Data Availability

Web Based

Introduction
What GRIB files are about is described on another my main GRIB page. A general review and comparison of some services, free and commercial can be found on the Which Service page. The links above are to brief descriptions of some of the basic free services and how they are accessed. Sailors, traditionally, have short arms and deep pockets. few see a need to pay for something that be obtained free. In this world, of course, you get what you pay for. The various commercial services have added facilities and, for some purposes, forecasts that may be better in some respects. For example, some use meso-scale models rather than global ones. See the NWP page for a description of the implications. of using different forecast models.	For some while, the free services all required users to send an email to the supplier. The reply email contains a highly compressed data file that software on your computer translates to a chart of wind vectors. Since those early days, services have been introduced that use a program on your own computer to access GRIB files directly using File Transfer Protocol. One such service, UGRIB, is available at no charge. This makes obtaining GRIB file forecasts easier and more reliable. For those for whom brand width is not a problem, there are also web based versions of GRIB data. A fairly extensive listing of GRIB and other objective forecasts is on another page.
What is available using GRIB files.
The primary data source
This is NOAA's "GFS" global model, requested by using the code "GFS:" (or "GRIB:") in a GRIB-request. Beginning in June 2006 data from other models is now available, as follows: GFS: The most-often used model is NOAA/NCEP's global "GFS" model. Data is generally available on a 0.5 x 0.5-deg grid every 3 hours out to 180 hours,	and then on a 2.5-deg grid out to 384 hours (16 days). The availability of the 0.5-deg data depends on availability from NOAA, and Saildocs will fall back to 1-deg data and 6 hours if the 0.5-deg files are not available. Suppliers may not make all the information available to users.
Web page versions
Given the band width, the quickest way to access charts derived from GRIB coded data is through your web browser. A listing of these can be found on another page of this site. Some of these provide charts of wind, wave and other parameters. Others simply give wind and other data at specific points using interpolation from the grid points provided by the NCEP GFS.	The advantages of web based versions is the immediate access. the drawback is the problem in storing them for future reference such as comparison with the next forecast to be issued. Using a PDA, it may be possible to display a web page but not process a GRIB file using the viewer software. Over a mobile phone the cost of viewing wind charts may be too large for other than occasional use.
Other available information
COAMPS
This is a meso-scale (i.e. more detailed) regional model provided by the US Navy. Data is available for three regions: eastern Pacific, west Atlantic, and Caribbean/Central America. Forecast data are available on a 0.2 x 0.2-deg grid at 6-hour intervals out to 48 hours (72 for west-Atlantic). For best results, use a grid of 0.2-deg or multiples of that to avoid interpolation.	The areas for the available COAMPS areas are: East-Pacific: 29N,60N,160W,114W West-Atlantic: 20N,55N,093W,055W Cent-Am and Caribbean: 00N,32N,120W,060W
WWave3
This is NOAA's WW3 wave model, data is available on a 1 x 1.25 grid (lat x lon), forecasts every 3 hours out to 180, updated every 6 hours usually by HH+06:00. WW3 parameters are defined at http://polar.ncep.noaa.gov/waves/products.html Wind forecasts from WW3 are only for Ocean waters. The model does not	generate forecasts for interior bodies of water such as the Mediterranean, Baltic, Black Sea, and Great Lakes. One issue is that WW3 data sometimes shows up late with the 00z data arriving at the NOAA server at 06:30 or thereabouts so it may not always be available.

NOGAPS
"NOGAPS" is a US Navy model and data are available on a 1-deg grid with forecasts every 3 hours to 24, then 6 hours to 96, then 12 hours to 144, and updated every 12 hours by HH+07:00. Available parameters of interest to the sailor are pressure, wind. ,The server is sometimes late which results in	missing valid-times. For example, Saildocs terminates the download task at HH+07:00. There is no particular advantage to NOGAPS over GFS, it is simply being made available as a 'second opinion".
QuikScat
QuikScat data are wind data calculated from wind-wave radar observations made by polar-orbiting satellites. These are now available in a gridded format just like model data. NOAA updates the dataset, generally once per hour although sometimes a few hours elapse between updates.	The data also includes layers for the age of each data-point (typically 2-24 hours) and a rain status flag (rain can corrupt the data). Also note that QuikScat data are used (along with traditional observations) to initialise the GFS model to there is arguably no advantage to looking at the QuikScat data separately.

