Originally, the page was based on an article in the Winter 2001 Hallberg Rassy Owners Association Magazine by
I am trying to keep up to date with the many services that are or are becoming available. The page will never be up to date, but it will be a start for many, I hope. Some services are commercial, some are free to the user and are paid for by someone else.
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Apple Mac & Linux users |
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Apple Mac and Linux users |
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The Ugrib software only
works on Windows, as does
Saildocs. Some commercial
viewers may work with
AppleMac and Linux.. For Apple Mac and OS X users, there is a navigation package called GPSnavX. that has been upgraded to display pressure and wind from GRIB files. It can request a GRIB file automatically covering whichever chart you have open (though don't try this with a world chart open as you will get a huge GRIB file). This will generate an email back to you which you can then be saved and opened for display. It has been reported to work well. |
Alastair Duncan, a CA
friend and an Apple Mac user says
that he uses the dedicated
Mac. navigation
system which also is able
to pull down the weather
GRIB files through
Saildocs. The programme is
MacENC and can be found at
http://www.macenc.com/ You could try zygrib http://zygrib.free.fr/, which is free. The only other Linux grib viewer that I have been told about is skyeye which costs $79. http://www.xaxero.com/gribplot.htm. .
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A Note on GRIB Files and models |
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| Output from GRIB files can look very impressive but it is necessary to remember the warning on my main GRIB page. Many GRIB file services simply relay output from NWP models, usually, but not always, the US General Forecast System (GFS) model. Therefore, none will be better than others in terms of reliability nor will any give more "accurate" forecasts than another. There will be differences in presentation, ease of access and in the data offered, whether it be from a commercial service or a free one. All operational weather forecast services are subject to occasional failures. Therefore, from time to time the forecast may not be the most up to date. Check with your supplier what they do in such eventualities. NWP models are not and never will be precise. Users are recommended to read my NWP page to get some idea about the limitations of weather |
prediction. All these factors should be borne in mind when using any forecast and, particularly, one where there is no vetting or modification by a human forecaster. That is the case for all GRIB services. As computer power increases, so meteorologists can become more sophisticated in their numerical modelling. To read about the differences between Global models such as the US GFS and the various meso-scale models. please go to the NWP page. Finally GRIB products are only one source of forecasts that the thinking sailor should use. Never go to sea without receiving and studying forecasts issued under the GMDSS. Crude and broad brush they may be, but they do have the benefit of experienced human interpretation. Amendments to GMDSS forecasts are broadcast on voice radio, NAVTEX or INMARSAT-C. There is no equivalent broadcast of GRIB amendment when at sea. |
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Navimail |
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| David Hide made the following notes for Navimail - the then (2001) new Météo France Navimail system which provides forecasts up to 5 days ahead for any part of the world. The system is Windows based and can be used through any telecom standard that supports e-mail (ie INMARSAT - A, B, C or Mini-M, GSM, telephone etc.). A credit account with Météo France | is needed. Other services offering many options will be set up along broadly similar lines. I have retained his notes because Météo France were among the first in the field and they give some idea about how other systems work in practice. |
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Operation of Navimail |
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| David Hide said, "First, download their free software (available in English or French): this is best done at home, on broadband or using a CD. This includes the MAXSEA software for decoding GRIB messages. MAXSEA is compatible with other charting programs such as Raytech. (Setting up is fairly simple, just follow the instructions.) Secondly, create a Météo France account using electronic billing. This involves paying a minimum of €15 upfront from which charges for services are deducted. The amount on credit is then topped up from time to time. (France Telecom INMARSAT customers do not need to subscribe; the service is directly charged on their usual telecom bill)". The system then enables automatic generation of an outgoing e-mail requesting several types of information, which can then be sent by any standard e-mail system, though the normal link is via Outlook Express. Samples of services |
available can be seen on a Météo France Navimail page. All items are charged for, except Security bulletins and satellite images which are free of charge (except for telecommunication cost). Routine forecasts and Flash warnings messages can be ordered for a few € a month. The GRIB service provides wind, pressure, sea state and sea temperature. The data are at 1 degree latitude/longitude intervals. Wind data can also be provided at 1/4 degree intervals, presumably from meso-scale model output. These may well only be available for 1 - 2 days ahead. However, they may give a better representation of topographical effects in such areas as the Dover Strait but not areas as small as, say Torbay or the Solent. Queries concerning this wide ranging and very useful service to Navihelp. Or see the Navimail FAQ page. |
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Météo Consult |
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This service is much wider than GRIB based products which are confined to wind forecasts only. When I last looked at it, it seemed expensive but that might have changed..
