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

27 October 2013

BOBGRAM issued 27-28 October 2013

WEATHERGRAM

YOTREPS

Issued 27-28 October 2013
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world of weather maps, so please fine-tune to your place. Dates are in UTC unless otherwise stated.

Only time for a quick Weathergram this week

WEATHER ZONES
South Pacific Convergence Zone SPCZ
The SPCZ is expected to spend most of this week north of 15S.
A squally low has developed over the Kermadecs area tonight and is moving off to the Se trailing behind a small trough that is fading away.
A low is expected to form offshore of Sydney on Monday/Tuesday and deepen as it crosses the Tasman sea on Wednesday/Thursday and New Zealand on Friday. Avoid. A southerly flow is likely to cover the NZ area and the area to north of NZ after this Low on Friday/Saturday/Sunday 1/2/3Nov, may be longer. Avoid.

Sub-tropical Ridge STR
The STR is expected to remain strong along 30 to 35S this week, and that means only mildly enhanced trade winds on the north end of the traveling highs.
One high is expected to move east along 32/35S from near NZ on Monday 28 October to 120W by Monday 4 Nov.
The next High is expected to form in the Tasman Sea from Friday 1 Nov and fade in the north Tasman Sea by Mon 4 Nov.

Route Briefings
Between tropics and NZ
Try and time your voyage from the tropics so the arrival tine in New Zealand does NOT coincide with a front or too much of a southerly flow—since the NZ area is likely to have a southerly flow for at least 1/2/3 Nov and maybe also 4/5/6 November, Tuesday 29 is the best day this week for departure

See my yotpak at http://lnk.ie/K7MU/e=bobmcd1.bobgram@blogger.com/http://www.boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is metbob.wordpress.com
Weathergram text only and translator is weathergram.blogspot.co.nz
Website http://lnk.ie/K7MV/e=bobmcd1.bobgram@blogger.com/http://www.metbob.com
Feedback to bob@metbob.com

20 October 2013

BOBGRAM issued 20 Oct 2013

WEATHERGRAM
YOTREPS
Issued 20 October 2013
Bob McDavitt's ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world of weather maps, so please fine-tune to your place. Dates are in UTC unless otherwise stated.

The Palolo are rising
For those lingering in the South Pacific until the end of the month : you may be in for an interesting delight this weekend with the waning moon, especially around the third quarter- when the tide starts ebbing just before dawn. In October or November this usually triggers a spawning of a coral worm called Palolo (or Balolo in Fijian). Sometimes this may be large enough to colour the sea – stuff can be netted and eaten raw or cooked. Ask the locals.

The South Pacific cyclone season:
The scientists in NZ, Fiji and Australia have issued a report about what to expect in the South Pacific for the cyclone season Nov 2013 to April 2014. They expect a near average numbers over the region as a whole (8 to 12), with increased activity late in the season.

Where to get weather information?
Last week this blog gave a few websites but the Group Mail server I am using distorted them so they didn't work. I'll try again here.
For the ECMWF model try bit.ly.ecoz
For the MetService view of the UK model try bit.ly/7daywx
For swell maps try swellmap.com
Even if you only have e-mail access you can request some text based Internet products thanks to saildocs. Send an email, no subject needed , to query@saildocs.com with one of these messaged:
For warnings : SEND http://lnk.ie/JV6J/e=bobmcd1.bobgram@blogger.com/http://m.metservice.com/warnings/marine
For high seas: SEND http://lnk.ie/JV6K/e=bobmcd1.bobgram@blogger.com/http://www.met.gov.fj/aifs_prods/10140.txt
For Fiji Marine :SEND http://lnk.ie/JV6L/e=bobmcd1.bobgram@blogger.com/http://www.met.gov.fj/aifs_prods/10060.txt
For Tonga Marine: SEND http://lnk.ie/JV6M/e=bobmcd1.bobgram@blogger.com/http://www.met.gov.to/index_files/routine_forecast.txt

TROPICAL TOPICS
Things remain busy in the Northern Hemisphere tropics with TC FRANCISCO skirting southern Japan. TC RAYMOND is off the west coast of North America and is not expected to make landfall. . Tropical depressions 01F and 02F, the first two of this new season, are being watched by the Fiji Met Service tonight. More about them soon.