Introduction

What GRIB files are about is described on another my main GRIB page. A general review and comparison of some services, free and commercial can be found on the Which Service page. The links above are to brief descriptions of some of the basic free services and how they are accessed. Sailors, traditionally, have short arms and deep pockets. few see a need to pay for something that be obtained free. In this world, of course, you get what you pay for. The various commercial services have added facilities and, for some purposes, forecasts that may be better in some respects. For example, some use meso-scale models rather than global ones. See the NWP page for a description of the implications. of using different forecast models.

For some while, the free services all required users to send an email to the supplier. The reply email contains a highly compressed data file that software on your computer translates to a chart of wind vectors. Since those early days, services have been introduced that use a program on your own computer to access GRIB files directly using File Transfer Protocol. One such service, UGRIB, is available at no charge. This makes obtaining GRIB file forecasts easier and more reliable. For those for whom brand width is not a problem, there are also web based versions of GRIB data.

A fairly extensive listing of GRIB and other objective forecasts is on another page.

What is available using GRIB files.

The primary data source

This is NOAA's "GFS" global model, requested by using the code "GFS:" (or "GRIB:") in a GRIB-request. Beginning in June 2006 data from other models is now available, as follows:

GFS: The most-often used model is NOAA/NCEP's global "GFS" model. Data is generally available on a 0.5 x 0.5-deg grid every 3 hours out to 180 hours,

and then on a 2.5-deg grid out to 384 hours (16 days). The availability of the 0.5-deg data depends on availability from NOAA, and Saildocs will fall back to 1-deg data and 6 hours if the 0.5-deg files are not available. Suppliers may not make all the information available to users.

Web page versions

Given the band width, the quickest way to access charts derived from GRIB coded data is through your web browser. A listing of these can be found on another page of this site. Some of these provide charts of wind, wave and other parameters. Others simply give wind and other data at specific points using interpolation from the grid points provided by the NCEP GFS.

The advantages of web based versions is the immediate access. the drawback is the problem in storing them for future reference such as comparison with the next forecast to be issued. Using a PDA, it may be possible to display a web page but not process a GRIB file using the viewer software. Over a mobile phone the cost of viewing wind charts may be too large for other than occasional use.

Other available information

COAMPS

This is a meso-scale (i.e. more detailed) regional model provided by the US Navy. Data is available for three regions: eastern Pacific, west Atlantic, and Caribbean/Central America. Forecast data are available on a 0.2 x 0.2-deg grid at 6-hour intervals out to 48 hours (72 for west-Atlantic). For best results, use a grid of 0.2-deg or multiples of that to avoid interpolation.

The areas for the available COAMPS areas are:
East-Pacific: 29N,60N,160W,114W
West-Atlantic: 20N,55N,093W,055W
Cent-Am and Caribbean: 00N,32N,120W,060W

WWave3

This is NOAA's WW3 wave model, data is available on a 1 x 1.25 grid (lat x lon), forecasts every 3 hours out to 180, updated every 6 hours usually by HH+06:00. WW3 parameters are defined at http://polar.ncep.noaa.gov/waves/products.html

Wind forecasts from WW3 are only for Ocean waters. The model does not

generate forecasts for interior bodies of water such as the Mediterranean, Baltic, Black Sea, and Great Lakes.

One issue is that WW3 data sometimes shows up late with the 00z data arriving at the NOAA server at 06:30 or thereabouts so it may not always be available.

NOGAPS

"NOGAPS" is a US Navy model and data are available on a 1-deg grid with forecasts every 3 hours to 24, then 6 hours to 96, then 12 hours to 144, and updated every 12 hours by HH+07:00. Available parameters of interest to the sailor are pressure, wind. ,The server is sometimes late which results in

missing valid-times. For example, Saildocs terminates the download task at HH+07:00. There is no particular advantage to NOGAPS over GFS, it is simply being made available as a 'second opinion".

QuikScat

QuikScat data are wind data calculated from wind-wave radar observations made by polar-orbiting satellites. These are now available in a gridded format just like model data. NOAA updates the dataset, generally once per hour although sometimes a few hours elapse between updates.

The data also includes layers for the age of each data-point (typically 2-24 hours) and a rain status flag (rain can corrupt the data). Also note that QuikScat data are used (along with traditional observations) to initialise the GFS model to there is arguably no advantage to looking at the QuikScat data separately.

Free GRIB Messages and other Objective Forecasts