Pre-Monsoon activities during March were more intense over North West and Central India. East North East and South Peninsula remained almost dry with on and off rain and thundershower activities. That is why these areas remained rain deficient during the month of March.
As of April 1st, the country was rain surplus by 46%. Central India remained best performer with a surplus of 211% followed by Northwest India which remained surplus by 80%. On the other hand, East and North-East India were rain deficient by 31%, South India was deficient by 14%.
Reason for surplus rain over North West and Central India could be attributed to the number of Western disturbances and confluence zone which persisted over Central parts of the country. Western disturbances gave good rain and thundershower over North West India and the confluence zone was responsible for intense pre-monsoon activities over Central India during March.
Overall rain surplus reduced over country from 46% to 25% by the end of April. As on April 30, the countrywide rain surplus has reduced to 25%.
Rain surplus of Central India reduced to 150%, North West India came down to 38%. Whereas rain deficiency of East and North East India reduced to 15% from 31%. South Peninsula which was deficient by 14% has become rain surplus by 14% as on April 30.
There was significant increase in pre-monsoon activities over East and North East India since the second week of April and are continuing until now. Cyclonic circulation persisted over North East India and Bangladesh. Humid winds from Bay of Bengal are dumping moisture over East and North East. Occasional troughs are also formed over East India. These weather parameters enhance pre-monsoon activities.
On the other hand, the South Peninsula also recovered and became rain surplus by 14%. Wind discontinuity formed and persisted from the Central part of the country to south Tamil Nadu. Moisture feed continued from the Bay of Bengal as well as from the Arabian Sea. Kerala and coastal Andhra Pradesh witnessed few heavy to very heavy spells during April.
We expect pre-monsoon activities to continue over many parts of the country until the first week of May. March and April did not witness any significant heatwave activity, we think that until the first week of May temperatures will not heat up much. Heatwave will commence over many parts of the country during the second and third week of May.