What Is a Synoptic Chart?

A synoptic chart provides information about climate conditions across a large area, big enough to encompass most major weather systems. Such charts are useful not just for meteorology on Earth, but also for depictions of magnetic fields and other phenomena on the Sun and other celestial bodies. Newspapers and other sources of weather news commonly reproduce synoptic charts for the benefit of members of the public. They are also used internally at a variety of agencies that track climate conditions and record data for various applications.

Such charts can discuss different kinds of climate conditions, depending on the purpose of a given synoptic chart. A common example provides information about atmospheric pressure. The chart delineates the boundaries between areas of high and low pressure and indicates the average observed pressure in a given region. This can provide important information about ongoing and upcoming weather patterns, for people who know how to apply atmospheric pressure data to weather forecasting.

Charts can also include information about temperature, precipitation, wind speed, and other matters of interest. Forecasters look at synoptic chart data to determine how the weather is going to shift, and where it will move to over time. By looking at a big area, forecasters can see telling signs of tropical storms, hurricanes, tornado weather, and other adverse meteorological conditions. This information can help them warn the public about upcoming weather events.

The key features of the synoptic chart are large area and information about one or more atmospheric conditions. Smaller charts provide more localized information and may conceal important data. For example, a person looking at a weather map of the west coast of the United States might think that fair weather is in store, based on available data. A synoptic chart spanning the Pacific, however, might show that storms are inbound. For this reason, such charts play a critical role in extended forecasts, where meteorologists need to think about what is happening at a distance.

Scientists also use synoptic charts for recording, tracking, and studying events on other planets and stars. A synoptic chart of the Sun can offer insight into sunspots and other phenomena, and can allow forecasters to predict particularly bad solar weather. While the information provided is very different from that associated with a chart on Earth, solar and terrestrial weather patterns can sometimes be very similar. The Sun has storms just like Earth, and these can be predicted by tracking key atmospheric events.