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 26 October 2025
The storm of 23 Oct
A trajectory analysis of air arriving in New Zealand on Thursday 23 October,
as seen at www.ready.noaa.gov
shows the collision between cold air from the south with warm air form the
north.
Squashed isotherms produce squashed isobars.
Indeed the isobars clustered together around a 958hPa low and over Kiwiland.
The pressure difference between Auckland (1012hPa) and Invercargill (970
hPa) known as Z1 or New Zealand's primary zonal parameter was 42 hPa .
The resulting wind damage was widespread and devasting:
www.nzherald.co.nz/nz/north-canterbury-farmers-begin-major-cleanup-after-des
tructive-storm/2VZAV2OPGRE65BGJNY7FPXOCGA/
www.odt.co.nz/southland/25000-without-power-south
The thermal clash has recently been abnormal, and this can be traced back to
the Sudden stratospheric warming in September.
Tonight, there is a polar jet stretching due north off Antarctica as far
north as Tasmania. It is squeezing the isobars closer together around a Low
in the Tasman sea.
TROPICS
In the past week..
. Tropical Storm Fengshen killed seven in the central Philippines from
flooding and then drenched China's Hainan Island and central Vietnam.
. Tropical Storm Melissa formed over the central Caribbean
.Cheng churned in the Indian Ocean
WEATHER ZONES
Rain accumulation this week from Windy.com below shows well defined SPCZ
zone in the tropics mainly along 12S .
Wind accumulation from windy.com below shows the trade winds to the north
and the roaring 40s to the south with subtropical ridge in-between.
LOWS and HIGHS
Low L1 in Tasman Sea is being energized by that Polar yet from Antarctica.
The thermal clash should bring more west to NW gales to NZ on Monday, (a
public holiday).
After that on Wednesday and Thursday the High H1 is expected to travel
quickly across Tasman Sea and northern NZ, as Low L2 deepens east of
Brisbane.
Low L2 is expected to travel quickly along around 30S past NZ on Thursday.
The High H2 is expected to cross the Tasman Sea NZ area in a more sedate
fashion from Sat 1 Nov to Tue 4 Nov and maybe with a lingering influence
until Thursday 6 Nov..but the models differ about that after 3 Nov.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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 October 2025
19 October 2025
Bobgram 19 Oct 2025
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 19 October 2025
The migration
The nominal start to the cyclone season in 1 November, so this is the time
of the year that yachts set sail from Fiji/Tonga to NZ /Australia
This evening's snap from Marine Traffic shows the migration in mid- flight
This is also a good time to consider the MJO. the madden Julian Oscillation
is the name given to a pulse of extra convection that ripples around the
world from west to east, from the Indian Ocen to the Pacific Ocean. This
takes around 4 to 6 weeks and then repeats. A good way to measure this
oscillation is via satellite measurements of outgoing radiation. Cloudy
skies block the OLR giving low measurements (blue), clear skies give high
measurements (yellow). The way I remember it is: blue is bubbly and yellow
is mellow.
The diagram to use is found at
www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml
The measurement done on 17 Oct shows the next MJO starting off as a blue
area in the Indian ocean. In the last panel we have the forecast for days
11 to 15 out from 17thOct at end of this month. By then this MJO is over
the Philippines. SO early in November it will be in the Pacific, but this
particular MJO episode is looking to be too far north to have much impact on
the South Pacific. So there seems to be little chance of it triggering a
tropical cyclone in the South Pacific.
NOAA has announced that a weak LA NINA has started, triggered by cooler than
normal seas around the eastern equatorial Pacific. In the South Pacific,
this climate driver allows the subtropical ridge to shift closer to New
Zealand. This LA NINA has a good chance of fading away by early 2026 and
may have a slight reducing impact of the cyclone risk in the next few
months.
TROPICS
Two named storms is active tonight
In the past week….
• Japan's Hachijōjima Island was raked in quick succession by typhoons
Halong and Nakri.
• Tropical storm Lorenzo threatened only shipping lanes in the Atlantic
. • Karen became the most northern named storm on record to form in the
Atlantic.
• Tropical Storm Raymond skirted Mexico.
WEATHER ZONES
Rain accumulation this week from Windy.com below shows well defined SPCZ
between Solomon Islands and Samoa thundery showers around an upper low west
of New Caledonia.
Wind accumulation from windy.com below shows a squash zone in the tropics
between New Caledonia and Fiji
LOWS and HIGHS
An upper trough has moved from Australia onto the Coral Sea /New Caledonia
area. This cooler air is dropping to the surface easing the trade winds
into a lull. It is also congealing the thundery showers of the SPCZ into a
rampart around this zone that spends the first half of this week mainly over
Vanuatu to east and south of New Caledonia. If in this zone may as well stay
put until it weakens late this week.
