Translator

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

25 December 2016

Bob Blog 25 Dec 2016

WEATHERGRAM
YOTREPS
Compiled Sun 25 December 2016
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.

Here's to a peaceful and joyful Christmas and end of the year to you all.
However, there is some activity in the South Pacific and around Australia this
week so there are a few potential tropical depressions that may be worth
avoiding.
There are five of them tonight and they can be seen on the windyty.com website.

The Tropics
TC NOCK TEN is moving west across the Philippines on Boxing day as a severe
tropical cyclone, and may end up near Vietnam coast at turn of the year. It's
track can be seen at ruc.noaa.gov/tracks/

Of all those Lows in the Australia/South Pacific area, the one that at present
has the most grunt is FORMER TC Yvette, now a monsoonal depression, bringing its
rain to South Australia. It's track may be seen at
www.tropicaltidbits.com/storminfo/02S_gefs_latest.png

Rain maps at trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif show
that activity is on the decrease around Fiji, and on the increase over
Philippines, Australia, and Southern Cooks. Also in the Indian Ocean and along
the Intertropical Convergence Zone.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is drifting south this wee,k and leaving a few smaller convergece zones
further north, Expect a tropcial Low over Southern cooks to peal around
Wednesday UTC, and another near Vanuatu by New year's weekend. Lows may come
and go around Australia all week.
Tropical accumulated rainfall for next week may be seen at windyty.com

Subtropical ridge (STR)
The HIGH in the Tasman Sea tonight is expected to remain slow-moving and drift
north to 30S and linger there until early next week
Next High is weaker and should appear over and east of Tasmania early in the
New Year.

Tasman Sea/NZ Area troughs.
A disturbed SW flow is likely over northern NZ this week. Next trough of
consequence should start arriving over southern NZ on wed, central NZ on Friday
and northern NZ over the New year weekend.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

18 December 2016

Bob blog 18 Sec 2016

WEATHERGRAM
YOTREPS
Compiled 18 December 2016

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.

There is a burst of near equatorial west to NW winds stretching from Indian
Ocean to the Western South Pacific. The associated monsoonal trough is expected
to drift close to North Australia and may deepen and contribute to tropical low
development.
The MJO index is currently weak and not really contributing much to this, but
when we get near equatorial west to NW winds in mid-December, something usually
develops within a week or so.

The Tropics
TC VARDAH was nearing its peak this time last week as it approached Chennai.
During the past week it went west completely across India and the Arabian Sea
and is now approaching the Somalia area as a depression.

TD04F/99P formed last week to NW of Fiji and has been a slow-moving tropical
depression, dropping its heavy rains over the Fiji area all week and, so far,
not quite making the required wind flow to be a Category 1 tropical cyclone.

This is a good time to show the various web sites that provide information about
the thinking of the monitoring meteorologists as you look at the satellite
imagery:

Fiji Met Service have the primary role for South Pacific cyclones east of 160
East and they issue daily a 3-day outlook at www.met.gov.fj/tc_outlook.pdf

Their latest discussion is at www.met.gov.fj/aifs_prods/20036.txt

Tonight this says:
Tropical Disturbance Summary For area Equator to 25S, 160E to 120WISSUED FROM
RSMC NADI Dec 172316 UTC.TROPICAL DEPRESSION 04F CENTRE [1000HPA] WAS ANALYSED
NEAR 16.5S174.9E AT 172200UTC. POSITION GOOD BASED ON HIMAWARI-8 VIS
IMAGERY.TD04F SLOW MOVING. CONVECTION DISPLACED TO SOUTHEAST OF LLCC. SYSTEM
LIES IN AN UPPERDIVERGENCE REGION AND IN A MODERATE TO HIGH SHEARED ENVIRONMENT.
GLOBAL MODELS MOVE TD04F INTIALLY TOWARDS THE WEST THEN SOUTHWARDSWITH LITTLE
INTENSIFICATION. POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE
IN THENEXT 24 TO 48 HOURS IS LOW.
********************************************************************
NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THEAREA.

If a feature is worthy enough, an advisory is issued at
www.met.gov.fj/aifs_prods/20032.txt
TROPICAL DISTURBANCE ADVISORY NUMBER A10 ISSUED FROM RSMC NADIDec 162013 UTC.
TROPICAL DEPRESSION TD04F CENTRE 1000HPA WAS ANALYSED NEAR 15.9S174.5E AT
161800UTC. POSITION GOOD BASED ON HIMAWARI-8 IR IMAGERY.DEPRESSION SLOW MOVING.
MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THECENTRE ESTIMATED AT ABOUT 25 KNOTS.
LLCC EXPOSED. CONVECTION DISPLACED TO SOUTHEAST OF LLCC. OUTFLOW GOODTO THE
SOUTH AND EAST BUT RESTRICTED ELSEWHERE. SST AROUND 29 DEGREE.SYSTEM LIES IN A
LOW UPPER DIVERGENCE REGION AND IN A MODERATESHEARED ENVIRONMENT. DVORAK
ANALYSIS BASED ON SHEAR PATTERN WITH LLCCABOUT LESS THAN 3/4 FROM DEEP
CONVECTION YIELDS DT=2.5, MET=2.0 ANDPT=2.0. FT BASED ON PT. THUS YIELDING,
T2.0/2.0/S0.0/24HRS. GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND KEEP IT SLOW
MOVING WITHSLIGHT INTENSIFICATION. POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A
TROPICAL CYCLONE IN THENEXT 24 TO 48 HOURS IS LOW. FORECASTS :AT 12 HRS VALID
AT 170600 UTC 15.7S 174.5E SLOW MOVING WITH 25KTCLOSE TO CENTREAT 24 HRS VALID
AT 171800 UTC 15.7S 174.4E SLOW MOVING WITH 30KTCLOSE TO CENTRE. OUTLOOK: AT 36
HRS VALID AT 180600 UTC 16.1S 174.4E SLOW MOVING WITH 30KTCLOSE TO CENTREAT 48
HRS VALID AT 181800 UTC 16.9S 174.2E SLOW MOVING WITH 30KTCLOSE TO CENTRE. THIS
WILL BE THE LAST TROPICAL DISTURBANCE ADVISORY ON TD04F. TD04FWILL CONTIUNE TO
BE MONITORED AND ADVISORY WILL BE REISSUED IF CHANCES INCREASES FOR IT TO
DEVELOP INTO A TROPICAL CYCLONE.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

And a TRACK and THREAT map are produced when a cyclone is being tracked.
The track map is at www.met.gov.fj/aifs_prods/65661.html

MetService in NZ have a cyclone monitoring website at
www.metservice.com/warnings/tropical-cyclone-activity
tonight it says:
Tropical Cyclone Potential Bulletin
TROPICAL CYCLONE POTENTIAL BULLETIN ISSUED BY METEOROLOGICAL SERVICE OF NEW
ZEALAND
AT 0236 UTC 18-Dec-2016
CURRENT STATUS OF CYCLONE ACTIVITY
There are presently no tropical cyclones in the Coral Sea or South
Pacific areas.
FORECAST TO 1200 UTC 19-Dec-2016
Tropical depression TD04F, currently near 16.5S 174.9E, or 160nm
northwest of Viti Levu, is in a moderate shear envoronment,and is
expected to remain stationary or slowly move south-southeast. An
approaching shortwave trough is expected to increase the vertical
wind shear of the system, and the potential for TD04F to strengthen
into a tropical cyclone remains LOW.
A weak low northwest of Rarotonga is not expected to strengthen into
a tropical cyclone. A weak low may develop over the Solomon Sea
during the next 48 hours, but is also not expected to develop into a
TC.
OUTLOOK TO 1200 UTC 22-Dec-2016
TD04F is expected to slowly move south tracking close to Fiji while
gradually easing. Tropical cyclone development is NOT expected
elsewhere in the forecast area during the forecast period.
The next bulletin will be issued by 0500 UTC Mon 19-Dec-2016
(C) Copyright Meteorological Service of New Zealand Ltd 2016

Streamline Analysis
This streamline analysis map indicates wind flow near the earth's surface. The
areas where the arrowed streamlines coloured in teal move together (convergence)
and move away from each other (divergence) help determine the location of
features within the wind pattern, such as lows or lines of significant weather.
The map also shows surface pressure coloured in black, for areas south of the
Tropics.