WEATHER ZONES
South Pacific Convergence Zone SPCZ
The SPCZ is activating so that TD01F has appeared on it between Solomons and northern Vanuatu as an open trough area. Also TD02F has appeared as a closed isobar centre to southwest of Funafuti. TD01F is expected to fade away on Monday and TD02F is expected to go S and SE then convert into a dose of very squally weather moving across Fiji on around Tuesday 22 Oct UTC. It is the expected to take an active part of the SPCZ onto Tonga on Thursday and Friday UTC and then onto Niue on Saturday/Sunday UTC. Avoid.
During Sat/Sun the trough near Niue is expected to link with a front from NZ and form a large slack trough of light winds over the Kermadecs area
Another branch of the SPCZ is lingering along 5 to 8S across Northern Cooks.

Sub-tropical Ridge STR
The STR is expected to remain strong along 30 to 32S this week, and that means enhanced trade winds on the north end of the traveling highs.
One high is expected to move east along 32S from NZ to 120W between Monday and Friday.

The next High is expected move from Australian on Saturday 16 Oct across the Tasman Sea at 33S and then the North Island by Tue/Wed 29/30 Oct.

NZ/Tasman Sea
This area continues to have periods of unsettled weather with enhanced winds south of 35S, especially in between the high cells of the STR. Thursday 24 to Monday 28 Oct is expected to be one of these periods, right in time for Labour week- a long holiday weekend celebrated in NZ. A front is expected to cross northern NZ on Friday night, proving an interesting challenge to those involved in this year's Coastal Classic from Auckland to Russell in the Bay of Islands. This front is expected to be followed by W/SW winds until late on the holiday Monday, good for the return home.

Route Briefings
Tahiti to Tonga:
A trough is lingering to east of Tahiti at present but should fade. The STR is maintaining useful trade-winds all the way to Tonga at present, but that trough reaching Niue on Sat/Sun 26/27 UTC may change this.

Between tropics and NZ
Looking OK to depart when the SPCZ in not visiting. For Fiji this is on Wednesday/Thursday/Friday, and from Tonga this is Monday /Tuesday/part of Wednesday.
After the SPCZ visits Tonga on Thursday and Friday a large slack trough is expected to form near the Kermadecs and that may delay departures from Tonga for a while.
Avoid arriving in New Zealand when a front crosses on Friday 25 UTC or the next front on Thursday 31 Oct.

Between New Caledonia and Australia
A trough is expected to be crossing the eastern seaboard of Australia around Tue/Wed/Thu 22/23/24 and another on Tue/Wed 29/30 Oct. Avoid arriving on these dates.

See my yotpak at http://lnk.ie/JV6N/e=bobmcd1.bobgram@blogger.com/http://www.boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is http://lnk.ie/JV6O/e=bobmcd1.bobgram@blogger.com/http://metbob.wordpress.com
Weathergram text only and translator is http://lnk.ie/JV6P/e=bobmcd1.bobgram@blogger.com/http://weathergram.blogspot.co.nz
Website http://lnk.ie/JV6Q/e=bobmcd1.bobgram@blogger.com/http://www.metbob.com
Feedback to bob@metbob.com

13 October 2013

BOBGRAM issued 13 Oct 2013

WEATHERGRAM
YOTREPS
Issued 13 October 2013
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world of weather maps, so please fine-tune to your place. Dates are in UTC unless otherwise stated.

Apologies to those who get this twice--- server is changes settings on me and I have to do a resend part way through.

Where to get the best weather?
If you are planning to sail from Tonga/Fiji/Vanuatu/ New Caledonia to NZ in October/ November, and looking to buddy with someone, then you may be interested in checking out the ICA's "All Points Rally" to Opua, see http://lnk.ie/JO19/e=bobmcd1.bobgram@blogger.com/http://www.islandcruising.co.nz/
Some sailors have asked me recently how good are the grib files they are downloading. Well, most of you are looking at data gleaned from the GFS model, and it's good, but not the best. A study done in 2012 shows ECMWF is usually the best. Grib data for EC is not easily available but when you have Internet you can check its latest for the next 10 days for http://lnk.ie/JO1A/e=bobmcd1.bobgram@blogger.com/http://bit.ly.ecoz
Second best is the UK model, again its grib data is not easily available, but MetService pick the model of the day to feed their regional model , and it is usually EC or UK that they pick, and then it is further processed to give maps at http://lnk.ie/JO1B/e=bobmcd1.bobgram@blogger.com/http://bit.ly.7daywx
So check these web sites when planning your trip (and add http://lnk.ie/JO1C/e=bobmcd1.bobgram@blogger.com/http://www.swellmap.com to look at the likely swells). And if your grib data agrees with these then all is good, but if not then you need to consider multiple scenarios.