HIGH H1 at around 35S and to NE of New Zealand is
quasi-stationary/slow-moving.
FRONTS associated with the disturbed westerlies are expected to visit
Sydney on Wed 22 and Sun 26 Oct and reach Opua on Friday 24 and Wed 29
October.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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 19 October 2025
The migration
The nominal start to the cyclone season in 1 November, so this is the time
of the year that yachts set sail from Fiji/Tonga to NZ /Australia
This evening's snap from Marine Traffic shows the migration in mid- flight
This is also a good time to consider the MJO. the madden Julian Oscillation
is the name given to a pulse of extra convection that ripples around the
world from west to east, from the Indian Ocen to the Pacific Ocean. This
takes around 4 to 6 weeks and then repeats. A good way to measure this
oscillation is via satellite measurements of outgoing radiation. Cloudy
skies block the OLR giving low measurements (blue), clear skies give high
measurements (yellow). The way I remember it is: blue is bubbly and yellow
is mellow.
The diagram to use is found at
www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml
The measurement done on 17 Oct shows the next MJO starting off as a blue
area in the Indian ocean. In the last panel we have the forecast for days
11 to 15 out from 17thOct at end of this month. By then this MJO is over
the Philippines. SO early in November it will be in the Pacific, but this
particular MJO episode is looking to be too far north to have much impact on
the South Pacific. So there seems to be little chance of it triggering a
tropical cyclone in the South Pacific.
NOAA has announced that a weak LA NINA has started, triggered by cooler than
normal seas around the eastern equatorial Pacific. In the South Pacific,
this climate driver allows the subtropical ridge to shift closer to New
Zealand. This LA NINA has a good chance of fading away by early 2026 and
may have a slight reducing impact of the cyclone risk in the next few
months.
TROPICS
Two named storms is active tonight
In the past week….
• Japan's Hachijōjima Island was raked in quick succession by typhoons
Halong and Nakri.
• Tropical storm Lorenzo threatened only shipping lanes in the Atlantic
. • Karen became the most northern named storm on record to form in the
Atlantic.
• Tropical Storm Raymond skirted Mexico.
WEATHER ZONES
Rain accumulation this week from Windy.com below shows well defined SPCZ
between Solomon Islands and Samoa thundery showers around an upper low west
of New Caledonia.
Wind accumulation from windy.com below shows a squash zone in the tropics
between New Caledonia and Fiji
LOWS and HIGHS
An upper trough has moved from Australia onto the Coral Sea /New Caledonia
area. This cooler air is dropping to the surface easing the trade winds
into a lull. It is also congealing the thundery showers of the SPCZ into a
rampart around this zone that spends the first half of this week mainly over
Vanuatu to east and south of New Caledonia. If in this zone may as well stay
put until it weakens late this week.
HIGH H1 at around 35S and to NE of New Zealand is
quasi-stationary/slow-moving.
FRONTS associated with the disturbed westerlies are expected to visit
Sydney on Wed 22 and Sun 26 Oct and reach Opua on Friday 24 and Wed 29
October.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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.
>>>>>>>>>>>>>>>>
12 October 2025
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 12 October 2025
The coming cyclone season
NIWA of NZ have issued their annual outlook for the coming cyclone season.
The main tropical climate driver at work is a "weak La Nina" pattern. Thia is likely to be augmented by the recent Stratospheric warming which may bring more wind to the Tasman Sea area until December, perhaps leading to stronger shearing forces in the tropics, which tend to prevent tropical cyclones from "winding up".
Here is NIWA's Cyclone forecast-- fewer cyclones than normal.
Greatest risk is in the Vanuatu /New Caledonian area with 3-4 cyclones likely.
SOLAR POWER IS NOW CHEAPEST
Solar energy is now so cheap it costs as little as €0.023 to produce one unit of power, a new study has found.
Solar energy has been branded the "key driver" in the world's transition to clean, renewable power due to its ultra-low cost.
A new study from the University of Surrey named solar energy the cheapest source of power, outranking other renewables such as wind, as well as coal and gas.
Researchers found that, in the sunniest countries, solar costs as little as €0.023 to produce one unit of power.
Even in the UK, which sits 50 degrees north of the equator and is infamous for its dreary weather, solar came out victorious as the cheapest option for "large-scale energy generation".
Due to the price of lithium-ion batteries falling by 89 per cent since 2010, the study also found that making solar-plus-storage systems is now equally as cost-effective as gas power plants.
