Bob Blog 30 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 Sunday 30 January 2022

Some interesting recent weather clips:
Antarctic Ice see: www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=304293

A MOAT of low pressure.
On weather maps you have probably heard of HIGHS and LOWS, TROUGHS and
RIDGES and may be of a COL. Have you heard of a MOAT?
A weather map in illustrated edition at
metbob.wordpress.com/2022/01/30/bob-blog-30-jan/ shows a "heat low" over the
North Island during a hot summer's day splitting the HIGH crossing the
country into two. A fairly common pattern.
If we zoom in on that weather map an interesting pattern is shown, with a
MOAT of low pressure over most of the central North Island and an island of
higher pressure over Lake Taupo. This is a reasonable representation, for
Lake Taupo is not likely to warm as much as the surrounding land, and thus
should hold cooler denser air over it as shown by slightly higher pressure.

TROPICS
The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical
Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html
TC BATSIRAI in the Indian Ocean is expected to be a severe system on Monday
when it passes to north of Rodrigues heading for Madagascar. There are zones
of potential formation in the Coral Sea and around NW Australia.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ remains active from Solomons to Vanuatu/Samoa to Southern Cooks.

HIGHS and LOWS
Subtropical Low L1 south of New Caledonia is expected to go South-southwest
across the Tasman Sea.

HIGH H1 over central New Zealand is expected to travel east and then
northeast.

Low L2 is expected to form on the northwest shoulder of H1, south of Niue,
by mid-week and then go southwest and fade over North Island by end of the
week.

Meanwhile tropical Low L3 is expected to form in the Coral Sea by Tuesday
and then travel across Vanuatu and to southeast of New Caledonia by end of
the week.

High H2 is expected to move from Aussie Bight to south Tasman Sea after
mid-week

If planning a trans-Tasman trip , avoid L1 next few days and beware of L3
next week.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more details, 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 txt 64277762212
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bob Blog 23 Jan

Bob Blog 23 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 Sunday 23 January 2022

Some interesting weather clips on you tube this week:

Snow in the Sahara: www.youtube.com/watch?v=NgJAgSFw2w4
Waves in Sc clouds: www.youtube.com/watch?v=S-BePB8CvVE
And www.youtube.com/watch?v=wAQjw1O5A30

THE WARMING OCEANS
In last Friday's Sea surface temperature anomaly SSTA map is shown the cool
zone over eastern equatorial pacific which manifests LA NINA.

I have noticed over the last decade or so that SSTA maps have been showing
larger areas that are warmer-than-normal than are cooler-than-normal. I
understand that the oceans have been warming up because of climate change.
On sunny and windless days in anticyclones the surface of the sea can absorb
heat directly from incoming sunshine. It also should lose heat to outer
space at night, but now there seems to be a imbalance in this. The amount of
carbon dioxide in the air has been increasing and this seems to allow the
oceans to store more heat.

By definition it takes one calorie to warm a gram of water (at 25C) by one
degree, or the thermal capacity of water is 1000 cal/Kg/K, or 4183J/Kg/K. So
water "holds warmth" over 4 times better than air (which has a thermal
capacity 1004J/Kg/K).

I've recently come across a paper in Advances in Atmospheric Sciences, Jan
2022 entitled: Another Record: Ocean Warming Conditions through 2021 despite
La Nina Conditions. Creative commons license
creativecommons.org/licenses/by/4.0/.

It contains a diagram which tracks the amount of heat stored in the oceans
since 1960 compared with a baseline using the 1981-2010 epoch. :
This diagram shows that ocean heat content was static until the late 1980s
and since then has been rising at a rate of between 8 and 9 Zettajoules per
year ZJ/yr. A Zetta is 1 followed by 21 zeros. The 2021 annual ocean heat
content is a new record and higher than the previous year by around 15 ZJ.
So the ocean now contains around 240 ZJ more than the 1981-2010 average. To
put this into perspective, the current oil consumption on this planet is
0.2ZJ per year, and electricity generation is 0.1ZJ/year.

See tinyurl.com/Trenberthoceanwarming

TROPICS
There are zones of potential formation around Northwest and North Australia
and the Philippines and dotted over the South Pacific.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ remains active from Solomons to Vanuatu/Samoa to Southern Cooks.

