Western Australia's improving weather services: Frequently Asked Questions


What is changing?

  1. How does the new system work?
  2. How will the forecasts change?
  3. Why doesn't my forecast print out on a single page?

City and Town Forecasts

  1. Why doesn't my town receive a forecast?
  2. When are the forecasts issued?
  3. What does 'rainfall total' mean?
  4. What does the 'chance of rain' mean?

District Forecasts

  1. Why have some district boundaries changed?
  2. Why does my town forecast say the 'chance of a shower' but the broader district forecast does not mention rainfall?

Marine Forecasts

  1. Why is the wind information in the written forecast sometimes different to the 'Forecast Wind for Marine Areas' maps?
  2. Where can I find information about wind warnings?
  3. Where is the Coastal Waters forecast with all the zones in it?


What is changing?

How does the new system work?

The Bureau of Meteorology is implementing a new forecasting system aimed at expanding services to the Western Australian public. The system allows the Bureau's forecasters to develop 7 day forecasts graphically, by "painting" the forecasts on their screen. Forecasters then save the information into a database which provides detail of the weather every 6km in a grid across the state.

The information stored in this database is then used to automatically generate text forecasts thereby enabling the Bureau to produce 7 day forecasts for many more locations than before.

Unlike automated systems the new system allows forecasters to input their local knowledge and thereby provide the best possible forecast for the community.

How will the forecasts change?

Forecasts produced by the new system will provide more detailed weather information including an expanded description of sunshine, cloud cover and rainfall, more detail about expected wind conditions, and greater clarity of expected temperatures.

Some forecasts will also be presented in a new format that combines text and graphics so they are more easily understood.

Forecast rainfall amounts and chance of rainfall for Perth Metro will be included on the Perth Metropolitan Day 1 forecast. In most situations this will relate to conditions across the larger metropolitan area.

Why doesn't my forecast print out on a single page?

Because of the extra detail included in the forecasts, some no longer fit on a single page.

If you have any issues with the new services, please send feedback.



City and Town Forecasts

Why doesn't my town receive a forecast?

With the launch of the new system the number of forecast locations for WA increases to 63. However, instead of just Perth receiving a 7-day forecast all 63 locations will receive a 7 day forecast.

The list of official forecast locations will be reviewed next year and will likely be increased. The additional locations will be selected based on population, geographical spread to provide a more equitable service across the state.

During 2013 we will also be providing graphical forecast maps on the a new display system called MetEye. This map interface will allow you to find, display and zoom into your location and show you the weather details for any 6 x 6 kilometre square in Western Australia.

When are the forecasts issued?

All forecasts will be issued twice a day - at around 5am and just after 4pm. The Bureau's forecasters will also update forecasts promptly if conditions change. See the list of forecast issue times.

What does 'rainfall total' mean?

A forecast of rainfall amount, expressed as a range, is issued for the Perth Metro. So forecasters can verify their forecast the rain gauge located in Mt Lawley is used as a proxy for Perth.

The forecast represents the likely rainfall range for the forecast period. Sometimes rain falls in a patchy pattern across an area with some locations receiving a heavy shower while an area nearby might miss out completely. On these days the rainfall range may be quite large, e.g. 5 to 30 mm. When steady rainfall is expected over a wide area, the range may be smaller, e.g. 10 to 15mm.

The locations that receive this information will be reviewed in 2013.

What does the 'chance of rain' mean?

The Perth metro service also provides a "Chance of any rain" forecast. This describes the likelihood of receiving a measurable amount of rain (>0.2mm) during the day. For example, if the chance of rain for Perth metro is 70%, it means that on 7 out of 10 days with similar weather conditions rainfall will be measured in the Mt Lawley rain gauge.

The following graphic illustrates that whilst there may be a 30% chance of rainfall, there is also a 70% chance of not receiving any rainfall at all.

Chance of rain example

The locations that receive this information will be reviewed in 2013.



District Forecasts

Why have some district boundaries changed?

There have only been minor changes to district boundaries, and these have been done to better align with local council boundaries.

Although the changes are generally minor you will need to check which district you are in. See the map.

Why does my town forecast say the 'chance of a shower' but the broader district forecast does not mention rainfall?

The town forecasts are specific to a small area, whereas the district forecast paints of picture of the weather conditions over a large area. If rainfall is only forecast for a small part of a district it would not be mentioned as it might suggest that the entire district would receive rain when that is not the case.



Marine Forecasts

Why is the wind information in the written forecast sometimes different to the 'Forecast Wind for Marine Areas' maps?

The state-wide wind forecast maps are automatically produced from computer models and may not always be the same as official forecasts which contain input from a professional forecaster. These differences will be seen most often when there are weather fronts, east coast lows or in rapidly changing conditions. You should always check the official forecasts and warnings as well as the maps. During 2013 there will be official wind and wave forecast maps provided via a new map interface.

Where can I find information about wind warnings?

Wind warnings are now issued as part of the Coastal Waters Forecast. The Bureau now issues wind warnings for today and tomorrow, rather than a rolling 24 hour period. Wind warning labels will be added alongside the forecast for today and tomorrow to clearly indicate if warnings have been issued for each day.

A separate wind warning summary for Western Australia will list the zones with warnings for today and tomorrow, grouped by each warning category. To see the detail of the conditions you will need to go direct to the appropriate Coastal Waters Forecast.

For more information please see the Wind Warning Changes [PDF, 629Kb].

Where is the Coastal Waters forecast with all the zones in it?

There are now 14 Coastal Waters Zones; North Kimberley Coast, West Kimberley Coast, Pilbara Coast East, Pilbara Coast West, Ningaloo Coast, Gascoyne Coast, Geraldton Coast, Lancelin Coast, Perth Coast, Bunbury Geographe Coast, Leeuwin Coast, Albany Coast, Esperance Coast and Eucla Coast. In addition the Perth Local Waters zone now runs from Two Rocks to Dawesville and out to Rottnest Island. There will also be a new 4 day forecast for the Melville Waters section of the Swan River.

These smaller zones allow more detailed forecasts to be written and each coastal zone forecast will have an improved layout for easier reading. You will also be able to select the forecast you need through an interactive map.



Brochures

Additional Information

Rollout Schedule

  • Queensland (Oct 2013)

Past Improvements