It's the sound which Jennifer and Ian Prosser still remember 20 years after the great fire swept over their home.
"I was on the roof and I saw the fire crest over the hill," Ian says with a clarity as though it were yesterday.
"We heard the roar of this tornado coming towards us just like a 747 engine. Everything was black. I scrambled off the roof and shouted 'Get inside'. We made it inside before it hit. Everything went orange and then dark. It was like the middle of the night.
"What was really scary was the sound. I knew we couldn't outrun it, and we had to be somewhere we could survive.
"It started to generate its own weather. It generated a tornado."
They had known about the fires in the Brindabellas for days before but thought there was enough safe distance - "empty land" as Jennifer puts it - between their edge of urban Canberra and the blazing bush.
But the fires suddenly took off - literally. Different fires converged and exploded, leaping over fire-trucks and fire-breaks right to their backyard in Lincoln Close.
Even in the early hours of January 18, the atmosphere felt awkward - apocalyptical even.
At four in the morning, the temperature was still in the 20s, still hot enough to expand glass in a frame and shatter it with a crack.
"It was an evil day. It was horrible," Ian said. "Both of us had dread in the pit of our stomachs. We just thought, 'This is bad'," Jennifer added.
As they realised that they and their home was in danger, they prepared for the worst, filling the bath and any vessel which would hold water. She took curtains down and put wet towels over any surface which might catch fire. They filled sandbags and he put them on the roof. They hosed down wooden decks.
They changed clothes, putting on non-flammable cotton shirts and thick shoes. They wore wet tea-towels around their shoulders.
The roof might have been what saved their home from total destruction. Unlike many other houses, their roof was metal and the metal was joined tightly to the walls so embers couldn't penetrate.
Where other houses had tiled roofs, the tiles were simply ripped off like a pack of playing cards flipped into the air. As the tornado of a fire front hit early afternoon, tiles flew like missiles, embedding themselves in other houses. With the tiles gone, homes were then left completely unprotected from the flying embers above.
But their metal roof stayed. Inside the house, though, smoke was everywhere. "We weren't thinking straight. We had a lot of smoke alarms, and they were going off," she says.
At about five o'clock in the afternoon, all the power went off so they were even more in the dark. There was no way of contacting others.
When the tornado hit, trees a metre wide snapped off at the base. A wind gauge on the street stopped working when the dial hit 160 km/hour.
"All the trees were on fire. Our neighbours' houses were on fire," he says. Some plastic gas-pipes melted and the gas caught light. "They were like flame throwers," he says.
They set about defending their property. "We had hoses all over the house and, remarkably, we had water pressure." They used the hoses to put spot fires around the house out - and to protect themselves, hosing each other down.
Late in the afternoon, officials arrived and ordered them to leave. A police car ferried them down the road to some safety, and then friends took them to the evacuation centre in Phillip. Friends failed to recognise them there because they were covered in soot.
The route to safety had added to the air of apocalypse. Trees blocked streets. Traffic lights just blinked constantly on amber. At one stage, it was so dark in the day that street lights came on.
But in safety, even after the heroic and herculean effort of the day, Jennifer couldn't sleep because of the images racing in her head. "We had watched our neighbours' home burn down. All I could see was their home burning down. It exploded. You could hear the roofing timbers cracking. This was someone I knew."
When they finally did return to their home, it was badly damaged but not destroyed. The roof and their bravery had saved it, and also its position: it is in a slight dip with the hill over which the fire came just above, so the fireball's greatest impact was on the homes just across the street.
All the same, because of the interior damage to their home from smoke and heat, and because the power was off for about a week, they had to live out on the deck. Refugees from neighbouring, completely-destroyed houses joined them.
One of the dark sides of the disaster was that strangers scavenged in ruined houses. "People were fossicking for copper pipes so the police increased their patrols," Jennifer says.
Jennifer reckons she was kept going on the day by adrenalin. "Everybody has a sense of survival. I have a crazy optimism. I don't give up," she says.
But scars only heal slowly. For some years, she couldn't look at sunsets. "It made me feel sick because that redness was the fire for me."
"We never want to go anywhere in summer, and I love it when it's cold and wet and rainy," she says 20 years on.
Out of grief can come good. Residents grew closer. If a few were seen on the street, more would gather. "A huddle would develop. It was as though we all became joined at the hip. We've all become extremely good friends."
They formed a Community Fire Unit. They meet on the deck of the house that survived in the street where the rest were destroyed on January 19.
