Tornado Season

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  • Tornado Season
    01.04.2017 18:36

    Recent storms in the USA
    It has been a fairly active start to tornado season in the USA with 153 tornadoes reported in March.  Intense storms broke out on Tuesday and continued into Wednesday morning across parts of Oklahoma and Texas, as a low pressure system pushed a cold front eastwards. The storms brought gusty winds with reports of tennis ball sized hail and several tornadoes.

    Tornado Climatology
    Tornadoes are most commonly seen in the USA between March and June when colder air aloft, along with increasingly warm air near the surface produces the instability and wind shear to form severe thunderstorms. Tornadoes mostly occur east of the Rocky Mountains, especially in a zone reaching from the southern states up into the Midwest, known as tornado alley.  Hot, humid air from the Gulf of Mexico provides the fuel for these storms to develop. Another important factor in tornado formation is wind shear through the atmosphere, whereby wind speed and direction change with height. Severe storms which form under an environment of wind shear can develop rotation and are known as supercell thunderstorms. The rotation from these storms can then lead to the formation of tornadoes. However, they are by no means essential to tornado development.

    Outside of the USA, tornadoes are most frequently seen in areas including Canada, Europe, Bangladesh, China and Australia. The UK actually receives the most tornadoes of any country relative to its land area but most of these are weak. However, stronger tornadoes do occasionally occur in the UK. For example, on 28th July 2005, a storm produced a tornado over Birmingham which brought damage to hundreds of buildings and injured 19 people. The tornado was estimated to have wind speeds up to 130mph.

    The tornado outlook for the USA over the next few days
    An outbreak of severe thunderstorms is forecast to develop tomorrow across parts of Texas and Louisiana as a cold front to the west will come up against very warm and moist air. The storms are expected to bring gusty winds with the risk of large hail and strong tornadoes.

    There is also the slight risk of isolated tornadoes on Monday, as severe thunderstorms develop in the south-eastern states. 

    By: Callum Stewart