TROPICAL TOPICS
It is a busy time in the Northern Hemisphere tropics with TC PHAILIN being the largest and most intense cyclone to make landfall from Bay of Bengal into India in the last 14 years. TC OCTAVE is off the west coast of North America and re-curving towards Baja California. TC NARI is about to travel from east to west across the Philippines and head for China, and TC WIPHA seems to making a bee line for Japan.

WEATHER ZONES
South Pacific Convergence Zone SPCZ
The SPCZ has been taken to the north of its range by that active squally trough which brought a S/SW change to Fiji/Tonga last Thursday night (as mentioned in my weathergram last week). During this week is should slowly drift south again, reaching Fiji and Samoa by the weekend. ECMWF model has a low forming on the SPCZ near Fiji early next week, and GFS mode, in a run dome today, has a deep low over Vanuatu early next week. Too far away to be sure at this stage, but something to keep aware about.

Sub-tropical Ridge STR
The STR is expected to be near 30S this week, and that means enhanced trade winds on the north end of the traveling highs.
One high is expected to move east along 30S from date to 140W between Monday and Friday.
Another High is expected to travel east along 30 to 32S from east Australia on Tuesday to northern NZ on Thursday , fading east of the dateline on Friday UTC.
A third high is expected to depart for eastern Australia along 32/33S on Friday and reach central NZ on weekend of 19/20 October. This southward shift of the high tracks is a sign that summer is coming and is linked to a similar southward shift occurring in the jetstreams aloft.

NZ/Tasman Sea
This area continues to have a period of unsettled weather with enhanced winds thanks to passing jetstreams. Activity seems to be shifting southwards. One active front is moving across the South Island on Monday and the North Island on Tuesday morning local. A weaker front is expected mainly over the South Island on Friday.

Route Briefings
Tahiti to Tonga:
Up until Thursday UTC this route has easterly wind son the north side of a travelling High , and travel is OK. Then a trough is likely to form on the SPCZ over Cooks by Friday UTC and is expected to deepen as it travels east to Tahiti by Sat/Sun 19/20 . So better to depart Tahiti by 16 Oct UTC to avoid this trough.

Between tropics and NZ
Looking OK to depart any time this week. Winds over Fiji/Tonga may be too strong for comfort by Friday 18 Oct UTC due to the HIGH pressure system south of them by then, so nicer to depart by Thursday UTC.

Between New Caledonia and Australia
Trough crossing the Tasman on Monday and Tuesday, then OK to go. Winds over New Caledonia May become strong this weekend or early next week so try and depart before then. Next significant trough expected for Brisbane should reach there around Tue 22 October.

See my yotpak at http://lnk.ie/JO1D/e=bobmcd1.bobgram@blogger.com/http://www.boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is http://lnk.ie/JO1E/e=bobmcd1.bobgram@blogger.com/http://metbob.wordpress.com
Weathergram text only and translator is http://lnk.ie/JO1F/e=bobmcd1.bobgram@blogger.com/http://weathergram.blogspot.co.nz
Website http://lnk.ie/JO1G/e=bobmcd1.bobgram@blogger.com/http://www.metbob.com
Feedback to bob@metbob.com

