TELL-TALES
Rod Heikell's very informal site on sailing around bits of the world and an eclectic collection of things nautical or nearly so.
Weather
Mediterranean weather forecasts (net)
Weather forecasts in the Indian Ocean
South Pacific weather (Bob McDavitt)
Analysis Paralysis: Looking at weather and Skylax's passage from Tonga to NZ
Weather when leaving NZ for New Caledonia, Vanuatu, Fiji and Tonga
For advice on getting weather on the SSB and Pactor modems go to Lu's Radio Page
Mediterranean weather forecasts on the internet
General forecasts for the Mediterranean
UGRIB Grib files from www.grib.us where you download the UGRIB viewer and can then select areas for up to a 5 day forecast. Easy to use and frighteningly accurate for computer only generated data.
Weather online
JCOMM GMDSS (Meteo
Windfinder www.windfinder.com Originally a windsurfing forecast site that has expanded. 7 day forecasts.
Meteosail www.meteosail.com Uses various other sites with links to get there.
Poseidon www.poseidon.ncmr.gr/weather.html Easy to use 5 day forecast.
Hellenic Meteo www.meteo.gr/sailingmapf.asp Excellent interface. Click on area and then on forward arrow on right. Up to 5 day forecast.
Note Most of the general Mediterranean forecasts and most of the regional forecasts now use GRIB files. It should always be remembered that these are computer only generated files, though in my experience the accuracy is as good as many human interpretations of weather data.
Turkish weather forecasts on the internet
The Turkish meteorological service has raised it's game with a revised internet site and some excellent resources for sailors. The site now has grib data in the style of the Greek Poseidon forecasts for both the eastern and western Mediterranean and other data as well. You can view the page in English.
Go to http://www.meteor.gov.tr/2006/english/eng-seamarine.aspx . I've reproduced the links below but no doubt some of them will change over time so it's best to go direct to the Turkish Met web site and then to Marine Meteorology.
TURKISH STATE METEOROLOGICAL SERVICE
Bu yazıcı çıktısı, http://www.meteor.gov.tr/2006/english/eng-seamarine.aspx adresindeki web sayfasından 22 Ocak 2008 Salı, 17:37:21 tarihinde alınmıştır.
Piri Reis Marine Meteorology Pages
Cities & Holiday Resorts . 5 Days Forecast (Map)
Sea Surface Temperature . METU3 Wave Model . Daily Marine Forecast Report
© Turkish State Meteorological Service - 2006
From the Skylax blog 28 June 2007
Stormy weather
This photo was taken of a summer thunder storm over Levkas with George Catchpole's Verdi (Halberg Rassey 42) coming into the CYS mole in Levkas harbour. Mavis Woods took the photo and has allowed me to reproduce it here. This is not a retouched photo - this is what it was like!
Weather Grib Files from UGRIB
Ugrib is a recent arrival on the grib file scene and works wonderfully well. You download the grib file viewer from www.grib.us and then after registration away you go. It chief virtue is it's simplicity (not too many buttons or menus) and once loaded you can download selected grib files for any defined area wherever you can get an internet connection. It has a little menu on the viewer for selecting how you are going to download the files including broadband, GSM phones, Inmarsat Fleet, etc. It should work with Iridium and other satellite phones although I don't know if it will work on Pactor modems connected to the SSB. I'll be experimenting with that soon (or rather Lu will).
And the best part is it's free. The individuals who put it together work on commercial weather projects and so far have committed to keeping UGRIB a free service. God bless them.
Screenshot from the Grib USA web site www.grib.us
Weather Forecasts
In the years since the first edition of this book was published weather forecasting has radically changed. The internet now provides more information than old fashioned Weatherfax and not surprisingly Weatherfax transmissions have declined while synoptic charts, annotated synoptic charts, and text forecasts via the internet have multiplied. Through all these changes cruisers have held onto MF and HF via SSB as a mainstay and both voice transmitted forecasts, weatherfax via SSB and compressed graphics using GRIB files received on Pactor modems have ensured the survival of the old ‘steam radio’.
