After fair bit of stuttering for the past two weeks things look good for a phase of active monsoon over Peninsular India. After stalling for nearly two weeks Southwest Monsoon has started to climb up gradually covering more parts of Central India. As of today except for Punjab, Haryana, Uttrakhand, HP, Delhi, J&K and Ladakh all other states has seen monsoon check in. A small portion of Uttar Pradesh around Jhansi has also seen Monsoon move in along with surrounding MP. IMD expects further progress of Monsoon in the coming days over remaining areas of Central India.
Two cyclonic circulations on either side of Peninsular India embedded in a large East West trough is driving monsoon ahead. Weather models indicated a very strong surge so far in real time monsoon conditions are slightly weaker than model estimates. Nevertheless the rainfall meter has started to tick along the Peninsular West Coast. Stations along the Ghats has not yet started to bring in the huge numbers normally associated with active monsoon conditions. The early morning satellite image though looks much better than the past couple of days. Possibly compared to model estimates there could be a lag in the strengthening of the monsoon dynamics.
This phase of active monsoon conditions for the next few days may be a welcome boon for Cauvery catchment areas. With the Mettur opening date of 12th June missed once again this spell of active monsoon may bring good inflows into Cauvery. The combined storage in Cauvery Basin dams at Karnataka stand at 38.5 TMC as of yesterday. While this is higher than last year’s 31.3 TMC things look bad when Mettur is brought into the equation. The overall storage this year with Mettur added is at 50.3 TMC while it was 89.6 TMC last year. Every bit of rain now becomes critical to improve the storage.
Look a little deeper a potential question mark though for Peninsular India though next few days may see active monsoon. Since the end of May MJO has been struggling against the transition base state over Pacific from Nino to Nina. This has prevented MJO to complete its canonical propagation for a global circuit. Weather models indicate a fresh pulse to start its journey from Indian Ocean by June end / July beginning. The caveat though when this pulse moves into Maritime Continent it may trigger a northward moving MISO. This northward propagating monsoon intra-seasonal oscillation may favour Gangetic Plains and adjoining Central India.
Sub seasonal weather outputs also indicate in this direction with weaker than normal monsoon dynamics as we head into July. Considering the fluid monsoon dynamics this could change as well with base Nina state strengthening. As the old saying goes let us cross the bridge when it comes. In the meanwhile it is time to look at current phase of active monsoon conditions. North Kerala, South coastal Karnataka and adjoining Malenadu region is likely to enjoy widespread heavy to very heavy rains for the next couple of days. Considering the pronounced North bias in models like ECMWF we can expect parts of Central Kerala also to come under very heavy rains.
Remnant moisture from the west may continue to trigger isolated thunderstorms over North Coastal TN. As was the case yesterday the storms may move very fast leading to short duration sharp burst of rains which may not happen at all places. Towards the second half of next week there could be another spell of thunderstorms for places like Chennai. More on that as we get closer to the event and there is better consistency among models.