HIGHS and LOWS
Subtropical Low L1 south of New Caledonia is expected to do a loop on Monday
and then travel slowly east and fade.
It should trigger a secondary Low L2 west of Taranaki by Tuesday night that
is expected to travel SE over central NZ bringing some much needed rain.
Meanwhile tropical low L3 south of Southern Cooks is expected to move off to
the Southeast from mid-week after bringing wind and rain last few days to
Southern Cooks.
Low L4 is expected to deepen over Vanuatu by Friday and may visit New
Caledonia by the weekend, and this may bring strong NE winds to Northland
area next week. Avoid.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for 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 txt 64277762212
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

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Bob Blog

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 16 January 2022

TONGAN VOCANO
The undersea volcano called "Hunga-Tonga-Hunga-Ha'apai", between Tongatapu
and Ha'apai, started erupting a few days before Christmas, and has been
spewing ash ever since and building a crater that was above sea level.

Last Friday (local) an eruption triggered a Tsunami watch. Then just before
dusk on Saturday (local) the volcano exploded.maybe the seafloor collapsed
into the caldera under it, releasing awesome amounts of energy.

Nukualofa, Tonga's capital, was inundated by Tsunami, then blanketed in
thick ash, and communications are still down. The sonic boom was heard here
in NZ, over 2000km away. And the pressure-shock waves circled the planet,
with a 2.5hPa fluctuation in barographs measured in Europe (as with Krakatoa
in 1883).

A summary of the news media imagery from iTV may be seen at
www.youtube.com/watch?v=d65BQ-Q7ftc

A combo of large waves from remains of TC CODY and the surge for the Tongan
Tsunami bashed boats in Tutukaka marina, near Whangarei, damaging many and
sinking a yacht.

The Tsunami surges can be seen on the NZGNS tide gauges:
The graph at North Cape shows the large "gravity" waves from the remains of
TC CODY.

Still too early to estimate how much ash got into the stratosphere. But if
it is significant then this may bring a period of cooling to the planet.

TROPICS
Last week CODY formed and brought heavy rain to Fiji, then travelled south
and southeast. It is now subtropical L1 and is expected to reach Chatham
Islands late Tuesday.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ remains active from Solomons to Vanuatu/Samoa to Southern Cooks.
Tropical low L2 over Southern Cooks is expected to deepen and be slow-moving
until mid-week then go off to south and southeast. Check
www.met.gov.fj/aifs_prods/20036.txt

HIGHS and LOWS
HIGH H1 south of Chathams is expected to travel east along 45S.
HIGH H2 west of North Island should linger there until mid-week then fade.
TROF now over Tasmania should go northeast and bring a southerly change to
South Island on Wednesday and North Island on Thursday.
HIGH H3 is expected to follow trof into Tasman Sea by Friday and onto North
Island at end of week.

After the swells ease by late Tuesday, it is looking OK to travel into Opua
anytime this or next week.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for 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 txt 64277762212
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bob Blog 9 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 Sunday 9 January 2022

TEN REASONS TO HATE A HIGH (Anticyclone)

Anticyclones are usually associated with light winds and sunny skies but
they also have some undesirable attributes, especially when they get blocked
and linger:

1. Near the centre are "dead" winds and usually an area of low cloud causing
dull days called "anticyclonic gloom", or dirty air which may turn into fog.

2 Round the rim, winds are strong. If the central pressure is over 1030,
look for a gale somewhere on the outside of a high. As the saying goes" When
barometer is over a thousand and thirty, weather can get dirty".

3. Highs intensify the trade winds in the tropics. It may take about a week
for a high to travel eastwards past New Zealand, and during this time the
stronger trade winds tend to give night-time rain to the eastern side of the
larger tropical Islands. In Fiji this is sometimes called BOGI WALU.

4. The bigger the highs are, the slower they move, blocking the fronts and
lows that are trying to follow them. When this block is released, the
northwestern ("back") end of a high is a zone where the barometer "falls"
and may become a breeding ground for storms. The tropical low affecting Fiji
tonight is an example of this.

