Typhoon Haiyan was one of 80 to 100 tropical cyclones which develop globally each year. Although many of these form and dissipate over the ocean, a number make landfall and can cause considerable damage to property and loss of life.
A tropical cyclone is the generic term for a low pressure system over tropical or sub-tropical waters, with organised convection (i.e. thunderstorm activity) and winds at low levels circulating either anti-clockwise (in the northern hemisphere) or clockwise (in the southern hemisphere). The whole storm system may be five to six miles high and 300 to 400 miles wide, although sometimes can be even bigger. It typically moves forward at speeds of 10-15 mph, but can travel as fast as 40 mph. At its very early and weak stages it is called a 'tropical depression'. When the winds reach 39 mph it is called a 'tropical storm'. If the wind should reach 74 mph or more the tropical storm is called a 'hurricane' in the Atlantic and the north-east Pacific or a 'typhoon' in the north-west Pacific. In other parts of the world, such as the Indian Ocean and South Pacific the term 'cyclone' or 'tropical cyclone' is used.
Typhoon Haiyan occurred in November 2013 and struck the central Philippines causing devastation due to its exceptionally strong winds and storm surge. Sustained winds averaged over 1-minute were estimated to be near 195 mph at landfall and the central pressure estimated as 895 mb. Typhoon Haiyan is likely to be the strongest tropical cyclone (in terms of wind speed) to make landfall on record. There are other tropical cyclones which were of a similar strength whilst still at sea, but Typhoon Haiyan joined an elite group as one of the strongest tropical cyclones on record. For more information on tropical cyclone intensity records see the NOAA Tropical Cyclone FAQ.
Regional Specialized Meteorological Centres have responsibility for the issues of tropical cyclone warnings in their area and should be used as a first source of information.
StormTracker provides a mapped picture of tropical cyclones (tropical storms, hurricanes, typhoons) around the globe with access to track history and six-day forecast tracks for current tropical cyclones from the Met Office Unified Model and latest observed cloud cover (infra-red and visible satellite) and sea surface temperature.StormTracker
The Met Office maintains a Twitter feed on storms which includes regular updates on latest tropical cyclones worldwide.