GFS 12z and 0z runs compared to 6z and 18z runs
I have heard before that 6z and 18z GFS runs are just as good as 0z and 12z runs. I hear the line frequently that "it's the 6z GFS it's trash" or "it's the 18Z throw it out". I know this is not true but I would love for someone to articulate this in a way that I can convey it to others.
Thanks in advance.
I debated whether or not to try and go through all this again, but I'll try. First, in terms of total volume of observations, you're first statement is dead wrong. The radiosonde network only forms a very tiny portion of the global observing system (though it is hugely important).
I have no idea what you mean when you say that the radiosonde data is "out of date" for 6z and 18z. At NCEP, we (currently) use a 3D analysis scheme with a 6 hour time window. If you use 12z as an example, we only