GMDSS forecasts and safety warnings are covered in this section and the following section on GMDSS. Because the majority of yachts are not equipped for some of these services they are not dealt with exhaustively.
Coast Radio services are NOT listed here. Refer to Admiralty List of Radio Stations NP281(1) and Admiralty List of Radio Stations NP281(2). Vol 1 covers Europe, Africa and
SSB Nets and Ham
The majority of cruising yachts communicate on informal and semi-formal nets. Many of the net controllers provide weather information. In any group of cruisers making a crossing there will often be an informal net where you can obtain information on the weather ahead and quite likely a forecast from a yacht set up to receive weatherfax and internet data.
Yachts without marine SSB transmitters can hear the transmissions on dedicated marine receivers and some non-marine receivers. These can cost as little as $100 though the more expensive sets have better tuning and gain facilities. NASA make a dedicated marine SSB receiver including a version with weatherfax capabilities for around £150 ($350). www.nasamarine.com
The following are long standing nets in the
- Mobile Maritime Net Richard Donaldson-Alves. Covers Japan to
- Radio "Peri-Peri".
- Tony's Net.
- German Maritime Mobile Net. Covers the Atlantic, Pacific,
Other nets
- Tony's Net.
- Russell Radio. (SSB)
- Robby's Net.
- Comedy Net. Oz - Southwest Pacific. Very informal, multi-purpose with position reports, Wx reports and local inter-yacht traffic. Net control rotates amongst members and has many shore-based regulars who help with local knowledge. 7087 kHz @ 2040hrs zulu.
- Mediterranean Maritime Mobile Net. Med. 7085 kHz @ 0700hrs zulu
GRIB weather files
(Gridded binary data files).
GRIB files are highly compressed weather files which cut download speeds compared to earlier compression formats. They can contain all sorts of data though commonly they have information on wind speed and pressure. The files can be downloaded off the internet or received by email and their small size makes them particularly suitable for receiving using slow modems like the Pactor modems connected to an SSB. You will need a GRIB viewer and for some forecasts you will have to pay a subscription fee to the provider. The first thing you will need is a GRIB viewer.
• A number of software plotting systems have a GRIB viewer including later versions of Raytech
Navigator , Max-Sea, and Nobeltec. In the future other software plotting systems are likely to include a GRIB viewer. There is also dedicated software for viewing GRIB files.
• There are a number of free GRIB viewers available including Airmail's Weather Fax Companion at www.siriuscyber.net/wxfax/ and I'm sure there are others out there.
• GRIB files can be received by any sort of data modem including Pactor SSB modems, satellite phones with modem capability, GSM phones, INMARSAT and other satellite receivers (Sky for example).
GRIB files are generated by various agencies, but those generated by NOAA (on Wavewatch III), are the source data for most GRIB viewers. You can download free GRIB files from various sources, but typically you will have to pay for some email services and for longer range data. Sailmail allow emails with GRIB files under their license agreement. Raytech allow free internet downloads (usually 3- day forecasts), but you must subscribe to the email service (up to 7-day forecasts). Have a look at the list below for sourcing GRIB data.
• It is important to know that GRIB files are entirely computer generated and have no human at the helm interpreting the data. GRIB-robot software from the supplier extracts the relevant data and sends it to you.
• GRIB files are compressed in different ways and you may need some software to decompress the files depending on the viewer you are using. Compression can be .zip (use Winzip), .grb, or .bz2 and there may be others. Shareware or relatively cheap software can be downloaded to decompress the file formats.
• These weather files are all fairly broad stroke and do not provide the sort of detailed information found in more dedicated websites for a country or sea area. They provide an overall picture for a large sea area rather than detailed data for planning your sailing within a country.
• To get an idea of what GRIB weather data is like have a look at UGRIB on the web.
