Tasmania's improving weather services:
Frequently Asked Questions

What is changing?

City and Town Forecasts

District Forecasts

Marine Forecasts

Inland Lakes

What is changing?

1. How does the new system work?

The Bureau of Meteorology is implementing a new forecasting system aimed at expanding services to the Tasmanian public. The system allows the Bureau's forecasters to develop 7 day forecasts graphically, by "painting" the forecasts on their screen, and saving them into a database of 3km grids. The information that is stored in this database is then used to automatically generate text forecasts. This enables the Bureau to provide 7-day text forecasts for many more locations than before.

Forecasters will be able to input their local knowledge to provide the best possible forecast for the community.

2. 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 can be easily understood.

Forecast rainfall amounts and chance of rainfall will be included on the Hobart and Launceston forecast on some days.

3. 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

4. Why doesn't my town receive a forecast?

With the launch of the new system we have increased the number of forecast locations from 6 to 30. The selection of the new locations was based on population and geography to provide a more equitable spread across the state. The list of official forecast locations will be reviewed next year.

Within a few months we will also be providing graphical forecast maps on the Tasmanian Forecast Explorer. 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 Tasmania. For a preview, test out the Victorian Forecast Explorer.

5. 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.

6. What does 'rainfall total' mean?

The rainfall totals are issued for single points (e.g. Hobart City, Launceston and the City of Burnie) and represent the likely rainfall amount for a 24 hour 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 big, e.g. 5 to 30 mm. When steady rainfall is expected over a wide area, the range may be smaller, e.g. 10 to 20mm.

7. What does the 'chance of rain' mean?

"Chance of rain" describes the likelihood of receiving a measurable amount of rain during the day.

For example, if the chance of rain for Hobart City is 70%, it means that on 7 out of 10 days with similar weather conditions; rainfall will be measured in the Hobart rain gauge.

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

District Forecasts

8. Why have some district boundaries changed?

District boundaries have changed to better align with the general weather conditions experienced over these large areas.

There are new districts and some of the district boundaries have changed so you will need to check which district you are in. There are new districts for King and Flinders Island, Upper Derwent Valley, and separate districts for Midlands and Central North. See the map.

9. Where are the observations for my town?

Following the changes to some district boundaries, the observations for some locations may have moved position within the lists on our website.

10. 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

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

The wind forecast maps are 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.

Within a few months there will be official wind and wave forecast maps provided via a new marine version of the Forecast Explorer.

12. What happened to the Southeast inshore forecast?

The Southeast inshore forecast has been replaced by more specific forecasts for Derwent Estuary, Storm Bay, Channel and Frederick Henry & Norfolk Bay areas. These forecasts will now provide wind and wave information for the next four days.

13. Where can I find information about wind warnings?

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 wind warning summary for Tasmania will list the zones under warning for today and tomorrow, grouped by each warning category.

For more information please see the Wind Warning Changes page.

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

Coastal Waters forecasts will be provided individually for each coastal zone, with an improved layout for easier reading. You will be able to select the forecast you need through an interactive map. Forecasts have been grouped for the Northern coastal zones and the Eastern coastal zones for mariners regularly traversing multiple zones.

15. Why are there two swells every now and then?

Swells are generated by distant weather systems such as cold fronts, Antarctic low pressure systems and Tasman Sea high pressure systems. As a result, two weather systems can generate swells on the Tasmania coastline originating from different directions. For example, an Antarctica low pressure system might generate a large southwest swell that wraps around the southeast corner of Tasmania, while at the same time a stationary high pressure system in the Tasman Sea might generate a smaller swell from the northeast direction. These two swells may interact with each other along the east coast of Tasmania for a day or two until the swells decrease in size or are replaced by a new swell from another weather system.

Two swells are important to mariners for estimating fuel requirements for long trips, boating comfort and safety when entering and exiting ports and harbours.

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

Inland Lakes

16. When is a small craft alert be issued?

When average wind speeds are equal to or greater than 20 knots (approx 40km/h).

17. Why doen't the Inland Lakes forecast have the same information as the coastal waters forecast?

Smaller craft operate on inland lakes and are affected by lower wind speeds than larger craft on coastal waters. Wave action is generally not the problem on inland lakes when compared to that of the coastal waters.