Grib ~ Free Access To Global Weather Data.

[Eclipse]

Grib is the format used by the meteorological institutes of the world to transport and manipulate weather data and is the foundation of the forecasts we see around us in our daily life.

GRIB.US is a company that empowers you to interactively extract your own custom GRIB weather files tailored to yourneeds.

Ugrib software (download) is provided to view this data so that you can look at weather data for anywhere in the world when you want to, where you want to.... free.

Not yet available for Mac OSX.

http://grib.us

[SeaOtter1]

Originally Posted by Eclipse

Grib is the format used by the meteorological institutes of the world to transport and manipulate weather data and is the foundation of the forecasts we see around us in our daily life.

GRIB.US is a company that empowers you to interactively extract your own custom GRIB weather files tailored to yourneeds.

Ugrib software (download) is provided to view this data so that you can look at weather data for anywhere in the world when you want to, where you want to.... free.

Not yet available for Mac OSX.

http://grib.us

We have been using Ugrib for quite some years now and the accuracy is not the very best. Last su,,er on the passage from southern Spain to northern Europe and Scandinavia, very often the winds shown on Ugrib became 180 degree wrong.

A recent example is the devastating storm over the Iberian peninsula the Bay of Biscay and western France, that didn't even show as a storm, but a mere 30knot depression going that way. We are wintering at the Azores and the times ugrib was correct in forecast here during the winter can be counted on one hands fingers.

There must be better alternatives (and there are) to ugrib. What do you long distance cruisers use for weather forecast? Have you found better accuracy in other grib systems?

[idpnd]

Try zygrib, free software, no registration required.

[JeanneP]

I was under the impression that grib files were the same whether obtained from Grib.US or zygrib, or any other source, in that they are meteorological data files without human analysis and interpretation. Is that not correct?

We have had very good results using grib files from Grib.us. For example, in 2007 we cruised the Baltic in company with several other PDQ power catamarans, and that summer was supposedly the worst summer in memory. Cold, rainy, etc. We were weathered in in Gothenburg, Sweden for a week, along with hundreds of other boats. We needed to cross the Kattegat to Jutland, Denmark and we were hoping for two days of calm weather so we could stop halfway across. Every day I would download a new GRIB file, and we would get the weather forecast posted every evening at the marina. Although the marina's forecast and the GRIB files pretty much agreed with each other, the GRIB files were easier for us because it was visual and we could see the entire crossing. We had to give up waiting for a two-day window when after a week the GRIB files gave us only a one day window and little hope of another window in the following week. So we, along with two other PDQs, set out. Just as the GRIB file told us, the weather was perfectly calm for the crossing, and we made it to Jutland well before sunset. The next day we started working our way down the coast and into one of the fjords that the guide books said was so lovely. And just as the GRIB files forecast, the wind came back with a vengeance that day, but we were now in the lee of the island and so spent a comfortable week cruising down the coast.

Our Bahamas trip in 2008 was also made more comfortable with the aid of GRIB weather forecasting, and again the forecasts were spot on.

We do not trust any long-range forecast from any source - we are keenly aware of the 1979 Fastnet disaster and 1994 Queen's Birthday storm - two disastrous weather "bombs" that were not forecast and in hindsight could not have been forecast. All we care about is a window that will get us away from land before we have to worry about survival tactics - at least we won't have to worry about running into land.

I would like to know of other sources of weather information, too. I haven't been very impressed with Weather Underground's marine weather - I found it less helpful to us than the raw GRIB data. But that's me, I guess. Anything else out there?

[Estarzinger]

Originally Posted by JeanneP

I was under the impression that grib files were the same whether obtained from Grib.US or zygrib, or any other source, in that they are meteorological data files without human analysis and interpretation. Is that not correct?

A "GRIB" is in fact only a file format - for compressed data that in lat/long tagged. You get get all sorts of data in this file format from all sorts of different sources. You can get current gribs for the gulf stream. You can get all sorts of met data - rain, wave heights, water temp, etc. You can get it from private models for pay, and some of these gribs have had human analysis and adjustment; or from many different national met services.

