Synoptic Analysis, Prognosis and Forecasting

'Synoptic analysis' describes the analysis of the state of the atmosphere by using charts containing plots of weather observations at various places and drawing isopleths of atmospheric elements such as pressure, temperature, wind, etc, and other boundaries or significant features, at the Earth's surface and at various upper levels. Synoptic analysis also involves the examination and interpretation of plots of the variation of wind, pressure, temperature and humidity in the vertical and plots of the time sequence of atmospheric elements at a particular location.

'Prognosis' (although usually synonymous with the term 'forecasting') is used here to signify the preparation of charts or diagrams depicting the expected pattern of meteorological parameters at a specific time in the future. These charts and diagrams depict the expected patterns of pressure, temperature, wind, fronts, etc on the Earth's surface and at upper levels.

The term 'forecasting' is used here with the specific meaning of the prediction of weather elements such as wind, cloud, temperature, rain, snow, hail, frost, fog, etc., for a specific geographical place or area. The forecast is generally expressed in words and figures. The form and scope of the forecast depends on the use to which the forecast will be put. Thus forecasts for aviators, mariners, sailors, fishermen, builders or for the general public are each likely to have a different form.

The conventional method of making forecasts was first to plot and analyse a series of synoptic charts and diagrams for certain times of the day (usually at three or six hourly intervals) and to construct prognostic charts and diagrams for specific times in the future. Those prognostic charts and diagrams (which we called 'proggos') were used as a basis (with any other relevant data) for making a weather forecast.

In the early days of my service in the Bureau (1939) the weather forecasting routine was largely left to the discretion of the individual forecasters at Divisional and field offices. Synoptic charts were limited to the surface of continental Australia and upper air and prognostic charts were not prepared.

The Central Analysis Office (CAO) of the Bureau's Central Office in Melbourne, to which I was posted in 1946, had evolved from separate offices established in the 1940s, AMFA in Melbourne and the Allied Air Forces meteorological section in Brisbane.

Bureau of Meteorology