This page also has an animated and colour coded IR satellite imagery to show the
convective clouds.
>>>>>>>>>>>>>>>>>>>>

Other sites watching tropical cyclones are
www.tropicaltidbits.com/storminfo/
and ruc.noaa.gov/tracks/

Rain accumulation weekly maps from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif shows the intense
prolonged rainfall from the depression near Fiji, and, to a lesser extent, the
rack of TC VARDAH. The Intertropical convergence zone seems to show decreasing
activity.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
TD04F/99P is expected to drift slowly south to 20S by Thursday and then move off
to the SE.
There is also likely to be a tropical low travelling SW along the coast from
Darwin towards Broome (NW Australia) from Tuesday to Saturday and this may then
go south and inland over the weekend.

Subtropical ridge (STR)
The subtropical high in west Tasman sea tonight is expected to travel northeast
and cross to north of NZ by Wednesday and then to east of NZ. This High is
blocking the travels of TD04F. Its seems that TD04F now has to wait and t and
finally go south after this ridge has gone east.
Just like last week, a new HIGH is expected to squirt from Australian Bight into
South Tasman sea on Thursday and then NE across central Tasman sea and North
Island on early next week. This High should be in central Tasman Sea on
Christmas day, so that the most likely option for NZ Christmas/Boxing day
weather is a SW flow, and an inland trough= some inland afternoon showers + for
the Auckland area, in a word, EASING. (but the SW winds may pick up again on the
27th in the next passing front).

Tasman Sea/NZ Area troughs.
A Front and SW flow is moving off the North Island on Monday.
Another front is expected on Thursday and Friday, followed by up to strong SW
winds on Saturday.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

14 December 2016

TD04F is deepening ....

Fiji Met are saying there is a moderate chance that the Low to NW of Fiji will earn a name as a tropical cyclone by Saturday:

See http://www.met.gov.fj/aifs_prods/20036.txt

Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Dec 140848 UTC.
TROPICAL DISTURBANCE 04F [‑‑1004HPA] ANALYSED NEAR 14.5S 175.5E AT
140600UTC SLOW MOVING. POSITION POOR BASED ON HIMAWARI IR IMAGERY AND
PERIPHERAL SURFACE OBSERVATION. SST AROUND 30 DEGRESS CELCIUS.
CONVECTION PERSISTENT IN THE PAST 24 HOURS. SYSTEM LIES UNDER A UPPER
DIFFLUENT REGION IN A LOW SHEARED ENVIRONMENT. CYCLONIC CIRCULATION
EXTENDS OVER TO 700HPA.
GLOBAL MODELS HAVE PICKED UP THE SYSTEM WITH SOUTHEAST MOVEMENT AND
GRADUAL INTENSIFICATION.
THE POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN
THE NEXT 24 TO 48 HOURS IS MODERATE.
NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE
AREA.

Or from http://www.met.gov.fj/aifs_prods/20032.txt

TROPICAL DISTURBANCE ADVISORY NUMBER A2 ISSUED FROM RSMC NADI
Dec 150807 UTC.

TROPICAL DEPRESSION TD04F CENTRE 1002HPA WAS ANALYSED NEAR 14.2S
174.8E AT 141800UTC. POSITION POOR BASED ON HIMAWARI-8 IR IMAGERY AND
PERIPHERAL SURFACE REPORTS. DEPRESSION SLOW MOVING. MAXIMUM 10-MINUTE
AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 25 KNOTS.


DEEP CONVECTION REMAINS PERSISTENT. ORGANISATION HAS ALSO IMPROVED
PAST 24 HOURS. OUTFLOW GOOD TO SOUTH DUE TO SUBTROPICAL JET TO SOUTH
OF SYSTEM. SST AROUND 29 DEGREE. SYSTEM LIES UNDER A MODERATE UPPER
DIFFLUENT REGION IN A LOW SHEAR ENVIRONMENT. DVORAK ANALYSIS BASED
0.3 WRAP YIELDS DT=1.5, MET AND PT AGREE. FT BASED ON DT. THUS
YIELDING, T1.5/1.5/D0.5/24HRS.

GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND SLOWLY MOVE IT SOUTHWARDS
WITH GRADUAL INTENSIFICATION.

FORECASTS :
AT 12 HRS VALID AT 150600 UTC 14.5S 174.5E MOV SW AT 02KT WITH 25KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 151800 UTC 15.1S 175.0E MOV SE AT 04KT WITH 30KT
CLOSE TO CENTRE.

OUTLOOK:
AT 36 HRS VALID AT 160600 UTC 15.8S 175.5E MOV SE AT 04KT WITH 35KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 161800 UTC 16.5S 175.9E MOV SSE AT 04KT WITH 40KT
CLOSE TO CENTRE.

THE NEXT TROPICAL DISTURBANCE ADVISORY ON TD04F WILL BE ISSUED AROUND
150200UTC.

Or see the map at http://www.met.gov.fj/aifs_prods/65661.html
bob@metbob.com

11 December 2016

Bob Blog 11 Dec 2016

WEATHERGRAM
YOTREPS
Compiled 11 December 2016
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.

Any visitors to New Zealand who are thinking of doing some sailing around the
Hauraki Gulf this summer: please note that I am President of CANANZ, a group of
yachties in AUCKLAND who are interested in cruising and navigation. We are also
interested in helping visiting cruising yachts with a little hospitality, and
willing to answer questions about Auckland and the Hauraki Gulf. See our
webpage at www.cananz.org.nz for more details.

MARLBOROUGH SOUNDS
Some visitors will at present be considering whether to visit Marlborough
Sounds, and if so, when may be the best time to visit?

Some are saying that there may be a weak La Nina at least for the start of our
summer --- if that happens then it is likely that the Highs of the subtropical
ridge may linger over central NZ on late Jan to late Feb and so a trip to
Marlborough then is a good idea as Northland may get onshore easterly winds on
north side of these highs, or even get side-swiped by tropical lows. See the
ENSO plume at
www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/figure06.gif

Others are saying it may remain neutral this summer in which case the highs may
wander across NZ at a wide range of latitudes, and things may be much the same
over Northland as over Marlborough sounds, so may as well stay put. Bureau of
met in Australia are saying it'll be a neutral Summer, see
http://www.bom.gov.au/climate/enso/outlook/

I'll have a "bob each way" as to what may happen, and I think Marlborough will
be at its best late Jan to late Feb.

As for getting there, it's quicker going along west coast. However, in the heat
of the day on a quiet summer's day (passing High), when the interior of the
North Island heats us, the coast gets sea breezes that are good for sailing, and
these ROTATE CLOCKWISE around the North island favouring the east coast.

SO, each argument has its good points. If you do take the west coast then may be
doing this in a northerly flow on the back end of a High, so that's the forward
side of an incoming trough, so you'll need to be aware of a possible wind change
in a few days (this applies to east coast too, but with different timing.

The Tropics
The cyclone that was mentioned last week as possibly heading for Bangladesh is
now moving west along 13N towards Chennai in India as TC VARDAH. This can be
seen at
metoc.ndbc.noaa.gov/ProductFeeds-portlet/img/jtwc/products/io0516.gif

The models are starting to agree on the possible formation of a tropical
depression to NW of Fiji by Thursday, deepening as it travels Se across Fiji on
Friday/ Saturday and then SSE to east of NZ. Till too early to be sure, and
plenty of time for things to change.
Fiji Met Service is watching and will advise via
www.met.gov.fj/aifs_prods/20036.txt
Worth watching.

Rain accumulation weekly maps at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif shows the track
of TC VARDAH. The Intertropical convergence zone seems to show decreasing
activity.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
My thoughts go out to those affected by the recent Solomon Islands (and
Indonesia) quakes. Terrible and terrifying things, these natural events, killing
more than any terrorist can ever do.

There is likely to be a burst of NW winds early this week from Solomon islands
to Tuvalu --- hard to see if this is a burst from the monsoon forming over
northern Australia, but when it forms in this area in December it usually
precedes a tropical low or cyclone. Combine that with the warmer than normal
Sea surface temperatures in the region, and a good looking High in the Tasman
Sea mid-this-week with strong SE winds on its northern side and it seems logical
that a tropical Low will deepen between Vanuatu and Fiji by mid week and
possiblly deepen as it crosses Fiji later in the week. Worth watching.
Tropical accumulated rainfall for next week can be seen at windyty.com

Subtropical ridge (STR)
The subtropical high in west Tasman sea tonight is expected to travel east and
cross to north of NZ on Thursday/Friday. There should be a squash zone of
enhanced trade winds on its northern side around 20S.

