Victoria’s thunderstorm asthma alert level has been raised for one of the first times this storm season as wild weather approaches the state.
Storms are expected to hit Victoria on Thursday, bringing heavy rainfall, damaging wind gusts and possible large hail to parts of the state.
In response, deputy chief health officer Angie Bone said the Mallee, South West and Wimmera weather districts were considered high risk.
“The combination of forecast high grass pollen levels and severe thunderstorms with strong winds means that there is a chance that a large number of people may develop asthma symptoms over a short period of time,” Dr Bone said.
The health department raised the epidemic thunderstorm asthma forecast to moderate for the north and northwest regions of the state on Thursday.
The central region, including Melbourne, and eastern parts of the Victoria remain at low risk.
A moderate risk forecast means that one of the elements necessary for an event may be present – in this case severe thunderstorms with strong winds are predicted from Thursday.
People with current, past or undiagnosed asthma or hay fever are considered to be at risk during a thunderstorm asthma event and should avoid exposure to any storms that may emerge, especially the wind gusts that precede them.
They should also have a reliever appropriately available and remind themselves of their asthma action plan. Up to date forecasts can be found on the health website.
Dr Bone said people at risk from the storms could protect themselves by staying indoors, taking their preventive medication and following their asthma action or first aid plans.
Weather bureau senior meteorologist Mark Anolak said a “very dynamic” weather system would evolve on Thursday.
“It will quickly intensify over the southwest corner of the state,” he said.
“As a result we’re likely to see increasing winds, but also showers and thunderstorms, possibly severe, extending across the state with heavy rainfall, damaging wind gusts and possible even some large hail across northern parts of the state.
He said the strong wind gusts would continue until early Friday morning, particularly in the northeast ranges.
Mr Anolak said the low pressure system would clear into the Tasman Sea by Saturday and showers and winds would ease throughout the weekend.
He said Melbourne would experience showers and cooler temperatures from Thursday through to Saturday, with parts of southwest Victoria forecast to receive between 25mm and 50mm of rain.
National Asthma Council Australia director and respiratory physician Professor Peter Wark said people with hay fever and allergy to rye-grass pollen may be at risk of thunderstorm asthma – even if they have never had asthma symptoms before.
“Check grass pollen counts for your region every day during spring and early summer on high grass pollen days and avoid exposure to outdoor air when a thunderstorm is approaching, especially during wind gusts just before the rain front hits,” he said.
“If you can you stay indoors with your windows closed and the air conditioner off or on recirculation mode, or if driving, shut your car windows and only use recirculating air.”
The weather bureau’s Victorian manager of hazard preparedness and response, Keris Arndt, said risk this year of thunderstorm asthma in late spring/early summer was higher than normal.
“Forecast wet and warm conditions will lead to good grass and vegetation growth over the spring period and this forecast is largely driven by a negative Indian Ocean Dipole (IOD), which is the first negative IOD event since 2016,” he said.
Ten people died when Melbourne experienced the world’s largest epidemic thunderstorm asthma event on November 21, 2016.
In the 30 hours from 6pm on that day, there was a 672 per cent increase in respiratory-related presentations to Melbourne and Geelong public hospitals, while triple-0 call outs also spiked.