Reasons for Delay
The Monsoon is an oceanic and atmospheric phenomenon wherein a number of parameters play a significant role. Only rainfall cannot be construed as manifestation of Monsoon. Along with rain, humidity, wind direction, wind strength and Outgoing Long Wave Radiation (OLR) that are in the Indian Ocean, in the proximity of the onset area need to meet the stipulated standards. Absence of any one of the criteria puts a question mark on the onset of Monsoon.
The clouds and winds in the area also need to be organized and persistent. Cloud build up on either side of the sea was looking promising till a few days back for the timely onset over Kerala. However, it slowed down and became a little diffused and unorganized. The cloud cover is also thin. So the OLR is on the higher side of the stipulated values.
The winds, one of the major parameters are currently northwesterlies instead of southwesterlies or westerlies, due to a high pressure area (Anticyclone) over the Arabian Sea. The anticyclone has to become insignificant for the winds to change their direction and assist in Monsoon.
The last factor is rainfall, which has to be widespread and must sustain for a longer period of time. Currently Peninsular India including Kerala is experiencing some rainfall activity, but they are patchy and moderate in intensity. For example, Kochi and Kottayam in Kerala have recorded 39.4 mm and 31.4 mm of rain, respectively in 24 hours, from 8.30 am on Sunday. While the state capital Thiruvananthapuram has observed only 15 mm of rain. Other than a few places, there’s not much rainfall in the state. Therefore, it can be said that Kerala is still observing pre-Monsoon rain.
However, weather models at Skymet indicate that the anticyclone is becoming less marked and may disappear by June 3 or June 4. This will allow the Monsoon parameters to fall in place, which will in turn help in the onset.
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