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

30 November 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 30 November 2014
Bob McDavitts ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world

I've just been introduced to another website presenting the weather data in
an interesting way http://www.meteoearth.com/

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, relaxed for a while in October, and dived below -
10 early in early November, but is now relaxing again.
We know that 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.
Well, as November draws to a close we can look at the average weather map
mid-month, thanks to NOAA and this shows Highs have been stronger than
normal in the north Tasman sea, and just south of South Africa, and lows in
the southern ocean have been deeper and more north than normal in south
Indian Ocean, and to SE of NZ, and to SE of South America. The extra highs
in north Tasman Sea and lows to SE of NZ have combined to give extra SW
winds over NZ.

NIWA have issued a news release about New Zealand's November weather at
http://www.scoop.co.nz/stories/SC1411/S00083.htm they say there has been
more SW winds than normal over New Zealand during November. The rainfall, as
measured by the SPI (Standardized Precipitation Index) has been close to
normal in most places but the extra SW winds show as patches of extra
rainfall in the W and south of the South Island.

The extra SW winds are causing soils to dry out faster than normal in
eastern North island places from Northland thru Coromandel and Bay of Plenty
to Gisborne/Hawkes Bay/and the southern quarter of the North Island, and the
eastern South Island.

They also say, and I quote It should be noted that this rainfall pattern is
commonly associated with El Nino events and while El Niqo has not been
officially declared, it may be an indication that such an event is
imminent.

TROPICAL TOPICS
Last weekend Cyclone Adjali was the first of the new season in the Indian
Ocean and was heading towards Mauritius before it weakened. The Volvo Race
fleet diverted clockwise around another system now near 20S 60E and one of
fleet, Sailing Vessel Team Vestas Wind, ended up sailing onto a reef (at
night) in the Cargados Carajos Shoals around 400 km to northeast of
Mauritius. Ouch.

At present the remains of Cyclone SINLAKU are fading over China.
Another area of interest is developing in the NW Pacific and is expected to
become a Cyclone over Micronesia by Tuesday and travel west towards
Philippines late this week.

There are a couple of areas of interest in the Indian Ocean, one near 20S
60E and another near 11S 90E  I suppose we can declare the Southern
Hemisphere cyclone season to now be officially open.

Weekly rain maps over the past fortnight show an increase in convection over
the past week in the Indian Ocean and in the zone from north of Solomon
Island along to Samoa. There was flooding in Samoa early last week, but the
feature responsible then faded as forecast in last weeks Weathergram.

This increase in convection in the Indian Ocean is possibly part of a MJO
cycle that will gradually make its way into the Pacific Ocean over the next
few weeks. By mid December this is expected to increases the risk of a
tropical cyclone generating in the area north of Vanuatu.


WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ may not be as strong as it was last week, and is expected to be located
near the north end of its normal range, stretching from north of Solomon
island to northern Vanuatu and the east across Tuvalu to Samoa/Tokelau, with
scattered convection also over French Polynesia.
A burst of northerly swell reaching 2 to 3metres is expected to spread south
and east over the next few days  it should be most noticeable about and
just north of the SPCZ and roughen the sea there. Not the best for good
diving or fishing between northern Vanuatu and Samoa this week.

STR= Sub-tropical Ridge
The STR is also strong and well defined and mostly at its normal latitude
for the time of year, but now north of normal in zone east of NZ. It has
been north of normal in the NZ area but is expected to be closer to normal
latitude this week as the HIGH tonight in the south Tasman Se is expected to
travel NE across the North Island on Tuesday night/Wednesday and then be
slow-moving off the NE of NZ until next week, so that approaching troughs
stall in the Tasman Sea.
HIGH near 35S 130W, to the south of Pitcairn Island, is expected to be
slow-moving and peak in intensity over 1032 hPa by Tuesday UTC and is
expected to stay put until Wednesday and then slowly weaken and move NE.
There are likely to be strong easterly and NE winds on the northern side of
this high, especially between 15 and 20S until Friday.

Between the tropics and NZ
Good weather this week for sailing from the tropics to NZ.
No good arriving on Monday 1 December because thats when a cold trough is
expected to cross the North Island. Then there is an easterly flow expected
on the north side of the high that is expected to cross the North Island on
Tuesday night/Wednesday.
After Wednesday there is expected to be a useful N to NW flow over northern
NZ, good for arrival. This NW flow may get strong and unsettled on Tuesday 9
December, as a trough travels east across southern NZ. The NW flow should be
Ok again on Wednesday 10 Dec for arrival, and then northern NZ may become
unsettled as troughs start to arrive from the Tasman Sea.

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.

