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9.28 Synoptic Meteorology

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Synoptic meteorology is primarily concerned with large-scale weather systems, such as extratropical cyclones and their associated fronts and jet streams but not as large as the global scale in the previous section. In this section, we will acquaint the student with the structure and behaviour of the atmosphere.

Synoptic means "view together" or "view at a common point". The forecast weather map (right) is for a common point in time, and each of the many different elements that create our weather (e.g. the high and low pressure systems, fronts, and precipitation areas) can be viewed together.

On surface maps you will often see station weather plots. Since meteorologists must convey a lot of information without using a lot of words, plots are used to describe the weather at a station for a specific time. When all stations are plotted on a map, a "picture" of where the high and low pressure areas are located, as well as the location of fronts, can be obtained.

There is a large number of weather symbols used for station plotting. Some are used for weather elements such as rain, snow, and lightning. Others represent the speed of the wind, types of clouds, air temperature, and air pressure. All of these symbols help meteorologists depict the weather occurring at a weather observing station.

Generally hand plotted maps usually contain the full weather information. However, most computer generated surface weather maps omit some data such as cloud types and heights. Recent synoptic research has dealt with such diverse subjects as the large-scale tropical and subtropical disturbances, extra-tropical cyclones, polar lows, the interactions between tropical and extra-tropical systems, and the large-scale effects of volcanic eruptions. Modelling and observational analyses are combined in an integrated approach to synoptic meteorology.

This simple plot represents a small amount of information about the current weather effecting Australia. At 06:00 UTC synoptic (weather) chart published by the Australian Bureau of Meteorology shows the following summer weather for Australia.

  • An anticyclone (1025 hPa) centred at 38°S 132°E, over the southern part of the Great Australian Bight.
  • An anticyclone (1029 hPa) centred at 41°S 168°E, just to the north-west of the South Island of New Zealand extending with a ridge to Sydney Australia.
  • A cold front from a Low over the Southern Ocean extending north-westwards to the vicinity of Melbourne.
  • A cold front from a Low over the Southern Ocean lying SE-NW well to the south of Western Australia.
  • A trough of low pressure associated with the Inter-tropical Convergence Zone (ITCZ), with Lows of 1000 hPa at 10°S 111°E, 1003 hPa at 18°S 130°E and 1004 hPa at 19°S 144°E.
  • There is a tropical cyclone Beni located 21°S 150°E which started as a tropical depression in northern Australia.
  • A Col located 28°S 118°E, represented by a “C”.
  • An occluded front located 48°S 128°E.
  • A warm front located 55°S 135°E.