said University of Santiago climatologist
Raul Cordero.
Scientists have been researching the cooling ocean around the south of
South America for a while. It has been called "the most important
unanswered question in climate science".
"It's about 1 degree Celsius, it's not a lot but recall that the
planet has been warming, now, more than one degree, so it's a huge
departure from what the rest of the planet is doing."
One theory is that the "cold tongue" is melt water from Antarctica's
rapidly disappearing icepack. Maybe this melt water is being
transported by winds and ocean currents. Much of the cold water comes
from directly south of New Zealand.
So as the cool pool accumulates around Chile, a corresponding warm
pool accumulates further west, near Aotearoa/ New Zealand. At this
stage we do not know the implications for our future weather.
TROPICS
Cyclone Ialy is travelling northwards and may make landfall in
Somalia.
The place of greatest potential for formation this week is skirting
the equator around New Guinea.
WEATHER ZONES
The South Pacific Convergence zone is active over New Guinea and from
Solomon Islands to southern Vanuatu, to south of Fiji.
A passing trough is expected to travel east-wards across Tonga
mid-week.
HIGHS and LOWS
HIGH H1 south of French Polynesia has been producing a squash zone of
enhanced wind
and swell near 20 to 25S last few days and as it moves off conditions
are relaxing.
LOW L1 is well east of NZ at present and expected to travel SE to
south of H1.
Low L2 is expected to deepen in the Tasman Sea on Monday and travel
east
across the North Island on Tuesday then go off to the east and
southeast.
It is followed by a southerly flow for a few days. Avoid.
High H2 is expected to cross Tasmania late in the week and then move
into southern Tasman Sea.
Panama to Marquesas:
Light winds for starters. Squally doldrums from 6N to 2N, intense
between 5N and 3N.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
13 May 2024
Collaboration request
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12 May 2024
Bobgram 12 May
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 12 MAY 2024
Snapshot of marine traffic show that this year the tropical migration
has started last week from Aotearoa/NZ but not yet from Australia:
Tahiti to Tonga - Beware the squash zone.
When planning to sail from Tahiti to Tonga you either go direct or
sail a path north of the direct path (to avoid uncomfortable swells
further south) or sail a path south of the direct path (to avoid the
squalls and convergence zones further north). Sometimes your best path
is partly north and partly south of the direct path.
This week I'll take a closer look at squash zones. These are easy to
forecast and avoid when you know how, yet every year we hear the
stories of yachts getting caught by them unawares.
The thing to look for is a HIGH passing over Aotearoa /New Zealand .
There is one doing that tonight:
Often (as is the case this week) these HIGHS migrate to the east and
intensify and expand to have a central pressure isobar over 1030 hPa
As the HIGH intensifies and accommodates some extra isobars around its
centre, the isobars on its northern periphery get squashed together.
Look at my illustrated blog for an animation of this.
So there is a zone of enhanced trade winds on the northern side of a
migrating High. In this squash zone conditions quickly become
uncomfortable due to increasing wind and swell, even if the baro
remains unchanged. Since the waves are and being compacted, they
become short and choppy. Squash zones cover more longitudes than
latitudes so if caught in one then go north or south to escape, rather
than west or east.
As the High moves further away there is a zone of lowering pressure on
the western end of the squash zone. This becomes a breeding ground for
squally rain and maybe a new trough, as is also something to avoid.
A tip for those doing voyage planning is to select the wind
accumulation map on windy.com and put this on 5 days accumulation.
This will help you identify the zone to avoid.
TROPICS
Last week, Coastal Tanzania was drenched by heavy rainfall from
Cyclone Hidaya, which formed unusually far north off the coast of
Africa. Again, there are no named storms. Tonight. The place of
greatest potential is skirting the equator around New Guinea.
WEATHER ZONES
The South Pacific Convergence zone is active over New Guinea and from
Solomon Islands to northern Vanuatu. to Samoa. A Low L2 is expected to
form on the SPCZ near Tonga at end of the week.
