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

25 January 2015

Bob Blog

WEATHERGRAM
YOTREPS
Issued 25 January 2015
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.

The Ocean: The extra heat that has been stored in the eastern equatorial
Pacific Ocean is now decreasing and no longer pointing to an El Nino
episode.

The Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
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. It has been negative since July and dived below -10
(Australian units) for much of September, and again for a week in November,
then relaxed in early December, and has been up and down over past few
weeks.

The Australian Bureau of Met have now wound down their El Nino outlook to
NEUTRAL for the next few months They are expecting the current episode to
now enter a decay phase. See http://www.bom.gov.au/climate/enso/

TROPICAL TOPICS
The recent new moon phase arrived within a few days of the moon's perigee
and the resulting king tides, combined with some heavy swells, managed to
bring sea inundation to Majuro and to some of the northern islands in the
Solomons group. The spring tides in January and February get extra oomph
from the warm seas in this area and sea inundation seems to be becoming an
annual January/February event. See
http://www.radionz.co.nz/international/programmes/datelinepacific/audio/2016
4672/marshalls-braced-for-more-king-tides
and
http://solomonstarnews.com/news/national/5665-food-shortage-fear

Cyclone NIKO took a brief visit to French Polynesia last Wednesday/Thursday
(local dates). The first named system of the year for the South Pacific.
Interesting how quickly it blossomed, but it was a small one.

A new MJO cycle is now starting in the Indian Ocean. There are no tropical
cyclones around at present but some small depressions in the mid Indian
Ocean may deepen later this week.

Extending the MJO cycle seems to have it moving into the Coral Sea area
around mid-February.

The weekly rain maps over the past fortnight show that the rain associated
with NIKO and the South Pacific Convergence zone during last week was the
most intense of the planet.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is expected to be strong this week from Tuvalu to Samoa to Northern
Cooks with strong westerly winds on its northern side. There is a risk that
a low may form on it near Samoa on local Thursday and Friday UTC and then
move to Niue area by Sunday UTC /Saturday local.

STR= Sub-tropical Ridge
The STR is well south of normal at present. The large HIGH east of NZ by
Monday is expected to only slowly travel east along 45S and should fade near
160W from Thursday.
A replacement High cell should squirt quickly across the south Tasman Sea on
Friday and build east of South Island on Saturday, then travel NE to 40S
then east along 40S next week.
The next HIGH should cross the central Tasman Sea at a more northern
latitude of 35S from Tues 3 Feb.

Over NZ/Tasman:
The NZ/Tasman area is NORTH of the STR this week, thus dominated by easterly
winds.
A weak trough is expected to fade in the north Tasman Sea near 160E with NE
winds on its eastern side and SE winds on its western side.
An interesting LOW near 35S 165W tonight is expected to travel westwards
towards Northland this week, reaching Northland on Thursday and Friday. This
system is caught in some easterly winds aloft, hence its strange track.
However the system is expected to weaken away nevertheless it does have some
strong SE winds and 3 metre easterly swells on its western side, especially
on Tuesday and Wednesday (local).
On Thursday, a LOW is likely to form in mid Tasman Sea, east of Tasmania.
This should then cross the South Island on Saturday/Sunday, and bring a
front/SW change to North Island on Monday/Tuesday 2/3 Feb, finally bringing
some welcome rain.

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

21 January 2015

BobBlog

Tropical cyclone NIKO is expected to visit Tahiti later today.

Latest report from Fiji Met Service :
STORM WARNING 019 ISSUED FROM RSMC NADI Jan 21/1906 UTC 2015 UTC.
TROPICAL CYCLONE NIKO CENTRE 995HPA CATEGORY 1 WAS LOCATED NEAR 16.3 SOUTH
148.9 WEST AT 211800 UTC.
POSITION POOR.
REPEAT POSITION 16.3S 148.9W at 211800 UTC.
CYCLONE MOVING SOUTH-SOUTHEAST AT 9 KNOTS. CYCLONE INTENSIFYING.
EXPECT SUSTAINED WINDS OF 40 KNOTS CLOSE TO THE CENTRE INCREASING TO
60 KNOTS BY 221800 UTC.
EXPECT WINDS OVER 33 KNOTS WITHIN 120 NAUTICAL MILES IN EASTERN SEMI-CIRCLE
AND WITHIN 90 NAUTICAL MILES IN SOUTHWEST QUADRANT
AND WITHIN 60 NAUTICAL MILES IN NORTHWEST QUADRANT
FORECAST POSITION NEAR 17.9S 147.7W AT 220600 UTC
AND NEAR 19.8S 146.6W AT 221800 UTC.

