sail-world.com
 
 
News Home Boats for Sale MarineBusiness-World Sail-World Racing Cruising Int Magnetic Is RW Photo Gallery FishingBoating
Sail-World.com : Weather - the long and short of it in the South Pacific
Weather - the long and short of it in the South Pacific

'Island Cruising Association seminar'    .

Island Cruising Association has for many years been operating successful rallies between New Zealand and the South Pacific and has recently enlarged its operations to include Australia and Indonesia. Choosing just the right weather to make that first crossing successful has always been key, and here rally organiser John Martin discusses this all-important feature of cruising


Weather - it’s the one thing, after making sure the boat and crew are properly prepared, that can make the difference between a pleasant trip and one perhaps no so pleasant. Let’s face it no one in their right mind goes in search of bad weather for an ocean passage and good weather routing can help you avoid the bad stuff, well most of the time.

Weather guru Bob McDavitt explains weather as a mix of pattern and chaos. If we have a look at the timing for getting the fleet off to the tropics this year in early May it was definitely a case of more chaos than pattern.
Typical May Weather.

Typically in May, leaving for the South Pacific Islands of Tonga, Fiji, Vanuatu and New Caledonia, you’d expect to see the usual migration of weather systems, low following high following low, in a procession from west to east. As winter starts to take hold the centres of the high pressure system tend further North (the STR or Sub tropical ridge) and the rate at which they migrate through accelerates. May is usually a great time to leave as winter is not yet in full swing, the high pressure centres or STR is only just starting to drift North and their rate of migration still gives a 7 – 9 day cycle between systems. With the centre pressures still well south the pressure gradient where the highs meet the sub-tropical low is still weak. As the STR moves north the gradient steepens and the trades start to reinforce.

That’s the pattern but this year we also got to see quite a lot of chaos in the mix.

During the summer months we have the cyclone season. To put it simply cyclones are intense tropical depressions and are born from convection and have a symmetrical warm central core that characterizes such systems. Convection is of course warm air rising and this is powered by the temperature of the sea. Autumn usually sees a cooling of the sea temperature’s in the tropics and therefore less convection. Not so this year, which saw severe cyclones as late as tropical cyclone Ita in mid to late-April and a string of tropical depressions forming over Vanuatu and Fiji through into the second week in May. It was these low pressure cells that made predicting the weather difficult and their spectre keeping the fleet safely ensconced in Opua.

Southern Oscillation -  .. .  


From a predictive point of view, highs and lows in their natural progression are reasonably easy to predict and an accurately forecast out as far as ten days in not uncommon. The problem with tropical depressions is their unpredictability and the sensitivity of the various weather forecasting models to predict them. Some lean on the conservative side and some look like they’re predicting Armageddon in a weeks’ time only to get more realistic as the time frame gets closer. While these systems may be born out of convection in the tropics they can deepen quickly when mixed with cold air as they travel south. When cold air meets warm air, the warm air is pushed upwards out of the way. If the upper winds remove the rising air faster than the lower winds can replace it, then the surface pressure in the immediate area falls rapidly causing a destructive low pressure system.

Human nature of course being what it is has a tendency when reviewing these forecasts to lean towards the forecast that best suits our needs, whether it be right or wrong, so it’s important to choose just one provider for your weather, we use the Predict Wind model. It’s not uncommon when you get a group of cruisers together, each advocating a different model, to have total confusion, better known as analysis paralysis.

So what caused this chaos?

The World Meteorological Organization now says that a recent weakening of trade winds has significantly warmed the sub-surface waters of the central Pacific. This warm anomaly is now rising to the surface and causing these areas of convection. This warming effect is also having an effect on the Souther Osilation Index or SOI. The Southern Oscillation Index SOI sums up the weather patterns over the South Pacific as one number. It is based on the standardized difference in the barometer readings between Tahiti and Darwin and is the precursor to the weather effects known as La Nina and El Nino.

Convection over the SW Pacific -  .. .  


The current prediction by the weather experts is when this stored energy reaches the surface we will have an El Nino episode which could manifest within the next month or two. The amount of extra heat currently stored in the tropical Pacific has been measured to be on a par with the amount that gave us the last big El Nino in 1997/8.

So what is an El Nino / La Nina event?

The experts say we are heading for an EL NINO event and Bob McDavitt sums up nicely the difference between the two events.

