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Why did cyclones give October a miss?

  • Posted By
    10Pointer
  • Categories
    Geography
  • Published
    7th Nov, 2020

This year, October passed without witnessing a cyclonic storm.

Context

  • This year, October passed without witnessing a cyclonic storm.

Key points

  • October to December period is among the favourable months for the development of cyclones in the Bay of Bengal and the Arabian Sea.
  • India’s east and west coasts are prone to cyclones with the maximum associated hazards such rain, heavy winds and storm surge.

Cyclonic disturbances

  • Cyclonic disturbance occurs either in the form of a well-marked low pressure, depression or a deep depression.
  • It is weather systems with varying wind intensities ranging from 31 – 61 km/hrformed either over sea or land, and are common in October.
  • Ocean disturbances enter the Bay of Bengal from the South China sea side and head towards the Indian coast.

Reasons behind no cyclone in October

  • IMD officials have attributed it to the weak La Nina conditions along the equatorial Pacific Ocean.
  • Cooler than normal sea surface temperatures over this region, termed as La Nina, has been prevailing since August this year.
  • Madden Julian Oscillation (MJO) was positioned in a favourable phase, the low-pressure systems intensified maximum up to a deep depression.
  • There was the high wind shear noted between the different atmospheric levels, last month.
  • The vertical wind shear created due to significant wind speed difference observed between higher and lower atmospheric levels prevented the low-pressure systems and depression from strengthening into a cyclone.
  • MJO is kind of an eastward-moving cyclic weather event along the tropics that influences rainfall, winds, sea surface temperatures and cloud cover. They have a 30 to 60-day cycle.

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