Monsoon – 2017 onset over Kerala


Southwest monsoon has set in over Kerala today i.e. 30th May 2017. It has also advanced into some parts of northeastern states (some parts of Nagaland, Manipur, Mizoram and Arunachal Pradesh.

Major features associated with onset of monsoon and advance

 Widespread rainfall occurred over Kerala, during past 2 days. 78% of monitoring stations for Monsoon onset over Kerala have reported rainfall for the last 48 hours.

 Westerly wind has strengthened in the lower levels (upto 20 knots) and deepened (upto 4 km) over the southern Latitudes. Westerly/ Westsouthwesterly winds were observed approximately upto 4.5 km over the south Arabian Sea (equator to Lat. 10oN and Long. 55oE to 80oE).

 There is persistent cloudiness from 27th May onwards. The Satellite (INSAT-3D) derived Outgoing Long wave Radiation over the region is less than 200 W/m2 .

In addition to the above features, the following developments are also noticed.

 An off-shore trough at mean Sea level runs from north Maharashtra coast to north Kerala coast.

 The Severe Cyclonic Storm ‘Mora’ over Bay of Bengal made land fall over Bangladesh coast today forenoon.

Northern Limit of Monsoon as on 30 May, 2017

  • Southwest monsoon has further advanced into some more parts of south Arabian Sea, remaining parts of Maldives –Comorin area, southern parts of Lakshadweep area, Kerala and Tamil Nadu, some more parts of southwest Bay of Bengal, remaining parts of southeast Bay of Bengal, some parts of west central Bay of Bengal, most parts of east central and northeast Bay of Bengal and some parts of Nagaland-Manipur-Mizoram and Arunachal Pradesh.

  • The Northern Limit of Monsoon (NLM) passes through Lat. 10 oN / Long. 60oE,

Lat. 10 oN / Long. 70oE, Kochi, Tondi, Lat. 14oN / Long. 87 oE, Lat. 17 oN / Long.oE, Lat. 20oN / Long. 91 oE, Aizwal, Kohima and Deomali. (Fig-1).

Forecast for further advance of Monsoon Conditions are favourable for further advance of southwest monsoon into remaining parts of south Arabian Sea, Lakshadweep area and Kerala, some parts of central Arabian Sea, coastal & south interior Karnataka, some more parts of Tamil Nadu, southwest, west central & east central Bay of Bengal, most parts of northeast Bay of Bengal and some more parts of northeastern states during next 3- 4 days.