Putting all the speculations of delayed onset on rest, Southwest Monsoon 2018 is knocking the door. According to Skymet Weather, not only the much-awaited arrival of Southwest Monsoon 2018 over Kerala will be on time but with a bang too.
Skymet Weather has already predicted that Monsoon would make an onset over Kerala on May 28, with an error margin of +/- 2 days. On Friday, the Monsoon made an onset over over Some parts of Southeast Bay of Bengal, South Andaman Sea and Nicobar Islands. The Northern Limit of Monsoon (NLM) is currently passing through latitude 5°N and longitude 80°E, 8°N and 87°E, Car Nicobar and 11°N and 99°E.
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Although cyclonic storms Sagar and Mekunu in Arabian Sea did play spoil sport initially in terms of slightly delaying the arrival of Monsoon current over Andaman and Nicobar Islands. However, courtesy the system moving far away, Monsoon 2018 is all set to cover Andaman and Nicobar Islands anytime now.
As reiterated earlier, onset of Monsoon has no relation with its progress as well as the performance. There have been several occasions in the past when Monsoon has even progressed further with a span of 24 hours of making onset.
According to Skymet Weather, present weather conditions are already indicating that all the criteria required for Monsoon are likely to be met, favouring its timely arrival.
Presently, a thick cloud mass is seen in the neighbourhood of southern peninsular, on both side in Arabian Sea as well as Bay of Bengal. Usually for the Monsoon onset, we give more weightage to Arabian Sea and adjoining parts India Ocean.
As mentioned before, we can expect a strong onset of Monsoon and the credit would go to Madden–Julian Oscillation (MJO). MJO is a wave of cloud and rain which moves in equatorial region from west to east and is a transient feature.
It is currently moving in favourable zone i.e. Indian Ocean, thus controlling the weather activities in Indian waters at the moment. MJO, when in Indian Ocean, is instrumental in cyclogeneses, as a result enhancing the rainfall over the Indian region.
As the progress, the onset of Monsoon is also different every year. No two Monsoons have behaved in similar patterns. Although there are three criteria for the arrival of Monsoon, out of which rainfall is the main feature. The other criteria are Wind field and Outgoing Longwave Radiation (OLR).
With cyclonic circulations in both Arabian Sea and Bay of Bengal getting more marked, the rainfall criteria of 60% of the specified 14 stations—Minicoy, Amini Devi, Thiruvananthapuram, Punalur, Kollam, Allapuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, Kannur, Kudulu and Mangalore report rainfall of 2.5 mm or more for two consecutive days have been already met.
Further, this rainfall feature is directly linked with the OLR, whose value should be below 200 wm-2 in the box confined by the Latitude 5-10°N and Longitude 70-75°N.
However, wind field might be variant on account of active systems in neighbourhood. Smooth, steady and uniform wind field over the specified area is only during the Monsoon surge and in absence of any weather system in immediate neighborhood.
Image Credit: NDTV
Any information taken from here should be credited to skymetweather.com
