Wthrman13 wrote:In general, the "synoptic" runs, initialized at 00 and 12 UTC, are more accurate than their 06Z and 18Z counterparts because they contain more upper-air sounding observations in the initial conditions. By convention, these are launched twice a day all over the world near 00 and 12 UTC. Contrary to popular belief, though, the 6Z and 18Z runs still contain plenty of data, including upper air data (satellite derived observations, aircraft obs, etc.), just not the usual upper air balloon soundings.
IIRC, there are studies that show that the the 0Z and 12Z runs are overall the best, but I don't know any off the top of my head; I could go look them up.
Can we just go ahead and have this reposted in every model thread from here on out?

I'm fairly certain every one in the past has contained the misconception that the 6Z and 18Z periods are just reruns with nothing new added.