Over the past few days Peninsular West coast has been fairly in active in terms of rainfall. Since 18th August the daily rainfall chart for Kerala has been below normal. In our last post we talked about how the rainfall deficit for Kerala during August was at 27%. This has now increased to -37% as of yesterday indicating the weak monsoon dynamics. Similarly Kanyakumari district in Tamil Nadu is currently on -44% for the month of August. Any active spell has been brief with the drier spells extending for longer duration. Overall Southwest Monsoon has seen its 4th active spell since the start of the season with 2 breaks, both in August, interspersed.
With back to back monsoon low impacting Central India under the favourable influence of MISO next few days may see active spell continue. The development of a fresh monsoon low over Northwest Bay though provides a window for rains to return over Peninsular West Coast. The window though may be once again brief for the southern parts. Kerala, TN Ghats and Kanyakumari district. Over the next 3 / 4 days we may see favourable monsoon dynamics along the Peninsular West Coast.
As the monsoon low continues its WNW journey over Central India from later parts of this week rains may once again slow down. Sub seasonal weather forecasts confirm a positive rainfall anomaly for this week for Peninsular West Coast. It is followed by negative rainfall anomaly next week over large parts of Peninsular India. One area though that may see enhanced thunderstorm activity is South TN and Delta districts. This reason for enhanced rains over these areas may be weaker westerlies.
Over the next couple of days parts of North Tamil Nadu may see moderate thunderstorms in a few places. Mid tropospheric wind convergence under the influence of the developing low may provide platform for these thunderstorms. With stiff westerlies the storms may move fast thereby giving a sudden burst of rains unlike last week. Last week steering was fairly poor so thunderstorms dumped a lot of rains over Chennai and suburbs.