ALL VESSELS WITHIN 300 NAUTICAL MILES OF CENTRE ARE REQUESTED TO SEND
REPORTS EVERY THREE HOURS TO RSMC NADI.
VOS REPORTING SHIPS USE NORMAL CHANNELS. OTHER VESSELS FAX PLUS 679 6720190
OR EMAIL NADITCC AT MET DOT GOV DOT FJ
Latest update of threat map is at
http://www.met.gov.fj/aifs_prods/65648.html
==

18 January 2015

Bob Blog

WEATHERGRAM
YOTREPS
Issued 18 January 2015

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

The COMET online weather training Program is pleased to announce the
publication of "Chapter 7, Synoptic and Mesoscale Systems" as a part of the
new 2nd Edition of their online textbook, "Introduction to Tropical
Meteorology". The textbook is being developed over time and its chapters are
being re-published incrementally. Please follow this link for more
information and link to the new textbook chapter: http://www.meted.ucar.edu/
(no charge to register). I also recommend their omega equation module.

AT the NZ Met Society Conference in Nov 2014 there was a poster detailing
progress of the SWFDDP, the Severe Weather Forecasting and Disaster Risk
Reduction Demonstration Project around the South Pacific. Thanks to the Met
Society this poster is now on line at
http://www.metsoc.org.nz/files/newsletters/2014/poster_tunster-lunny-ready_s
wfddp_poster_rav-16.pdf

If you are one of the lucky who are involved in this project then check this
poster and share with friends (if access allows). Data from this project's
website is checked as part of the data used for these Weathergrams.


The Ocean: extra heat has been stored in the Pacific Ocean for a while now
and all the Oceanic indices have crossed the threshold into El Nino
territory.

The Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
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. It has been negative since July and dived below -10
(Australian units) for much of September, and again for a week in November,
then relaxed in early December, and has been relaxing over last few weeks.

TROPICAL TOPICS
AT present Cyclone MEKKHALA is in the NW Pacific (weak, but it did help
bring some rain to Manila for Pope's Mass), and there are two named systems
in the India Ocean: BANSI (which formed last week and is now easing near 25S
74E) and CHEDZA (a weak system east of Madagascar). A new Tropical Low is
over the West Kimberly and may deepen into a named system on Monday UTC as
it skirts the NW Australian coast. Check http://www.bom.gov.au/cyclone/ for
updates

The MJO cycle I mentioned in last week's edition showed up as extra oomph in
the South Pacific Convergence Zone that brought heavy rain to Vanuatu last
Thursday. This oomph this already cleared away from the Coral Sea and is now
over the French Polynesia area and may help develop a tropical depression in
the area by Monday UTC. This system should travel slowly south and there is
likely to be a squash zone of strong to gale easterly winds between this
system and a large HIGH near 40S. Avoid.

The Vanuatu/New Caledonia area is having a respite at present but another
tropical low may form there on Monday/Tuesday UTC. This feature is expected
to travel south and, by Friday, turn into a stationary trough located
mid-Tasman and west of North Island.

The weekly rain maps over the past fortnight show last week's burst of rain
over Vanuatu and a build up over French Polynesia. These maps also show the
recent rain about Madagascar - and inland to Mozambique and Malawi, South
Africa. Also the cyclone track of MEKKHALA in the NW Pacific.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is expected to be strong this week from Tuvalu to Northern Cooks to
French Polynesia, with another convergence zone over Fiji /Samoa and Niue
and a third over Vanuatu and New Caledonia.

STR= Sub-tropical Ridge
A large HIGH is expected to travel slowly east along around 45 to 40S well
east of NZ,
A weaker HIGH is expected to cross the southern Tasman Sea from Mon to
Wednesday and then central NZ on Thursday and then travel east along 40S,
east of NZ, from Friday onwards.

Over NZ
A trough is expected to affect the South Island on Monday and the North
Island on Tuesday and Wednesday.
On Thursday and early Friday, light winds with a passing high.
Then, from late Friday to Sunday, another trough is expected to travel
across NZ.

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

11 January 2015

Bob Blog

WEATHERGRAM
YOTREPS
Issued 11 January 2015
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

The Ocean: extra heat has been stored in the Pacific Ocean for a while now
and all the Oceanic indices have crossed the threshold into El Nino
territory.

The Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
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. It has been negative since July and dived below -10
(Australian units) for much of September, and again for a week in November,
then relaxed in early December, and has been stuttering down and up again
over last few weeks.

