For the past 36 hours or so parts of Kerala particularly places around the High Ranges have been receiving heavy rains on account of a strong wind convergence that has been persisting over Peninsular India creating very highly volatile atmospheric conditions. Places along the West coast over Karnataka and Kerala remain very vulnerable for the next two days due to wind pattern that is not likely to change much due to the presence of East West Shear Zone type of conditions that is evolving very slowly.
With break in monsoon type of conditions continuing the East West Shear zone is a very critical component of Monsoon dynamics getting back on track. This zone typically spawns a low latitude low pressure area over Central Bay region to drag back the Monsoon trough which has moved closer to the foothills of Himalayas creating break in monsoon conditions. During this sequence of events when the East West Shear zone prevails thunderstorms increase over the interior areas of Tamil Nadu as well.
As the east west shear zone climbs up the Westerlies strengthen and bring back the monsoon dynamics as well. Presently what we are seeing is a wind convergence that is providing for the convergence of moist air from the west and drier air through the continental winds from NW creating highly volatile conditions over parts of Central Kerala which is expected to trigger very heavy to extreme rains in a few places potentially triggering flooding risk on account of high levels of water storage in most dams along the Western Ghats.
The risk aggravates for Kerala due to the steep gradients some of the rivers like Chalakudy, Manimala etc have providing for very little advance notice in the event of a cloudburst type of conditions in the ghats triggering flash floods. Similar threat exists for Kanyakumari district as well due to the sudden drop in gradients for rivers like Kodayar providing a very small window for water managers to reach to a sudden burst of extreme rains in the catchment areas.
While rains for Chennai may be touch and go today, we could see one or two days of good rains before the end of the week when the Westerlies streamline as the circulation / East west shear zone type of condition climbs up the latitdue.