23 November 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 23 November 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.

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, slightly relaxed for a while in October, and dived below
-10 early in November, but is now relaxing a little.

TROPICAL TOPICS
Tropical cyclone activity has now reduced to one possible area in the Indian
Ocean, and an area of interest to the NW of Samoa.

The latest tropical disturbance summary at www.usno.navy.mil/NOOC/nmfc-
ph/RSS/jtwc/ab/abpwweb.txt
has this to say about this system:
ABPW10 PGTW 230600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/SIGNIFICANT
TROPICAL WEATHER ADVISORY FOR THE WESTERN AND /SOUTH PACIFIC
OCEANS/230600Z-240600ZNOV2014// RMKS/ 1. WESTERN NORTH PACIFIC AREA (180 TO
MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 8.2S 177.1W, IS NOW
LOCATED NEAR 11.5S 174.4W, APPROXIMATELY 204 NM NORTH OF PAGO PAGO, AMERICAN
SAMOA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS UNORGANIZED FLARING
CONVECTION ASSOCIATED WITH AN ELOGATED LOW-LEVEL CIRCULATION CENTER. A
230354Z NOAA-19 MICROWAVE IMAGE REVEALS VERY FRAGMENTED CONVECTIVE BANDING
ON THE EASTERN SIDE BROADLY WRAPPING INTO THE CENTER. ALSO, A CIMMS 230300Z
850MB RELATIVE VORTICITY PRODUCT SHOWS AN ELONGATED VORTICITY SIGNATURE.
UPPER-LEVEL ANALYSIS INDICATES THE DISTURBANCE IS LOCATED NORTH OF THE RIDGE
AXIS IN A FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (05 TO 15 KNOT)
VERTICAL WIND SHEAR AND EXCELLENT POLEWARD OUTFLOW.
ADDITIONALLY, SEA SURFACE TEMPERATURES WITH A RANGE OF 26 TO 28 DEGRESS
CELCIUS IN THE AREA ARE FAVORABLE FOR DEVELOPMENT. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.
(2) NO OTHER SUSPECT AREAS.//

It is judged as having a low chance of any further deepening. The GFS
models and their GRIB files are picking that this system may deepen into a
depression on Mon/Tuesday and bring clockwise gale winds between the Niuas
and Niue, then Southern Cooks on Wednesday/Thursday- but the more reliable
ECMWF model suggests this isn't likely.

Weekly rain maps over the past fortnight show an increase in convection over
the past week in the Indian Ocean. This is possibly part of a MJO cycle
that will gradually make its way into the Pacific Ocean over the next few
weeks. For the next week or so, it increases the risk of a tropical cyclone
formation in the area to NW of Aussie. For the following weeks this
increased risk spreads east. This is shown at
www.meteo.nc/cyclone/coin-des-experts

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ has strengthened in the past week and is expected to drift south onto
northern Tonga and SE onto NIUE, then later onto southern cooks.
The GFS model is picking that a depression may form on the SPCZ and move
along it to the SE, but other models only have a weak feature. The GFS
model also has a tropical low forming SE of French Polynesia. These may not
actually happen but if you are sailing in these areas this week then brace
for strong winds anyway.

STR= Sub-tropical Ridge
The STR is strong and well defined and mostly at its normal latitude for the
time of year, but north of normal in the Tasman Sea/ NZ area.
HIGH at 30S between New Caledonia and New Zealand is expected to stay put
until Wednesday and then slowly fade away as it travels east from Thursday
to Saturday.
NEXT High cell is expected to travel east along 45S from Saturday 29 Nov ,
reaching North island around Wed 3 December - followed by a northerly flow
-that is GOOD for arriving in NZ  late next week (Thursday to Saturday 4-6
Dec).

Between the tropics and NZ
At North Minerva:
Trade winds until Thursday, light and variable on Fri 28 to Mon 1 Dec, then
more trade winds. Good idea to depart around Thursday so as to catch a
northerly flow when approaching NZ  voyage will encounter a period of
southerly winds around Sun 30 Nov/Mon 1 Dec and requires waypoints.

Over northern NZ:
Westerly flow on Monday/Tuesday, then an active trough on Wednesday followed
by a SW/S flow on Thursday 27 to Tues 2 Dec. NOT the best week (after
Tuesday) for arriving in 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 from
WordPress: click the "unsubscribe" link on the bottom of the email.
Or, if email wasnt from WordPress then send a reply email saying LEAVE.

16 November 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 16 November 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.

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 standardised 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, slightly relaxed for a whole in October, and is now
diving below -10 again. If this index remains below -10 for more than a
month then this will the start of a full blown El Nino episode.

