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 16 February2025
Over 50 years of MJO
Fifty years ago, I started forecasting at Wellington Airport. In 1976 I started a 3-year period of forecasting at Nadi Airport and in 1979 I returned there another stint. During that summer in my spare time, I did some (unpublished) research investigating the extent and persistence of the South Pacific convergence zone SPCZ by compiling daily a cloudiness measure from the past 10 days of satellite imagery (thanks to then Director of Fiji Met Service Ram Krishna).
The story is that when we analysed the tropical weather maps in Fiji we would write the 24 hour pressure change next to each observation. Red for falling and blue for rising. We even had special red/blue pencils for this. I noticed that once a month or so we would go thru a period with a pulse of falling pressure travelling east across our map, followed by a pulse of blue, then a few weeks of relative quiet. In my stint starting 1979 I designed my cloudiness experiment to check the impact of this pulse on the SPCZ. You can see an animation of these maps here https://www.youtube.com/watch?v=dyXXHMA0_ro Very poor quality and jerky animation, and it didn't seem to show much, so I never bothered publishing anything. I wasn't aware of it at that time, but Madden and Julian had already published THEIR paper on this phenomenon
"Detection of a 40-50 day oscillation in the zonal wind in the Tropical Pacific."
https://journals.ametsoc.org/view/journals/atsc/28/5/1520-0469_1971_028_0702_doadoi_2_0_co_2.xml
Back in the early 70s, Roland A. Madden and Paul R. Julian were working for NCAR in Boulder Colorado, studying the QBO (Quasi -biennial Oscillation) n almost two-yearly switch of the zonal wind sin the stratosphere, and its impact on cyclone formation (one year more have increased risk, then be followed by a year with less risk). They wanted to find equatorial waves, so they examined 10 years of radiosonde (balloon flight data) from Canto Island. And found this 40-50day wave, now called the MJO.
The MJO is a pulse of extra convection that goes eastwards around the tropics, mainly noticeable from Indian Ocean, across the Indonesian to "top of Australia" region and the across the pacific. It is easy enough to track and thus worth following for it is indeed a forecasting tool.
In the following 50 years this mechanism has been studied by many, bringing with it many new terms to meteorology such mesoscale convective systems (MCSs), and convectively coupled equatorial waves (CCEWs). Papers have been written about how it triggers cyclones, extreme weather (even outside the tropics), and the onset of monsoons.
To use this forecasting tool in your own cruise planning, I recommend a trip to
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml
and to help you read the imagery, remember my mnemonic
BLUE is BUBBLY .................. YELLOW is MELLOW
The forecast shows an initial position and date, and then the trend for the following fortnight. Try to avoid the bubbly blue areas.
The website also shows recent data as a time /Longitude plot centred on the 180 meridian.
This graph shows the cyclic nature of the MJO and how it mainly manifests just from near 0 to near 180, and each pulse seems to have its own pace and intensity.
Anyway, today's data shows that the active phase of the MJO that has been affecting North Australia, and the South Pacific convergence zone is now slowly exiting, stage right. However, the activity near Tonga by midweek might deepen rapidly near southern Cooks late this week. Avoid.
This means that over the next few weeks of February there should be a period of relatively quiet weather with the SPCZ.
It also means that the next MJO active pulse is likely to move across the north end of Australia early in March and then into the Pacific around mid-March. Avoid.
TROPICS
Category-5 Cyclone Zelia took aim on a coastal stretch of northwestern Australia, halting mining and port operations in the remote region. * Cyclones Vince and Taliah lost force over the central Indian Ocean.
WEATHER ZONES
Rain accumulation this week from Windy.com shows an intense SPCZ with heavy rain especially from Rotuma to the Niua (N Tonga) to Niue to Southern Cooks associated with passing lows.
The wind accumulation shows wind zones associated with lows L2, L3 and L4.
Light winds this week for Vanuatu, after all that thundery weather there last week.
LOWS and HIGHS
The series of tropical lows L1, L2 and L3 are all expected to be steered slowly to south or southeast. L3 might grow to be a tropical cyclone affecting Southern Coos area late this week. Take note and check.