In an El Nino the Sea temperatures of the Equatorial Eastern Pacific (the STEEP for short) are WARMER than normal. This is caused by the trade winds being LESS intense than normal-- so that the sun-heated sea is NOT physically blown off into the western Pacific as much as is normal.

The extra heat causes more evaporation and thus more cloud over the Peru end of the Pacific and all the weather zones are drawn closer to the equator. The SPCZ is sifted further north and thus further east. The subtropical ridge , the rail track for the High systems-- in winter gets to go between 20 and 30S ,rather than 25 to 35S

The disturbed westerlies of the roaring 40s get to go as far north as 35S maybe 30S in winter , so the whole of New Zealand gets frequent cold fronts and SW winds.

A LA NINA episode occurs when STEEP is cooler than normal , making eastern end of Pacific dry (and Australian end wet) All the weather zones mentioned above are pushed further than normal AWAY FROM the equator.

There is also the Pacific Decadal Oscillation , around a 20 years cycle. IT has been negative since 1997 and encouraging La Nina's . It is likely to turn positive by 2017 and then encourage El Nino episodes for the next twenty years or so.

South Pacific Convergence Zone -  .. .  


So what does this mean for the average cruiser?

If past El Nino events are anything to go by then stronger dry easterly trades for the SW Pacific tropic areas and more westerly, wet conditions for New Zealand. With the STR moving north the region of accelerated trades will also move north with it placing the squeeze zone between the high pressure systems and the inter tropical low between 12 and 18S instead of the recent 18 to 25S.

Island Cruising Association -  .. .  
This should mean an easier passage south from the tropics at the end of this season and a dryer than usual winter in the tropics.

That means the water maker will get more use, you’ll need to put on more sun screen and you’ll need a couple of extra cans of diesel for the passage south in October or November.

For more information about the Island Cruising Association, to join one of their rallies, or even to attend one of their highly informational cruising seminars, click here.


by John Martin, Island Cruising Association


  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=123042

10:01 PM Sat 7 Jun 2014GMT


Click here for printer friendly version
Click here to send us feedback or comments about this story.







Sail-World Cruising News - local and the World

Michael Thurston, the owner of the Australian yacht Drina, sent us a message from Nome, Alaska, to inform us that he and his crew had reached the Pacific Ocean thus successfully completing a transit of the Northwest Passage. A late opening of the Bellot Strait allowed Drina to reach the central part of the Northwest Passage only by mid-September. ... [more]  

Minister for Natural Resources, Lands and Water, Kevin Humphries and Minister for Roads and Freight Duncan Gay have announced the successful tender for the dredging of Swansea Channel has been awarded to Neumann Dredging Pty Ltd. ... [more]  

The World ARC fleet departed the Cocos (Keeling) Islands this morning, embarking on the second longest sail of their circumnavigation; a 2350 nautical miles journey to Mauritius. Their stay in the tropical atoll has certainly been one to remember. ... [more]  

Pantaenius, the world’s leading specialist yacht insurance company, has been at the forefront of yacht insurance for more than 40 years, earning a reputation for transparency and commitment to customer service that provides round-the-clock international support and reliable, speedy claims settlement. ... [more]  

Auckland On The Water Boat Show: Images from the final day by Richard Gladwell, Sail-World.com/nz
The Auckland International Boat Show concluded today having enjoyed four days of moderately acceptable weather. Attendance figures have not yet been announced however they are expected to be close to or exceed last year's Show. ... [more]  

World-wide the development of marine wind farms will grow. Britain's RYA is taking a proactive stance that can serve as an example for other yachting bodies. If wind farms could be an issue in your waters, its important to follow just what is happening in GBR. Speaking today Stuart Carruthers, RYA Cruising Manager said 'The RYA will now be responding to those of the Panel’s questions that have bee ... [more]  

How to make a distance scale for faster navigation by Captain John Jamieson, Florida
If you are anything like me, sailing navigation can be a challenge when short- or single-handed sailing. But you still need to be able to plot fast and accurate positions for sailing safety. Here one little-known sailing tip used by the pros that will help you do just that! ... [more]  

A new provisional World Record was set on the Viaduct Harbour today with 52 paddlers covering the 100 metre course on the Lancer SUP. There were no incidents in the attempt - which sets a new mark category in the Guinness World Records. ... [more]  

Marine Rescue Forster-Tuncurry has been named a winner in the 2014 NSW Water Safety Awards, taking out the prize for the Water Safety Event of the Year. The Award, presented tonight, is for the unit’s successful Water Expo, staged in January at the peak of the summer holiday and boating season. The award was accepted by Deputy Unit Commander Ray Mazurek. ... [more]  