The Ocean
The amount of heat that is being stored in the sea in the Eastern Equatorial
pacific has also increased, as measured by the NINO3.4index.
This indicates that the atmosphere and the ocean are in cahoots.

TROPICAL TOPICS
There are no tropical cyclones around at present: Tropical cyclone activity
has now reduced to just one possible depression area in the Indian Ocean.
Weekly rain maps over the past fortnight show less rain around in the past
week than the previous week.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ has weakened in the past week but is expected to intensify this week
and slowly drift south. It is possible (but models are not yet in
agreement) that a tropical depression may form over Tokelau by Friday 21 Nov
and then move SE across Samoa and near Niue over following few days.

STR= Sub-tropical Ridge
The STR is strong and well defined and north of normal at present (all El
Nino traits).
HIGH between Tonga and NZ at present is expected to travel east along 30/35S
as it peels off to east of 140W by Thursday. Light winds at Minerva from
Monday to Wednesday.
A new HIGH is expected to travel into the Tasman sea around 30S on Mon/Tue
/Wed and then travel east along 30/35S across and to east of NZ on
Thu/Fri/Sat/Sun/Mon 20/21/22/23/24 Nov.

Between the tropics and NZ
At north Minerva:
Light winds in a ridge are expected until Wednesday, then trade winds are
expected to return for the next week or more, good for sailing to NZ.

Over northern NZ:
There is a disturbed westerly flow until Wednesday, and then a slowly
passing High from Thu 20 to Mon 24 Nov, then a passing trough, around Tue
25 Nov , then another passing High from on Wed/Thu 26/27 Nov, and then an
unsettled period with a trough on Fri/sat/ Sun 28/29/30 Nov .
Try and use this to time your arrival in NZ to be in settled weather.

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.

09 November 2014

Bob Blog

WEATHERGRAM
YOTREPS

Issued 09 November 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

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 standardised 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, slightly relaxed for a whole in October, and is now
diving more negative again.

The Ocean
The amount of heat that is being stored in the sea in the Eastern Equatorial
pacific has also increased, as measured by the NINO3.4index.

The chances of a full blown El Nino episode over the next few months are now
considered to be no more than 58% (less than this time last month).

TROPICAL TOPICS
Tropical cyclone activity has now reduced to a few possible potential areas.

Weekly rain maps over the past fortnight show some local regions of intense
rain due to a few tropical cyclones. There also has been a notable build-up
of convection in the past week between India and Indonesia. Not much change
in South Pacific.


WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is steady in position and fluctuating in intensity. Mainly over the sea
between Solomons and Wallis /Futuna then along 15S.
The Low that has formed between Fiji and New Zealand near 25/30S 180 is
expected to travel SE and fade-away by Wednesday.
A Low is expected to form near 30S 140W by Tuesday and then travel to east
then south east.

STR= Sub-tropical Ridge
High is expected to cross Tasmania on Tuesday and then travel NE towards 20S
between New Caledonia and Kermadecs by the end of the week, bringing a zone
of light winds.

Between the tropics and NZ
At north Minerva a front visited on Saturday accompanied by squally showers
and strong E/NE winds. As the Low in the region travels east/southeast over
the next few days, expect strong WNW winds there from Monday morning to
Tuesday morning, peaking pre-dawn on Tuesday. Then expect moderate SW winds
there on Tuesday and Wednesday. After that the STR is expected to get north
of Minerva for a few days so that it has W/SW/S winds on Thursday and
Friday, finally reverting to SE this weekend.

An intensifying trough is expected to cross NZ on Monday and Tuesday,
followed by an outbreak of strong to gale SW winds in the Tasman Sea on
Wednesday and Thursday. These winds are expected to help propagate an area
of big SW swells (from the Southern Ocean) that spread NE into the region
between NZ and Fijias far north as 25S on Thursday and 23S on Friday.

Voyages from New Caledonia /Fiji/Tonga to New Zealand should wait for the
Low to go away by late Tuesday, and then try and avoid the big swells on
Thursday /Friday. This can be done with a Friday departure and a few
waypoints.

AT this stage, the outlook next week over NZ looks reasonable for voyages
aiming to arrive there between Tue 18 and Friday 21st ( but this may
change).

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.

03 November 2014

Bob Blog extra

WEATHERGRAM
YOTREPS
Issued 04 November 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 Special edition aimed at those at the Minerva Reef yacht
club

DEPART BEFORE 1pm WEDNESDAY

This morning most (not all) computer models are picking that a tropical
trough may trigger the development of a low near 25S 175E ( south of
Fiji) on Sunday 9 Nov, and this low may then travel east for a few days
pushing a front with strong to gale NE winds over Minerva by late Sunday and
forming a squash zone of easterly gales near 30S 18 on Sunday/Monday.