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Theyr.net |
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| Many sailors will have seen and used the service in its trial stages when it was available at no cost. Most have found it to be good. This web page based service gives wind vector, and other parameters, for up to 5 days ahead for Europe, most of the N Atlantic and N America. There is a limited zoom facility. Data can be viewed as a movie or in static mode. Having been merges with ProGRIB the service has been upgraded from the US ETA model to the NMM running with a grid length of about 6 NM (0.1 degree latitude) . This uses input from the US GFS model but reworks the calculations using more topographical data and better representation of the physics of the atmosphere. This is one of the most advanced meso-scale models in operational use. |
Although the forecasts are produced on a 0.1 degree grid, the data are only displayed at a 0.2 degree, 12 NM resolution. This, very sensibly, recognises the limitations of all NWP models. The output, is, in any case, more detailed than is normally available to the sailor. Theyr.net operates a very modest subscription service. It is well proven and not expensive. Size of downloads means that it is likely to be costly to access over a mobile phone connection. The option for GRIB files either by direct access or email takes you to the ProGRIB service is in place. |
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ProGRIB |
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Like several GRIB services, ProGRIB is under development as a commercial service The starting point is a simple graphical chart based area selection. Data can be received by email or directly to your computer The data can be viewed through any standard format GRIB viewer or there is a free viewer provided as a 28 Mb download. The GRIB data are produced twice a day at 1/2 degree (~30 NM) resolution to 6 days ahead using the US GFS model. Meso-scale forecasts are also available providing data on a 0.1 degree (6 NM) resolution to 4 days ahead from the very advanced NMM meso-scale model. Forecasts are available for wind, waves, temperature, pressure and sea surface temperature. The number of days and the time interval for the forecasts (1,3 or 6 hours) can be requested. Areas covered are the North Atlantic, European waters, Mediterranean, Scandinavian seas, Caribbean, Gulf of Mexico and Californian Bay area. Very high resolution data at 0.02 degree resolution, (~ 1.4 NM) are available for the English Channel area for 1-3 days ahead and they can generate these data for specific areas on request. As with all meso-scale and higher resolution it is important to be aware of the limitations, see the notes above. |
An important plus to a sailor is that you can subscribe for periods of a month at a time. £20 a month gives up to 70 Mb download. Naturally, there are the telecommunications charges on top. The downside is that, at the time of writing this, the choice of area, time interval and grid spacing is not flexible enough for many and downloads can be unnecessarily large. Although they are zipped, the originals are in 8-bit format so scope for compression is limited. The very high resolution forecasts may be more of a service for commercial users or racing yachtsman who want and are willing to pay for (including the communications costs) large amounts of high resolution, very short period forecasts. As a cruising yachtsman. I am generally looking for low cost, general guidance. The idea of a three day forecast at this resolution seems very ambitious scientifically, but the user will be the best judge regarding cost/benefit. There is a demo version to give an idea of what the output from the various scales looks like - and costs. For those around N America, Saildocs provides, free of charge, COAMPS output for East-Pacific, West-Atlantic:, Cent-America and Caribbean and the Continental USA. This gives an impression of what high resolution forecasts can offer. |
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Theyr.tv |
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| Background. This is where it becomes complicated and confusing in a business sense. Theyr.tv is run by the
developers of the original Theyr.net. This became 51% owned by the owners of ProGRIB. In late 2006. the two split up. This was for reasons too complex to describe, and probably unwise for me to try and explain, even if I could without courting legal problems. Both sides had their say on their websites and, if pressed, will no doubt send you copies. The present Theyr.net is described above. For a while Theyr.tv was, as far as I could see, "off air". They say that they are in business again. Theyr.tv is using the old ETA meso-scale model as it was, and as many will remember it, when it was a free and still developing service known as |
Theyr.net. The ETA model is not as advanced as the NMM used by Theyr.net although this may or may not be very apparent to the user. If you want a web based service, then you may wish to try both, see which you prefer and which is the easier to use - taking all factors into account - ease of access, cost, ease of payment, perceived value
etc.... I am offering no judgement on any aspect. Although the forecasts are produced on a 0.1 degree grid, the data are only displayed at a 0.2 degree, 12 NM resolution. This, very sensibly, recognises the limitations of all NWP models. The output, is, in any case, more detailed than is normally available to the sailor. |
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SmartMet |
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| SmartMet is a system that allows downloading of detailed weather reports and forecasts. It is a complete package of weather information that will interest sailors
