Mumbai: The monsoon entered Andaman-Nicobar and the South Arabian Sea earlier than usual this year. The monsoon in Kerala is expected to start on May 27, according to the Indian Meteorological Department (IMD). However, the monsoon, which started earlier than normal, seems to have slowed down in the north.
How is the arrival of monsoon announced in Kerala?
After 10 minutes, at least 60 per cent of the 14 meteorological stations in Kerala received 2.5 mm or more of rain for two days in a row, while the next day the monsoon arrives in Kerala. However, other factors are also taken into account.
Other criteria for announcing the arrival of monsoon in Kerala are as follows:
– From the equator to ten north latitudes and 55 to 80 east longitudes, the winds coming from the west should have reached an altitude of 4 km above sea level.
– In areas of 5 to 10 north latitude and 70 to 80 east longitude, wind speed should be 27 to 35 kmph up to about 800 meters above the ground.
– The value of outgoing longwave radiation (energy emitted from the ground into space) between five to ten north latitudes and 70 to 75 east longitude should be less than 200 watts per square meter area. This means that there should be enough clouds over that area.
The arrival of monsoon in Kerala is announced if the technical criteria like rain, wind and cloud cover are met. When the monsoon arrives in Kerala around June 1, the monsoon travels further north. The northern boundary of monsoon progress is generally determined by the area of rainfall moving northwards.
Why is the progress of monsoon slowing down now?
– Although monsoon winds from the southern hemisphere crossed the equator and entered the Arabian Sea, they are currently heading northwest towards the west coast of India. According to meteorologists, the monsoon will be strong enough when the direction is west-southwest.
– Maiden Julian Oscillation (MJO), a region of clouds moving eastward in the tropics, is expected to be unfavorable for India by the end of May. The region is expected to return to favorable conditions for India from June 8, following which various meteorological models are predicting an increase in rainfall.
According to the IMD’s department-wise forecast, below-average rainfall is expected in 30 of the 36 meteorological sub-divisions of the country during the week of May 27 to June 2. During the week of June 3-9, 27 out of 36 sub-divisions may receive below average rainfall. The low rainfall states will include states in all parts of the country, including Maharashtra, the IMD estimates.
