[gradsusr] GFS hourly clouds output

[Ivan Toman]

Hello always helpful GrADS community;

I have problem with displaying GFS 0.25deg hourly clouds. It seems to me 
that something is broken. It is hard to explain, but best explanation is 
this 24h animation: http://www.meteoadriatic.net/pub/clouds_01.gif

So, it seems that clouds somehow "jump" at every 6th hour, and inbetween 
are less and less defined, something like averaged more and more every 
hour, until they "jump" little bit and become defined again well. And 
then again in loop that repeats it's behaviour every 6 hours...

What is going on there?

Many thanks,

Ivan Toman