There is a Low approaching North Island on Monday from the north, and another deepening in Tasman Sea by Tuesday. These should cross NZ next few days and combine as L4 to south of South Island by late Wednesday, followed by a front and a southerly change Thu/Fri.
High H1 is expected to travel from Southern Bight to central Tasman Sea on Friday 21 Feb. Then this High H1 is expected to cross NZ on Sat/Sun 22/23 February.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
16 February 2025
02 February 2025
Bobgram 2 Feb 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 2 February 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 at youtu.be/iXd4tg4toU8
During January the climate modellers agreed the Pacific is in ENSO neutral territory and have given up on the idea a La NINA trending in. The MJO built over Indian Ocean and has moved onto northern Australia., with several tropical systems now around Australia.
The 500hPa heights and anomalies shows last month's trough fading then a series of large HIGHs south and east of NZ for a few weeks in January
For much of the month a HIGH straddled southern and eastern NZ as seen here on 21Jan.
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
show a fading blue tongue along the central Pacific so we are now in ENSO neutral territory.
Average isobars for past month (below)
From http://www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html
show that The Aleutian low has relaxed, and the Greenland low has deepened.
The subtropical ridge in the Southern hemisphere is still weak but has recovered a little from its December extreme.
The anomaly pressure pattern highlights these differences.
The 1010 trough-anomaly has sifted east off NZ.
The 1015 line south of Australia has shrunk.
TROPICS
There are no named storms around at present, but there are 4 tropical depressions being watched and a fifth in Gulf of Carpentaria too close (at present) to land to be able to spin-up however is bringing flooding rains to the eastern Qld coast. The MJO is active around Australia.
WEATHER ZONES
Rain accumulation this week from Windy.com shows an intense SPCZ and the heavy rain especially with the tropical low near New Caledonia and about eastern Qld coast.
The wind accumulation shows trails of wind mapped out by tropical lows L1 and L2.
LOWS and HIGHS
Low L1 now near Raoul Island is expected to deepen a lot as it travels southeast.
Tropical Low L2 near New Caledonia is also expected to deepen and bring heavy rain to Loyalty islands then move slowly southeast towards Minerva reef, so is mostly south of Fiji/Tonga.
Tropical Low L3 is expected to stay slow-moving over inland Australia, like a monsoonal low, feeding flooding rains onto Qld east coast.
High H1 in Tasman Sea is Quasi stationary. It may fade away on Thursday/Waitangi Day, as a brief passing front brings a southerly wind change to NZ East Coast, then H1 may reform.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 2 February 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 at youtu.be/iXd4tg4toU8
During January the climate modellers agreed the Pacific is in ENSO neutral territory and have given up on the idea a La NINA trending in. The MJO built over Indian Ocean and has moved onto northern Australia., with several tropical systems now around Australia.
The 500hPa heights and anomalies shows last month's trough fading then a series of large HIGHs south and east of NZ for a few weeks in January
For much of the month a HIGH straddled southern and eastern NZ as seen here on 21Jan.
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
show a fading blue tongue along the central Pacific so we are now in ENSO neutral territory.
Average isobars for past month (below)
From http://www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html
show that The Aleutian low has relaxed, and the Greenland low has deepened.
The subtropical ridge in the Southern hemisphere is still weak but has recovered a little from its December extreme.
The anomaly pressure pattern highlights these differences.
The 1010 trough-anomaly has sifted east off NZ.
The 1015 line south of Australia has shrunk.
TROPICS
There are no named storms around at present, but there are 4 tropical depressions being watched and a fifth in Gulf of Carpentaria too close (at present) to land to be able to spin-up however is bringing flooding rains to the eastern Qld coast. The MJO is active around Australia.
WEATHER ZONES
Rain accumulation this week from Windy.com shows an intense SPCZ and the heavy rain especially with the tropical low near New Caledonia and about eastern Qld coast.
The wind accumulation shows trails of wind mapped out by tropical lows L1 and L2.
LOWS and HIGHS
Low L1 now near Raoul Island is expected to deepen a lot as it travels southeast.
