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Bob McDavitt's ideas for sailing weather around the South pacific

30 March 2014

BOB's BLOG

WEATHERGRAM
YOTREPS
Issued 30 March 2014
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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

SOI The Southern Oscillation Index SOI sums up the weather pattern over the
South Pacific as one number.
It is based on the standardized difference in the barometer readings between
Tahiti and Darwin.
SOI (30 day running mean) has dived negative in the past few weeks.
After a high late January/early February its 30 March reading was MINUS
1.18 units.
IF an El Nino cycle is approaching THEN this usually shows itself around or
soon after the equinox, so maybe this swing marks the beginning of a trend.
According to AccuWeather Long Range Forecaster Mark Paquette, "We are
confident that an El Niqo is in the early stages of developing and may reach
moderate strength moving forward into mid- to late (northern) summer of
2014."

WEATHER ZONES
Panama to Galapagos: There is a burst of NE winds across Las Perlas at
present and this is expected to last until Tuesday 1 April local. Voyage map
in my graphic blog shows the forecast for a yacht that can motor/sail up to
6 knots may encounter taking off from Las Perlas on the high tide on local
Monday afternoon. This window of good NE winds closes soon after that.


SPCZ= South Pacific Convergence Zone
This is weak at present and should slowly rebuild mainly between Solomons
and Fiji/Tonga.
A small tropical Low with strong winds around it is expected to form
between Niue and Southern Cooks on Monday UTC and then travel SE.
Associated squally weather is expected to move over southern Cooks during
the next 24 hour.

There is an interesting convergence zone that is expected to fire up along
5S between 90W (just SW of Galapagos) and all the way west to Marquesas.
This zone seems to be related to the equinox and should weaken during the
next few weeks.

STR= Sub-tropical Ridge
The STR is expected to maintain good strength between 45 and 35S with
ridge-tongues sticking out well from transient HIGH centres.
There may be a zone of enhanced SE winds on the north side of each of these
HIGHS.
One of these should be located between the HIGH that spends much of the
coming week east of NZ and that low forming between Niue and Southern Cooks.
The next transient high from the west is expected to travel eastwards along
45S to south of Tasmania on Sat/Sun 5/6 April.

New Zealand area
Sad to say, another dry week for the drought areas in parts of North Island,
and NW of South Island.
Trough currently in the mid Tasman Sea is having difficulties penetrating
the high pressures left behind by a ridge
over central NZ by the large Transient HIGH east of NZ. These wet
clouds need rail-tracks of falling pressure to make traction
--- They are most like to go south and weaken, sideswiping the south end of
the country.
The ridge has locked a layer of moisture near the surface that keeps
appearing as low cloud by day or fog by night = anticyclonic gloom.
Another trough/low combo is expected to cross Tasmania on Wednesday and the
South Island on Friday/Saturday/Sunday/Monday 4/5/6/7 April.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz My
website is at metbob.com - To unsubscribe, send an reply email saying
unsubscribe.
Feedback to bob@metbob.com

23 March 2014

BOBGRAM issued 23 March 2014

WEATHERGRAM
YOTREPS
Issued 23 March 2014
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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.
20 March at 16:57 UTC the sun seen from earth was directly overhead the
equator--- this was the equinox, and marked a significant turn in our annual
solar orbit.
ALSO Today, 23 March, marks WORLD METEOROLOGICAL DAY The theme this year is
Weather and Climate: engaging youth If you know any 8 to 12 year olds,
consider giving them a barometer for their next birthday. That seems to be
the most susceptible age for this sort of gift (teenagers tend to be so
easily bemused, and those 7 or younger tend to prefer toys rather than
instruments.
One thing that barometers give us is the SOI:
SOI The Southern Oscillation Index SOI sums up the weather pattern over the
South Pacific as one number. It is based on the standardized difference in
the barometer readings between Tahiti and Darwin.
SOI (30 day running mean) has dived negative in the past few weeks. After a
high late January/early February its 23 March reading was MINUS 1.29 units.
IF an El Nino cycle is approaching THEN this usually shows itself around or
soon after the equinox, so maybe this swing marks the beginning of a trend.