BOBGRAM issued 13 Oct 2013

WEATHERGRAM
YOTREPS
Issued 13 October 2013
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world of weather maps, so please fine-tune to your place. Dates are in UTC unless otherwise stated.
Where to get the best weather?
If you are planning to sail from Tonga/Fiji/Vanuatu/ New Caledonia to NZ in October/ November, and looking to buddy with someone, then you may be interested in checking out the ICA's "All Points Rally" to Opua, see http://lnk.ie/JO10/e=bobmcd1.bobgram@blogger.com/http://www.islandcruising.co.nz/
Some sailors have asked me recently how good are the grib files they are downloading. Well, most of you are looking at data gleaned from the GFS model, and it's good, but not the best. A study done in 2012 shows ECMWF is usually the best. Grib data for EC is not easily available but when you have Internet you can check its latest for the next 10 days for http://lnk.ie/JO11/e=bobmcd1.bobgram@blogger.com/http://bit.ly.ecoz
Second best is the UK model, again its grib data is not easily available, but MetService pick the model of the day to feed their regional model , and it is usually EC or UK that they pick, and then it is further processed to give maps at http://lnk.ie/JO12/e=bobmcd1.bobgram@blogger.com/http://bit.ly.7daywx
So check these web sites when planning your trip (and add http://lnk.ie/JO13/e=bobmcd1.bobgram@blogger.com/http://www.swellmap.com to look at the likely swells). And if your grib data agrees with these then all is good, but if not then you need to consider multiple scenarios.

TROPICAL TOPICS
It is a busy time in the Northern Hemisphere tropics with TC PHAILIN being the largest and most intense cyclone to make landfall from Bay of Bengal into India in the last 14 years. TC OCTAVE is off the west coast of North America and re-curving towards Baja California. TC NARI is about to travel from east to west across the Philippines and head for China, and TC WIPHA seems to making a bee line for Japan.

WEATHER ZONES
South Pacific Convergence Zone SPCZ
The SPCZ has been taken to the north of its range by that active squally trough which brought a S/SW change to Fiji/Tonga last Thursday night (as mentioned in my weathergram last week). During this week is should slowly drift south again, reaching Fiji and Samoa by the weekend. ECMWF model has a low forming on the SPCZ near Fiji early next week, and GFS mode, in a run dome today, has a deep low over Vanuatu early next week. Too far away to be sure at this stage, but something to keep aware about.

Sub-tropical Ridge STR
The STR is expected to be near 30S this week, and that means enhanced trade winds on the north end of the traveling highs.
One high is expected to move east along 30S from date to 140W between Monday and Friday.
Another High is expected to travel east along 30 to 32S from east Australia on Tuesday to northern NZ on Thursday , fading east of the dateline on Friday UTC.
A third high is expected to depart for eastern Australia along 32/33S on Friday and reach central NZ on weekend of 19/20 October. This southward shift of the high tracks is a sign that summer is coming and is linked to a similar southward shift occurring in the jetstreams aloft.

NZ/Tasman Sea
This area continues to have a period of unsettled weather with enhanced winds thanks to passing jetstreams. Activity seems to be shifting southwards. One active front is moving across the South Island on Monday and the North Island on Tuesday morning local. A weaker front is expected mainly over the South Island on Friday.

Route Briefings
Tahiti to Tonga:
Up until Thursday UTC this route has easterly wind son the north side of a travelling High , and travel is OK. Then a trough is likely to form on the SPCZ over Cooks by Friday UTC and is expected to deepen as it travels east to Tahiti by Sat/Sun 19/20 . So better to depart Tahiti by 16 Oct UTC to avoid this trough.

Between tropics and NZ
Looking OK to depart any time this week. Winds over Fiji/Tonga may be too strong for comfort by Friday 18 Oct UTC due to the HIGH pressure system south of them by then, so nicer to depart by Thursday UTC.

Between New Caledonia and Australia
Trough crossing the Tasman on Monday and Tuesday, then OK to go. Winds over New Caledonia May become strong this weekend or early next week so try and depart before then. Next significant trough expected for Brisbane should reach there around Tue 22 October.

See my yotpak at http://lnk.ie/JO14/e=bobmcd1.bobgram@blogger.com/http://www.boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is http://lnk.ie/JO15/e=bobmcd1.bobgram@blogger.com/http://metbob.wordpress.com
Weathergram text only and translator is http://lnk.ie/JO16/e=bobmcd1.bobgram@blogger.com/http://weathergram.blogspot.co.nz
Website http://lnk.ie/JO17/e=bobmcd1.bobgram@blogger.com/http://www.metbob.com
Feedback to bob@metbob.com

06 October 2013

BOBGRAM issued 6 Oct 2013

WEATHERGRAM
YOTREPS
Issued 06 October 2013
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world of weather maps, so please fine-tune to your place. Dates are in UTC unless otherwise stated.