In an El Nino event the latitudes of the normal weather zones are drawn
closer to the equator, causing the South Pacific Convergence zone to shift
further north and east of its normal position.

TROPICAL TOPICS
As mentioned in my Weathergram on 21 Dec, we have been in-between" MJO
cycles for the past few weeks. These MJO cycles of extra oomph are known to
activate the South Pacific Convergence Zone and sometimes here trigger
tropical depressions/cyclones.

Well, we now have an MJO cycle heading into the Coral Sea and towards the
180 line over the next week or so.

Indeed there are TWO tropical cyclone popping up in the Coral sea at present
as shown on the weather map from MetService NZ as seen on the Solomon
Islands Met web site at
http://www.met.gov.sb/mean_sea_level__streamline_anal.htm

Thanks to my friends in the Solomon Islands Met Service for keeping me
informed of their warnings.

These tropical depressions have been picked up by the computer models.
According to the GFS ensemble one (90P) is expected to travel to the
southeast across Vanuatu and then towards the zone between NZ and
Fiji/Tonga, and t other (91P) might go WSW then bounce off Aussie coast then
head east for zone SW of New Caledonia. If these tracks get close to you
then remain vigilant and seek updates as these tracks will likely change.

A low shown of the weather map near 3N 154E is a possible equatorial twin
for 90P. For more about equatorial twinning see
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2402&page
=11

If you are a budding meteorologists looking for a topic for Masters or PhD,
then this could well be just right for you.
This feature has been picked up by the computer models as 92W and is
expected to travel WNW to Philippines then re-curve.

There is also a tropical depression in the Indian Ocean between Madagascar
and Mauritius and this one is expected to go SE and fade away.

The weekly rain maps over the past fortnight show that rain is increasing
all along the South Pacific Convergence Zone and, especially on both sides
of the equator near 155E, as well as NE tip of Australia and around
Madagascar.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is expected to strengthen this week and split into two with one section
over Coral Sea, across Vanuatu and between Fiji and NZ, and the other
section across Southern cooks and stretching to southeast.

STR= Sub-tropical Ridge
A new High cell is expected to cross Tasman Sea on Mon/Tue and NZ on Wed.
Next High is expected to cross South Tasman Sea on Sun/Mon and South Island
on Tuesday/Wednesday 20/21 Jan.

Over NZ
A series of troughs should cross NZ from Thursday to Monday, progressing NE
across the country.

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

04 January 2015

Bob Blog

WEATHERGRAM
YOTREPS
Issued 4 January 2015

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

The Ocean: extra heat has been stored in the Pacific Ocean for a while now
and all the Oceanic indices have crossed the threshold into El Nino
territory.

The Atmosphere: The Southern Oscillation Index SOI (30 day running mean)
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. It has been negative since July and dived below -10
(Australian units) for much of September, and again for a week in November,
then relaxed in early December, and has been stuttering down and up again
over last few weeks.

In an El Nino event the latitudes of the normal weather zones are drawn
closer to the equator, causing the South Pacific Convergence zone to shift
further north and east of its normal position.

TROPICAL TOPICS

There are no tropical cyclones around at present, but a squally and intense
tropical low is expected to form over NW Australia by Thu 8 Jan and then
travel SE across Australia and reach the Tasman Sea by Tuesday
13 January. Avoid.

The weekly rain maps over the past fortnight show that rain is easing over
South Pacific Convergence Zone and, finally, in Malaysia. There is also a
recent build up in rain over NW Australia.

During December the averaged isobars show that in the Northern Hemisphere
the roaring 40s have been stronger than normal and the sub-tropical ridge
and trade winds weaker than normal, BUT in the Southern hemisphere the Highs
in the sub-tropical ridge have been picking certain longitudes to be
stronger than normal.--- Thus those in the Northern Hemisphere are getting
typical El Nina seasonal weather, but us in southern Hemisphere are having a
mixed bag of seasonal weather lately.

A look at the Standardized precipitation index map over NZ for the past
month shows a wet area around Opua/Whangarei and dry to almost drought
conditions near Dunedin/Balclutha.

WEATHER ZONES

SPCZ=South Pacific Convergence zone.
SPCZ is expected to weaken this week.

STR= Sub-tropical Ridge
A new High cell is expected to cross Tasmania on Monday and then travel east
across the Tasman Sea and the on to NZ on Thursday 9 Jan.

Over NZ
A Trough is expected to follow that High on Friday and the coming weekend
bringing unsettled weather mainly to the South Island.

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

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