The onset of the Southwest Monsoon over Kerala is likely to be slightly delayed this year from its normal date, which is June 1, according to the IMD.
The monsoon's onset over Kerala is now likely to be on June 4 with a model error of plus/minus 4 days, the Kerala State Disaster Management Authority said quoting the IMD report.
Here is how IMD monitors the arrival of monsoon:
The IMD monitors the arrival of monsoon by recording the rain data at the 14 weather stations located at Lakshadweep, Kerala and in Karnataka's Mangaluru.
From May 10 onwards the officials monitor the rains and if 60 percent of the stations or more record 2.5 mm of rain for two consecutive days, then it satisfies the criterion that the monsoon has arrived.
Wind, clouds as indicators
Another yardstick that the IMD looks at is the strength of wind.
Cloud movements are also a key indicator for the weathermen when it comes to announcing the monsoon.
In the past decade, the IMD operational forecasts have turned out to be correct.
(With inputs from IANS)