A new HIGH is expected to squirt from Australian Bight into South Tasman sea on
Thursday and then across central Tasman sea and North Island on Friday and
Saturday.

Tasman Sea/NZ Area troughs.
The strong SW flow over NZ should continue Monday and weaken on Tuesday.
Another front is expected on Wed and Thursday followed by more strong SW winds
on Friday.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

04 December 2016

Bob Blog 4Dec 2016

WEATHERGRAM
YOTREPS
Compiled 4 December 2016
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.

Any visitors to New Zealand who are thinking of doing some sailing around the
Hauraki Gulf this summer: please note that I am President of CANANZ, a group of
yachties in AUCKLAND who are interested in cruising and navigation. We are also
interested in helping visiting cruising yachts with a little hospitality, and
willing to answer questions about Auckland and the Hauraki Gulf. See our
webpage at www.cananz.org.nz for more details.

Last Month
The averaged isobars for November shows pattern, with the normal weather
features in the normal places: The Siberian high, the north pacific low and its
"Pacific" or "Marine" high between California and Hawaii, the Azores high and
the high that is quasi-stationary in the South pacific, which I call the "Andes
High" for it is struck west of South America by the Andes mountains. The
monsoonal trough extending in November from Indonesia to Darwin. The low/brief
rainy seasons over Kilimanjaro, and the start of the low/rainy season over the
Amazon.

Averaged isobars for November from
www.esrl.noaa.gov/psd/map/images/fnl/slp_30.fnl.anim.html

By looking at the variations of these isobars from there long term November
values we can see a measure of the chaos the was operating last month, the
anomalies. That "Marine high" in the NE pacific id more intense than normal and
located closer the Hawaii, making a squash zone of stronger than normal easterly
winds just south of Hawaii. The Azores High is displaced towards UK so there is
a cold northerly flow over UK. And the pressures are much lower than normal in
the Southern Ocean, breeding stronger westerly wind onto south Australia and all
of NZ

November pressure anomalies as seen at
www.esrl.noaa.gov/psd/map/images/fnl/slp_30a.fnl.anim.html

A look at November's rainfall and its anomaly shows some wet patches in the
tropics from a few depressions and cyclones. One interesting feature these maps
shows is the at there is a detectable shift AWAY from the equator of the
Intertropical Convergence zone. This is a La Nina trait, and there does seem to
be a trend towards a weak La Nina pattern in the east pacific anyway. The La
Nina causes weather patterns in the tropics and subtropics to moves away from
the equator. The implication of this in the Australia /NZ area is that the
subtropical ridge may shift southwards---no sign of this yet, but we may well
see a southward shift of the highs that travel along the subtropical ridge
during December. That's my prediction anyway.

Rainfall for November as seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/thirty_day.html

The Tropics
The two depressions that were in the South pacific last week faded away OK.
No cyclones around at present and none are expected in the South Pacific this
week, but this next increase in activity is likely after 15 Dec.
Rain accumulation weekly maps shows wet patches in the tropics from passing
lows. The Intertropical convergence zone seems to show increasing activity.
Rain for the past week can be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
A weak trough is expected to pass off to southeast of Fiji on Monday UTC and
pass across the Tonga Niue area on Tuesday /Wednesday UTC, then deepen into a
low and it travels off to the southeast. Trade winds should return to Fiji by
Tuesday UTC and to Tonga from late Thursday UTC.
Tropical accumulated rainfall for next week may be seen at windyty.com

Subtropical ridge (STR)
The subtropical ridge spread out across NZ /Tasman Sea tonight should travel off
to east along 40S on Mon/Tues and continue along 40 to 35S.
A new HIGH is expected to form east of New South Wales late in the week and
remain slow-moving in the north Tasman sea at around 30S next week, stretching a
tongue out eastwards along 30S. This is a light-wind barrier to tropical/NZ or
Aus sailing, but its low swells should be good for power vessels.

Tasman Sea/NZ Area troughs.
Two troughs to avoid this week. First is expected to cross Sydney on local
Monday night/Tuesday, mid Tasman and South Island on wed, and then weaken over
the North Island on Thursday local, preceded by NW winds accompanied by rain and
followed by disturbed SW/W winds.
Second trough is expected to reach New South wales area by late Thursday, mid
Tasman on Friday and NZ area by Saturday local with STRONG winds and squally
showers.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe from WordPress: click the "unsubscribe" link on the bottom of the
email. Or, if email wasn't from WordPress then send a reply email saying LEAVE.
============================================================

27 November 2016

Bob Blog 27 Nov

WEATHERGRAM
YOTREPS
Compiled 27 November 2016
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 Tropics
A tropical low formed in Coral Sea last week and faded as it travelled southward
to west of New Caledonia.
We start this week with another tropical low in the Coral Sea, and this one is
likely to fade somewhere near New Caledonia mid-week. It has been picked up in
the tropical tidbits web site and here is its likely track according to some
weather models, as seen at
www.tropicaltidbits.com/storminfo/96P_tracks_latest.png

Fiji Met service is watching another tropical low tonight located near
Rarotonga.
Their latest idea on its future can be downloaded from
www.met.gov.fj/aifs_prods/20036.txt
>>>>>>>>>>>>>>>
Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Nov 270833 UTC.

TROPICAL DISTURBANCE 02F [1006HPA] WAS ANALYSED NEAR 20.0S 164.0W AT
270600UTC.
TD02F MOVING SOUTHEAST AT ABOUT 07 KNOTS.POSITION POOR BASED ON
HIMAWARI-8 AND GOES IR IMAGERY WITH ANIMATION AND PERIPHERAL
OBSERVATIONS. SST AROUND 27 DEGREES CELCIUS.

CONVECTION REMAINS PERSISTENT NEAR LLCC. ORGANISATION REMAINS POOR.
CIRCULATIONS EXTENDS UPTO 700HPA. TD02F LIES JUST EAST OF AN UPPER
TROUGH IN A MODERATE SHEARED ENVIRONMENT.

MOST GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVE IT TOWARDS THE
SOUTHEAST WITH SLIGHT INTENSIFICATION.

POTENTIAL FOR TD02F TO DEVELOP INTO A TROPICAL CYCLONE IN THE NEXT 24
TO 48 HOURS IS LOW.

*********************************************************************
NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE
AREA.
>>>>>>>>>>>>>>>>
Rain accumulation maps from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif show easing
activity around French Polynesia, continuing activity in the Coral Sea area and
around central America, and an increase in activity over equatorial Indian
Ocean. The burst of rain west of Hawaii from a rather peculiar moving tropical
depression.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The tropical low near Rarotonga is expected to move off to the SSE and deepen
near 30S. It is expected to "steal" the winds from the French Polynesia
/Southern Cooks area and should leave behind a lingering convergence zone.
Another tropical low is in the northern coral Sea and is expected to go Se and
fade around the New Caledonia area around mid-week. Worth watching as this is a
system that may need to be avoided.
The SPCZ around Tuvalu and Tokelau may drift southwards this week, and remain
intense. There could be convective showers over Samoa and Fiji by end of the
week.
Tropical accumulated rainfall for next week may be seen at windyty.com

Subtropical ridge (STR)
The subtropical ridge are continuing to be well defined and reasonably wide,
allowing anticyclones to migrate easterly in a patterned fashion.
The HIGH which is in the western Tasman sea tonight is expected to travel east
along 30/33S this week crossing northern NZ on Tuesday /Wednesday. There may be
a squash zone of enhanced westerly winds south of this high, especially until
Tuesday, but it seems to be reasonable on north side of this high.

Another High is expected to follow across the South Tasman Sea on Tue and Wed
and then stall over central NZ on Thursday and Friday, and move off to east of
NZ this weekend.

These subtropical highs offer reasonable weather for any yachts still seeking to
get from tropics to NZ/Australia, however there are light winds in the centre of
the ridge, and there are troughs in-between the ridges, so travelling in the
winds around the back side of a passing ridge may require sailing thru a
trough-that's OK if you do it at a good latitude mid trip, but may be
disconcerting if both you and the trough arrive at the destination the same day.


Tasman Sea/NZ Area troughs.
Strong westerlies over NZ on Monday and Tuesday, then the next trough should
arrive over the weekend and linger over North Island early next week.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.
==================================================

20 November 2016

Bob Blog 20 Nov

WEATHERGRAM
YOTREPS
Compiled 20 November 2016

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.

