ASYNOPTIC

over the many years that operational meteorology has developed, certain hours have been designated 'synoptic' hours, and observation times standardised around these points; the MAIN synoptic hours currently being 00, 06, 12 and 18 UTC(formerly GMT), with intermediate hours at 03, 09, 15 and 21 UTC. Increasingly however, observing systems (e.g. satellite, radar-networks, drifting buoys etc.) provide data at times other than these 'fixed hours' - these are designated non, or 'asynoptic' observations. NWP models can assimilate these observations during the initialisation process. (q.v.)