Severe Storms Location description They are localised disturbances in the atmosphere accompanied by thunder, lightning rain, snow or hail. They can occur anywhere in Australia and are responsible for more damage (as measured by insurance costs) than tropical cyclones, bushfires or earthquakes.

Causes Storms develop when warm moist air rises rapidly in an unstable atmosphere. Sometimes this upward movement is initiated by the passage of a cold front. On other occasions (often in summer), the heating of the earths surface is enough to start the rapid upward movement of the air. Most of these storms do not reach the level of intensity needed to produce widespread damage, but they all produce lightning, which can cause death, injury and damage. Sometimes they are accompanied by hail, wind gusts and flash flooding.

Impacts- Each year, on average, severe thunderstorms are responsible for more damage (as measured by insurance costs) than tropical cyclones, earthquakes, floods or bushfires. Unfortunately, thunderstorms also kill people - between 5 and 10 deaths are caused by lightning strikes each year. More deaths occur when strong winds cause tree limbs to fall, debris to become projectiles and small boats in open water to capsize.

Management Solutions WHEN A SEVERE THUNDERSTORM APPROACHES Listen to your local radio station for thunderstorm warnings. Shelter and secure pets and animals. Put garden furniture, toys, etc. inside. Fill garbage bins with water to hold them down. Park vehicles under solid shelter or cover with firmly tied tarpaulins/blankets. Secure all external doors and windows and draw curtains. Put valuables, medications and spare warm clothing in plastic bags with your emergency kit and keep handy. Disconnect all electrical items, external TV/radio aerials and computer modems.

Key Geographical processes Thunderstorms develop when warm, humid air near the ground receives an initial upward push from converging surface winds and rises rapidly in an unstable atmosphere. Thunderstorms can become severe when the atmosphere is particularly unstable and/or additional energy is drawn in from surrounding winds.

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