nz-weathergram
Date: Sun, 30 Nov 2025 23:37:18 +1300
Subject: 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 30 Nov 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
For the month of November youtu.be/YSxd15lSIrs
It was a month with large anticyclones, and between them some big passing
troughs.
Cyclone FINA marked an early start to the Australian Cyclone. Alos on 265
November a serious looking Low developed south of TONGA
The 500hPa heights and anomalies shows these Lows.
From http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_sh_anim.shtml
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
shows that .....
The North Pacific "blob" is now weakening. The La Nina cool waters are
not very intense. A large zone of warmer than normal sea is sitting over the
Coral Sea and also there are warm waters along Aussie west and especially SW
coast-rain seems likely as a consequence.
Average isobars for past month from
www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html show that :
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.
Pressure anomalies for past month From
www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html show that
The anomaly pressure pattern for November has a dominant HIGH east of NZ,
and a large low breeding area around Tasmania.
TROPICS
Tonight there are no named storms
In the past few weeks.
. Severe Cyclone Fina knocked out power and uprooted trees around the
Australian city of Darwin before making final landfall on the Kimberly
Coast.
. Typhoon Koto passed over the South China Sea after forming over the
west-central Philippines.
. Monsoons exacerbated by tropical storms has caused some of the worst
flooding in years, with millions affected in Indonesia, Malaysia and
Thailand. The death toll on Indonesia's Sumatra Island has passed 300 and
there are dozens missing.
WEATHER ZONES
Rain accumulation this week from Windy.com shows well defined SPCZ mainly
in the north but visiting Vanuatu at times
Heavy rains are forecast for French Polynesia , associated with a
tropical low L1.
Wind accumulation from windy.com shows windy areas associated with a
tropical low south of French Polynesia, L1. Also a windy area around
Chatham Islands associated with a Low crossing NZ on Wednesday, L2.
Low L1 is expected to form over French Polynesia on their Sunday and Monday
bringing wind and rain and then travel to the southeast. Avoid.
HIGH H1 is quasi-stationary to northeast of NZ and is expected to travel to
southeast , getting south of L1/ is expected to rebuild near 40S 150W from
Tuesday
and then travel off well southeast of NZ is expected to move slowly over
Southern Ocean as HIGH H1 now just NE of Auckland travels ENE along 35 to
30S.
Low L2 is expected to form over the Lord Howe area on Monday night and then
deepen as it crosses central NZ on Wednesday. This is expected to form a
westerly gale on its northside between 30 and 34S on Wednesday with over 4m
swells . avoid.
L2 is followed by a HIGH H2 which should travel steadily East-southeast
from Lord Howe ion Wednesday to North Island on Saturday, followed by a
front over NZ next Monday.
The recent intense Monsoonal rains have been assisted by an plus of extra
convection associated with an MJO. This is expected to intensify the SPCZ
in the Coral Sea area during the next few weeks.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>
Subject: 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 30 Nov 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
For the month of November youtu.be/YSxd15lSIrs
It was a month with large anticyclones, and between them some big passing
troughs.
Cyclone FINA marked an early start to the Australian Cyclone. Alos on 265
November a serious looking Low developed south of TONGA
The 500hPa heights and anomalies shows these Lows.
From http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_sh_anim.shtml
Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml
shows that .....
The North Pacific "blob" is now weakening. The La Nina cool waters are
not very intense. A large zone of warmer than normal sea is sitting over the
Coral Sea and also there are warm waters along Aussie west and especially SW
coast-rain seems likely as a consequence.
Average isobars for past month from
www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html show that :
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.
Pressure anomalies for past month From
www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html show that
The anomaly pressure pattern for November has a dominant HIGH east of NZ,
and a large low breeding area around Tasmania.
TROPICS
Tonight there are no named storms
In the past few weeks.
. Severe Cyclone Fina knocked out power and uprooted trees around the
Australian city of Darwin before making final landfall on the Kimberly
Coast.
. Typhoon Koto passed over the South China Sea after forming over the
west-central Philippines.
. Monsoons exacerbated by tropical storms has caused some of the worst
flooding in years, with millions affected in Indonesia, Malaysia and
Thailand. The death toll on Indonesia's Sumatra Island has passed 300 and
there are dozens missing.
WEATHER ZONES
Rain accumulation this week from Windy.com shows well defined SPCZ mainly
in the north but visiting Vanuatu at times
Heavy rains are forecast for French Polynesia , associated with a
tropical low L1.
Wind accumulation from windy.com shows windy areas associated with a
tropical low south of French Polynesia, L1. Also a windy area around
Chatham Islands associated with a Low crossing NZ on Wednesday, L2.
Low L1 is expected to form over French Polynesia on their Sunday and Monday
bringing wind and rain and then travel to the southeast. Avoid.
HIGH H1 is quasi-stationary to northeast of NZ and is expected to travel to
southeast , getting south of L1/ is expected to rebuild near 40S 150W from
Tuesday
and then travel off well southeast of NZ is expected to move slowly over
Southern Ocean as HIGH H1 now just NE of Auckland travels ENE along 35 to
30S.
Low L2 is expected to form over the Lord Howe area on Monday night and then
deepen as it crosses central NZ on Wednesday. This is expected to form a
westerly gale on its northside between 30 and 34S on Wednesday with over 4m
swells . avoid.
L2 is followed by a HIGH H2 which should travel steadily East-southeast
from Lord Howe ion Wednesday to North Island on Saturday, followed by a
front over NZ next Monday.
The recent intense Monsoonal rains have been assisted by an plus of extra
convection associated with an MJO. This is expected to intensify the SPCZ
in the Coral Sea area during the next few weeks.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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.
>>>>>>>>>>>>>>>>