Thanks to Kevin Fawcett (of Charlotte, New Carolina) for informing me that the
Niue Yacht club website at www.NYC.NU has a webcam looking out over Alofi Wharf,
with a library of 30 minute images. If there is weather data from the airport
that is added to the image.

Our week of perigean tides from that super moon is now over. I hope you all took
adequate precautions.

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) slipped into La Nina territory for a few weeks in
September and this triggered a few meteorological web sites to say "We are now
having a La Nina". Well, I'll let you judge the veracity of that: during October
it relaxed and in the past few weeks the SOI has been negative.
SOI trend (x10) since 2013 showing us in neutral territory may be seen at
www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=soi

The Ocean: The warmer the sea the quicker it evaporates, tossing water vapour
into the air, where is rises and cools into cloud. The equatorial Pacific region
hosts the widest and warmest sea on the planet. Thus its sea surface
temperatures SST may be thought of as a factor in the running of planetary
weather engine. When SST in the target zone (equatorial Pacific between dateline
and Galapagos, called NINO3.4) are notably cooler than normal, this is called a
La Nina episode.
Sea surface temperature anomaly are cooler than normal, but not yet in La Nina
territory, and may be seen at
www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=nino34&p=monthly
Compare the recent El Nino (warm seas) with its extreme predecessor in 1998.

The Tropics
The tropics are still taking a rest.
Rain accumulation maps show an increase in activity in the Coral Sea, and around
Panama, and a decrease around Fiji/Samoa. Rain maps are at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
The MJO has move out of the Pacific and is over the Americas are heading for the
Indian Ocean, so we should expect a few quiet weeks in the South Pacific
now..and activity to peak late in December.
A tropical low [1004] has formed today in Coral sea to NW of New Caledonia and
this is expected to travel south into Tasman Sea where it is expected to merge
or get captured by a deepening trough/low forming east of New South Wales on
Thursday and to travel mainly over southern NZ on Friday.
Tropical accumulated rainfall for next week may be seen at windyty.com

Subtropical ridge (STR)
The subtropical ridge is becoming stronger and wider this week.
The HIGH which is travelling east along 35S tonight past NZ and further east on
Mon/Tue/wed may briefly have a small squash zone of strong SE winds on its
northern side on Monday near 20S.
Next High in Tasman Sea is expected to form on Saturday and then travel slowly
along 30S and 35S during next week, enjoy.
These subtropical ridges offer reasonable weather for any yachts still seeking
to get from tropics to NZ/Australia, however there are light winds in the centre
of the ridge, and there are troughs in-between the ridges, so travelling in the
winds around the back side of a passing ridge may require sailing thru a
trough-that's OK if you do it at a good latitude mid trip, but may be
disconcerting if both you and the trough arrive at the destination the same day.

Tasman Sea/NZ Area troughs.
The tropical low [1004] NW of New Caledonia tonight is expected to travel south
into Tasman Sea on Monday and fade on Tuesday and merge or get captured by a
deepening trough/low forming east of New South Wales on Thursday and all this
should travel mainly over southern NZ on Friday. Associated trough is expected
to reach Opua around Friday afternoon- about the same time that I am scheduled
to give a talk about weather to the ICA seminar at Opua . hopefully it won't be
too much of a distraction, and will be over by BBQ time.

As of sailing Noumea to Australia: try and avoid that low which is expected to
form off New South Wales on Thursday morning. It looks like it may bring a
southerly buster.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website http://www.metbob.com for information on tailor-made voyage
forecasts
- Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.

13 November 2016

Bob Blog 13 Nov 2016

WEATHERGRAM
YOTREPS
Compiled 13 November 2016
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.

Thanks to the generosity of 24 donors. the "weather stations for Tonga"
fundraiser at tinyurl.com/hn5k42k raised $615 in the past week, 2% of it's goal.


Many of us know there are gaps in the Google earth data. Here's a link to a
recent blog written by Max Shaw of Fluenta, introducing another app SAS Planet
(an alternative to Ovitel Maps).
See sv-fluenta.blogspot.com/2016/11/using-satellite-imagery-to-assist.html

Also Max and I have noticed that Predictwind.com has recently added ECMWF data
to their sites. I recommend ECMWF data, especially in the tropics. At present
GFS and GEM have the idea of a Low in the Coral sea by Fri 18 Nov, but ECMWF is
showing nothing there until Tue 22 Nov. ECMWF is more reliable. To learn more
about Predictwind.com's use of ECMWF data
see
www.sail-world.com/Australia/Predictwind-now-offers-European-high-quality-model-
for-forecasting/149609


And you may know that Tuesday's full moon is the closest and therefore the
largest since 1948. Tides are not exceptional. They depend on harmonics of sun
and moon gravitational forces, so having a closer moon is not a guarantee of
extreme tides-mind you if you have been taking shortcuts across a sandbar or
reef recently then take care at low tides over the next week.

The Tropics
After a few busy weeks, the tropics seem to be taking a rest for now.

>>>>>>>>>>>>>>>>>>>>>
There has been flooding, ponding and slipping around parts of New Zealand.
---and just now a severe long-lasting lateral quake
see earthquake.usgs.gov/earthquakes/eventpage/us1000778i#executive,
revised to M6.6 then M7.5, plus a tsunami warning for South Island East coast
To see the Tsunami arriving in Kaikoura and Wellington and Christchurch:
check www.geonet.org.nz/tsunami/
>>>>>>>>>>>>>>>>>>>>>>>>>

Rain accumulation maps looks less intensive rain in most areas, but an increase
around Samoa.
Rain for the past fortnight from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES

SPCZ=South Pacific Convergence zone.
SPCZ: The intensity that built up over Samoa during the past week is likely to
move towards French Polynesia this week, but in a disorganized fashion. May be
some small tropical lows forming on the zone this week with squally showers. but
models don't have anything deepening at this stage. We do have a MJO event
occurring at present but no organised equatorial westerly winds, so maybe just a
few tropical lows are likely.

Tropical accumulated rainfall for next week may be seen at from windyty.com

Subtropical ridge (STR)
Small high travelling east along 30S between Fiji and NZ tonight and moving off
to the east.
Next High in Tasman Sea is not expected until Thursday and is then expected to
travel slowly east along 30S. This is likely to be followed by a weak trough and
then another even slower and larger high next week, so this should offer a good
weather opportunity for yachts wanting to travel from tropics to NZ or
Australia.

Tasman Sea/NZ Area.
There is a parameter called SAM (Southern Annular mode) that measure the
strength of the Polar Vortex (the ring of winds around Antarctica), and when it
goes negative there is an increased chance anywhere in the Southern Ocean for
polar chilled SW winds to burst further north. It's now negative, but forecast
to turn most positive week.
See
www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/new.aao_index_en
sm.html


There was a polar blast off South Africa over last few days.
And now it looks like there MAYBE a small polar blast in the Tasman Sea and off
to northern NZ on Thursday 17/ Friday 18 Nov, with strong to gale cold and
squally SW winds with huge swells.
Swells over 4 metres may extend as far north as around 26S on Friday. These are
long period swells, sometimes called gentle giants, but somewhat disconcerting
sailing, so avoid.
After Friday, there should be good sailing conditions to NZ.
As of sailing Noumea to Australia: Looks OK after the trough clears off Noumea
on Wednesday.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe from WordPress: click the "unsubscribe" link on the bottom of the
email. Or, if email wasn't from WordPress then send a reply email saying LEAVE.

06 November 2016

Bob Blog 6 Nov 2016

WEATHERGRAM
YOTREPS

Compiled 06 November 2016

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.

Weather models and weather advice depends primarily on a good network of useful
observations. I have been approached by GREG JUST on Tonga this week and he has
started a crowd-funding appeal to set up an account to add new weather stations
especially to the marine ports around Tonga and later on a few nearby Island
groups. This is a just cause (pun) and I support it. If any of you have ever
thought that I may be worthy of a bottle of wine for my efforts with this blog
or my forecasting, then here's your chance to make me proud and appreciative.

Please donate the equivalent of a bottle of beer or wine to this fund and
comment "thanks to MetBob"
I'll be watching to see just how much I'm appreciated, and you get the
opportunity to share your bottle of beer/wine for me on Facebook.Even if you
don't contribute, I'd like you to share this item with your friends.

