Slowly and steadily country is inching closer towards the pre-Monsoon season that kick starts from March. This season not only marks the beginning of pre-Monsoon rains and thundershowers in the country but is also know as the pre-Cyclone season for Indian Seas.
There are two cyclone seasons for Indian seas of Bay of Bengal and Arabian Sea, which are pre-Monsoon and post-Monsoon. The pre-Monsoon season spans from March to June, while the post-Monsoon season extends from October to December. June though is an onset month for the Southwest Monsoon, but since it takes 2-3 weeks to establish, the month can host some pre-Monsoon storms.
The origin of these cyclonic storms take place in ITCZ (Inter Tropical Convergence Zone) which starts moving up towards Northern Hemisphere March onward. Thus, making sea conditions conducive in Indian Ocean, Arabian Sea and Bay of Bengal for tropical storms and scores of weather systems that trigger pre-Monsoon rains in the country.
In span of last 20 years i.e. from 2000 to 2019, there have been only three years when there were no storms recorded during the pre-Monsoon season which include 2005, 2011 and 2012. While 10 years saw one storm on each side of the coast, five years saw two cyclones in Bay of Bengal as well as Arabian Sea. 2007 and 2010 were the only two years to witness three storms in both the seas during the season.
2019 had been a record breaking year, with country hosting maximum number of cyclones, 9, in the year gone by. Will this year would be as active as last year for the Indian waters? Let us have a look at the monthwise probability for formation of the cyclones during the pre-Monsoon cyclone season.
MARCH: The month has the least probability for formation of any cyclonic storm. However, if any is formed they tend to fizzle out, well before reaching the coast. As per the records, there is no single storm in March that caused any damage.
APRIL: During this month, probability of formation of a cyclonic storm is more over Bay of Bengal, while it is least over Arabian Sea that is known for cold waters. Also, it is the second half of the month which is more active for hosting a tropical storm.
Main feature of the storms forming during this month is that they usually head toward Myanmar and Bangladesh. Very seldom they re-curve and hit Indian coast. For instance, Extremely Severe Cyclone Fani had made landfall over Odisha coast. In fact, it was the strongest ever cyclone to strike Odisha since 1999.
MAY: This is the peak month for formation of the cyclones, with equal probability in Arabian Sea as well as Bay of Bengal. In Arabian Sea, cyclonic storms forming during this months tends to move towards Oman, Yemen and Somalia coast. They have tendency to dissipate before making landfall, specially in the Northern Arabian Sea on account of cold sea surface temperatures. But, as reiterated above, very few re-curve and threaten Gujarat coast but no storm has directly hit Gujarat coast in the pre-Monsoon season since 2000. There was an extremely severe cyclonic storm in 2001 that has threaten Gujarat but had fizzled out before reaching the coast.
In Bay of Bengal, majority of the storms head towards Bangladesh, while few also move towards West Bengal.
JUNE: Probability of cyclonic storms are much more in Arabian Sea than Bay of Bengal during June. One forming Arabian Sea also move towards Yemen and Oman but most storms are for shorter duration and dissipate in the sea itself. Storm Gonu has been only one super cyclone during the pre-Monsoon season since 2000.
Bay of Bengal has hosted only one storm since 2000. Cyclone Yemyin in 2007 had made landfall near Kakinada, Tamil Nadu. Meanwhile, Arabian Sea had two exceptions Cyclone Gonu in 2007 and Cyclone Vayu in 2019 . However, they both dissipated before making landfall.
The cyclones forming during this month are of prime importance since they collide with the onset of Southwest Monsoon. It is seen on several occasions that these cyclones delay the onset of Monsoon over the Indian mainland of Kerala. In fact, it has the maximum impact on the progress of Monsoon which becomes sluggish under such circumstances.
PREDICTION FOR PRE-MONSOON SEASON 2020
While 2019 was a record breaking year that had kept both Arabian Sea and Bay of Bengal active, this year seems to be a normal one. Formation of cyclones has strong linkages with El Niño and IOD (Indian Ocean Dipole), where in the earlier one was present during the pre-Monsoon season 2019 while the latter one was strong prevalent during the post-Monsoon season 2019. As a result, we saw highest number of cyclones in the Indian history.
However, this year, both the oceanic parameters El Niño as well as IOD are in the neutral phase. Thus, we do not expect rigorous activity in the Indian seas, at least during the pre-Monsoon season. Weathermen are predicting that the chances of ant tropical storm is very less in March and that we do not expect any storm before April.
Image Credit: NDTV
Any information taken from here should be credited to skymetweather.com