Tropical Low L2 near New Caledonia is also expected to deepen and bring heavy rain to Loyalty islands then move slowly southeast towards Minerva reef, so is mostly south of Fiji/Tonga.
Tropical Low L3 is expected to stay slow-moving over inland Australia, like a monsoonal low, feeding flooding rains onto Qld east coast.
High H1 in Tasman Sea is Quasi stationary. It may fade away on Thursday/Waitangi Day, as a brief passing front brings a southerly wind change to NZ East Coast, then H1 may reform.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 January 2025
Bob Blog 26 Jan 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 26 January 2025
New Zealand weather review 2024
Rainfall
Around the globe the average rainfall rate is just less than a metre
per year.
NOAA's Global Precipitation Climate Project have been watching this:
Roughly every fifth year is wetter, as it was in 2024.
The Southern Hemisphere is drier and has been showing a drying trend,
but bucked that in 2024.
The Australia BoM shows the regional forecast rain terciles for
February at http://www.bom.gov.au/climate/pacific/outlooks/
In this map some places between the Coral Sea and Tonga are expected
to have an over 80% chance of being above normal. And the shading is a
good proxy for the expected average position of the Thundery South
Pacific Convergence zone for the coming month.
Fingers of extra wetness spread from the Coral Sea to northern NZ.
TROPICS
The MJO is now in the Indian ocean and moving onto the NW end of
Australia.
There are currently no named cyclones anywhere
Last week Cyclone Sean brought torrential rains in northwestern
Australia but caused little damage in the region.
WEATHER ZONES
The wind accumulation shows that the wind builds up in areas such as
he Coral Sea and NW of New Caledonia, but not along the SPCZ (whose
position is shown in the rain accumulation).
So for the coming week they may be soe wind and some rain, but they
are NOT expected to combine.
A tropical low L4 is expected to form on the SPCZ in the New Caledonia
area from mid-week Avoid,
LOWS and HIGHS
LOW L1 is well south of Tahiti tonight and expected to travel off to
the Se
LOW L2 is crossing NZ tonight and expected to travel off to the
Southeast.
HIGH H1 is expected to cross NZ on Tuesday.
Low L3 and accompanying front is expected to travel across NZ
mid-week.
After that High H3 should move onto NZ, then to east of NZ this
weekend.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 26 January 2025
New Zealand weather review 2024
Rainfall
Around the globe the average rainfall rate is just less than a metre
per year.
NOAA's Global Precipitation Climate Project have been watching this:
Roughly every fifth year is wetter, as it was in 2024.
The Southern Hemisphere is drier and has been showing a drying trend,
but bucked that in 2024.
The Australia BoM shows the regional forecast rain terciles for
February at http://www.bom.gov.au/climate/pacific/outlooks/
In this map some places between the Coral Sea and Tonga are expected
to have an over 80% chance of being above normal. And the shading is a
good proxy for the expected average position of the Thundery South
Pacific Convergence zone for the coming month.
Fingers of extra wetness spread from the Coral Sea to northern NZ.
TROPICS
The MJO is now in the Indian ocean and moving onto the NW end of
Australia.
There are currently no named cyclones anywhere
Last week Cyclone Sean brought torrential rains in northwestern
Australia but caused little damage in the region.
WEATHER ZONES
The wind accumulation shows that the wind builds up in areas such as
he Coral Sea and NW of New Caledonia, but not along the SPCZ (whose
position is shown in the rain accumulation).
So for the coming week they may be soe wind and some rain, but they
are NOT expected to combine.
A tropical low L4 is expected to form on the SPCZ in the New Caledonia
area from mid-week Avoid,
LOWS and HIGHS
LOW L1 is well south of Tahiti tonight and expected to travel off to
the Se
LOW L2 is crossing NZ tonight and expected to travel off to the
Southeast.
HIGH H1 is expected to cross NZ on Tuesday.
Low L3 and accompanying front is expected to travel across NZ
mid-week.
