The Depression in Bay of Bengal intensified into a Deep Depression last evening and now lies at about 300 kms to the East of Nagappattinam. Over the course of the past 24 hours or so the disturbance has predominantly moved in a Northward direction with a slight skew towards West bringing up the Deep Depression up to 10 N Latitude while continuing to stay east of Chennai longitude. This has meant the bulk of the convection to the Northeast of the disturbance has stayed in the open waters of Bay of Bengal.
This has also meant except for some very light to light rains along the coastal places of Tamil Nadu most of the rains have stayed away from land. With the Deep Depression now expected to gradually take a turn to the west we can expect some bit of near stationary movement from it as it tries to turn around its steering from NNW to WNW. This near stationary movement for the next 12 to 18 hours would mean once again most of the day light hours of today will see very little rainfall activity over the coastal areas of Tamil Nadu.
This slower than expected movement by the Deep Depression has potentially opened a window of unfavorable conditions that could not only put a halt on the intensification but potentially influence the rainfall impact as well. Under the influence of an incoming Westerly Trough increasing wind shear from tomorrow morning could shake the structure of this Deep Depression while the advent of possible dry air from the NE of the disturbance could rob off its moisture supply chain thereby bringing the end game for the deep depession. This could mean the overall rainfall impact may be lesser than the extreme rainfall event which models were forecasting associated with this disturbance. Nevertheless as with any sheared system the chance for isolated extreme rainfall threat continues to persist.
With rains likely to stay away for most of today also we may see some light rains along the caost from Chennai to Delta dts with occasional moderate to heavy spell of rains in a few places. Incease in intensity may be expected from tomorrow