I would like to revive this thread.
The timeseries output option is a great addition, however writing every model timestep is incredibly inconvenient considering it was meant to alleviate the need for post-processing. The filesize is also an issue if you're running a long simulation.
From what I can see in the WRF3.8 user guide there isn't any indication that you could control the writing to ts output.
This seems to have been an issue a while back as well.http://forum.wrfforum.com/viewtopic.php?f=12&t=6015
Anyone with some ideas?