TROPICAL TOPICS
A pulse of extra tropical convection has been moving across the South
Pacific Coral Sea over the past few weeks-This is called a Madden Julian
oscillation or MJO and it triggered TC GILLIAN, HADI, LUSI, and, last week,
MIKE. The low that was once GILLIAN is still an entity and may redevelop as
it travels south into the Indian Ocean but should fade in a few days time.
This MJO cycle has now exhausted itself and the convection in the South
Pacific Convergence Zone SPCZ has been mostly removed. It is likely to take
a few weeks for the convection to rebuild, and by the time the next MJP
cycle arrives, it may be late April--- too late and too long after the
equinox for another cluster of tropical cyclones.
SO this is a good indication that TC MIKE (and GILLIAN) mark the swansong of
this Cyclone season.

Weather Zones
Panama to Galapagos: Winds become mainly light and variable between Panama
and Galapagos from tomorrow, also there is expected to be some convection
around Isla Mapelo reaching a peak on Wednesday UTC= Tuesday local. Also,
there is expected to be some convection around the Galapagos.
SO not the best this week.

SPCZ South Pacific Convergence Zone
This is weak at present and should slowly rebuild mainly between Solomons
and Fiji/Tonga. There is a zone left over-convection about Northern Cooks
and central French Polynesia, and another zone over Tuvalu/Tokelau. The zone
along 5S is still reveling in the overhead sun it has had in the past few
weeks and tends to get extra convection around the equinox because of this,
but the sun is now heading for 5N. The SPCZ branches are not expected to do
much. It looks like an OK week for Island hopping.

STR Sub-tropical Ridge
The STR is expected to maintain good strength between 45 and 35S with
ridge-tongues sticking out well from transient HIGH centres. There may be a
zone of enhanced SE winds on the north side of each of these HIGHS, found
half way between the H and the SPCZ a squash zone at 20S. On Wednesday one
of these may be between Noumea and central Queensland.
These squash zone travel EAST with the HIGH centre, even though they
comprise of SE trade winds.

New Zealand area
Remains of MIKE are throwing a 2-metre long-period swell onto NZ east coast
at present and for next few days, along with local light winds = wonderful
surfing.
On Tuesday, expect a Front and SW wind change.
Then a HIGH should cross Tasmania on Wednesday and travel slowly NE across
Tasman Sea and then over North Island on Friday/Sat Sunday
28/29/31 March. Enjoy.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe. Weathergram text only (and translator) is at
weathergram.blogspot.co.nz My website is at metbob.com - To unsubscribe,
send an reply email saying unsubscribe. Feedback to bob@metbob.com

16 March 2014

Bob's blog, issued 16 March 2014

WEATHERGRAM
YOTREPS
Issued 16 March 2014

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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

SOI The Southern Oscillation Index SOI sums up the weather pattern over the
South Pacific as one number. It is based on the standardized difference in
the barometer readings between Tahaiti and Darwin.
SOI (30 day running mean) has dived negative in the past few weeks. After a
high late January/early February its 16 March reading was MINUS 0.86 units.
IF an El Nino cycle is approaching THEN this usually shows itself around or
soon after the equinox, so maybe this swing marks the beginning of a trend.

TROPICAL TOPICS
A pulse of extra tropical convection is now moving across the South Pacific
Coral Sea.
This is called a Madden Julian oscillation or MJO and it has already
triggered TC GILLIAN, HADI and LUSI.
The low that was once GILLIAN is still an entity and may redevelop as it
travels west along around 10S out of the Gulf of Carpentaria.
This MJO cycle may trigger a few more cyclones this week and then fade out
and be the last, or swansong, of this Cyclone season.

WEATHER ZONES
Panama to Galapagos: There is an episode of useful NE winds for departing
from Panama to Galapagos between now and Tuesday local, and then the winds
become mostly light and variable again.

SPCZ= South Pacific Convergence Zone
There is a zone of convection across the Coral Sea along about 15S from the
Aussie coast to Fiji and a small tropical low may form on this branch but is
not expected to come to much.
The main branch of the SPCZ this week stretches from Samoa to the Southern
Cooks.. The GFS model is picking that Low may develop near Suwarrow around
Monday UTC (Tuesday local) and then deepen as it travels south to southeast
across the Southern Cooks. However not all models are picking this scenario,
so it is only a possibility at this stage.