HIGHS and LOWS
HIGH H1 east of the North Island is expected to travel east from 35S
to 40S and intensify.
A squash zone of enhanced trade winds on northern side of the High is
expected between Tahiti and Tonga along around 20S (as illustrated
above).
Low L1 has formed off Sydney tonight and it and associated trough is
expected to cross the North Island on Wednesday and Thursday followed
by a westerly flow. Avoid.
High H2 is expected to move from Australian bight across NSW during
the week and into the central Tasman Sea by end of the week.
L2 provides an opportunity for sailing eastwards from Australia to New
Caledonia.
Also, when this trough gets east of Northland that should make a good
opportunity for sailing from NZ to the tropics.
Panama to Marquesas:
Light winds for starters. Squally doldrums from 6N to 2N, intense
between 5N and 3N.i
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Disclaimer: Weather is a mix of pattern and chaos; these ideas are
from the patterned world.
Compiled Sunday 12 MAY 2024
Snapshot of marine traffic show that this year the tropical migration
has started last week from Aotearoa/NZ but not yet from Australia:
Tahiti to Tonga - Beware the squash zone.
When planning to sail from Tahiti to Tonga you either go direct or
sail a path north of the direct path (to avoid uncomfortable swells
further south) or sail a path south of the direct path (to avoid the
squalls and convergence zones further north). Sometimes your best path
is partly north and partly south of the direct path.
This week I'll take a closer look at squash zones. These are easy to
forecast and avoid when you know how, yet every year we hear the
stories of yachts getting caught by them unawares.
The thing to look for is a HIGH passing over Aotearoa /New Zealand .
There is one doing that tonight:
Often (as is the case this week) these HIGHS migrate to the east and
intensify and expand to have a central pressure isobar over 1030 hPa
As the HIGH intensifies and accommodates some extra isobars around its
centre, the isobars on its northern periphery get squashed together.
Look at my illustrated blog for an animation of this.
So there is a zone of enhanced trade winds on the northern side of a
migrating High. In this squash zone conditions quickly become
uncomfortable due to increasing wind and swell, even if the baro
remains unchanged. Since the waves are and being compacted, they
become short and choppy. Squash zones cover more longitudes than
latitudes so if caught in one then go north or south to escape, rather
than west or east.
As the High moves further away there is a zone of lowering pressure on
the western end of the squash zone. This becomes a breeding ground for
squally rain and maybe a new trough, as is also something to avoid.
A tip for those doing voyage planning is to select the wind
accumulation map on windy.com and put this on 5 days accumulation.
This will help you identify the zone to avoid.
TROPICS
Last week, Coastal Tanzania was drenched by heavy rainfall from
Cyclone Hidaya, which formed unusually far north off the coast of
Africa. Again, there are no named storms. Tonight. The place of
greatest potential is skirting the equator around New Guinea.
WEATHER ZONES
The South Pacific Convergence zone is active over New Guinea and from
Solomon Islands to northern Vanuatu. to Samoa. A Low L2 is expected to
form on the SPCZ near Tonga at end of the week.
HIGHS and LOWS
HIGH H1 east of the North Island is expected to travel east from 35S
to 40S and intensify.
A squash zone of enhanced trade winds on northern side of the High is
expected between Tahiti and Tonga along around 20S (as illustrated
above).
Low L1 has formed off Sydney tonight and it and associated trough is
expected to cross the North Island on Wednesday and Thursday followed
by a westerly flow. Avoid.
High H2 is expected to move from Australian bight across NSW during
the week and into the central Tasman Sea by end of the week.
L2 provides an opportunity for sailing eastwards from Australia to New
Caledonia.
Also, when this trough gets east of Northland that should make a good
opportunity for sailing from NZ to the tropics.
Panama to Marquesas:
Light winds for starters. Squally doldrums from 6N to 2N, intense
between 5N and 3N.i
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
05 May 2024
Bobgram 5 May
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 5 MAY 2024
A review of last month's weather
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/jVwSiLqZk_4
April was a quiet month in the South Pacific tropics. There were two
very weak MJO phases, but they didn't produce much.