To see the website, go to tinyurl.com/hn5k42k

A note to anyone passing thru TONGA
This is to inform all members of the public that His Majesty's Cabinet on 21st
October 2016 has approved daylight savings in Tonga and to be effective from
Sunday the 6th of November 2016 and end from Sunday the 15th of January 2017.
This time change is to extend daylight hours in the evenings to allow the public
to make better use of day light hours for economic and social activities.
At 2am on Sunday 6th of November 2016 members of the public are advised to move
their watches and clocks ahead to 3am. This notice has been copied from today's
Tongan Marine forecast at www.met.gov.to/forecast/html/FCST_BULLETIN.html

The Tropics
TC MEARI is located east of Philippines but not expected to affect land. And
there are a couple of interesting lows in the NW Pacific that are not expected
to come to much.
Rain accumulation maps looks more intensive in the Philippines area and along
the ITCZ across the Pacific, and less sin the South pacific
Rain for the past fortnight can be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to build especially over Samoa area and by mid-week
may produce a tropical LOW that will then travel Southeast across Southern Cooks
by end of the week. The Low should carry squally showers with 30 to 40 knot wind
gusts. It may affect French Polynesia after 14 Nov. Avoid.
Tropical accumulated rainfall for next week can be seen at windyty.com

Subtropical ridge (STR)
A HIGH is travelling east across Tasman Sea along 25 to 30S from Sunday night to
be east of NZ from Friday.
Next Tasman High is a brief one on sat/Sun, crossing NZ on MONDAY 14 and
lingering east of NZ on Tue 15 Nov.
Not strong enough this week to produce any squash zones in the tropics.

This is the time of year that yachts are staging themselves in Tonga (or Fiji or
New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.
The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a seminar 16 to 26 November in
Opua.
Boats joining the rally are assisted with weather info, resources and planning
tools to help make the passage to NZ as easy as possible. On arrival
participants are welcomed to Opua and entertained with a week of entertainment
and seminars on a range of topics. This rally is FREE thanks to the assistance
of Main Sponsors Bay of Islands Marina and Boatyard and the Opua business
community. See www.islandcruising.co.nz/?page_id=717

Travel between Tropics and NZ:
The arrival times to avoid because of passing fronts are 7/8 Nov, 12/13 Nov and
16/17 November.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website http://www.metbob.com for information on tailor-made voyage
forecasts- Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE

30 October 2016

Bob Blog 30 oct

WEATHERGRAM
YOTREPS
Compiled 30 October2016
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 Tropics
A reminder that the NOMINAL South Pacific cyclone season starts on Tuesday.
Nothing expected this week.

After a few busy weeks, the tropics seem to be taking a rest for now. There are
a few small tropical lows around but nothing of much significance tonight.

Rain for the past fortnight from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
shows that last week looks similar to the previous week, except for less rain
last week in the ITCZ and the North Atlantic (than previous week).

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to go thru a venting process and send an bundle of
wet tropical air across Fiji tonight and across Tonga on Monday then off to the
southeast as a Low. There may be squally showers in this, so avoid departure
from Tonga on Monday. After that the zone should be reasonably quiet for the
remainder of the week.
Tropical accumulated rainfall for next week may be seen at windyty.com

Subtropical ridge (STR)
A HIGH is travelling east across central NZ on Monday-this is typical of a
summer pattern, but wrong month, so may bring some frosts, unwelcome in
vineyards at this stage.
Next high is likely to cross Tasman sea along 35S from Tuesday to Thursday and
fade west of NZ.
From Thursday onwards there should be a weak ridge along 30 to 35S across the
whole South Pacific.
Not strong enough this week to produce any squash zones.

Travel from Tahiti to Tonga:
Avoid departing from Tahiti area on local 1 to 2 Nov due light winds and a weak
passing trough. Winds looks OK for getting to Tonga, but there may be a trough
in the Tongan area early next week (7/8 Nov) so avoid that for arrival.
==============================
This is the time of year that yachts are staging themselves in Tonga (or Fiji or
New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.
The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a one-week seminar 16 to 20
November in Opua. Boats joining the rally are assisted with weather info,
resources and planning tools to help make the passage to NZ as easy as possible.
On arrival participants are welcomed to Opua and entertained with a week of
entertainment and seminars on a range of topics. This rally is FREE thanks to
the assistance of Main Sponsors Bay of Islands Marina and Boatyard and the Opua
business community. See www.islandcruising.co.nz/?page_id=717
Further west there is the GO WEST Rally. Again from any port (most are leaving
from Noumea) this time to BUNDABERG, with welcome week starting 6 November 2016.

See www.downunderrally.com/westrallyfee
==============================
Travel between Tonga and NZ:
South Pacific convergence zone or maybe an upper trough expected to cross Tongan
area on Monday= possible squally showers, southerly winds gusty and lightning.
May as well stay put for that.
Remainder of week looks OK for departure; the next rough is expected early next
week.
The arrival times to avoid getting S of 30S to NZ are Mon to Wed 7 to 9 Nov.

Travel between Fiji and NZ
Diwali Public holiday on Monday
South Pacific convergence zone or maybe an upper trough should clear off by
Tuesday morning then OK to depart for remainder of the week.
The arrival times to avoid getting S of 30S to NZ are Mon to Wed 7 to 9 Nov.

Travel between New Caledonia and NZ
Public holidays on Monday and Tuesday (All Saints) so can't check out until
Wednesday,
Weather traffic along the way -there's a mediocre trough on Tue/wed 1/2 Nov,
then a weak low on Fri/sun 4/6 Nov, Avoid getting south of 30S Mon to Wed 7
to 9 Nov.

Travel for New Caledonia to Australia
Public holidays on Monday and Tuesday (All Saints) so can't check out until
Wednesday,
A trip to Bundaberg goes through a passing mediocre trough, no strong winds but
a period of variable winds to challenge you.
Going to NSW, the weather traffic along the way is the challenge of active cold
front on Sat 5 Nov followed by strong to gale southerly winds and rough seas,
and a trough off Coffs on Fri 11 Nov.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe from WordPress: click the "unsubscribe" link on the bottom of the
email. Or, if email wasn't from WordPress then send a reply email saying LEAVE.

23 October 2016

Bob Blog 23 Oct 2016

WEATHERGRAM
YOTREPS
Compiled 23 October2016

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 CYCLONE SEASON OUTLOOK
The South Pacific/Australian tropical cyclone season is from nominally from 1
Nov to 30 April. A neutral to weak or moderate LA NINA is expected to affect the
tropical Pacific Ocean over the next six months. This tends to nudge the South
pacific convergence zone to the south and west of its normal position,
increasing the cyclone risk around Australia and Coral Sea, and perhaps reducing
this risk in places east of the dateline.
The Bureau of Meteorology have considered this and say that the cyclone risk
over Northern Australia is increased. The average number of cyclones per season
across the entire region is 11.
See more at www.bom.gov.au/climate/cyclones/australia/

Looking at the behaviour of the sea surface temperature over the past year, NIWA
has searched the database for analogue years that may point the way as to how
this season may develop. The top analogues are 1969/70; 1983/84; 1992/93;
1995/96; 2005/06; 2010/11 and using this data they have compiled a cyclone risk
map, as
at www.niwa.co.nz/news/southwest-pacific-tropical-cyclone-outlook
They have applied these risks to the average occurrence of tropical cyclones to
come up with a map showing likely numbers of TC in each sub area this season.
See www.niwa.co.nz/news/southwest-pacific-tropical-cyclone-outlook
The average number of cyclones across the South Pacific region per season is
12.4 cyclones.

TROPICS
Philippines got a double hit last week from TC SARIKA (KAREN in the Philippines)
and HAIMA (LAWIN in the Philippines).
NASA have produced a video showing the resulting extreme accumulated rainfall at
www.eurekalert.org/pub_releases/2016-10/nsfc-nme102116.php

At present there are two tropical depressions that are being forecast by the
computer models to become cyclones this week (one in Northern India Ocean and
one west of Mexico), and there possible fture tracks are seen at
ruc.noaa.gov/tracks/

Rain accumulation maps show the two cyclone tracks over the Philippines, and the
track of NICOLE in the Atlantic, and a rebuild of the South Pacific Convergence
Zone.
These may be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES

This is the time of year that yachts are staging themselves in Tonga (or Fiji or
New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.

