Monday 21 November 2016 was Victoria’s hottest day since March. As the temperature in Melbourne reached 35°C, the Bureau of Meteorology (BoM) issued a severe thunderstorm warning at 1.58pm for damaging winds, heavy rainfall and large hailstones in Victoria’s Mallee, South West, Wimmera, and parts of Northern Country districts.
The State Control Centre (SCC) was operating at a Tier 2 readiness level in response to the declaration of a Total Fire Ban for the Mallee region and in preparation for the potential heat impacts and the forecast thunderstorm. At 4.00pm the BoM extended its warning to other parts of Victoria, including Geelong and Melbourne.
The gust front reached Geelong at 5.00pm and during the next hour moved rapidly eastwards across metropolitan Melbourne, as many people were making their way home after work.
Hot, dry northerly winds ahead of the change contributed to a high pollen count, mostly from rye grass on the plains to the north and west of Melbourne. Moisture from the storms then caused the pollen grains to break apart into particles small enough to penetrate the lungs, causing an asthmatic reaction.
On the evening of 21 November, the Emergency Services Telecommunications Authority (ESTA), Ambulance Victoria and hospital emergency departments across Melbourne experienced an unprecedented surge in people with asthma and respiratory distress. Initially, the cause was unknown.
The peak of calls to Triple Zero gradually decreased. However, between 9.00pm and midnight ESTA still answered calls for emergency ambulance at volumes of 147 per cent above forecasted levels.
Although primarily a health emergency, this event impacted the Metropolitan Fire Brigade (MFB) in its Emergency Medical Response (EMR) capability. The event saw an increase in EMR calls, and the MFB also provided 11 emergency responses to support
At approximately 7.00am on Tuesday 22 November, Triple Zero emergency ambulance calls dropped below expected numbers for the first time in 13 hours. A high number of people with breathing problems continued to present at hospitals and other health providers. The Department of Health and Human Services (DHHS) received reports of deaths that might be attributable to respiratory
problems associated with the storm of the previous evening.
The Victorian Department of Health and Human Services has attributed nine deaths to this thunderstorm asthma event.