What is a twister? Why are the majority of twisters observed in areas around the Gulf of Mexico?

A twister is a violent windstorm, often land based, characterised by a twisting funnel-shaped cloud. In the United States, twister is used a colloquial term for tornadoes. While they occur in many parts of the world,  the United States experiences the most: more than 1,000 per year have been reported every year since 1990 in the U.S.

The latest tornado activity comes after dozens of twisters were reported in the Plains and Ohio Valley in the USA. 

Other countries experience tornadoes, including Germany, Australia, South Africa, eastern China, Japan, Bangladesh, Argentina, and more.

Mechanism of formation of twisters:

• Wind Shear – The Role of Thunderstorms (Supercells): 

• Winds moving in different speeds and directions at different altitudes cause the rising air to start spinning. 

• The rising, moisture-laden plume in a thunderstorm is called an updraft. 

• Formation of a Mesocyclone (Rotating Updraft): Lifting mechanisms can include fronts, drylines, outflow boundaries and other entities in which there is a density difference.
• Formation of the Tornado: Instability is what allows air to rise once lifted to produce explosive storms.

Reasons why majority of twisters observed in areas around the Gulf of Mexico

• • Unique geography – 
    • flat terrain, Great Plains and Mississippi river valley, which can heat up quickly most times of the year, creating pockets of rising warm air.
    • Presence of Rockies – helps in sinking down of the airmass.

• Presence of Hot Humid air: Westerlies from the west coast – From the Gulf of Mexico

• Presence of cold dry air: Incoming of the cooler air from the Upper Great Plains and Canada.
• Increased humidity:  from the winds originating from Gulf of Mexico and Moisture released by the region’s vegetation→heavy downpour and hailstorms.

The extent of above conditions determine the longevity of twisters in the central US and these ingredients often come together perfectly several times a year, making the region famous as  “Tornado Alley”.

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