When to head out of the tropics?
Well the chances of encountering some nasty weather in the tropics is rather low at present and gradually increasing to be not worth the risk from around mid-December. Many Insurance companies do not cover weather damage in the South Pacific tropics from 1 November so that many cruising sailors leave by then—however if you wish to hang around for a few more weeks (because there are still a few cold outbreaks reaching NZ and South Australia) then, on average, there isn't much change in the risk during that time.

If you are planning to sail from Tonga/Fiji/Vanuatu/ New Caledonia to NZ in October/ November, and looking to buddy with someone, then you may be interested in checking out the ICA's "All Points Rally" to Opua, see http://www.islandcruising.co.nz/

Those who are seeking access to a weather map with isobars and fronts and convergence zones that can be down loaded via Internet can request one in FLEET code by sending an e-mail to query@saildocs.com, no subject needed, with the message "SEND nadi-fleetcode". To be able to view this map, save the number-table in it to a *.txt file and then open this with PhysPlot- You will need to FIRSTLY download and install PhysPlot from http://www.pangolin.co.nz/physplot

I shall supply more information regarding web sites for checking the weather models next week.

TROPICAL TOPICS

In East Asia TC FITOW is taking a track across northern Taiwan and into China. Following it is TC DANAS but this cyclone is expected to re-curve to the northeast and move onto Japan. In the Gulf of Mexico tropical Depression KAREN is expected to move onto southern states of USA, full of rain but wind is easing.

WEATHER ZONES

South Pacific Convergence Zone SPCZ
The SPCZ is active from Solomons to just NW of Fiji. During Fiji's Independence day holiday on Thursday 10 Oct the zone is expected to cross Fiji, and then on Friday a low is expected to deepen rapidly about and to south of Tonga, moving off to the SE. Avoid.
There is another convergence zone which is active mainly along 10S from Tuvalu to Northern Cooks. This zone is a mirror of the ITCZ that tends to form for a few weeks around the equinox and is expected to remain active this week, staying north of 11S.

Sub-tropical Ridge STR
The STR is expected to be north of its normal position this week, and that means a week of weak trade winds.
The high that is over eastern Australia on Wednesday 9 Oct is expected to move east across the Tasman Sea along around 30S and fade away just to south of New Caledonia by Fri 11 October. This is expected to be followed by another High along 30S from Sat 12 Oct and that High is likely to spread out, making mainly light winds in the tropics.

NZ/Tasman Sea

This area continues to have a period of unsettled weather with passing troughs. A Low is expected to form in the Tasman Sea on Monday and cross the North Island during Tuesday/Wednesday, deepening as it tracks to the southeast.
Another Low is expected to form on a cold front as it crosses the South Island on Friday 12 Oct. This Low should cross northern North Island on Saturday 12 Oct.

Route Briefings

Tahiti to Tonga:
Trough is expected to affect Niue on or around Tues 8 Oct and another over Tonga and Niue around Friday 11 Oct followed by a rare period of W/SW winds there on Sat 12 Oct UTC. Otherwise expect light winds this week.

Between tropics and NZ
The southerly flow in the NZ/Tasman area following the low on Tuesday makes for a period of headwinds for anyone trying to sail from New Caledonia/Vanuatu/Fiji mid to late this week. Not Good.
Those trying to get from Tonga to NZ may have a passable voyage with a departure on Wed 9 October, skirting around weather systems.

See my yotpak at http://lnk.ie/JGZ9/e=bobmcd1.bobgram@blogger.com/http://www.boatbooks.co.nz/weather.html for terms used.
Weathergram with graphics is http://lnk.ie/JGZA/e=bobmcd1.bobgram@blogger.com/http://metbob.wordpress.com
Weathergram text only and translator is http://lnk.ie/JGZB/e=bobmcd1.bobgram@blogger.com/http://weathergram.blogspot.co.nz
Website http://lnk.ie/JGZC/e=bobmcd1.bobgram@blogger.com/http://www.metbob.com
Feedback to bob@metbob.com

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