although few will want, need or use the whole
package It is part of SmartCom. SmartMet uses the MIDAS service to provide weather data. These to include the US GFS low resolution weather forecasts of pressure, wind, cloud, precipitation and temperature - 0.5 degree resolution, 3 hour (or more) time steps as well as the Theyr high resolution weather forecasts of pressure, wind, cloud, precipitation and temperature - 0.2 degree resolution, 1 hour time steps. Wave forecasts using WW3 low resolution oceanographic forecasts are planned as well as the QinetiQ tidal stream forecasts for NW Europe - 10 km resolution, 1 hour time steps . There are high resolution surface current forecasts for the Mediterranean, |
current weather reports from surface observations, QuikScat surface wind speed and direction from satellite, NOAA and MODIS 1km resolution colour AVHRR satellite images, NOAA and MODIS 1km resolution sea surface temperature AVHRR satellite images and NOAA and MODIS 1km resolution water clarity AVHRR satellite images. The user can select the area, time period and parameters for which they want data, and data are downloaded directly into the SmartMet database, which is less fiddly than using e-mails, and also gives smaller downloads. The user can display data, combine forecasts with satellite imagery and weather reports. All this sounds very ambitious and,
possibly, more than the average yachtsman will need. It may be a service more intended for the specialist or racing sailors. |
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Other Service Providers |
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| There have been other companies offering GRIB based services for some while now. Some of these services, such as Transas with its Weather Wizard are not appropriate to the leisure market and are concerned largely with shipping and offshore exploration, construction and operations.. Other services for the leisure community can be provided by makers of chart plotting equipment. Obviously, the cost initially is built into the equipment and associated software price. One such is MaxSea, the French company Informatique de Mer, Having bought the package, you get free downloads of GRIB (GFS) data - as many as you want, whenever you want. I believe that SeaPro and NobelTEC offer similar services. Use of the MaxSea system starts with the user sending an automatically generated request. It is clearly very flexible and gives the options of different service providers and products including Navimail and the US high resolution (COAMPS) forecasts available for sea areas around the US. Tidal current data can be overlaid with the weather information, making it a useful tool, for motor boats especially, where wind over tide can be more critical for comfort than for a yacht. From a demonstration, I got the impression that MaxSea |
was, perhaps, a little too complex or sophisticated for some to use but, no doubt, familiarity with the system could well change that view. The displays are "static" but can be paged down quickly to give a movie effect. With RayTech Navigator 3.0 or later, an "Advanced Weather" facility is available. This gives 7 day animated forecasts (using GRIB files), text advisories, and NOAA Nowcast buoy reports. This is included with Sail Racer and Fishing Pro for one year, but, thereafter, Raymarine charge US$98 (about £57) for a one year subscription. Whether there are follow on charges or update costs will vary with company and service required. Commercial firms do not normally write blank cheques. I have only seen MaxSea and cannot comment on any costs, ease of use, flexibility etc of other systems such as SeaPro, NobelTec or RayTech.. However, using GRIB files from the same basic sources, there is no reason why these should be any better or worse than the services mentioned on this page. Of course, they are only available if you have bought the relevant hardware and software. These are not cheap. |
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Free GRIB Services |
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| Limited but free email services are available from several sources of which I have used or looked at
Saildocs, GMN, MailASail. These are very basic services of GRIB files primarily for wind, pressure, and temperature. Many will find them quite sufficient. These are all based on the US NWS General Forecast System model and, so, are as good as any other service using these data. Data are requested by an email and received by return or on a regular daily basis after a single request. Setting up is quick and only small downloads are needed; in the case of Saildocs, two downloads totalling less than 2 Mb for a good viewer albeit with very crude topography. Although the displays are static, it is an easy matter to hold down or tap the down arrow key on the keyboard to get a good movie effect. Saildocs can also provide meso-scale forecasts from the US Navy COAMPS for areas around the USA. The new (December 2006) and still being developed service UGrib (formerly GRIB.US offers a free service that uses neither email nor a browser. On the face of it, |
it seems to be a cut down version of Movingweather with several advantages over its various commercial rivals. For occasional use go to the MaxSea Navcenter. This lets you select a predetermined region and download a GRIB file for a large area at no charge. Using the direct download, files can be viewed using the MaxSea viewer. Using the zipped form allows other viewers, eg the Saildocs Viewfax,. to be used. The service is an advertisement for the MaxSea Chopper which allows the selection of an area and a smaller download. The data are at 3 or 6 hour intervals depending on the area and at 1 x 1 degree or 1 x 1.25 degree lat/lon. Some forecasts are for 7 days ahead, some are for 15 days! That far out, the results re highly unreliable! A similar list of areas is on the Raytech site. These 3-day forecasts are larger downloads - for larger areas and can be viewed with Viewfax and other viewers. This free service is to advertise Raymarine Weather Services. To see what is available and to gain access to a free 7-day forecast in a Beta version, click on Raymarine to register - free. |