For more information and GRIB data sources look at
UGRIB A free internet site with map and robot to extract GRIB files. www.grib.us
Airmail Probably the most commonly used source for Pactor modems connected to an SSB. Also an excellent section on GRIB files and how to get them. www.siriuscyber.net/wxfax/
Meteo-France www.meteofrance.com
Unzipping software
EF Commander www.bhs.com or WinRar 3.0 www.rarlab.com
Raytech Navigator (all-in-one GRIB viewer and receiver)
Xaxero (I use their weatherfax software, the GRIB viewer is a later addition) www.xaxero.com
Maxsea www.maxsea.com
Sailmail www.sailmail.com
Marinenet www.marinenet.net
Navcenter www.navcenter.com
Satellite phones and data
These are included here for reference, although of course they have a wider use for voice and other data like email.
Using either Inmarsat, Iridium or Thuraya you can receive weather forecasts either by voice from a dedicated service provider (usually a weather routing company) or receive data files. Both Iridium and Thuraya have relatively low data speeds (around 9.6kb) so they are really only useful for receiving GRIB files or emailed text forecasts.
Iridium Covers all of the Indian Ocean except
Official: www.iridium.com Unofficial www.ee.surrey.ac.uk/Personal/L.Wood/constellations/iridium.html
Thuraya Covers part of the
Inmarsat
Most Inmarsat satellites are generation 2-3 though generation 4 with effective broadband coverage is currently being implemented.
Inmarsat services are detailed below with the latest and fastest services first. There are numerous hardware suppliers and other service suppliers.
BGAN High speed data (432kb/s) and voice in a small portable device. Doesn’t cover all sea areas.
GAN Global voice and data (64kb/s) using MPDS.
RBGAN Introduced 2003. Data service using MPDS (144kb/s).
Fleet Services F77, F55, F33 Introduced in 2002. Marine version of GAN. Range of three services offer varying levels of service and coverage.
Mini-M Introduced 1995. Compact voice and data (2.4kbs). Popular proven unit though data speed means using GRIB files.
Inmarsat B Introduced 1992. Global coverage. Voice and data (9.6kbs). Larger unit.
Inmarsat-2 satellites: Inmarsat-2F1/Inmarsat-2F2/Inmarsat-2F3/Inmarsat-2F4
Inmarsat-3 satellites:
· Inmarsat-3F1 / Coverage: IOR / 65 degrees East longitude 1996
· Inmarsat-3F2 / Coverage: AOR-E / 15 degrees West longitude / 1996.
- Inmarsat-3F3 / Coverage: POR / 178 degrees East longitude / 1996.
- Inmarsat-3F4 / Coverage: AOR-W / 142 degrees West longitude / 1997.
- Inmarsat-3F5 / Spare (IOR-W) / 25 degrees East longitude / 1998.
Inmarsat 4 satellites:
- Inmarsat-4F1 / Coverage: IOR / 64 degrees East longitude / 2005.
· Inmarsat-4 F2 / Coverage: AOR-West / 53 degrees West Longitude / 2005.
Compared to other regions, the
Weather
UGRIB The free viewer and software for GRIB files. www.grib.us
NOAA Wavewatch III.
Jcomm All metarea text forecasts. http://weather.gmdss.org
Weather Underground Go to marine and then select an area. Gives text Metarea forecasts. www.wunderground.com
Tropical storm warnings
Tropical storm Risk http://climate.mssl.ucl.ac.uk Go to tropical storms.
World Meteorological Organization http://severe.worldweather.org
MF/HF Weather Forecasts
For a list of shore radio stations giving MF/HF forecasts refer to:
Admiralty List of Radio Stations NP281(1) and Admiralty List of Radio Stations NP281(2). Vol 1 covers Europe, Africa and
MRCC AND MRSC STATIONS ARE NOTED ON THE MAPS UNDER GMDSS. WHERE APPLICABLE IN THE HARBOUR DETAILS I GIVE VHF AND MF/HF FREQUENCIES.
Weatherfax
If there is one thing that is certain in the world, it is that the weatherfax transmission you want will be late, corrupted by bad reception or plain absent. Weatherfax stations are slowly disappearing as the internet becomes more important for weather routing, especially for big ships. It is likely that some of the stations listed below will close in the next few years. Fortunately SSB and Ham radio networks are good at disseminating information on what works, what works well, and what is not worth bothering with. Consult with these neglected experts wherever possible.