Marine Rescue NSW volunteers have been recognised for their enormous contribution to safety on the water, with the rescue service taking out a prestigious title at the 2014 NSW Water Safety Awards. MRNSW won the Most Outstanding Contribution to Water Safety by an Organisation category at the annual awards, presented tonight. ... [more]  

The 14th edition of the Atlas also includes a new double page map of the Arctic Ocean, which highlights the dramatic long-term decline of Arctic sea ice cover. The sub-ice maps draw on bedrock data, provided by the British Antarctic Survey, to show physical features which are obscured by ice cover. ... [more]  

An attempt will be made on Saturday afternoon set set a new Guinness World Record mark for the most people on a Stand Up Paddleboard (SUP) The SUP used for the record attempt will be supplied by leading New Zealand inflatable manufacturer, Lancer Industries, and the SUP uses Lancer's AirDock technology.. ... [more]  

Rescue vessel Point Danger 30 from Marine Rescue Point Danger base, went to the aid of a yacht with mechanical and sail failure shortly before 10 o’clock this morning. The yacht, with three people on board had been experiencing strong winds east of Cook Island off the coast of Northern NSW and was forced to seek help when its engine failed and mainsail blew out. ... [more]  

A win for sharks by Nathaniel Pelle
Earlier this year, thousands of Australians, including you, united to stop this brutal and unnecessary practice. I’ve never seen anything quite like it - protesters gathered on beaches from Manly to Margaret River and flooded Environment Minister Greg Hunt’s inbox with nearly a quarter of a million emails calling on him to stop the cull. ... [more]  

Sail-World did a quick tour of the on the water exhibits at the Auckland On The Water Boat Show. Her's a quick selection of some of the almost 200 boats on the water in the Viaduct Harbour. ... [more]  

The Auckland On The Water Boat Show opened this morning in brilliant Spring sunshine. Based on the Viaduct Harbour, Auckland, there are nearly 200 exhibiting companies and over 200 boats are at the event which runs through to Sunday September 28. ... [more]  

On Monday 22 September the EU Naval Force flagship, ITS Andrea Doria, met the Chinese Navy ship, CNS Changbaishan, in the Gulf of Aden. ... [more]  

RBT only applies when vessel is underway by Boating Industry Association
Following some reports RBT testing was occurring whilst at anchor, Michael Drake Principal Manager Boating Safety, Maritime Management Centre, Transport for NSW, has confirmed with RMS legal team that 'RBT only applies when a vessel is underway (i.e. not at anchor, moored or berthed at a wharf or marina)'. ... [more]  

Iridium have recently released the Iridium GO!, their latest product in the satellite communication market. It’s portable, battery powered, and creates a WiFi hotspot. www.predictwind.com!PredictWind!new have partnered with Iridium to put together a package catering specifically to the marine market. ... [more]  

In the early morning of Friday 19 September, EU Naval Force frigate, ESPS Navarra, came to the aid of a stricken yacht in the Gulf of Aden. The yacht had been detected on the warship’s radar in the early morning. ESPS Navarra’s Bridge team initially tried to hail the yacht via their VHF radio. ... [more]  

The Canberra Yacht Club is looking for a Dinghy Sailing Instructor/Coach in its very busy Sailing School. The CYC Sailing School is the fourth largest centre in Australia training over 1,000 kids and adults from Opti learn to sail to HP coaching. ... [more]  

Making its debut at the Gold Coast International Marine Expo, the BRIG Navigator 700 is 7-metres of versatility and durability, with room for 11 people in comfort – 12 in the twin engine version. ... [more]  

Lost your rudder at sea? Michael Keyworth perfected a way to steer using drogues. To engineer this solution, he removed the rudder from his own boat(!), and experimented with different method, and has summarized his technique in this terrific article. ... [more]  

The operator of a Portsmouth-based barge has today been made to pay almost £111,000 in fines and costs after pleading guilty to a breach of maritime legislation. Serco Ltd admitted an offence at Portsmouth Crown Court in relation to the health and safety of workers aboard the barge 1706, which is operated as part of a service contract with the Ministry of Defence. ... [more]  

You scratched my seagrass! by Steven Katona, Newport, RI
Sailors for the Sea publishes monthly articles that translate the language of marine science into fascinating articles about ocean health. ... [more]  

