surface analysis chart
A standardized map of the weather that shows the distribution of meteorological conditions over any area at a given time. A synoptic chart shows isobars, fronts, and weather symbols. These normally are drawn at three hourly intervals, usually at 000, 0300, 0600, 0900, 1200, 1500, 1800, and 2100 h GMT (Greenwich mean time). Also called a surface analysis chart.