Some warnings

These charts are provided for interest only and are no substitute for professional weather maps provided by national meteorological services (NMS -- see the NMS equivalents links). While the AWN charts provide more observational detail than most "weather maps" on the web, they suffer several deficiencies:

• The charts only provide isobars, isotherms, isohyets etc. for the data that you can actually see on the map. There is, for example, no or limited data provided over ocean areas, so the isopleths there may be completely wrong. Charts produced by national meteorological services such as the Bureau of Meteorology fill in these gaps between land-based observations by the crafty use satellite imagery, comparison with recent charts, aircraft and drifting buoy observations and more.

• The 3-hourly Australian synoptic charts progressively fill with data as the relevant clock time occurs in each state, so there are times when the same situation applies to land areas as to water areas. Similarly, the first runs of the international charts will give a poor analysis over ocean areas. The last run of each international chart, about 3 hours after observation time, includes buoy data which may marginally improve the analysis. Don't believe any isopleths (the lines on the charts) unless you can see data around them.

• The data is as received in real time from the Bureau of Meteorology or other national meteorological services. There has been no quality control, other than that provided at point of entry by the service or its observers. There will be errors, the most obvious of which will show up in the isobars if a pressure reading is wrong. If a cyclone appears to be bearing down on Alice Springs, or if there's a persistent low over Bourke, chances are that it's a single wrong pressure reading, or a systematic error affecting repeated readings.

• Be sure to check the date/time on the actual chart. This is an experimental service subject to lots of variables (data flow, computer networks, functioning of the Digital Atmosphere program that prepares the charts) and stoppages do occur. Always check the time/date stamp (UTC) at the top left corner before using any chart. The time the chart depicts is also given in UTC in the bottom left corner. Current time (UTC), according to your computer, is shown at the top of this page.

A quick guide for first time users

• Data is provided by the Bureau of Meteorology, and any redistribution of these charts must be accompanied by a reference to the Bureau.

• Full synoptic charts are the tools used by weather forecasters to get a detailed overview of the current surface weather. They pack a huge amount of detail onto a page by using symbols, so they take a little effort to understand and use effectively. If you're unfamiliar with full synoptic charts, keep this chart guide open to help you, and print out the symbol reference charts showing the weather and cloud symbols.

• Charts all open in new windows. To compare several charts, open them in full size windows, then click between them.

• Most of the charts are designed to fit comfortably on an A4 sheet of paper when printed, either in landscape or portrait format.

• If the latest chart is blank or has just a few plots showing 'M' for 'missing', the data was probably late in being posted by the Bureau of Meteorology. Check back in about 15 minutes. This Bureau problem happens most during afternoons.

• There is no frontal analysis. You can, however, pick up the location of cold fronts from the charts that show isotherms (temperature) and wind streamlines.

• 3-hourly synoptics show rainfall for the previous 3 hours at 00, 06, 12 and 18 local (not previous 1 hour as indicated in the legend). Rain is for the previous 6 hours at 03, 15 and 21 local, and for the previous 24 hours at 09 local.

• The charts are produced from two streams of data:

  • Hourly charts are prepared from Automatic Weather Station reports, and are available about 20 minutes past each hour. They are updated with any late information about 40 minutes past the hour. There is a short archive of the past two hours charts.

  • More detailed 3-hourly charts (and the international 6-hourly charts) are prepared from a mix of AWS and manned station reports at midnight, 3am, 6am, 9am, noon, 3pm, 6pm and 9pm. The manned station reports contain useful additional information such as the types of weather and cloud. Because of Australia's different time zones, the charts for each synoptic hour gradually fill as the data becomes available, with updates occurring about 20 and 50 minutes past the hour. The international charts are prepared from observations taken simultaneously around the world at the main synoptic hours -- 00, 06, 12 and 18utc. Because Australia's observational pattern is linked to clock time, only AWS observations are available for our part of the world on the international standard charts.