The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a one-week seminar 16 to 20
November in Opua. Boats joining the rally are assisted with weather info,
resources and planning tools to help make the passage to NZ as easy as possible.
On arrival participants are welcomed to Opua and entertained with a week of
entertainment and seminars on a range of topics. This rally is FREE thanks to
the assistance of Main Sponsors Bay of Islands Marina and Boatyard and the Opua
business community. See www.islandcruising.co.nz/?page_id=717

Further west there is the GO WEST Rally. Again from any port (most are leaving
from Noumea) this time to BUNDABERG, with welcome week starting 6 November 2016.
See www.downunderrally.com/westrallyfee

Travel between Fiji/Tonga and NZ:
The next trough to affect Fiji is expected on 29 /30 Oct an winds should return
to SE on 1 Nov. For Tonga that trough is expected 31 oct/1 Nov wit winds
returning to S/Se on 2 Nov. Avoid departing during this trough.
There are expected to be large slow-moving highs crossing between Tonga/Fiji and
NZ this week, so try and go around the back end of these highs to avoid their
light winds (unless motoring). The highs are NOT expected to be intense enough
to form squash zones between Tonga/Fiji and NZ, but may be some in the Coral
Sea.
Try and avoid arriving at NZ when a trough passes Northern NZ on Tue night/ Wed
1/2 Nov.

Travel between New Caledonia and Brisbane/Bundaberg area:
That weekend surcharge is a factor to consider. As for departing from Noumea,
well there are only light winds forecast for local Monday and Tuesday, so that
makes Wednesday onwards the best days to depart this week. The next trough to
reach Bundaberg is expected on 31 Oct but really that trough is further south,
so that's when Bundaberg may have light variable winds.

Travel from New Caledonia to New South Wales
No real point in taking the rhumb line for such a voyage as the subtropical
ridge should be gone around rather than thru. Instead head for Brisbane, and
around 158E turn to your destination. This should also give you the benefit of
the assistance of the East Aussie current. However, note that there is an active
trough south of 30S on Monday 31 Oct/Tue 1 Nov.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts
Feedback is to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.

16 October 2016

Bob blog 16 Oct

WEATHERGRAM
YOTREPS
Compiled 16 October2016
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.

FLEET CODE
Regarding the notes I wrote last week about FLEET code, Chuck on JACARANDA has
replied as follows:
>>>>>
We use two methods to view it
Physplot - The easiest way to use this is to just drag the unopened email right
onto the fleetcode icon on our desktop. It automatically opens and loads.
(This is using sailmail)
By sliding the viewing screen slightly to the right the actual text appears and
you can read about what you are seeing on the screen.

OpenCPN
We prefer this as it gives us greater visibility of the overall area. You can
download the fleet code plug in from opencpn.org website.
>>>>>
When referring to the Fiji Day LOW last Monday I noticed that the upper trough
responsible was also shifting a "Vorticity max" out of the Tasman Sea and onto
Vanuatu. See my Facebook post at www.facebook.com/metbobnz/
An upper trough penetrates the South Pacific convergence zone over Fiji on 10
Oct, causing winds to spin and spiral downwards forming a surface low over
Fiji=The Fiji Day low. The extra upward motion brought heaps of RAIN. and as a
sideline, an entity of the west side of the upper trough known as a Vorticity
Max is taken by the southwest winds aloft from the Tasman Sea onto New Caledonia
then onto Vanuatu.
Well, A village just north of Port Vila (Tongamea) had a significant HAIL STORM
as a consequence.
I received photos of this hail from my good friend Alex from Honiara Weather
Office.
===========
We are having a full moon this weekend, and so next weekend is the start of the
last quarter of the waning moon. That's when the full tide is overnight, and
it's the first of these events after the equinox that triggers the season for
PALOLO. when the coral worms spawn. They drop off their worm-tails or pods; jade
(female) or brown (male); and these mix together in the swirling tide, with each
having a light sensitive spot that directs it towards the moon as it sinks in
the west (or to a flashlight). At dawn the pods dissolve, allowing eggs and
sperm to get together and start the new generation. The rising is only on the
turn of that one tide and only takes place for a few hours. Samoan Met Office
say Oct 22/23 is this year's best chance.
Ask the locals about this and if you time it right you may be about to collect
some of this rare delicacy, or photo it. They might look yucky, but taste really
nice on toast, something like caviar, so I'm told.
=======
TROPICS
Bureau of Met and NIWA have both issued their cyclone forecast for the coming
season in the past few days-I'll cover that next week for you.
======
In the NW Pacific tonight we have TC SARIKA and HAIMA, see them at
ruc.noaa.gov/tracks/
And in the Atlantic, after a very destructive path last week from MATTHEW, we
have NICOLE keeping well offshore, but making a direct hit over Bermuda as a Cat
3 (Saffir-Simpson scale). The radar image of this can be seen at
www.wunderground.com/blog/JeffMasters/

Rain for the past fortnight (from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif) show an increase
in convection over Philippines, the track of MATTHEW and NICOLE in the Atlantic,
and a burst of rain over Fiji thanks to the Fiji Day low, but a removal of
convection from Solomons as a consequence.

WEATHER ZONES
Tropical accumulated rainfall for next week can be seen at windyty.com

Tropics to NZ/ Australia: - Strategy
This is the time of year that yachts are staging themselves in Tonga (or Fiji
or New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.

The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a one-week seminar 16 to 20
November in Opua. Boats joining the rally are assisted with weather info,
resources and planning tools to help make the passage to NZ as easy as possible.
On arrival participants are welcomed to Opua and entertained with a week of fun
and games, entertainment and seminars on a range of topics. This rally is FREE
thanks to the assistance of Main Sponsors Bay of Islands Marina and Boatyard and
the Opua business community. See www.islandcruising.co.nz/?page_id=717

Further west there is the GO WEST Rally. Again from any port (most are leaving
from Noumea) this time to BUNDABERG, with welcome week starting 6 November 2016.
See www.downunderrally.com/westrallyfee

In deciding upon a departure date, it's as simple as 1.2.3:

1.The first factor to consider is the local weather: the South Pacific
Convergence Zone SPCZ sometimes brings squalls, but is well to the north this
week and still recovering after being vented by the Fiji day Low last Monday.
However, we have a passing (mainly upper) trough over Fiji on Monday/Tuesday,
and this trough is expected to slowly cross Tonga area on Tuesday/Wednesday.
This trough is likely to bring squalls and maybe some strong SE winds, so better
to wait for it to go before departing.
Some like to use Minerva reef as an extra staging post since it is 1.5 to 2 days
sail south of Tonga, and just out of the tropics (so marine insurance that may
be void in the tropics may work in Minerva). But it only shelters you from the
waves (so long as they don't topple over the reef) and not from the wind or
rain. It has that passing trough on Tuesday (local) with some rain until
Thursday, and is only likely to have fresh easterly winds form this feature.

2.The second factor to watch are the HIGHS that travel along the Subtopic ridge
STR, that zone between the trade winds of the tropics and the disturbed
westerlies of the roaring 40s. This zone is usually near 30S, and if there is a
big high then on its northern side there is usually an accompanying are of
enhanced trade winds, what I call a SQUASH ZONE. This week there is a HIGH
moving along 30S from N Tasman Sea tonight to east of NZ on Wednesday, and there
is a squash zone between that High and the trough over Tonga, mainly on
Wednesday/Thursday. The next High should start further south and cross the
Tasman Sea from Thursday to north of NZ on Sat 22 Oct, without any squash zone.

3.The third factor is to avoid bursts of strong southerly winds and heavy swells
during the trip or upon arrival. These come from the Southern Ocean and on a
different pattern to the passing troughs in the tropics. Sometimes a southerly
burst inter-reacts with a tropical trough and things get nasty. Not this week.
You can use windyty.com to see expected weather features at your arrival point
for the next week, and aim to arrive "in-between active features", but remember
that these outlooks are just ideas, and real world will do its own thing. Over
northern NZ there is expected to be a weak passing trough on Thursday, and then
northern weakening trough on Sunday 23, and then maybe some strong SW winds from
a passing southern Low on Mon 24/Tues 25 Oct. And over the Australian coast
there is a passing trough this Monday and another mainly south of 30S, on
Friday, weaker further north on sat/Sun. I think you can handle these fronts
with suitable waypoints/timing.

Let's apply this 1,2,3 rule to some popular destinations:

Travel between the Tropics and NZ:
If heading from Fiji or Tonga, wait for that trough to go first. Maybe Wed from
Fiji and Thu from Tonga. but that may change. Arrange waypoints so as to
encounter that Sun 23 over NZ front near 30S. That depends on boat speed, and
configuration, so will vary from vessel to vessel.