Dedicated stand-alone weatherfax receivers for yachts are few and far between these days. Given a simple software program and audio coupler, faxes can be received with an SSB receiver and PC. Modern programs use the sound card of the PC to receive the fax from an SSB capable radio, so no extra hardware is required. Suitable programs include JVCOMM32, and Xaxero, Weather Fax 2000, which are available as trial versions from www.jvcomm.de or www.xaxero.com
Many people experience problems with fax reception. The best thing you can do, is to find a sailing radio amateur to help you. Failing this the following may help. Remember that the set is usually tuned about 1.7 KHz below the published frequency on upper sideband. At sea broadcasts are often heard best on frequencies between 10 and 16 MHz. Choose a much lower frequency when close to the station. It helps to have a choice of frequencies for a particular station programmed into the receiver. Reception is often better around dusk and dawn. Inverters are a common source of interference, if a clear signal is not received use a laptop run from it's batteries and try turning off all other electric's on board. The need for a good antenna (often a stay or shroud) is obvious, grounding a metal part of the frame of the receiver can also make a big difference. Get used to the sound of a good fax signal and don't be afraid to try fine adjustment to the tuning to make the picture clearer. (from Ocean Passages and Landfalls by Rod Heikell & Andy O’Grady)
The best source for weatherfax schedules (frequencies and times) is published by NOAA and is free to download as a .pdf file. www.nws.noaa.gov/om/marine/rfax.pdf
Bob McDavitt
From the Skylax blog 07-09-08
South Pacific weather and Bob McDavitt
In this part of the Pacific Bob McDavitt is THE MAN when it comes to weather. He has an enviable reputation for interpretting the weather in the South Pacific and then putting into simple terms that simple yachties can understand. Below is the weekly weathergram for the coming week and it may explain why we are holed up here searching through the GRIB files and weatherfaxes for a chink of a weather window. On the GRIBs it doesn't look too bad but when Bob says only go if you like riding a bucking bull then you have to listen. We'll keep pulling down the GRIBs and weatherfaxes to see if we can leave towards the end of this week. Fingers crossed and thank you Bob.
Bob McDavitts Weathergram
WEATHERGRAM
YOTREPS
Issued 7 Sep 2008 NZST
Bob McDavitt's ideas for South Pacific sailing weather.=20
(Disclaimer: Weather is a mix of pattern and chaos, these ideas come
from the patterned world of weather maps, so please fine-tune to your
place).
TROPICS AND SUBTROPICS
South Pacific Convergence Zone SPCZ is steady in strength and patchy in
coverage... It is strongest about Papua New Guinea and Solomons...
Another burst of activity at times between Tokelau and Samoa, and
occasionally over north Tonga, then it sort of stretches from about
Suvarov to midway between Southern Cooks and French Polynesia. There
has been a squash zone between the SPCZ and a Big fat high recently-this
squash zone still affects Southern Cooks to Niue with strong trade winds
and rough seas.
Highlight of the coming week to look for is for a build up in activity
near Suvarov on wed 10 Sep UTC moving South onto Southern Cooks by sat
13 UTC, There will enhance that squash zone even further, with tropical
squalls on its north side and steep big swells on its south side, so I'd
say it IS NOT the week to sail from French Polynesia to Tonga, unless
you like riding a bucking bull.=20
When this system moves off to the south early next week, it may pave the
way for a Low to possibly form about or south of Niue then SW towards
Niue early next week. After that we may have a good weather for sailing
westward ho!
Rest of the South Pacific between Tonga and Australia is looking OK this
week-a gentle subtropical ridge along 30S and average trade winds mainly
along 20S. Computers are picking some kind a drawn out surface trough to
form south of New Caledonia and extend towards Kermadecs by Friday---
probably caused by an upper Jet Stream and - this trough is forecast to
cross Fiji and Tonga on 14 and 15 Sep utc, but not much in it until it
possibly forms that Low south of Niue early next week.
