Southwest Monsoon all set for Green Signal

Weather Update
Reading Time: 3 minutes

For the past week to 10 days Southwest Monsoon progress has to come to a grinding halt over both arms. In a rare instance Monsoon simultaneously made onset over Kerala and Northeast India at the same time on 30th May. Except for covering parts of Sikkim on 31st the eastern arm of Southwest Monsoon pretty much collapsed. For the past 3 weeks it has stalled over the Bangla / West Bengal border resembling a cross border tourist who has lost his passport.

After onset the western arm stuttered its way up to Mumbai latitude making weak onset in the process. For the past 10 days or so Southwest Monsoon has been rooted around Mumbai latitude. As Monsoon dynamics collapsed completely North India bore the brunt of extended heat wave conditions. Many places in the region saw night time temperatures hit 35°C leading to extreme heat stress with no respite.

However the weak monsoon conditions gave a bonus window of thunderstorms for leeward Tamil Nadu. Being a leeward state the plains of Tamil Nadu do not benefit directly from Southwest Monsoon. Convective thunderstorms that gets enhanced under weak monsoon conditions that provide bulk of rains for places like Chennai. Over the recent years Southwest Monsoon has been contributing more to annual rainfall of Chennai. The IMD observatory at Chennai AP now has recorded 15 cms or more for the 3rd straight year. To give a perspective roughly 6 cms is the monthly average for the month of June. While Chennai AP scored nearly 250 mm most parts of the city also received excess rains during this weak monsoon phase.

With the monsoon expected to pick up gradually from now on Chennai can get back to spectator mode. Both operational and sub seasonal weather model forecasts indicate an active phase of Monsoon for the next couple of weeks. In a much needed revival wind charts indicate strengthening of lower level westerlies from today over Arabian Sea. Gradually towards the weekend / early next week a surge in monsoon dynamics is expected. A pair of cyclonic circulations, one after the other, is expected to drag monsoon onset across the Indian sub continent.

Over the next few days we can expect monsoon to cover more areas of East and Central India gradually pushing its way towards Gangetic Plains. This will bring about a reduction in temperatures as well over North India pulling curtains on the heat wave. Peninsular West Coast can also look forward to the return of widespread heavy to very heavy rains from the weekend. As the surge picks up we can expect rains to increase along the Ghats as well with moisture getting pushed across. While it may be too early to look for some improvement in the Cauvery basin things are turning positive though.

The leeward areas of Tamil Nadu will see a substantial reduction in thunderstorms from today. At the same time we can expect places along the Ghats and South TN like Kanyakumari to see increased rainfall activity. During the weekend few places in the Nilgiris ghats may see very heavy rains as the surge picks up. There is a slight chance on Sunday parts of North TN may see some fast moving thunderstorm due to increased moisture from West. But overall from today the late evening / night slow moving thunderstorms dumping heavy rains will take a break.