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
Regionally, the warmer Atlantic is a worry and a sign of a big cyclone
season coming there next few months. The seas around NZ are now near
normal. There is a build-up pf cool water near Galapagos. The
equatorial current is running like a wide river taking warm water
westwards. A sign that El Nino is over.
Average isobars for past month (below) From
www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.htmlclip_image008
During April the subtropical ridge in the Southern Hemisphere
strengthened.
The anomaly pressure pattern for April shows HIGHS south of Australia
and in Southeast Pacific with a trough in-between, south of NZ. The
TROUGH north of Fiji to Tahiti has deepened.
In April the average weather map had a stronger subtropical ridge,
typical of mid autumn.
The 1015 isobar has shifted north over Australia and onto New
Caledonia., but remains in much the same place near 47S. f
TROPICS
Again, there are no named storms. The place of greatest expected
potential is now skirting the equator around New Guinea.
WEATHER ZONES
The South Pacific Convergence zone is active over New Guinea and from
Solomon Islands to northern Vanuatu. Trade winds are expected to
prevail south of 15S.
HIGHS and LOWS
HIGH H1 east of the North Island is expected to travel east from 35S
to 40S and weaken.
Low L1 is expected to form to NE of NZ by end of Tuesday, along with
strong easterly winds on its south side and a lull on its north side.
It should travel east and then SE allowing its tropical trough to
linger rover Islands between Tonga and Southern Cooks. Avoid.
HIGH H2 is expected to stall south of Tasmania.
For NZ: a passing trough is expected on Monday and another on
Wednesday/Thursday.
Off East Australia: Next offshore trough is likely around Sunday 12
May.
Panama to Marquesas:
If heading south and you wish to start with northerly winds, then do
so before local Tuesday.
Squally doldrums from 6N to 2N.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Disclaimer: Weather is a mix of pattern and chaos; these ideas are
from the patterned world.
Compiled Sunday 5 MAY 2024
A review of last month's weather
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/jVwSiLqZk_4
April was a quiet month in the South Pacific tropics. There were two
very weak MJO phases, but they didn't produce much.
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
Regionally, the warmer Atlantic is a worry and a sign of a big cyclone
season coming there next few months. The seas around NZ are now near
normal. There is a build-up pf cool water near Galapagos. The
equatorial current is running like a wide river taking warm water
westwards. A sign that El Nino is over.
Average isobars for past month (below) From
www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.htmlclip_image008
During April the subtropical ridge in the Southern Hemisphere
strengthened.
The anomaly pressure pattern for April shows HIGHS south of Australia
and in Southeast Pacific with a trough in-between, south of NZ. The
TROUGH north of Fiji to Tahiti has deepened.
In April the average weather map had a stronger subtropical ridge,
typical of mid autumn.
The 1015 isobar has shifted north over Australia and onto New
Caledonia., but remains in much the same place near 47S. f
TROPICS
Again, there are no named storms. The place of greatest expected
potential is now skirting the equator around New Guinea.
WEATHER ZONES
The South Pacific Convergence zone is active over New Guinea and from
Solomon Islands to northern Vanuatu. Trade winds are expected to
prevail south of 15S.
HIGHS and LOWS
HIGH H1 east of the North Island is expected to travel east from 35S
to 40S and weaken.
Low L1 is expected to form to NE of NZ by end of Tuesday, along with
strong easterly winds on its south side and a lull on its north side.
It should travel east and then SE allowing its tropical trough to
linger rover Islands between Tonga and Southern Cooks. Avoid.
HIGH H2 is expected to stall south of Tasmania.
For NZ: a passing trough is expected on Monday and another on
Wednesday/Thursday.
Off East Australia: Next offshore trough is likely around Sunday 12
May.
Panama to Marquesas:
If heading south and you wish to start with northerly winds, then do
so before local Tuesday.
Squally doldrums from 6N to 2N.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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