NZ/TASMAN AREA
In a reversal of pattern back to winter NZ had a ridge over the weekend
(frosty in places) and is following up with a LOW from the Tasman Sea
this week. The frontal zone is likely to cross the North Island on
Monday and may linger across the south end until Thursday and the Low
itself slowly works its way in pieces across central NZ. On the north
side of this LOW, over the North Island, will likely be squally
westerlies from Tuesday til Thursday. A Southwest flow should clear the
weather over NZ on Friday and then the outlook is for another ridge of
light winds for next weekend. =20
Conditions should be OK for sailing from NZ to Fiji/Tonga after the
Monday front, but wait til Friday if sailing NZ/New Caledonia.
Best day this week to sail Tonga to NZ would be, depending on your
cruising speed, around Mon/tue utc -so that you encounter that trough at
around 30S on Fri 12th, and time you arrival in NZ with a SE flow
maintained by that weekend ridge.
The terms used are more fully explained in the METSERVICE Yacht Pack.
More info at http://weathergram.blogspot.com
Feedback to bob.mcdavitt@metservice.com
TOP
Analysis Paralysis
From the Skylax blog 11-11-08
Looking at weather and Skylax's passage from Tonga to Opua in NZ
Analysis Paralysis
The passage from Tonga to NZ
'Analysis Paralysis' is Bob McDavitt's term for the condition that afflicts cruisers in Tonga and Fiji waiting for a weather window to NZ. The passage from Tonga (or Fiji or New Caledonia/Vanuatu) to NZ is the great lemming leap from the Tropics and settled Trade Wind weather into the sub-Tropics and unsettled Spring weather. Hours, days, weeks are spent analysing weather, signing up for weather routing, downloading shed-loads of GRIB files and generally just worrying about it.
There was a time when you left on passage with just a 24 hour synoptic forecast from a newspaper. Then along came stand-alone weatherfaxes and phoning the local Met office. And then came the internet, GRIB files, and lots of bad advice in forums and other cobbled together web sites. The internet and weather routing services has spawned a group of cruisers who somehow believe that you can pull down a seven day set of GRIB files and set off anticipating a smooth trip with little disruption from naughty lows, fronts, ridges and any other meteorological phenomenon that might blight your trip. Well it doesn’t work that way: weather is weather and as Bob McDavit, the NZ weather guru who helps route yachts down to NZ will tell you, forecasting is just trying to make a pattern out of chaos. We aren’t anywhere close to understanding the complex interactions of pressure systems and making sub-Tropic passages like hopping on a train or plane to get from A to B.
Squall watch on passage to Opua
One of the problems for the Tonga to Opua passage is that lows come across from Australia every 6-7 days. Given that most yachts can’t maintain a sufficient speed to do the 1100 mile passage in 6 days, the likelihood is that you will hit a low somewhere on passage. So it’s a matter of judging how low a low is and how dirty the associated front is going to be. This is where getting weather routing from someone like Bob McDavit helps make sense of GRIB files. While GRIBS are great for the general picture, they don’t give you much of an idea what fronts, troughs and ridges are going to be like and how strong squalls will likely be.
In settled weather for the sub-Tropics the general advice is that you leave on the back of a low and keep to the west of the rhumb line, heading for somewhere around 30S and 175E before turning south for Opua or other ports on the east coast of NZ. The thinking here is that when the next low comes along you will likely have SW winds and getting a bit of westing in will help you lay a course for Opua with SW winds.
There is another consideration not too often thought about. When the lows are not around there will generally be a high and motoring through the high can take a couple of days assuming you are not going to be sitting around waiting for wind. At this time of year most boats have been in the Tropics for some time and the antifouling has lost a lot of its ‘anti’. Boats are pretty fouled up on the bottom. On Skylax we went down and scrubbed the bottom on a number of occasions and it seemed that just a few days later the bottom was dirty, I mean really dirty with fronds of growth all over it, despite our attention. The prop also fouls up badly and you need to try to get it as clean as possible. The result of all this is that you are going to be a lot slower motoring through the low in whatever leftover swell there is compared to when the boat is clean. This all increases the passage time to NZ.