Travel between New Caledonia and Brisbane/Bundaberg area:
Trough that was over New Caledonia yesterday has gone east now, but there is a
squash zone between it and the Tasman Sea High. That should ease during Monday.
Then OK to go anytime, but expect to encounter a weak passing trough around next
Sat/Sun as you approach coast. If you arrive over the weekend then there's a
surcharge to pay.

Travel from tropics to New South Wales
No real point in taking the rhumb line for such a voyage as the subtropical
ridge should be gone around rather than thru. Instead head for Brisbane, and
around 158E turn to your destination. This should also give you the benefit of
the assistance of the East Aussie current. However, remember that there is an
active trof south of 30S on Friday 21/Sat 22 Oct.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.
Follow me on Facebook at www.facebook.com/metbobnz

09 October 2016

Bobgram 9 October 2016

WEATHERGRAM
YOTREPS
Compiled 9 October2016

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.

FLEET CODE
Back when I was a boy the FLEET CODE was established allowing a weather map to
be sent to the whole Fleet all at once via Morse code transmitted over
Shortwave. In this age of readily available GRIB data (from some models) the
FLEET code has fallen off the back shelf of technology. However, the Fiji Met
Service are still manually converting their analysis map into fleet code and,
thanks to Mike Harris of Pangolin and the people at saildocs these maps can be
downloaded as email and drawn on your own computer as you travel around the
South Pacific.

They have an advantage over GRIB files in that they contain convergence zones,
as seen by Fiji Met Service meteorologists using satellite imagery to fine tune
placements.
To download the latest Nadi Fleet code send an email to query@saildocs.com, no
subject needed, saying SEND nadi-fleetcode.
When you receive the reply email, use something such as notepad to save the data
as a file and store this, say, on your desktop, as, e.g. fleet.txt
Mike Harris' PANGOLIN website contains a page which allows you to save a beta
version of PhysPlot. Go to www.pangolin.co.nz/physplot . This is a windows
program physplot.exe (now called a desktop ap) which can open that file
fleet.txt and turn it into a weather map for you.
Tonight's situation on Fleet map shows a convergence zone north of Fiji shifting
south, and a weak trough has been drawn over Fiji.

The Tropics
Tonight in the Atlantic, TV MATTHEW, after hitting Haiti hard last week, has
finished grazing the east USA coastline and is now moving east out to sea. TC
NICOLE is on the SE side of MATTHEW. See ruc.noaa.gov/tracks/

And in the Pacific TC SONGDA is likely to recurve soon, but TC AERE in the China
Sea may make landfall over Vietnam, rather an usual event.


Rain for the past fortnight as seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
shows an increase in convection Christmas Island area to NW of Australia, and in
the South Pacific, especially to north of Fiji. MATTHEW's rain-footprint stands
out clearly.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to congeal into a wet trough over Fiji during Monday
= Fiji Day. A Low may form over the Lau group late on Monday, bringing some
strong winds and squally rain to Tonga on Monday night and Tuesday. Avoid.
This Fijian trough is expected to spread westwards, so that a zone of LIGHT
WINDS is expected over western Fiji to Vanuatu. Not good for sailing.
So the South Pacific convergence zone this week goes thru a period of
intensification, then congealment (over Fiji) and then a venting of its energy
off to the southeast. This pattern is consistent with the arrival of an MJO
(Madden Julian Oscialltion) in the South Pacific , as seen at
www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_mjo_index/mjo_index.html
When the blue shaded area in this MJO time/latitude cross section enters the
South Pacific we tend to see tropical lows. Note that these MJO arrivals occur
once every 4 to 8 weeks at this time of year, but may be more regular during the
coming cyclone season. Worth watching.

Subtropical ridge (STR)
This is expected to remain weak and further north than normal along round 25S
between Australian coast and 180. Further east it should spread south. No squash
zone this week.

Travel from Tahiti to Tonga:
Winds may be Ok for a departure on local Sunday, then just light winds are
expected over Tahiti area until next week,

Travel between the Tropics and NZ:
Light winds over western Fiji and Vanuatu area this week, so maybe stay put and
wait for trade wins to return.
There is a Low affecting Tongan area on Monday/Tuesday, then light variable
winds for the remainder of the week. So maybe wait for something better.
If you are already on your way to NZ then be mind-fall that a LOW from Tasman
sea is likely reach northern NZ around Sun 16/Monday 17, and another maybe
around Thu 20/Fri 21 Oct. try and avoid these dates for arrival, but these are
provisional and may change, so also seek an update.

Travel between New Caledonia and Brisbane area:
Weak trough is expected to cross Brisbane area on Tue 11 Oct. followed by a few
days with southerly winds. This trough should spread east reaching New Caledonia
around Sat 15 Oct and then lingering there until Sunday 16 Oct
No strong winds expected with this trough so maybe Ok to sail thru it, but not
100%.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.

06 October 2016

Fiji Day tropical Low

FIJI DAY Tropical Low
The GFS model persists in picking that a tropical low may form on Fiji Day Mon
10 Oct and then deepen as it travels SE across Tonga

This could bring brief strong to gale winds to Tonga on Tuesday 11 Oct. But
other models still come up with different scenarios, and, of course, the real
world will do its own thing.

Listening to warnings that are now being issued as TC MATTHEW heads to Florida,
I am reminded that we should hope for the best, but prepare for the worst. And
so when the models differ from each other, as they do in today's run for early
next week, we need good tools so that we can see the difference.

One good tool I recommend in such cases is www.tropical
tidbits.com/analysis/models
Select the Southwestern pacific region and it defaults to GFS models and you can
click thru to 12Z Mon 10 Oct= midnight end of Monday Fiji time/1am Tuesday
Tongan & NZ time. This looks yucky for Tonga.
Then the website allows you to click GLOBAL (models) and switch to ECMWF, it
keeps the same timestamp.
Or CMC (the other two options, NAVGEM and JMC, don't work in the Southwestern
Pacific region).

This quickly shows you the difference between the models, and that in itself is
a helpful step. As to trying to surmise what may happen in the real world, well
that takes skill and experience, and is a job for meteorologists. My pick is
the Low may actually be placed SW of Tonga on Tuesday, sort a merger of the
above models.

A similar tool is provided by windyty.com, which can flick between EC and GFS
models.

Also Predictwind.com offers a side-by-side page comparing itt PWG and PWC
models, but this may require a subscription.



Cheers from Bob

02 October 2016

Bob Blog 2 Oct 2016

WEATHERGRAM
YOTREPS
Compiled 2 October2016

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.

SEPTEMBER was an interesting month.
September averaged isobars may be seen at
www.esrl.noaa.gov/psd/map/images/fnl/slp_30.fnl.anim.html
Pressure anomalies seen at
www.esrl.noaa.gov/psd/map/images/fnl/slp_30a.fnl.anim.html show that
for much of September HIGHS lingered south and east of NZ.
A time-longitude cross section of the blocking index shows this blocking was
strongest between 6 and 11 September.
See
www.cpc.ncep.noaa.gov/products/precip/CWlink/blocking/real_time_sh/real_time_ind
ex_nrm.shtml

The lingering highs in this area led to more NE winds onto eastern parts of the
North Island, so that by the end of the month some parts of Coromandel had an
accumulated rainfall around a metre --- an amount more typical of Fjordland.
Topsy-turvy weather.

The Tropics
Tonight TC MATTHEW is Cat 5 as it moves to the Jamaica /Haiti/ Cuba area.
May be seen at ruc.noaa.gov/tracks/
And in the NW Pacific TC CHABA is moving towards Japan.

Rain for the past fortnight may be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
Rain accumulation maps show an increase in convection over Indonesia and
Philippines and along the Intertropical Convergence zone across the central
Pacific, and to north of South America. Also a decline in activity in the North
Atlantic and Tasman Sea. The front that knocked the power out over South
Australia last Thursday shows up well.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to remain much the same in the Solomon Islands to
Tokelau area, with another finger covering northern Vanuatu and the sea between
Vanuatu and Fiji. Another branch of the SPCZ may cover the zone from Niue to
Gamier Islands in a loose and scattered manner.
A tropical LOW is expected to form in the Vanuatu to Fiji area on Sun 9/Mon 10
Oct and then MAY go SE across Fiji on Fiji day holiday on Mon 10 Oct-to Thu 13
Oct, consider avoiding.

