Weather Forecast Data Sources

Grib files have become essential for navigation software users. Thanks to them, it is possible to read always more reliable and precise weather forecast on longer time periods. But where are these data coming from? And who are the different providers?

What is a GRIB file?

It is a numerical file displayed in the form of a geo-localized mesh and incorporating data on the grid intersections. One or several data can be found on each point (wind, waves, rain, pressure, air temperature, current…) displayed in the software navigation in the form of barbules, arrows or colored areas. The grib incorporates several grids spaced out by a time step defined by the model (between 1h and 12h) in order to see the evolution of the weather forecast on several days.

Where are these data coming from?

Weather forecasts are calculated by computing models which try to assess the most predictable scenario based on the initial situation and the experience of the evolution of these situations in the past.

This task is made by a lot of weather centers making use of scientific resources and the necessary computing power.

1.       The National Oceanic and Atmospheric Administration (NOAA)

Certainly being the agency provided with the biggest quantity of global weather data, the NOAA gives access for free to grib files issued from different calculation models. 

GFS model

It is the most common and used model. Global weather forecasts are delivered for free by the NOAA.

Global Real-Time Ocean Forecast System model (RTOF)

Data available are about ocean current which are also delivered by the NOAA.

Wave Watch 3 model (ww3)

This model is dedicated to oceanographic analysis and gathers information about the waves.

These files are available for download with Adrena NOAA toolbar, UGrib, Squid, Zygrib and many other websites and applications.

2.       European Centre for Medium-Range Weather Forecasts (ECMWF)

The intergovernmental organisation created in 1975 produces global numerical weather forecasts (IFS models) as well as local weather forecasts (CEP). Gribs files provided for a fee are a combination of atmospheric, oceanic and onground calculation models.

 CEP model

This is a high-resolution model in medium range based on very precise observations and then compared to 50 overall models in order to estimate the reliability.

 These files are available for download with Adrena Great Circle toolbar and Squid.

3.       HIRLAM (High Resolution Limited Area Model)

Issued from the collaboration between ALADIN European consortium initiated by Meteo France and HIRLAM, this model delivers short term weather forecasts. It is indicated for day coastal races.

These files are available for download with Adrena Great Circle toolbar and Squid.

4.       Météo France

The French weather agency now provides for free forecasts issued from Arpege and Arome calculation models.

ARPEGE

The Arpege model covers the whole globe with a finer resolution in France. It is used to predict the evolutions of large scale phenomenon (depressions, anticyclones). Meteo France provides two types of file for download: a worldwide grib at 0.5° (30 nm) and a Europe grib at 0.1° (6 nm).

Global Grib (Glob05)

Europe Grib (Eurat01)

AROME

AROME model belongs to a new generation: regional models with very fine mesh. Its particularity is to integrate observations coming from satellites and radars and to take into account 250 types of surface (lakes, vegetation, urbanized areas).

As a result, it provides forecast files integrating the impact of sites effects (sea breeze, effects linked to landscape, thunderstorm …). The geographical coverage is very limited and is spread just a little bit beyond the metropolitan France.

These files are available for download with Navimail2 (not free) and Meteo France (for free) website.

Gribs from Météo France in ADRENA

These files are in GRIB V.2 format, a format that has been read by Adrena since version 9.

To get gribs  about wind, pressure and air temperature data on Meteo France website, it is necessary to select “SP1 – Paramètres courants à la surface”, then to integrate the grib into the navigation software.

Be careful, data by default – “SP3 – Paramètres additionnels (2) à la surface” – are data about humidity and period of sunshine and are not read by ADRENA.

Contrary to Navimail2, Météo France website requires the download of heavy files containing the whole GRIB coverage with a short deadline (6h). Then, it is not suitable for an on-board use at the moment.

5. Great Circle

The company is specialized in editing and providing high-resolution weather data. Based on the American model GFS and above all on the recent WRF (Weather Research Forecasting), Great Circle produces the GCWF and the GCWF racing.

In some geographical areas, resolution is raised to 0.03° for more precision (Le Havre, Cherbourg, North Brittany, Cape Finisterre).

And Itajai (Brazil).

These files are available for download with Adrena Great Circle toolbar and Squid.

6.       Predictwind

Predictwind uses its own calculation model. Like AROME from Meteo France, Predictwind can integrate local specificities and their impacts on weather forecasts (sites effects or linked to landscape…). Calculations are made from American GFS and Canadian CMC weather data with different levels of precision (60km, 8km and 1km). The initial weather conditions files are entered into the model. The 60km resolution model forecasts are first calculated and edited to create a 5 day forecast. For each 60km*60km region, the model uses many complex equations to calculate all meteorological fields, such as wind, temperature, humidity, pressure, rain and their interaction. This process is then repeated for the 8km model run (for each 8km*8km area) based on the 60km model run. Finally, the finest resolution model (1km) is created from the 8km model run on localized areas. Significant computing resources are required to run the 3 models in this configuration.

The process is automatically repeated every 12 hours. There is no historical data involved in the calculation. Contrary to other models, PredictWind estimates the most predictable scenario based on the initial situation and without any historical data involved, so that each 12h forecast is independent from the previous one.

Used in high-level, the local model provides a forecast every hour over a day.

60 km Area

 8 km Area

These files are available for download with Adrena Predictwind toolbar, Predictwind app and website.

7. Tidetech

The Australian company located in Hobart (Tasmania) mainly provides tidal stream and ocean currents data in grib file format. Tidetech applies the science of oceanography to create data based on satellite observation and hydrodynamic models. The Australian company also provides customized products and analysis for international races. Grib files download is unlimited after having subscribed on their website (one-month, six-month or one-year subscription).

More information and fares.

Tidal stream data

Ocean currents data 

Combined currents (tidal stream and ocean current)  

Grib catalogue available here.

Tidetech GRIBS in Adrena

All Tidetech GRIB files can be directly downloaded from Adrena thanks to the download toolbar integrated in the navigation software menu.