After that High H3 should move onto NZ, then to east of NZ this
weekend.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
19 January 2025
Bobgram 19 Jan 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 January 2025
New Zealand weather review 2024
In a time-latitude plot of the air temperature measured over a
north-south slice of Aotearoa/ NZ as it travelled through 2024.
It clearly shows temperature is cooler further south and during
winter.
This time section makes a "bar-code" graph which reveals the annual
trend and the daily variation. It gives a rough indication of the
extremes and provides a visual image for quick comparison with any
another year to see seasonal variations. The land silhouette is
provided to help relate the latitude axis to your place.
Looking at a similar diagram for the barometric air pressure provides
a graph that combines all the daily weather maps into one image.
This produces a more random looking barcode. The yellow and red lines
correspond to passing HIGHS on the weather map, and the blues show the
LOWS or depressions/storms. Th "HIGH JULY" stands out (see
https://blog.metservice.com/node/1192)
There is a notable swing to blue low pressure that started from 20
December. This continued into January 2025.
The rain image is probably the most interesting as it highlights the
dry periods in Northland last February, April and late November to
early December
TROPICS
The MJO is now in the Indian ocean and moving onto the NW end of
Australia.
Tropical cyclone Sean is travelling out to sea from the Karratha
region.
WEATHER ZONES
TC Sean's forecast stands out in the wind and rain accumulation maps.
The South Pacific Convergence zone SPCZ is expected to have a routine
week and mainly be between Solomon Islands and Tokelau, north of
Samoa.
LOWS and HIGHS
The High which has been lingering well to southeast of Tahiti for past
ten days is expected to move off to Southeast this week.
The Low which has been lingering near Chatham Islands for past 10 days
is also expected to now move quickly off to the Southeast. This allows
the High that is currently around southern NZ to also move off to the
east following that Low/
A multi-centred complex low L1 in the Tasman Sea to NW o Auckland is
expected to travel southeast across Northland on Tuesday then weaken.
An active front is expected to reach Tasmania on Tuesday night and
then cross NZ on Thursday and Friday and weaken.
That Low is expected to be following by a High H2, and that front is
expected to be followed by a High H3 starting in the Aussie Bight.
These highs should combine in the Tasman Sea and then cross NZ on
Friday/Saturday.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 January 2025
New Zealand weather review 2024
In a time-latitude plot of the air temperature measured over a
north-south slice of Aotearoa/ NZ as it travelled through 2024.
It clearly shows temperature is cooler further south and during
winter.
This time section makes a "bar-code" graph which reveals the annual
trend and the daily variation. It gives a rough indication of the
extremes and provides a visual image for quick comparison with any
another year to see seasonal variations. The land silhouette is
provided to help relate the latitude axis to your place.
Looking at a similar diagram for the barometric air pressure provides
a graph that combines all the daily weather maps into one image.
This produces a more random looking barcode. The yellow and red lines
correspond to passing HIGHS on the weather map, and the blues show the
LOWS or depressions/storms. Th "HIGH JULY" stands out (see
https://blog.metservice.com/node/1192)
There is a notable swing to blue low pressure that started from 20
December. This continued into January 2025.
The rain image is probably the most interesting as it highlights the
dry periods in Northland last February, April and late November to
early December
TROPICS
The MJO is now in the Indian ocean and moving onto the NW end of
Australia.
Tropical cyclone Sean is travelling out to sea from the Karratha
region.
WEATHER ZONES
TC Sean's forecast stands out in the wind and rain accumulation maps.
The South Pacific Convergence zone SPCZ is expected to have a routine
week and mainly be between Solomon Islands and Tokelau, north of
Samoa.
LOWS and HIGHS
The High which has been lingering well to southeast of Tahiti for past
ten days is expected to move off to Southeast this week.
The Low which has been lingering near Chatham Islands for past 10 days
is also expected to now move quickly off to the Southeast. This allows
the High that is currently around southern NZ to also move off to the
east following that Low/
A multi-centred complex low L1 in the Tasman Sea to NW o Auckland is
expected to travel southeast across Northland on Tuesday then weaken.
An active front is expected to reach Tasmania on Tuesday night and
then cross NZ on Thursday and Friday and weaken.
