The Atlantic Ocean has seen a historic record number of 30 tropical storms till November 30 this year, the World Meteorological Organisation (WMO) has said. The previous highest number was 28 storms in 2005.
The high number of storms has meant that, among other things, the WMO’s annual list of storm names for a calendar year was exhausted by September and it had to use Greek alphabets to name the storms thereafter.
Interestingly, this list — comprising male and female names — is used alternatively to identify the storms formed in the Atlantic Ocean. It contains names starting with 21 alphabets, excluding those with Q, U, X, Y and Z. Normally, the Atlantic Ocean experiences 12 storms annually and this list often remains fully used.
But given the frequency of hurricanes formed in 2020, the WMO has had to, so far, make use of nine Greek alphabets — Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta and Iota. It is only the second time ever, after 2005, when Greek alphabets were used to name Atlantic storms.
Meteorologists world over observe that 2020 continues to remain a very active year, favouring formation of cyclonic storms and hurricanes across the world.
Here, in the north Indian Ocean region — the Bay of Bengal and the Arabian Sea together, Super cyclone Amhpan (May), cyclones Nisarga (June) and Gati (November), severe cyclone Nivar (November) and the recent cyclone Burevi developed this year. Normally, India records five cyclones in a year, of which four originate in the Bay of Bengal.
Six of the 13 hurricanes developed in the Atlantic Ocean till November 30 were major hurricanes. Of the total 30 hurricanes, 12 made landfall in the continental US.
“This is the second highest number of storms on record and the second-highest number of hurricanes on record in the Atlantic Ocean,” stated a WMO report.
Along with frequent hurricanes, the WMO observed that most of these systems showed rapid intensification and relatively slower movement. Only 10 hurricanes — Hanna, Laura, Sally, Teddy, Gamma, Delta, Epsilon, Zeta, Eta and Iota — displayed remarkable strengthening within a very short duration.
The prevailing La Nina conditions, coupled with inter-related ocean atmospheric conditions linked to warm Atlantic Multi-Decadal Oscillation, led to such a record number of storms, said the WMO.
La Nina is a phenomenon when cooler-than-average sea surface temperatures are recorded along the equatorial and central Pacific Ocean.
“Stronger west Africa monsoon and weak wind vertical shear coming off Africa were all favourable for the storm formation,” read the WMO statement.
Meteorologists, including experts at the India Meteorological Department (IMD), have noted the warmer-than-normal ocean temperatures and linked the phenomenon to climate change. “We have noted warmer sea surface temperatures in the north Indian Ocean,” said Dr D Sivananda Pai, head of Climate Research and Services at IMD, Pune.
This is the main reason for the longer-than-average cyclone season and numerous events of rapid intensification, said Jim Kossin of National Centres for Environmental Information, operating under NOAA.
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