There are three qualities needed moisture in the air, warm air, and an updraft. The warm air and moisture form a cumulonimbus cloud that gets pushed by the updraft into the atmosphere and a low pressure system. To be classified as a severe thunderstorm it must have either hail, 75.5mph winds, or a tornado contained within the storm.
Victoria Australia 2005
On February 4, 2005 a large storm blow over Victoria, Australia. It caused blackouts and loss of power in about 40,000 homes and damaged 12,000 homes. It ended up costing 100 million dollars. There was 120 milimeters rain that fell.
Bay of Skiall, Scotland 1850
A storm whipped through the Bay of Skiall in Scotland pulling the land off the knoll. In the end the storm killed around 200 people. The most suprising fact is that it obliterated a whole village that was contained within the bay.
Scientists have developed storm radars and weather apps with warnings to alert and prepare us. They have also developed sirens to alert us when it gets bad enough to kill people. In general newer houses are more sturdy than the houses of the past. Also people go into rooms without windows or into basements when they are scered that they could be harmed.