That Low is expected to be following by a High H2, and that front is
expected to be followed by a High H3 starting in the Aussie Bight.
These highs should combine in the Tasman Sea and then cross NZ on
Friday/Saturday.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 January 2025
Bob Blog 12 Jan
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 January 2025
Is this a La Nina Modoki?
Modoki is a Japanese word loosely translated to "similar, but
different" or in New Zealand slang "Yeah, nah". Professor Toshio
Yamagata and a colleague named the phenomenon while investigating the
causes of Japan's hot summer in 2004.
This occurs when the Sea surface temperature SST in the central
equatorial Pacific coos, while the SST in the western and eastern
parts warm.
This differs from the regular La Nina where the cool zone is in the
eastern equatorial Pacific as shown here on the left.
A La Nina Modoki shifts the Jetstream that intercepts western north
America. This explains the drought over central California, a primary
factor in this week's wildfires.
A recent time section of SST anomalies near the equator and across the
Pacific,
For a deeper look t La Nina Modoki see
www.youtube.com/watch?v=VxIwP9V0pTs
TROPICS
The MJO is now in the Indian ocean. Tropical cyclone DIKELEDI is
skirting Madagascar.
In the Pacific PITA formed briefly on the South pacific Convergence
zone near Niue and is now weakening near the Southern Cooks.
WEATHER ZONES
The wind accumulation shows the windy signature of the Lows.
The South Pacific Convergence zone SPCZ is very active from Solomon
Islands to Samoa to Southern cooks
and expected to visit the Society Islands mid-week. Avoid
LOWS and HIGHS
For the next few days there is still a lot of wind around the
south-eastern sector of the now subtropical low L1, the remains of
cyclone PITA, south of the Southern Cooks.
The large deep Low southeast of Chatham Islands is expected to remain
in force until mid-week and then go southeast.
The High H1 in the Tasman Sea is expected to cross NZ on Tuesday and
Wednesday. These are good days for sailing south along NZ west coast
The Low L3 is expected to form east of Brisbane on Monday and then
slowly deepen and travel east to be near Norfolk Island by Thursday
and then to go to the south. Avoid.
Another Low L4 is expected to cross south of Tasmania on Wednesday and
then move off to the southeast.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 January 2025
Is this a La Nina Modoki?
Modoki is a Japanese word loosely translated to "similar, but
different" or in New Zealand slang "Yeah, nah". Professor Toshio
Yamagata and a colleague named the phenomenon while investigating the
causes of Japan's hot summer in 2004.
This occurs when the Sea surface temperature SST in the central
equatorial Pacific coos, while the SST in the western and eastern
parts warm.
This differs from the regular La Nina where the cool zone is in the
eastern equatorial Pacific as shown here on the left.
A La Nina Modoki shifts the Jetstream that intercepts western north
America. This explains the drought over central California, a primary
factor in this week's wildfires.
A recent time section of SST anomalies near the equator and across the
Pacific,
For a deeper look t La Nina Modoki see
www.youtube.com/watch?v=VxIwP9V0pTs
TROPICS
The MJO is now in the Indian ocean. Tropical cyclone DIKELEDI is
skirting Madagascar.
In the Pacific PITA formed briefly on the South pacific Convergence
zone near Niue and is now weakening near the Southern Cooks.
WEATHER ZONES
The wind accumulation shows the windy signature of the Lows.
The South Pacific Convergence zone SPCZ is very active from Solomon
Islands to Samoa to Southern cooks
and expected to visit the Society Islands mid-week. Avoid
LOWS and HIGHS
For the next few days there is still a lot of wind around the
south-eastern sector of the now subtropical low L1, the remains of
cyclone PITA, south of the Southern Cooks.
The large deep Low southeast of Chatham Islands is expected to remain
in force until mid-week and then go southeast.
The High H1 in the Tasman Sea is expected to cross NZ on Tuesday and
Wednesday. These are good days for sailing south along NZ west coast
The Low L3 is expected to form east of Brisbane on Monday and then
slowly deepen and travel east to be near Norfolk Island by Thursday
and then to go to the south. Avoid.
