The Southwest Monsoon is two days behind schedule, suggests the latest update issued by the India Meteorological Department (IMD) on May 30. The rainfall season would begin in the southern coastal state of Kerala from June 3, the weather body stated.
The onset of monsoon over Kerala has been pushed ahead due to a cyclonic circulation along the coast of neighbouring Karnataka, IMD Director General M Mohapatra said, adding that this cyclonic circulated has hindered the progress of the monsoon winds.
“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 Ministry of Earth Sciences quoted the IMD as saying in a press release.
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.
Due to strengthening of lower level southwesterly winds, fairly widespread rainfall activity with isolated heavy falls are very likely over northeastern states during the next five days.
The normal onset date for the monsoon over Kerala is June 1. This marks the start of the four-month rainfall season for the country.
Earlier this month, the IMD had predicted the arrival of monsoon over Kerala by May 31 with an error margin of plus or minus four days.
On Sunday morning, the IMD, in its daily bulletin, said the onset of the monsoon over Kerala was expected to be around May 31. However, by afternoon it said the onset is expected to be by June 3.
According to the IMD, the onset of the southwest monsoon over Kerala depends on three parameters.
If after May 10, 60 percent 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.
The arrival of monsoon is keenly awaited by scores of Indian citizens, as the season not only provides relief from the scorching heat, but, more importantly, remains crucial for the prospects of lakhs of farmers. According to the IMD, the monsoon is “expected to be normal” this year.