Following a relatively short stopover in Christmas Island, eleven of the World ARC fleet have now arrived in their next paradise, the Cocos (Keeling) Islands. From first settlement in 1826 by English merchant Alexander Hare, through decades of administration by the Clunies-Ross dynasty, most island inhabitants had little freedom or contact with the outside world. ... [more]  

This might be the Texting and Facebook generation but boaters need to use VHF radio says volunteer rescuers from Weston-super-Mare's lifeboat station who rescued a yachtsman whose boat sank in the middle of the Bristol Channel and who then texted his girlfriend. ... [more]  

Earlier this year two men died in their bunks of carbon monoxide poisoning caused by the highly toxic fumes given off from a poorly maintained butane gas cooker. The cooker which was located in the wheelhouse had been lit to heat the wheelhouse and sleeping area. A carbon monoxide alarm was not fitted. ... [more]  

The Arctic is an ocean surrounded by land and Arctic sea ice is the thin layer of frozen ocean water that forms and grows during the winter, and melts in the summer. Dr Jeremy Wilkinson from the British Antarctic Survey provides a scientist’s perspective on the trend for decreasing Arctic sea ice. ... [more]  

Eight students from grades four through six took part in the Hamilton Island State School sailing and leadership programme this year, taking place every Friday during terms two and three. Students participating not only learned the rigours of theoretical and practical sailing skills, but also life skills. ... [more]  

The Virgin Islands are an archipelago. That part, which is a British overseas territory, is commonly referred to as the BVI. About 30,000 people live in the BVI, most of which live on the island of Tortola. The BVI are comprised of about 50 islands the majority of which are not inhabited by humans. ... [more]  

Owner Paul Darrouzet and Marketing and Business Development Manager Luke McCaul talk about the redevelopments over the last year. See for yourself how Abell Point Marina has changed and our commitment to our customers. ... [more]  

Dangerous conditions forecast for NSW boaters by Roads and Maritime Services
Roads and Maritime Services has issued an alert after a Bureau of Meteorology warning about dangerous surf conditions from Gabo Island to Tweed Heads developing tomorrow, Sunday 21 September. ... [more]  

The Galley Guys take on the Vancouver International Boat Show
Are you ready to enter that marina?
African nations unite for lifesaving training
New Zealand boating industry showing strong growth
World ARC fleet moored at Christmas Island
Blue Planet Odyssey welcomed to Bora Bora
Volvo Ocean Race: Win a stopover trip by designing an ECsix T-Shirt
New Zealand's largest on water boat show kicks off next Thursday
Where the audience is matters a lot for advertisers
Remember to properly dispose of obsolete distress beacons
Blue Planet Odyssey - Aventura makes landfall in the US
World ARC fleet bids farewell to Bali
Superior prepares for Monaco Yacht Show debut *Feature
Impressive new catamaran set to power onto world stage
Antarctic Team discovers mechanism for massive ice shelf collapse
Baltic 4 Nations - Next edition sets sail July 2015
Yachts prepare for second Atlantic Odyssey, departing this November
Thai drama with Phuket yacht clampdown
Airlie Beach Music Festival 7th – 9th November 2014
P&O and Princess Cruise Ships to continue operating into Abell Point
Sailing Rallies launch two new events at PSP Southampton Boat Show   
Multihull Central: Record sales, Outremer blog, Regattas and much more   
World ARC crews in Bali   
Could your sailing navigation use a tune-up?   
Images of marine sunsets by Tripadvisor   
4th Multihull Solutions Whitsunday Rendezvous an outstanding success   
Citizen science model proposed to fill fundamental ocean data gap   
Evans Head volunteers rescue charter boat in dawn operation   
Ocean Cruising Club celebrates 60th Anniversary with record gatherings   
Shedding light on the life of former lighthouse keepers + Video   
Southport Yacht Club celebrates opening of 68th season *Feature   
Marine Auctions adds new recruits   
2014 Auckland on Water Boat Show: Coming up at the end of September   
The Boat Cookbook   
Indian Ocean-wide tsunami exercise to test readiness   
Blue Planet Odyssey - Aventura makes landfall at St John’s   
Round the World racer joins Southern Pacific Inflatables   
New exhibition explores role of Royal Australian Navy in WWI   
18 anti-piracy weapons for ships to fight pirates   
World ARC fleet now arriving in Bali   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph, contact the photographer directly.
XLXL NEW Cru SH
LocalAds   DE  ES  FR  IT