Another Low L4 is expected to cross south of Tasmania on Wednesday and
then move off to the southeast.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 January 2025
Bobgram 5 Jan 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 5 January 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 at
youtu.be/VwQ10R1FMR0
December had an MJO period over North Australia and into the South
Pacific between 20 and 30 December. An unnamed and minimal tropical
storm skirted Australia's remote Cocos Islands territory, in the
eastern Indian Ocean. And some small tropical depressions formed
between Vanuatu and northern Tonga, drenching Fiji.
Next MJO may be in late January.
The 500hPa heights and anomalies show interesting upper troughs
spreading from the north onto NZ during that MJO.
This led to a series of Lows mainly east of NZ, for example on
Christmas Day
Sea Surface temperature anomalies as at
psl.noaa.gov/map/clim/sst.shtml
show a fading blue tongue along the central Pacific shows that the
trend to a La Nina is stalling.
Average isobars for past month
show that the Aleutian low has deepened.
The subtropical ridge in the Southern hemisphere has weakened, and
around NZ has been replaced by a trough.
Pressure anomalies for past month highlights these differences.
The 1020 over New Zealand has dropped to between 1000 and 1010hPa.
It snowed on the Dessert Road today, gulp.
TROPICS
There are no named storms around at present.
WEATHER ZONES
Rain accumulation this week from Windy.com shows an intense SPCZ over
Solomon Islands to Samoa/northern Tonga.
The wind accumulation shows that the Low east of NZ, L1 is surrounded
by lots of wind.
LOWS and HIGHS
The Low L1 east of NZ is expected to become a slow-moving complex.
Avoid.
A Low L2 is expected to form on the SPCZ near norther Tonga and go SE
towards Southern Cooks
then south and join the L1 complex. Avoid
High H1 now in Australian Bight is expected to move around south side
of Tasmania on Tuesday
then around south side of NZ late in the week and expand over whole of
at end of the week to early next week.
Low L3 over inland Australia is associated with a heatwave and
expected to move slowly to Victoria by end of the week.
It may deepen in Tasman Sea next week.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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 5 January 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 at
youtu.be/VwQ10R1FMR0
December had an MJO period over North Australia and into the South
Pacific between 20 and 30 December. An unnamed and minimal tropical
storm skirted Australia's remote Cocos Islands territory, in the
eastern Indian Ocean. And some small tropical depressions formed
between Vanuatu and northern Tonga, drenching Fiji.
Next MJO may be in late January.
The 500hPa heights and anomalies show interesting upper troughs
spreading from the north onto NZ during that MJO.
This led to a series of Lows mainly east of NZ, for example on
Christmas Day
Sea Surface temperature anomalies as at
psl.noaa.gov/map/clim/sst.shtml
show a fading blue tongue along the central Pacific shows that the
trend to a La Nina is stalling.
Average isobars for past month
show that the Aleutian low has deepened.
The subtropical ridge in the Southern hemisphere has weakened, and
around NZ has been replaced by a trough.
Pressure anomalies for past month highlights these differences.
The 1020 over New Zealand has dropped to between 1000 and 1010hPa.
It snowed on the Dessert Road today, gulp.
TROPICS
There are no named storms around at present.
WEATHER ZONES
Rain accumulation this week from Windy.com shows an intense SPCZ over
Solomon Islands to Samoa/northern Tonga.
The wind accumulation shows that the Low east of NZ, L1 is surrounded
by lots of wind.
LOWS and HIGHS
The Low L1 east of NZ is expected to become a slow-moving complex.
Avoid.
A Low L2 is expected to form on the SPCZ near norther Tonga and go SE
towards Southern Cooks
then south and join the L1 complex. Avoid
High H1 now in Australian Bight is expected to move around south side
of Tasmania on Tuesday
then around south side of NZ late in the week and expand over whole of
at end of the week to early next week.
Low L3 over inland Australia is associated with a heatwave and
expected to move slowly to Victoria by end of the week.
It may deepen in Tasman Sea next week.
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Contact is bob@metbob.com or text 64277762212.
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