Subtropical ridge (STR)
This is expected to remain weak and further north than normal along round 25S
between Australian coast and south of French Polynesia. It is likely to get
wider and stronger from this weekend and stretch to 30S.

Travel from Tahiti to Tonga:
Light winds over Tahiti area until local Tuesday. Then winds may be Ok for
getting as far west as Niue. As for Tonga, well, a passing trough associated
with the Fiji Low is expected around Mon 10/Tue 11 Oct local. Avoid.

Travel between the Tropics and NZ:
A trough is expected to bring strong winds and showers to northern NZ on Tuesday
night and another more intense trough is expected to bring strong winds to
northern NZ on Thursday /Friday followed by SW swells from the Southern Ocean
over 4 metres reaching as far north as 22S on Friday might/Saturday NZ time.
Peak swells are likely to be over 8 metres near northern NZ on Thu night/Fri 7
Oct. Avoid.

Travel between New Caledonia and Brisbane area:
A ridge is expected to travel along 25/30S across Tasman Sea from Thu night 6
Oct and to get east of NZ from Mon 10 Oct. This should provide good conditions
for sailing from Fiji to New Caledonia or from New Caledonia to Brisbane, but
NOT for going east.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts
- Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.

25 September 2016

Bob Blog 25 Sep 2016

Bob Blog 25 Sep 2016
Posted on September 26, 2016
WEATHERGRAM
YOTREPS
Compiled 25 September 2016

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.

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 slipped into La Nina territory during past two
weeks. It was above 10 units on this Australian scale. If it can hold this high
for a month in a row the we can say we are having a La Nina.
SOI trend (x10) since 2013 showing us in La Nina territory may be seen at
www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=soi

The Ocean: The warmer the sea the quicker it evaporates, tossing water vapour
into the air, where is rises and cools into cloud. The equatorial Pacific region
hosts the widest and warmest sea on the planet. Thus its sea surface
temperatures SST may be thought of as a factor in the running of planetary
weather engine. When SST in the target zone (equatorial Pacific between dateline
and Galapagos) are notably cooler than normal, this is called a La Nina episode.
Sea surface temperature anomaly may be seen at
http://www.farmonlineweather.com.au/climate/indicator_enso.jsp?c=nino34&p=monthl
y
We now have cooling seas in the target area, and there MAY be a weak La Nina in
the next few months

The Tropics
TC MEGA is in the NW Pacific, there are two tropical systems between Hawaii and
Mexico, and TC KARL and LISA are in the North Atlantic.
Cyclone tracks seen on ruc.noaa.gov/tracks/

Rain for the past fortnight may be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
and these rain accumulation maps show an increase in convection over Indonesia
and Philippines from the west, and an easing in convection over the South
Pacific.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to stay quiet in the Solomon islands to Tokelau area
No squash zones. A Passing trough may affect from Tonga to Niue late in the
week.

Subtropical ridge (STR)
This is expected to remain weak and along about 20 to 30S.It is NOT often this
far north and is weakening all the trade winds, offering rare opportunities for
getting east in an Island hopping fashion if you like.
Rain accumulation may be seen at windyty.com
Next High is expected to spread to east of NZ from the SOUTH after Wednesday,
shovelling polar chilled southerly winds northwards so that they deepen a LOW
near 35S 165W late in the week. Avoid travelling direct between NZ and Tahiti.

Travel from Tahiti to Tonga:
The weak winds that have been affecting Tahiti recently should be over from
tomorrow. Go for it. No squash zones, and no strong convergence zones, but
voyages are likely to encounter a passing trough with maybe some showers and
varying winds for a day or two. It is looking OK to venture via Suwarrow this
week.

Travel between the Tropics and NZ:
A series of LOWS continue to travel across Tasman Sea/Northern NZ area over next
10 days, with a brief break for a passing ridge on Thu/Fri. These lows are not
really making gales, but the fronts do have strong winds. Avoid
arrival/departure on Sat 1 Oct or Thu 6 Oct.

Travel between New Caledonia and Australia:
Intense TROUGH crossing north Tasman sea on Mon 26 Sep, then OK weather for
Australia to New Caledonia. Another intense trough in N Tasman sea on Thu/Fri
29/30 Sep to avoid.
As for getting form New Caledonia to Australia: not this week, too much
headwind, and probably not next week. Maybe OK from around 8-10 Oct.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website http://www.metbob.com for information on tailor-made voyage
forecasts- Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.

18 September 2016

Bobgram issued 18 Sep

WEATHERGRAM
YOTREPS
Prepared 18 September 2016 NZST

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 Tropics
TC MALAKAS is heading for Japan and JULIA is off to Florida and the Carolinas
whilst KARL should stay offshore in the Atlantic. Cyclone tracks may be seen on
ruc.noaa.gov/tracks/

Rain for the past fortnight can be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
They show an easing in activity everywhere.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to remain steady in the Solomon Islands to north of
Fiji area.
Rather weak further east.
A Passing trough may affect from Niue to Southern Cooks during the week (after
Tuesday local).

Subtropical ridge (STR)
This is expected to remain weak and along about 25 to 30S.
Net High is NOT expected to enter Tasman Sea until around 1 Oct.

Travel from Tahiti to Tonga:
No squash zones, and no strong convergence zones, but voyages are likely to
encounter a passing trough with maybe some showers and varying winds for a day
or two. It is looking OK to venture via Suwarrow this week.

Travel between the Tropics and NZ:
Remember that NZ changes to NZDT next Sunday 25 Sep.
A series of LOWS are expected to travel across Tasman Sea / Northern NZ area
over next two weeks with lows crossing Northland on Wed 21, then next on Sat/Sun
24/25 Sep then wed/tue/fri 28/29/30 Sep, then maybe Sun 2 Oct.
Try and arrange arrival in NZ BETWEEN these lows.

Travel between New Caledonia and Australia:
Too many lows crossing the Tasman sea next two weeks. Maybe try again when that
IGH arrives around early October.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website http://www.metbob.com for information on tailor-made voyage
forecasts- Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

11 September 2016

Bob Blog 11Sep

WEATHERGRAM
YOTREPS
Prepared 11 September 2016 NZST
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.

Northland Radio
Northland Radio has moved to a Facebook page so everybody can view it.
Please tell your cruising friends. it's at www.facebook.com/northlandradio.nz/
And Schedule is at www.northlandradio.nz/frequencies/

The Tropics
TC MERANTI is heading for the China Sea and ORLENE is off the Mexican West
Coast.
There is a tropical depression in the Gulf of Mexico-not expected to make
landfall,
and are several in the Atlantic with one that may reach UK by end of the week.
Cyclone tracks may be seen at ruc.noaa.gov/tracks/

RAIN around the tropics:
Rain for the past fortnight from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
show an easing in activity over Indian Ocean, but much the same in South West
Pacific.

WEATHER ZONES
Weather Zones (see text) as expected mid-week on Wednesday (GFS model) showing
wind, isobars, current, swell black arrows / Sig wave height purple lines, swell
and wind waves, SPCZ and STR.

SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to remain strong in the Solomon Islands to north of
Fiji area, with a burst of activity along 10S between Tokelau and Northern
Cooks. The SPCZ is likely to pass across Fiji and Tonga /Niue around early to
mid-week (as seen at windyty.com using Rain accumulation).

Subtropical ridge (STR)
High that is over North island tonight is expected to stretch out along 35S to
east of NZ this week. It is somewhat of mediocre intensity, and that's good news
for there isn't really any associated squash zone on its northern side in the
tropics.
Next HIGH is NOT expected to travel into Tasman Sea until mid-next-week.

Travel from Tahiti to Tonga:
Voyage along about 20S is likely to encounter the passing SPCZ around local wed
to Friday 14 to 16 Sep, and that may be squally.
It is looking OK to venture via Suwarrow this week.

Travel between NZ and the Tropics:
Over northern NZ expect NW winds ahead of a front travelling on Fri 16 Sep,
maybe OK for arrival.
But avoid arriving Sat /Sun 17/18 Sep when there is a front or Mon 19 Sep when
the maybe a gale change to SW winds.
Then OK to arrange departure so as to arrive with a ridge of light winds wed 21
Sep--- such a voyage may go thru a front near 32S but with no more than 25 knots
for a brief time, possibly an acceptable compromise.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
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.
To unsubscribe send a reply email saying LEAVE.

Blog Archive