THE GRIB that almost all sailing programs draw their free data from is called the "GFS" model and is run by NOAA. This is a straight computer model output with no human interpretation. It is also what is typically called a low resolution model, in that the data comes on 1/2 degree squares. This is normally perfectly good in the open ocean but can miss important coastal effects. There are other models called 'high resolution' that produce data on a much smaller grid and these tend to have much improved accuracy around coasts. COAMPS is a freely available high resolution model on a .2 degree grid and SWS also produces some free gribs on a high resolution grid.

I personally feel the best grib free grib viewer is Viewfax (http://www.siriuscyber.net/wxfax/ a standalone component of the airmail program). Most grib viewers, like Ugribs, force you to use only one model - usually GFS. Viewfax allows you to toggle between 7 different models. This is important because if several different models agree you can have increased confidence in the forecast, but if they disagree you know there is reduced confidence and this knowledge of the confidence level will/should affect how you use the information.

[SeaOtter1]

Thanks for that info Evans! I wasn´t sure whether the grib files came from one source only or there were grib files from like Meteo France etc. I will try the viewer you suggest and see with the higher resolution if it would be more accurate.

[Estarzinger]

Originally Posted by SeaOtter1

Thanks for that info Evans! I wasn´t sure whether the grib files came from one source only or there were grib files from like Meteo France etc. I will try the viewer you suggest and see with the higher resolution if it would be more accurate.

Meteo France does in fact produce gribs but does not distribute them for free.

I did weather forecasting for the America's cup and found COAMPS and SWS http://206.166.134.206/PUBLIC/grib.html to be the most accurate free gribs for Valencia. The Spanish met service had an excellent high resolution model but again not for free.

as an aside, passage weather (http://www.passageweather.com/) is a web viewer that gives you the choice of a couple different models (usually gfs, and either coamps and/or sws) for most locations. But I don't really like their graphic presentation and prefer to look at gribs on my computer with one of the better viewer programs.

[bvimatelot]

Originally Posted by Estarzinger' date='28 February 2010 - 06:28 PM

A "GRIB" is in fact only a file format - for compressed data that in lat/long tagged. You get get all sorts of data in this file format from all sorts of different sources. You can get current gribs for the gulf stream. You can get all sorts of met data - rain, wave heights, water temp, etc. You can get it from private models for pay, and some of these gribs have had human analysis and adjustment; or from many different national met services.

THE GRIB that almost all sailing programs draw their free data from is called the "GFS" model and is run by NOAA. This is a straight computer model output with no human interpretation. It is also what is typically called a low resolution model, in that the data comes on 1/2 degree squares. This is normally perfectly good in the open ocean but can miss important coastal effects. There are other models called 'high resolution' that produce data on a much smaller grid and these tend to have much improved accuracy around coasts. COAMPS is a freely available high resolution model on a .2 degree grid and SWS also produces some free gribs on a high resolution grid.

I personally feel the best grib free grib viewer is Viewfax (http://www.siriuscyber.net/wxfax/ a standalone component of the airmail program). Most grib viewers, like Ugribs, force you to use only one model - usually GFS. Viewfax allows you to toggle between 7 different models. This is important because if several different models agree you can have increased confidence in the forecast, but if they disagree you know there is reduced confidence and this knowledge of the confidence level will/should affect how you use the information.

I downloaded the program and it looks really nice. However, when I ask to download a grib, a message comes up "cannot allocate socket" There isnt any help page as such (that I could find anyway!) Any ideas? (I'd love top be able to use this!)

[Spike_dawg]

Sailmail has an extensive weather catalog for downloads, including gribs and text. You can get the AIRMAIL program for free and just use the weather catalog. Then email query@saildocs.com. Here is an example

mailto: query@saildocs.com

Subject: Weather request

Send FZPN40.PHFO

send GFS:16N,00N,160E,178W|1.5,1.5|12,24,48..96|PRMSL,W IND,WAVES,RAIN

send GFS:13N,00N,169E,177W|1,1|24,48..120|PRMSL,WIND,WA VES,RAIN

Note that I prefer the GFS model rather than the nogaps or caoamps model. The other models are also available at this site. All free.

Download program at http://www.sailmail.com/download.htm

You can view grib files in MaxSea, Mapsource, Fugawi and most other navigation packages. You can also view it in the airmail program.