SUJET :

I use use XYGRIB frequently at work (on a tugboat) and wanted to start downloading GFS Gribs directly from the NOAA NOMADS server. Unfortunately, I do not really understand how to do so and have not had much luck reading and rereading through information on the NOAA website. I suspect my difficulty stems from not really understanding how the gribs are produced, assembled and viewed. I'm hoping this forum can provide some simple explanations about how to get the gribs from NOAA and thereby take some of the load off of your server. So my specific questions are:

1: Simply, can anyone explain how to download the gribs from the NOAA server for viewing in XYGRIB?
2. Is it possible and/or practical to offer a choice of servers (noaa or the current XYGRIB) within the XYGRIB Software?
3. I understand that requesting files through the NOMAD server involves a complicated string of codes. each for a specific data set and time being requested. Does XYGRIB use these codes in requesting its files and, if so, can these codes be exported in some way to make the requesting through the NOMAD server a little easier?

In closing, I want to say I love this software and find it amazingly useful. I would gladly do my little part in reducing the load on your server once I understand how to download the grib data directly from NOAA. Thank you all for your time.

Hi there,
It is possible to download hourly subsets of GFS output at the NOMADS grib filter at url nomads.ncep.noaa.gov/gribfilter.php?ds=gfs_0p25
To automate the process and concatenate the hourly files you will need to run a script file which usually requires a linux terminal window. Details on how to do this at url www.cpc.ncep.noaa.gov/products/wesley/sc...ing_grib_filter.html

Hello and thank you for your reply. Previously, I have tried some downloads from the grib filter at the URL you provided and have been able to view them via XYGRIB. What I have not been able to figure out is how to do so with more than a single hourly forecast in the same downloaded file in the way that XYGRIB provides multiple forecasts at selected intervals that you can toggle through. In looking through the scripting URL you provided, I'm not sure I see how to provide multiple forecast hours into a single download. Is it possible to edit the URL generated by the GRIB Filter to include a set group of parameters from multiple forecast hour files? And is it possible to combine forecasts from multiple models (such as atmospheric and ocean for wind/wave forecasts) into a single file download?

Thank you again

It is actually quite simple. GRIB files concatenate together very well and very simply.
First place all your hourly atmospheric files in the same folder. Then add any sea condition files to the same folder (this assumes that there is no duplicate file names).
Following this in a linux terminal you just give the command "cat *.grb2 > myOneBig.grb2"
Instead of the wild card one can list the individual files with just a space between them.
It can be done in MS windows with slightly different syntax.
I suggest to Google the linux cat command.

Thank you so very much for your help! I never would have thought it would be so simple to combine these files I have been very successful using the cat command and downloading small batches via curl on the command line. Now I am working on the scripting process to automate the downloads. Very satisfying to finally understand how this works.

When downloading gribs via xygrib, I have typically selected the "GWAM" for the wave model. I have not had much luck googling around for where to download these forecasts. Are they also freely available?

Happy to hear that things are working out.
For wave data try the DWD opendata at opendata.dwd.de/weather/maritime/wave_models/