See www.euronews.com/green/2025/10/08/
TROPICS
One named storm is active tonight
In the past week….
•Hurricane Priscilla lashed western Mexico with pounding surf and strong winds before its remnants drenched northwestern Mexico and the southwestern United States.
• The northern Philippines and far southern China were lashed by Typhoon Matmo.
• Category-4 Halong passed just off eastern Japan.
• The Leeward Islands were brushed by strengthening Hurricane Jerry.
• Category-1 Cyclone Shakhti churned the northern Arabian Sea.
WEATHER ZONES
Weather Zones Mid-week GFS model showing isobars, winds, waves (purple), rain (red), MT (Monsoonal trough), STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) CZ (Convergence Zone)
Rain accumulation this week from Windy.com below shows well defined SPCZ between Solomon Islands and Samoa and another convergence zone between Loyalty Islands and Fiji.
Wind accumulation from windy.com below shows some squash zones in the tropics one between New Caledonia and south of Fiji.
LOWS and HIGHS
HIGH H1 at 35S south of French Polynesia is moving off to the east allowing a procession of weather systems to flow eastwards this week.
Front associated with LOW L1 in this procession is crossing North Island on Tuesday and then travelling off to the southeast.
Another Low is expected to travel from Southern Ocean to the NE in wake of L1, reaching Chathams area by Friday, and maybe bring a brief southerly change to Northland next Sunday night.
HIGH H2 should cross northern NZ on Thursday to Saturday bringing a lull along 30S S
Next front across Northern NZ is expected on Tuesday or Wednesday 21 or 22 October.
One model is starting to have the idea of forming a tropical trough in the Coral Sea late this week and taking this to northern NZ mid next week. So far this is only an idea, but it might grow to be a threat so is a risk.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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 12 October 2025
The coming cyclone season
NIWA of NZ have issued their annual outlook for the coming cyclone season.
The main tropical climate driver at work is a "weak La Nina" pattern. Thia is likely to be augmented by the recent Stratospheric warming which may bring more wind to the Tasman Sea area until December, perhaps leading to stronger shearing forces in the tropics, which tend to prevent tropical cyclones from "winding up".
Here is NIWA's Cyclone forecast-- fewer cyclones than normal.
Greatest risk is in the Vanuatu /New Caledonian area with 3-4 cyclones likely.
SOLAR POWER IS NOW CHEAPEST
Solar energy is now so cheap it costs as little as €0.023 to produce one unit of power, a new study has found.
Solar energy has been branded the "key driver" in the world's transition to clean, renewable power due to its ultra-low cost.
A new study from the University of Surrey named solar energy the cheapest source of power, outranking other renewables such as wind, as well as coal and gas.
Researchers found that, in the sunniest countries, solar costs as little as €0.023 to produce one unit of power.
Even in the UK, which sits 50 degrees north of the equator and is infamous for its dreary weather, solar came out victorious as the cheapest option for "large-scale energy generation".
Due to the price of lithium-ion batteries falling by 89 per cent since 2010, the study also found that making solar-plus-storage systems is now equally as cost-effective as gas power plants.
See www.euronews.com/green/2025/10/08/
TROPICS
One named storm is active tonight
In the past week….
•Hurricane Priscilla lashed western Mexico with pounding surf and strong winds before its remnants drenched northwestern Mexico and the southwestern United States.
• The northern Philippines and far southern China were lashed by Typhoon Matmo.
• Category-4 Halong passed just off eastern Japan.
• The Leeward Islands were brushed by strengthening Hurricane Jerry.
• Category-1 Cyclone Shakhti churned the northern Arabian Sea.
WEATHER ZONES
Weather Zones Mid-week GFS model showing isobars, winds, waves (purple), rain (red), MT (Monsoonal trough), STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) CZ (Convergence Zone)
Rain accumulation this week from Windy.com below shows well defined SPCZ between Solomon Islands and Samoa and another convergence zone between Loyalty Islands and Fiji.
Wind accumulation from windy.com below shows some squash zones in the tropics one between New Caledonia and south of Fiji.
LOWS and HIGHS
HIGH H1 at 35S south of French Polynesia is moving off to the east allowing a procession of weather systems to flow eastwards this week.
Front associated with LOW L1 in this procession is crossing North Island on Tuesday and then travelling off to the southeast.
Another Low is expected to travel from Southern Ocean to the NE in wake of L1, reaching Chathams area by Friday, and maybe bring a brief southerly change to Northland next Sunday night.