5. Intensifying highs tend to squash together the isobars between themselves
and any nearby low-pressure centres, creating "squash zones".

6. A deepening low-pressure system and an intense or lingering anticyclone
get together like the arms of an eggbeater and create a zone of enhanced
wind and rain in-between where the isobars are straightest and barometer is
"steady".

7. As air flows around a high, it spins out across the isobars and speeds up
until it is as much as 20% MORE than that indicated by the isobar-spacing.

8. Terrain effects: At present the windy.com wind map is showing strong
winds around East Cape and through Cook Strait.

If a range of mountains blocks the air flowing around a high, the air tends
to squeeze around the mountains rather than flow over them. This splits the
wind flow over New Zealand into rivers of wind and puddles of calm.
Sometimes a narrow gap is made just above the mountains through which
pent-up air may be suddenly released at a rapid rate.

9. In winter and spring the clear night skies in a high may bring unwelcome
frost.

10. In summer and autumn a high may allow sea breezes to converge and, if it
is cold enough aloft, this can form thunderstorms and hail. Today's
MetService radar is showing showers over the midriff of the northern North
Island


TROPICS
SETH finally went inland onto Queensland yesterday/Saturday, bringing severe
flash flooding (at least one death).
www.theguardian.com/australia-news/2022/jan/08/unexpected-floods-in-queensla
nd-leave-15-missing-as-ex-cyclone-seth-wreaks-havoc
The tropical depression near northwest of Fiji is currently called 03F but
may well earn a cyclone name by Monday. Check
www.met.gov.fj/aifs_prods/20036.txt

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ remains active from Solomons to Tuvalu to Fiji and from Samoa to
French Polynesia. Low L1 is expected to form in the southeast extension of
this zone near 30S 159W by local Tuesday and then deepen and travel to
southeast.
The tropical low T near Fiji is expected to deepen next few days and take a
slow and twisting path to the south, then, from mid-week , speed up and go
south-southeast to east of the North Island.

HIGHS and LOWS
HIGH H1 starts the week east of North Island and is expected to travel off
to the east remaining south of L1.
On Tuesday a trough in between H1 and H2 is expected to cross New Zealand,
followed by a southwest flow on Wednesday.
Then, later in the week H2 is expected to travel east across the south
Tasman Sea reaching the South Island by the end of the week.
Avoid arriving in Opua between 14 and 16 Jan due to possible strong winds
and large swells..
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for 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 txt 64277762212
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bob blog 2 Jan 2022

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 2 January 2022

An interesting article on how the marine heatwave is affecting the fishing
(and swimming) around New Zealand is available from NIWA:
niwa.co.nz/news/will-it-be-a-fintastic-fishing-year with a video clip
showing how this marine heat wave is related to the current cool equatorial
waters of LA NINA

TROPICS
The latest cyclone activity report is at tropic.ssec.wisc.edu and Tropical
Cyclone Potential is from www.ssd.noaa.gov/PS/TROP/TCFP/index.html

SETH formed in the Coral Sea a few days ago and is now weakening.

There is a high chance of another tropical feature deepening between Vanuatu
and Fiji late this week, and then coming south towards NZ next week, but
this development and track is still uncertain. Maybe stay put between
Vanuatu, Fiji, and NZ this week and next week.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The SPCZ remains active from Solomons to Tuvalu to Fiji/Samoa.
SETH is expected to weaken and drift slowly South
A new tropical low is expected to form between Vanuatu and Fiji by end of
the week.
A convergence zone is expected to linger around the Tuamotu Islands


HIGHS and LOWS
HIGH H1 starts the week east of South Island and travel off to the
northeast.
Low L1 to east of North Island is expected to do a clockwise loop to the
west by mid-week and then peel off to the SE.
A weak replacement trough is expected to travel across NZ on Tuesday and
then High H2 should travel northeast across the Tasman Sea onto central NZ
by the weekend.
LOW L2 is expected to travel from interior of Australia across Tasmania on
Thursday and to southern NZ by Sat.

OK to arrive in Opua this week, and maybe stay put between Vanuatu, Fiji
this week, extended to NZ next week.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If you would like more detail for 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 txt 64277762212
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>