One of the key things that come up with better observations is long term record keeping. This long term record keeping serves as a good remainder to how things happened many years back decluttering some of the noise that comes around “Climate Change and Global Warming”. August 2023 set many unwanted records as Southwest Monsoon went through a complete collapse of monsoon dynamics. The country as a whole saw a deficit of 36% during the month of August with South Peninsular India seeing a whopping 60% deficit during the month. The cumulative rainfall of 161.7 mm nationally during the month of August is the lowest since 1901 beating the earlier record of 191.2 mm set during the year 2005. Both Central India and South Peninsular India, part of the core monsoon region, saw the lowest recorded rainfall during August since 1901. Incidentally Kerala not only recorded its lowest monthly rainfall during August since 1901 with just 59.7 mm but also the lowest cumulative rainfall between June and August as well.
The poor monsoon performance not only reflected in record breaks as far as rains go but also showed up in anomalous temperatures as well. 2023 August saw the highest All India Maximum and Mean temperatures during the month of August and 2nd highest minimum temperatures since 1901. South Peninsular India saw its highest Maximum, Mean and Minimum temperatures since 1901 in a fair state of reflection of how poor monsoon was over Peninsular West Coast.
As the saying goes “There is always light at the end of the tunnel” monsoon could go through a much needed revival on the back of a favorable passage of MJO over Indian Ocean and adjoining Maritime Continent. If one remembers one of the biggest strengths for Monsoon during the month of July was the conveyor belt of disturbances that moved into Bay of Bengal from Maritime Continent as MJO struggled to move further west against the base state of El Nino. This time around models expect a quick passage over Indian Ocean and possibly a successful transit from Maritime Continent to West Pacific Ocean.
This potentially gives a window of at least 15 days for Monsoon to revive over West Coast and bridge some of the gap. While it may not be possible to completely bridge the gap for basins like Cauvery and for states like Kerala a near normal or slightly above normal September will go a long way in mitigating the effects of a poor August. Not to forget there is a slight chance October first fortnight could also be good in case the transit to West Pacific from MTC gets delayed contrary to model estimates. Hopefully this shaking off large scale suppression over the Indian Sub Continent kicks restores normalcy and ensures Northeast Monsoon passes through without any issues this year.
Before the monsoon picks up though there is still a three day window for the leeward areas of Tamil Nadu to catch up some thunderstorms. Places like Bengaluru which saw an extremely poor August got widespread rains last night and similar conditions are seen today and tomorrow as well for South Interior Karnataka and adjoining Northwest Interior Tamil Nadu.
While North coastal Tamil Nadu has already completed the seasonal southwest Monsoon tally with September still to be done the upcoming spell of rains over the next couple of days will add a sizeable amount to the seasonal tally. Additionally in the event multiple circulations evolve over Bay of Bengal during September each of these will give a window of one or two days of thunderstorm activity to North Coastal Tamil Nadu through wind convergence to keep the rain meter ticking at regular intervals.