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NOAA offers from this link grib files about GFS Forecasts, containing values of forecasted weather attributes. Each file a 3-hour output timestep. Every day is composed of 4 grib files, each one having one of the following time reference; 00:00, 06:00, 12:00, 18:00. The time reference is the time that forecast starts.

This implies that the grib files cover only the following periods of a day; 00:00-03:00, 06:00-09:00, 12:00-03:00, 18:00-21:00.

Are there any other files publicly available, covering the whole day?

Nicholas Kou
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  • the link you gave lists exactly 12 different GFS forecasts, plus two analyses. Can you give the exact ftp or http link with file pattern you are using. – kakk11 Dec 10 '18 at 16:30
  • @kakk11 I am using the GFS Forecasts Product type with Grid/Scale 004 (0.5º) - Domain. The ftp [link](ftp://nomads.ncdc.noaa.gov/GFS/Grid4/) that i downloaded the grib files. – Nicholas Kou Dec 11 '18 at 09:39

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No. New forecast is created every 6 hours, giving new set of files covering hours 0..384. In the archive you are using, it is 3h step for first 240h and 12h step afterwards. The file pattern is gfs_4_YYYYMMDD_REFT_STEP.grb2, where YYYYMMDD is the date for forecast start time, REFT is hour for forecast start, in CF convention called forecast reference time. STEP is count of hours from the forecast start.

Variables in each file are either instantaneous (like temperature at particular time) or aggregates (precipitation sum over 3h/6h, average radiation over 3h/6h etc.).

So, in order to use data for say the first 12 hours, you should take steps 00, 03, 06, 09 and 12. It is data with 3h interval. Just be careful about the time aggregates in the files, there is a surprise there.

kakk11
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  • you say that each file with different step (00,03, 06,09,12) has a 3-hour interval. Do you mean that the data of each file apply only for the next 3 hours? – Nicholas Kou Dec 11 '18 at 15:07
  • There are instantaneous variables, which go only for a particular time, and aggregates. And the aggregates are usually for the period before the data time. – kakk11 Dec 12 '18 at 16:13