Epidemic thunderstorm asthma risk forecast

Maps of current epidemic thunderstorm asthma risk forecast

The epidemic thunderstorm asthma risk forecast runs from 1 October to 31 December each year.

Today

Tomorrow

Risk forecasts are issued twice daily during the grass pollen season (October through December). They cover three consecutive days and use a colour-coded scale: green (low), orange (moderate) and red (high).

For up to date information on epidemic thunderstorm asthma risk visit the VicEmergency website or download the VicEmergency app from Google Play or the App Store and set up a 'watch zone'.

What do the risk forecasts mean?

The epidemic thunderstorm asthma risk forecasting system combines the forecasting of a certain uncommon type of thunderstorm and forecasting of grass pollen levels across Victoria.

It spans three days (today, tomorrow and the day after) and uses a colour-coded scale from low to high risk: green (low), orange (moderate) and red (high).

• A low risk (green) forecast means that the elements necessary for an epidemic thunderstorm asthma event are not expected and an event is unlikely.
• A moderate risk (orange) forecast means that one of the elements necessary for an event may be present (i.e. a high pollen forecast or a severe thunderstorm with strong winds) and there is a moderate chance of an epidemic thunderstorm asthma event occurring.
• A high risk (red) forecast means that there is a high pollen forecast and severe thunderstorm(s) with strong winds are likely to be present increasing the risk of an epidemic thunderstorm asthma event occuring.

Forecasts are not a formal 'warning' and are designed to inform people at risk that they should be prepared. The forecast only indicates whether the chance of an epidemic thunderstorm asthma event occurring is increased – a higher forecast does not mean than an event is certain to happen, nor does a lower forecast mean that an event will not happen.

The risk forecasting system is not designed to forecast the seasonal increase in asthma and hay fever symptoms which occur every year during the grass pollen season, which can be triggered by pollen and changes in weather generally.

What should I do on days with increased risk?

People should be aware of the heightened risk of thunderstorm asthma in general throughout the grass pollen season and be appropriately prepared. The forecast should not replace appropriate prevention and good asthma and hay fever management, which is the best way to protect yourself from thunderstorm asthma.

People with current, past or undiagnosed asthma or hay fever are considered to be at risk. Having both asthma and hay fever or poorly controlled asthma increases the risk further. Those at increased risk should:

• avoid exposure to any storms that may emerge, especially the wind gusts that precede them
• have a reliever appropriately available (as discussed with your doctor or pharmacist)
• remind themselves of their asthma action plan if they have one and know the four steps of asthma first aid.

On a high risk day the department will issue up-to-date relevant advice and warnings on the VicEmergency warning platform.

The risk forecast for the current day is only updated once, at approximately 12:30pm. Any further updates (such as public advice and warnings) will be posted on the VicEmergency website and app.

How is epidemic thunderstorm asthma risk forecast?

The risk of an epidemic thunderstorm asthma event occurring is forecast daily during the Victorian grass pollen season (typically 1 October to 31 December).

The department has worked with the Bureau of Meteorology and a number of partner organisations to develop the risk forecasting system. The system combines weather and pollen observations and data to forecast the risk of an epidemic thunderstorm asthma event.

Weather conditions associated with epidemic thunderstorm asthma include wind changes and strong gusts typically observed with thunderstorms. This information comes from the Bureau of Meteorology's numerical weather models and weather forecasters monitoring the most recent weather observations.

Pollen forecasts are dependent on many factors including wind, temperature, rainfall, relative humidity and satellite-estimated grass coverage and condition. The current pollen forecasting model uses information about pollen counts collected over many years in Melbourne and four years across the state. Pollen collection at the current eight Victorian sites during the grass pollen season helps to verify and refine the pollen forecasting model.

The risk forecasting system serves two purposes:

• to enable health and emergency service systems to be suitably prepared on days of increased risk
• to raise community awareness of possible events so, where possible, those at increased risk can take action to reduce the health impacts of a potential event.