This scenario still has only around 66% chance of actually happening, but
its likely impact is worth avoiding. To do so , anyone at Minerva should
depart for NZ by around noon Wednesday ( and those in Tonga should now stay,
or , if they depart today , brace for strong easterly winds near 31S on
Sunday /Sunday night.

NOTE that if this feature does NOT form, then the waypoint given in the
forecast below will still work OK, but winds near NZ will be westerly rather
than easterly.

===================================================
Here is a voyage forecast for any yachts in Minerva with a cruising speed or
around 6 knots, departing for North Minerva on 1pm Wednesday
(050000UTC) and heading for Opua.

DISCLAIMER: weather is a mix of pattern and chaos. The real world unravels
away from the model output shown here. Computer data does NOT do well near a
coast or in a trough. In a convergence zone computer gives averaged-out
light winds, but occasional squalls can deliver 30 knots for
30 minutes. If your baro strays away from target pressure more than 5 hPa
the forecast needs updating.

DECODE: Time HH:MM is hours and minutes in UTC. Lat and Long are in degrees
and minutes. hPa is barometer in hPa, Wind is compass octant coming FROM and
lull~avg~gust is speed range in knots. Crs-Bsp is boat course to in degrees
TRUE and speed in knots. TWA is the angle between the wind and the boat
course, minus for wind on port. Waves are significant wave height in
metres=average of top third, or are exceeded around once in 7 waves or once
a minute. Add 50% to get the occasional wave which occurs or is exceeded
around once every 10 minutes.

Table is in UTC and degrees True

Head off along 220 True to 29S 176E , to get ready for ESE winds near NZ.
Timestamp | POSITION | Air | WIND | BOAT
|waves
UTC- HH:MM|----Lat:/ Long----:| hPa | lull~avg~gust |Crs-Kt|TWA|Sig~ocnl
05-Nov-00:00|23:37S/178:58W|1017|ENE11~14~21|219-06|-154|2.0~3.0m
05-Nov-04:15|23:57S/179:16W|1016|ENE09~11~17|219-06|-148|2.3~3.4m
05-Nov-08:30|24:18S/179:34W|1018|ENE10~13~19|219-06|-151|2.3~3.4m
05-Nov-12:43|24:38S/179:52W|1017|-NE10~13~19|219-06.1|-164|2.2~3.2m
05-Nov-17:01|24:58S/179:49E|1016|-NE09~11~17|219-05.9|-170|2.1~3.1m
05-Nov-21:24|25:19S/179:31E|1017|-NE09~11~17|220-06.0|-175|2.0~3.0m
gybe
06-Nov-01:56|25:39S/179:12E|1016|NNE06~08~12|220-06|152|1.9-2.8m*
06-Nov-06:47|25:59S/178:54E|1018|NNW02~02~03|220-05|109|1.8-2.7m*
around here we encounter the north end of a passing front- kills the wind,
maybe some drizzle, then new wind from DE, keep going along 220 true
06-Nov-12:05|26:20S/178:35E|1019|SSE05~07~10|220-05|-64|1.7-2.6m**
06-Nov-17:17|26:40S/178:16E|1018|-SE11~14~21|220-05.3|-81|1.7~2.6m
06-Nov-22:01|26:59S/177:57E|1020|-SE14~18~27|220-05.6|-83|1.7~2.6m
07-Nov-02:33|27:20S/177:38E|1019|-SE14~18~27|220-05.6|-81|1.6~2.4m
07-Nov-07:05|27:40S/177:18E|1020|ESE13~16~24|220-05.7|-99|1.5~2.3m
07-Nov-11:38|28:00S/176:59E|1021|ESE12~14~22|221-05.9|-111|1.4~2.2m
07-Nov-16:03|28:20S/176:39E|1020|ESE13~17~25|221-06.2|-116|1.4~2.0m
07-Nov-20:14|28:40S/176:20E|1020|-E-13~17~25|221-06.4|-125|1.4~2.2m
once winds turn E we can go direct
08-Nov-00:22|29:00S/176:00E|1019|-E-12~16~23|194-05.7|-97|1.4~2.0m
08-Nov-06:04|29:31S/175:51E|1019|-E-13~17~25|194-05.9|-101|1.4~2.0m
08-Nov-11:25|30:02S/175:43E|1019|-E-15~18~27|194-06.1|-107|1.4~2.0m
08-Nov-16:33|30:34S/175:34E|1018|-E-14~18~27|194-06.0|-103|1.4~2.0m
08-Nov-21:39|31:05S/175:25E|1019|-E-17~21~32|194-06.1|-102|1.5~2.3m
09-Nov-02:44|31:36S/175:16E|1017|-E-16~20~30|194-06.2|-105|1.6~2.4m
09-Nov-07:54|32:07S/175:06E|1019|-E-16~20~29|194-06.0|-98|1.6~2.4m
09-Nov-13:15|32:38S/174:57E|1018|ESE16~19~29|194-05.8|-87|1.6~2.4m
09-Nov-18:38|33:09S/174:48E|1019|-E-16~20~29|194-05.9|-92|1.6~2.4m
10-Nov-00:18|33:41S/174:38E|1020|ESE14~17~26|194-05.6|-88|1.6~2.4m
10-Nov-06:05|34:12S/174:29E|1019|ESE12~15~23|194-05.5|-90|1.5~2.3m
10-Nov-11:58|34:43S/174:19E|1020|ESE10~12~18|195-05.4|-90|1.4~2.0m
10-Nov-18:08|35:14S/174:09E|1019|ESE08~10~15|ETA off Opua around 8am local
Route distance 807.31nm| route time 5d 18h 08m|||
*= motoring with light winds **= motoring into the wind, or fall off for
comfort but that will take longer.
SWELL : From east until 25S, then from SW until 29S , then from S until
30S, then from SE until 32S then from East/ENE.

