Southwest Monsoon has been flexing its muscles on & off for the past couple of days, while it remains debatable whether the cloud burst like rains that happened over parts of Kangra district in Himachal Pradesh were Monsoon Rains or Thunderstorms derived out of atmospheric instabilities. Of course there is always a question whether Thunderstorms are a part of the overall Larger Monsoon Circulation. Considering during Monsoon depressions there is more often than not wind convergence triggered thunderstorms in the leaning edges / trailing edges
The current phase of Active Monsoon Conditions incidentally showing its own split personality partially aided by the presence of a East West Shear Zone around the northern parts of Peninsular India. Normally one sees such East West Shear Zone just as the Monsoon makes its onset over Peninsular India gradually moving up under favorable conditions. This shear zone now sitting over parts of Maharashtra, Telangana & Andhra Pradesh is keeping the heaviest spells of rains just south of the shear zone while places in North Konkan is left to fend for scraps as the trough effect is compensated by the shear zone.
The end result of this shear zone is பட்ட காலிலேயே படும், கெட்ட குடியே கெடும் bringing rains to the same region increasing the flood risk. The Global Flood Awareness System from ECMWF indicates parts of Krishna & Godavari basin is likely to see flood levels that may be the highest in 5 years before the end of August. It remains to be seen if the presence of multiple dams in the Krishna Basin modulates the flood flow into the downstream areas.
In the meanwhile yesterday saw monsoon rains over parts of Tamil Nadu aided by the strong surge. Interestingly the friction present between land & sea along the coast intensified the remnant moisture into thunderstorms just off along & off the coast. This phenomenon is the reverse of what happens occasionally during Northeast Monsoon when rains intensify just as the touch the coast of Tamil Nadu. Today once again we could see these fast moving monsoon rains over some parts of North TN with Chennai & suburbs likely to receive one or two spells.