How do I set up a watch zone to receive advice and warnings when a high risk is forecast in my area?

• Open the VicEmergency website or the app.
• Select 'Create a Watch Zone'
• On the following screen, type your address or suburb into the search box at the top, and select your location from the suggestion list that drops down.
• You can also adjust the radius of your watch zone by selecting the plus (+) or minus (-) button.
• Once you are happy with the radius of your Watch Zone, select 'Next'
• Choose a name for your new watch zone, for example 'Asthma' and type it into the text box.
• Ensure that the 'advice warning' option is selected.

You will now receive automatic warnings that are issued in your selected Watch Zone.

How accurate is the epidemic thunderstorm asthma risk forecasting system?

The science of epidemic thunderstorm asthma risk forecasting is new and as with all forecasts, there is an element of uncertainty. The epidemic thunderstorm asthma risk forecast is based on a synthesis of the modelled grass pollen forecast combined with the forecast for a particular type of thunderstorm. These complex models have multiple inputs, including from satellite data and land and ocean-based measurements. Accuracy of the epidemic thunderstorm asthma risk forecasting system is limited by how precisely these complex phenomena can be observed and modelled.

Epidemic thunderstorm asthma events are relatively rare, and therefore, it may take some time until the accuracy can be measured with high confidence.

Additionally, the forecast only indicates whether the chance of an epidemic thunderstorm asthma event occurring is increased – a higher forecast does not mean than an event is certain to happen, nor does a lower forecast mean that an event will not happen.

People should be aware of the heightened risk of thunderstorm asthma in general throughout the grass pollen season and be appropriately prepared. The forecast should not replace appropriate prevention and good asthma and hay fever management, which is the best way to protect yourself from thunderstorm asthma.

Where are the pollen traps located in Victoria?

The Victorian pollen monitoring network that contributes data to the epidemic thunderstorm asthma risk forecast comprises pollen traps at the following locations:

• Parkville
• Waurn Ponds (Geelong)
• Hamilton
• Creswick (near Ballarat)
• Bendigo
• Dookie (near Shepparton)
• Churchill (near Morwell)

These pollen traps across Victoria support the verification and refinement of the forecasting model by providing a more detailed understanding of pollen levels and the spread/movement of pollen across the state.

Where can I find data from pollen traps in my area?

As part of the epidemic thunderstorm asthma forecasting system, the Victorian Government funds grass pollen monitoring during the grass pollen season. Pollen information is provided to the Bureau of Meteorology as one important element to the epidemic thunderstorm asthma forecast, and to the public for personal use.

Information from Victoria’s pollen monitoring sites is available from the Melbourne Pollen mobile app (download from the App Store for iOS devices or Google Play for Android devices) and Melbourne Pollen website.

Why is grass pollen only counted between 1 October and 31 December?

Plants release their pollen when they are flowering, and different types of plants flower at different times of year. Many deciduous trees such as birch, plane and elm flower in late winter and early spring, for example, whereas many grasses flower in the period from October to December. Research shows that grass pollen is by far the most common cause of spring hay fever (seasonal allergic rhinitis) in Victoria. The specific grass that is thought to be involved in epidemic thunderstorm asthma events in Victoria is rye grass.

Grass pollen data collected in Melbourne for more than 20 years shows that the highest levels start occurring, on average, in mid-October and fluctuate daily until the end of December. By the end of November grasses start dying off and the levels of grass pollen in the air begin to reduce. The exact start and finish of grass pollen season varies slightly from season to season but is typically from 1 October to the end of December.

How is a pollen forecast different from an epidemic thunderstorm asthma risk forecast?

Grass pollen forecasts simply reflect the expected amount of pollen in the air. They can help people with hay fever (seasonal allergic rhinitis) to prepare for these days.

Epidemic thunderstorm asthma risk forecasts combine grass pollen forecasts with the prediction of a certain type of thunderstorm thought to produce a thunderstorm asthma event.

Map of Victorian forecast districts