Updates from ZKLF Radio fax on 3247.4, 5807, 9459, 13550.5 or 16340.1 kHz Or
HIGH SEAS on ZLM 6224 kHz and 12356 kHz at 0303Z, 0903Z, 1503Z and 2103Z and
on 8297 kHz and 16531 kHz at 0333Z,1003Z,1533Z and 2203Z or, for warnings,
send email to query@saildocs.com, No subject, saying SEND
http://m.metservice.com/warnings/marine
Or SEND http://www.met.gov.fj/aifs_prods/10140.txt
or let me know at bob@metbob.com or TXT/PHN to +6427 776 2212

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.

02 November 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 02 November 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 TROPICAL TOPICS Tropical cyclone activity at present
includes VANCE off the west Mexican Coast and NURI off the east of Japan.
Weekly rain maps show that the main rain has been associated with tropical
cyclones. In the South Pacific the convergence zone seems to have cleared
last week over northern Vanuatu and intensified from northern Fiji to Samoa.
Otherwise not much change.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is steady in position and fluctuating in intensity and expected to be
weaker this week than last week. Many over the sea between Solomons and
northern Vanuatu, with another branch from northern Fiji to Samoa extending
SE towards French Polynesia.
Part of the energy from the SPCZ is expected to help deepen a low in the
mid- latitudes near 35S 150W (South of French Polynesia) by Wednesday.

STR= Sub-tropical Ridge
The STR has been strong during October.

High between Tonga and NZ today is expected to stall near 30 to 40S 160W
from Tuesday to Thursday and then fade  should maintain steady ESE winds in
the tropics on its northern sidemay be somewhat enhance along 12 to 18S
from 165 to W to 180.
Second HIGH crossing Tasmania on Monday is travel NE onto northern NZ by
Friday and then travel east away from northern NZ early next week.

Between the tropics and NZ
Vessels in the All Points Rally (www.islandcruising.co.nz/?page_id=1687)
are mostly underway now with a good weather pattern for sailing to Opua, NZ
from Tonga, Fiji, or Vanuatu. This rally is free of charge (thanks to the
sponsors) and helps participants with planning, weather info, clearance, and
seminars on how to enjoy NZ.

The first factor to consider a departure date is the local weather: the
SPCZ does have some convective cloud over northern parts of Fiji at present
but is not very intense and isn't really strong enough to delay departure
this week.

The second restraint on a weather window is to pick an ETA over northern
NZ that does NOT have strong adverse winds. Northern NZ is expected to
have a period of light winds early next week as the second High mentioned
above passes bylooks good -- until Wed 11 Nov when the next front and SW
winds arrive.

The third factor is to avoid gales and heavy swells during the trip.
Good news is there isn't much to report this week. The replacement trough
between the Highs is crossing the North Island on Monday and may form a
little secondary low east of the North Island on Wednesday/Thursday, but
this doesn't affect Northland. There is a possibility that a week tropical
trough may cross the region between Fiji and NZ on Sunday 09 /Monday 10 Nov
 that could form some showers and enhance the easterly winds just north of
NZ and so shouldn't be a hassle and may be a help.

Minerva is likely to have winds between ENE and ESE 10 and 20 knots this
week with swell from E then S then SE around 2 metres.

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
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