Thiruvananthapuram/New Delhi: The arrival of monsoon over Kerala is likely to delayed by two days and it is now expected to make an onset over the state by June 3, the India Meteorological Department (IMD) said on Sunday.
IMD Director General M Mohapatra said there is cyclonic circulation along the Karnataka coast which is hindering the progress of the southwest monsoon.
"The southwesterly winds could strengthen further gradually from June 1, resulting in likely enhancement in rainfall activity over Kerala. Hence the monsoon onset over Kerala is likely to take place around June 3," the IMD said.
Due to strengthening of lower level southwesterly winds, fairly widespread rainfall activity with isolated heavy falls are very likely over northeastern states during next five days.
However, Skymet Weather, a private forecasting agency, said monsoon has already made an onset over Kerala.
G P Sharma, President (Meteorology) of Skymet Weather said it is a "very weak onset" this year.
Skymet Weather had earlier predicted that monsoon will make an onset over Kerala on May 30.
Kerala has received summer rains in excess this year, which bypassed the showers received in 2018. All districts south of Thrissur received more rains after 2018, while in the north, only Kannur got excess rain than in 2018.
Water levels in the State’s dams have touched a five-year high with the reservoirs’ catchment areas receiving torrential rain over the past few days. The dams have been filled 35.40 per cent, up seven per cent from the corresponding day a year ago, a rarity before the monsoon.
The Arabian Sea as well as the Bay of Bengal witnessed two cyclones - Tauktae and Yaas – in May. Several parts of the country have witnessed an intense rainfall activity due to these two circulations.
The normal onset date for monsoon over Kerala is June 1. This marks the start of the four-month rainfall season for the country that accounts for 80 per cent of the country's rainfall.
Earlier this month, the IMD had predicted the arrival of monsoon over Kerala by May 31 with an error margin of plus or minus five days.
Monsoon is expected to be normal this year.
According to the IMD, the onset of the southwest monsoon over Kerala depends on three parameters.
If after May 10, 60 per cent of the 14 stations – Minicoy, Amini, Thiruvananthapuram, Punalur, Kollam, Allapuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, Kannur, Kudulu and Mangalore report rainfall of 2.5 millimetres or more for two consecutive days, the onset over Kerala be declared on the second day, provided other two criteria are also in concurrence.
This has to be supplemented by the wind speed. The depth of westerlies should be maintained up to 600 hectopascal (hPa), in the box equator to Latitude 10-degrees north and Longitude 55 degrees to 80-degrees east. The zonal wind speed over the area bounded by Latitude 5 to 10-degrees north, Longitude 70-80-degrees east should be of the order of 15 20 knots at 925 hPa.
The Outgoing Longwave Radiation (OLR) should be below 200 watt per square meter (wm-2) in the box confined by Latitude 5-10 degrees north and Longitude 70-75 degrees east.
Sharma said all the IMD parameters are fulfilled to declare the onset of Southwest Monsoon over Kerala.
"In the absence of any major monsoon trigger, the onset may be slightly mild. Conditions are favourable for its further advancement to more parts of the south peninsula and east-central Bay of Bengal. Timely progress is expected over northeast India," Sharma said.
Mohapatra said the depth of westerlies is not as much as it is expected. Plus, the rainfall parameters remain unfulfilled to declare onset of monsoon over Kerala.
(With PTI inputs)