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Which GRIB Service? (A summary, not a beauty competition!) |
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| The Météo France Navimail gives access to both objectively produced GRIB data and to forecasts written by a human being. There are also Météo France meso-scale forecasts. For reasons discussed elsewhere, these should be better than other, private company, meso scale forecasts. The Météo Consult GRIB service, again, is part of a wider service. Moving weather is one of the easiest and quickest ways of getting an instant forecast. It can also be used to provide forecasts as an email attachment. It has more options regarding parameters and their display than some others. Area selection is easy but there is no control for grid point spacing and time resolution of the data. The chart projection may distract some. Theyr.net is web page based system giving meso-scale forecasts out to 5 days ahead. Data volume might be a problem for a large area. There is an email version - ProGRIB which offers both Global model and meso-scale model output for direct download with no browser or email needed, although it can be sent via email if preferred. Some will find it too inflexible in terms of download size. It is the only current service offering information at very high resolution |
MaxSea is flexible and gives access to a variety of suppliers and products, such as Navimail GRIB, US GFS, wave/swell forecasts and COAMPS. Its very flexibility may be too complex for some. I do not have knowledge of the other chart plotter GRIB services to comment. The free services from Saildocs, GMN and MailASail are more basic. Saildocs can provide output from other models eg NOGAPS and COAMPS.. MailASail is still developing. UGrib is also in development but looks to be a very good and flexible free basic service. GMN and Saildocs have the repeat request facility so that a forecast can arrive automatically by email each day. Sailors are advised to look at examples of the various services and to decide which they prefer. The free services can, of course be tried with no financial penalty. Météo France Navimail has only a small upfront payment. Movingweather has a demo version to help decisions before paying any charges. ProGRIB/Theyr.net and Theyr.tv also have demo version but a short trial with either will not break the bank. In all cases of objective forecasts, do not use them as a one-stop service. ALWAYS refer to GMDSS forecasts for important decision making. |
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Some more considerations |
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| Setting up Movingweather, Navimail, Theyr.net, ProGRIB and UGrib is simple in all cases, through the use of Windows based guidance.
Saildocs and GMN are less intuitive to set up and use. In use, unless you are using the Airmail package for email, then both Saildocs and GMN will need an email request with exact formatting for Saildocs and GMN. However, using the repeat request facilities, a cruising sailor may only need to send one or two emails a year to receive a daily forecast for his sailing area. In terms of costs, and looking solely at the GRIB products., see below, the Météo Consult GRIB service looks expensive. Météo France Navimail may be economical for those cruising for short periods but costs could easily mount up. Movingweather offers more facilities than either but requires an annual, albeit modest charge for unlimited downloads ProGRIB and Theyr.net have monthly as well as annual rates. ProGRIB sets a 70 mb limit per month for £20 subscription. . Remember that, whichever service is used, download times for data will be virtually the same for equal amounts of data any compression will be relatively |
small. They all use the same GRIB file format as provided by National Weather Services under international agreement. GMN, Saildocs and UGrib ProGRIB all have varying degrees of flexibility allowing the user to determine the download size. Some are better than others. In that sense, they are more flexible than other systems and may be more appropriate for blue water sailors wanting to receive forecasts for large areas and several days using email over Marine HF radio, HAM radio or Iridium satellite phones. Similarly they will attract coastal sailors who have to use mobile phones for their Internet connections.. Individual decisions will depend on personal choice and preferences. I have had good reports of Navimail and MaxSea. I have used Saildocs and GMN satisfactorily. Movingweather is probably as easy to use as any and easier than some. UGrib is also very easy to use. I have trialled ProGRIB satisfactorily. There are various viewers, some are free - Saildocs Viewfax, ExpeditionLT that comes from ProGRIB, the UGrib viewer can all be used with .grb files. |
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CostsFor costs, click on the service name - Navimail, Météo Consult, ProGRIB, Theyr.net, Movingweather, SmartMet Services linked to chart plotters require purchase of the specific equipment. Whether there are charges for data will depend on the company. For SailDocs, GMN, MailASail, and UGrib there are no charges. As stated earlier, communications costs will depend solely on the size of file requested ie the number of grid points, number of elements required and for how many specific times ahead. |
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