Chennai: Did extreme rain catch IMD off guard?

Chennai and its surrounding districts were pounded by more than 100 and 200 cms of rainfall between Thursday morning till early Friday throwing the life of residents out of gear and leaving three people deadThe state government declared a holiday on December 31 owing to further prediction of heavy rainfall in Chennai Kancheepuram Tiruvallur and Chengalpattu districts due to heavy rainfall as a precautionary measureBut could the three lives have been saved Could the damage to property waterlogging leading to traffic jams on Chennai roads people being stuck in many offices and in general the troubles for the common citizen been avoidedThe India Meteorological Department IMD had in its All India Impact Based Weather Warning Bulletin on Thursday afternoon predicted Thunderstorm accompanied with lightning at isolated places very likely over Tamil Nadu Puducherry and Karaikal and for Friday predicted Thunderstorm accompanied with lightning at isolated places very likely over coastal Andhra Pradesh and Yanam Tamil Nadu Puducherry and KaraikalEven the Qualitative Precipitation Forecast QPF in IMDs Hydromet Bulletin from Chennai did not indicate anything beyond 25 mm rains with a NIL warning for heavy rainfallIt was however the nowcast special forecast for metro cities that warns of changing weather conditions twothree hours in advance that predicted the extreme rainfall in Chennai and surrounding districtsThe IMDs nowcast has a limited reach and most people suffered due to sudden torrential downpour as they had no knowledge of itIMD Chennai had informed the disaster management and other relevant authorities with appropriate colour coding mention an IMD official said Colour coding refers to yellow orange red alerts commensurate to the quantum of precipitationStating that they were expecting the rainfall to increase from Friday but it occurred one day in advance IMDs DirectorGeneral Dr Mrutyunjay Mohapatra said There was a trough in westerly winds and the easterly winds from northeast monsoon was approaching both interacted Large scale wind flow patterns which interacted with each other led to this type of activityK Srikanth who runs a widely followed blog about Chennai weather Chennaiyil Oru Mazhaikkallam but popular as Chennai Rains concurred that nobody predicted yesterdays eventHe uses global model output and IMDs satellite and radar images for issuing warnings forecasts on Chennai Rains social media handles and writing his blogs The models did not show this event at all he saidWhile the focus was on the lowerlevel easterlies bringing in moisture from Bay of Bengal the midtropospheric winds created perfect conditions for the available moisture to develop into intense thunderstorms around Chennai and surrounding Srikanth said adding The sudden change in direction of winds at 55 kms above sea level ASL off the coast of Chennai enhanced the lowerlevel moisture brought in from the BayAlso Read After heavy rains govt offices schools colleges shut in Chennai adjoining districtsThe IMD has predicted further rains on Friday and Saturday which would be heavy but widespread unlike Thursdays rainfallThis story has been sourced from a third party syndicated feed agencies Midday accepts no responsibility or liability for its dependability trustworthiness reliability and data of the text Midday managementmiddaycom reserves the sole right to alter delete or remove without notice the content in its absolute discretion for any reason whatsoever