STR= Sub-tropical Ridge
The STR is expected to maintain good strength around 40S across much of the
SW Pacific.

New Zealand area.
LUSI brought some useful rain, but farmers would have liked more.
A cold front is set to cross the South Island late on Monday (local) and
another front should cross the South Island.
For much of the remainder of the week NZ has light winds under a weak High
pressure system.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz My
website is at metbob.com -
To unsubscribe reply to this email saying UNSUBSCRIBE WEATHERGRAM. Feedback
to bob@metbob.com

09 March 2014

Bob's Blog

WEATHERGRAM
YOTREPS
Issued 09 March 2014
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 of weather maps, so please fine-tune to your place.
Dates are in UTC unless otherwise stated.

SOI The Southern Oscillation Index SOI sums up the weather pattern over the
South Pacific as one number. It is based on the standardized difference in
the barometer readings between Tahiti and Darwin.
SOI (30 day running mean) has dived negative in the past few weeks. After a
high late January/early February its 8 March reading was MINUS 0.75 units.
IF an El Nino cycle is approaching THEN this usually shows itself around or
soon after the equinox, so maybe this swing marks the beginning of a trend.
Kiwi-born Kevin Trenberth, a senior scientist at the National Centre for
Atmospheric Research, agrees that an El Nino is brewing: see http://www.
willitsnews.com/drought/ci_25294918/el-nino-may-provide-some-weather-
relief-at

"This could be a substantial event and I think we're due," Trenberth said.
"And I think it could have major consequences."

TROPICAL TOPICS
A pulse of extra tropical convection is now moving from northern Australia
into the Coral Sea.
This is called a Madden Julian oscillation or MJO and it seems clear to me
that is episode of tropical activity is going to be the last, or swansong,
of this Cyclone season.
HOWEVER it may trigger several cyclones over the next few weeks.
The first has already formed in the Gulf of Carpentaria and is called
GILLIAN:
( as seen at http://www.bom.gov.au/products/IDQ65004.shtml)
Another tropical Low in the Coral Sea is on the verge of becoming a cyclone
as seen at http://www.bom.gov.au/products/IDQ65002.shtml. It seems to be
about to go further northeast/offshore.
And a third tropical system over Vanuatu is very likely to develop into a
tropical cyclone between Vanuatu and Fiji by Tuesday (next name on their
list is LUSI). This system should then travel south or southeast, but is
somewhat at the whim of the weather feature around it so MIGHT REACH
NORTHERN NEW ZEALAND ON SAT 15 MARCH. Those making plans for that day
should check on the progress of this system and take it into

WEATHER ZONES
Panama to Galapagos: I am aware that some are almost ready and looking at
this leg, waiting for the occasional burst of NE winds that is good for this
voyage. Well, indications are that the wins between Panama and Galapagos
are likely to be light and variable this week, and mainly head winds. Might
be better to delay departureand might be OK next week.
Stay tuned.
I advise those thinking about this route to check http://earth.nullschool.
net and see the ocean currents (click earth, mode=ocean, earth) and prepare
accordingly. Notice that the surface current is WITH you, even if the wind
isn't.

SPCZ= South Pacific Convergence Zone
Apart from the cyclonic activity in the Coral Sea and around Vanuatu, the
SPCZ is active mainly between Samoa and between Southern Cooks and French
Polynesia this week.

STR= Sub-tropical Ridge
The STR is expected to maintain good strength around 40S across Tasman Sea
(Wellington should continue to enjoy good weather the NZ Festival), and
around 35S in SE Pacific.

New Zealand area= a mixed bag
Slow-moving HIGH across central NZ from Monday to Thursday. Then the next
HIGH should sideswipe Southern NZ on Friday to Sunday with light winds.
However, IF that tropical system now near Vanuatu does come south THEN
Northern NZ is in for strong winds and heavy rain on Sat 15 March--- the
Ides of March (http://en.wikipedia.org/wiki/Ides_of_March)-- so this needs
watching.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
right to subscribe. Weathergram text only (and translator) is at
weathergram.blogspot.co.nz My website is at metbob.com - To unsubscribe send
an email to bob@metbob.
com saying unsubscribe. Feedback to bob@metbob.com

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