HIGH H2 should cross northern NZ on Thursday to Saturday bringing a lull along 30S S
Next front across Northern NZ is expected on Tuesday or Wednesday 21 or 22 October.
One model is starting to have the idea of forming a tropical trough in the Coral Sea late this week and taking this to northern NZ mid next week. So far this is only an idea, but it might grow to be a threat so is a risk.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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 October 2025
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 05 October 2025
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 youtu.be/l4EARdhOSlo
Lows crossed NZ on12 and 24-25, with several stormy fronts in-between
The Low on 12 September t was especially squally and thundery:
The 500hPa heights and anomalies shows these Lows.
at http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_sh_anim.shtml
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
The North Pacific "blob" is no longer as intense as it was in August. North
Atlantic has warmed. The warm area between Java and West Australia is a
NEGATIVE IOD (Indian Ocean Dipole)
This evening's satellite and radar imagery shows this negative IOD at work
There was a sudden stratospheric warning over that part of Antarctica south
of Australia during past few weeks and this is likely to trigger outbreaks
of cold air due to a weak polar vortex. The parameter I use to watch this is
not being updated by NOAA at present due to "US Government shutdown".
TROPICS
Tonight there are 5 named storms.
In the past few weeks…
• Typhoon Bualoi left 20 people dead in the Philippines before unleashing
days of heavy rain in Vietnam, killing an additional 29.
• Remnants of Hurricane Gabrielle brought high winds to Portugal, then
triggered flash flooding in eastern and southern Spain.
• Hurricane Imelda sent pounding surf into the U.S. East Coast, while
Tropical Storm Octavia formed briefly off western Mexico.
• An unnamed tropical storm drenched India's central Bay of Bengal coast.
WEATHER ZONES
Rain accumulation this week from Windy.com below shows well defined SPCZ
between Solomon Islands and Samoa and almost drifting south onto Fiji.
Also a passing trough for Minerva .
Wind accumulation from windy.com below shows some squash zones in the
tropics one to north of Fiji and one in the Coral Sea. The strong winds
southeast of French Polynesia are associated with a passing trough. Ther
strong wind trails near Philippines and west of Mexico are associated with
tropical cyclones.
LOWS and HIGHS
Front associated with LOW L1 is crossing New Zealand on Monday and then
travelling off to the southeast.
HIGH H1 is travelling east along around 30S and crossing northern NZ on
Tuesday/Wednesday.
A warm front is expected across Northern NZ on Sunday 12 Oct followed by a
cold front around Wed 15 Oct.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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 05 October 2025
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 youtu.be/l4EARdhOSlo
Lows crossed NZ on12 and 24-25, with several stormy fronts in-between
The Low on 12 September t was especially squally and thundery:
The 500hPa heights and anomalies shows these Lows.
at http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_sh_anim.shtml
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
The North Pacific "blob" is no longer as intense as it was in August. North
Atlantic has warmed. The warm area between Java and West Australia is a
NEGATIVE IOD (Indian Ocean Dipole)
This evening's satellite and radar imagery shows this negative IOD at work
There was a sudden stratospheric warning over that part of Antarctica south
of Australia during past few weeks and this is likely to trigger outbreaks
of cold air due to a weak polar vortex. The parameter I use to watch this is
not being updated by NOAA at present due to "US Government shutdown".
TROPICS
Tonight there are 5 named storms.
In the past few weeks…
• Typhoon Bualoi left 20 people dead in the Philippines before unleashing
days of heavy rain in Vietnam, killing an additional 29.
• Remnants of Hurricane Gabrielle brought high winds to Portugal, then
triggered flash flooding in eastern and southern Spain.
• Hurricane Imelda sent pounding surf into the U.S. East Coast, while
Tropical Storm Octavia formed briefly off western Mexico.
• An unnamed tropical storm drenched India's central Bay of Bengal coast.
WEATHER ZONES
Rain accumulation this week from Windy.com below shows well defined SPCZ
between Solomon Islands and Samoa and almost drifting south onto Fiji.
Also a passing trough for Minerva .
Wind accumulation from windy.com below shows some squash zones in the
tropics one to north of Fiji and one in the Coral Sea. The strong winds
southeast of French Polynesia are associated with a passing trough. Ther
strong wind trails near Philippines and west of Mexico are associated with
tropical cyclones.
LOWS and HIGHS
Front associated with LOW L1 is crossing New Zealand on Monday and then
travelling off to the southeast.
HIGH H1 is travelling east along around 30S and crossing northern NZ on
Tuesday/Wednesday.
A warm front is expected across Northern NZ on Sunday 12 Oct followed by a
cold front around Wed 15 Oct.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details about your voyage, check metbob.com
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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