A lot yachts head for Minerva Reef before setting off for NZ and this gives you a 250 odd mile start on the passage. You can then sit here are wait for a weather window for the passage from Minerva Reef to NZ.
As it turned out our weather window wasn’t all that settled. We left Tonga heading for Minerva Reef, but 150 miles out it looked OK, not great, to head on a rhumb line course for Opua. So WE did. We had a front pass over with gusts to around 35 knots though with the wind in the east if just bustled us along towards NZ. Afterwards came the SW winds and we tightened Skylax up getting nudged just to the east of our rhumb line, though secure in the knowledge we would have a couple of days of motoring and then in all probability easterlies for the final part of the passage. Bob McDavit advised us on this and provided routing info by email to our sailmail address.
Motoring through the high was slow with an awkward sea and dirty bottom, but then the promised easterlies slowly kicked in rising to 30 plus knots and times and then even went to the ENE making for a fast final part of the passage. We slowed up on the last night out so we would have a daylight approach to the Bay of Islands and Opua and sailed right down to the buoyed channel leading to Opua.
One other thing that cruisers in the Tropics encounter here is that it is cold after Tropical days and nights. All the woollies come out of the locker where they have been consigned for nearly a year and wet weather gear keeps the wind chill out. Its only Spring in NZ and sitting here in Opua it’s definitely a lot more chilly than up north.
Weather when leaving NZ for New Caledonia, Vanuatu, Fiji and Tonga
From the Skylax blog 14-06-09
Weather when leaving NZ for New Caledonia, Vanuatu, Fiji and Tonga
Weather in NZ is determined by high and lows moving eastwards from Australia. A lot of these lows cross the bottom of Australia and then track over the South Island of NZ. Some of them track over the North Island and you often get fronts tracking over the North Island. Most cross the middle or southern North Island, but not all.
Highs in this part of the southwest Pacific can be really high. 1030 is common and there are a significant number of 1040’s. These are much higher than you get in say the North Atlantic around Europe. Bob McDavitt, NZ’s weather guru (officially he is the NZ MetService Weather Ambassador), says that when ‘highs are a 1030 the weather gets dirty, when highs are a 1040 the weather gets naughty’. We’ll see why in a mo.
So the highs and lows trundle across to NZ from Australia. The problem is what Bob McDavitt calls the squash zones. When you get a big fat high and a deep low next to each other, you get squash zones where the isobars are very tight together and there is a lot of wind.
Leaving NZ encompasses the same problems as getting to NZ (see Analysis Paralysis: The passage from Tonga to NZ). Most cruising yachts will not be able to get to Fiji, Vanuatu, New Caledonia without hitting a front somewhere along the way. Yachts usually leave at the end of the Southern Pacific cyclone season (November to May) in late April to May. Some like us are a bit later (mid-June) and there are a number of yacht races from NZ to the islands in June. Picking the weather is really a matter of looking for a front lite to take on. Once a low has moved through the wind will go SW and then you hop on its coat-tails and go assuming there is nothing else naughty around.
One of the talking points for this trip is the 1994 June ‘bomb’. Yachts set out at the end of May with a 1030 high over NZ. In the Tropics a low formed. As Bob McDavitt points out, lows do form in the Tropics outside cyclone season and can generate gale force winds. This low started out between Vanuatu and Fiji and from Friday noon to Saturday noon dropped from 1001 to 986 hPa. In the next 24 hours it dropped to 978 hPa. This low squashed up against the 1030 high over NZ produced winds over 60 knots and seas of 10-14 metres. Over this period sixteen yachts set off EPIRBS and 21 people were rescued. Three people were lost and seven boats lost. The ‘bomb’ is embedded in the NZ yachting psyche much like the 1979 Fastnet in the UK and the 1999 Sydney Hobart in Aus.
I’ve mentioned Bob McDavitt and wholeheartedly recommend his book on SW Pacific weather Mariners Met Pack: South West Pacific. It has some of the clearest explanations and best advice on interpreting weather in this part of the world that I’ve yet to encounter. You can get it from Boatbooks NZ.
Metpack SW Pacific. The photo on the front is from the June 1994 bomb.
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