U.S. — As Irma makes its way towards the eastern U.S., it has now been upgraded from a tropical storm to a Category 5 hurricane. <br /> <br />Hurricanes are classified into five categories using the Saffir-Simpson scale, with the highest number representing the most powerful storm. <br /> <br />Hurricanes are categorized based on wind speed. The wind speed is measured from an unobstructed area at a point 33 feet (10 meters) above the ground for one minute, according to the National Hurricane Center. <br /> <br />The higher the category, the stronger the winds, and the more damage to be expected. <br /> <br />Storms moving less than 38 mph are classified as a tropical depression, while those moving between 39 to 73 mph are considered tropical storms. <br /> <br />In a Category 1 hurricane, wind speeds blow between 74 to 95 mph. Downed power lines, broken tree limbs, and minor home damage can be expected. <br /> <br />With a Category 2 hurricane, wind speeds are between 96 to 110 mph. There can be "extensive damage" to houses and trees, while power outages can last for days or weeks. <br /> <br />A Category 3 has wind speeds from 111 to 129 mph and the potential to cause "devastating damage" to roof decking and gable ends. <br /> <br />In a Category 4 hurricane, wind speeds range from 130 to 156 mph and have the ability to cause "catastrophic damage," with the possibility of leaving areas uninhabitable for weeks to months. <br /> <br />The last is a Category 5, which has wind speeds of 157 mph and over. During a Category 5, there's a "high percentage" that a home can be totally destroyed.
