Rains in Tamil Nadu set to comeback, Isolated Rains likely today

Rains in Tamil Nadu went missing since the start of July coinciding with the active phase of Southwest Monsoon in Central India.  Chennai was no different like rest of Tamil Nadu seeing fairly hot and dry conditions during this period.  A casual observation of the Daily Rainfall Chart for TN & Pondy reveals how the rains in Tamil Nadu slowed down during the first fortnight of July.  It is no coincidence this weak phase happened at the same time Central & West India received heavy rains under the influence of the Monsoon Low that traveled along the Northern edges of Peninsular India.   For those who follow Southwest Monsoon actively this phenomenon is not something which is unexpected.  More often than not when the monsoon is very active in the core monsoon zone the thunderstorms possibilities are limited for Tamil Nadu.

With the monsoon trough expected to move closer to the foothills of the Himalayas which indicates a break in monsoon conditions for the core monsoon zone we can expect an increase in thunderstorms possibilities for Tamil Nadu.  One another factor which plays a crucial role in the thunderstorm probabilities is the velocity of Monsoon surge. If the monsoon surge is very strong in the west coast as indicated by very strong Westerlies at lower levels of the atmosphere the thunderstorm possibilities are limited.  Most of us would remember the gusty conditions which prevailed during the early part of the week and little earlier.


As indicated above the monsoon trough is expected to move north closer to the foothills of Himalayas which will give extremely heavy rains for North India particularly around the Terai region & Himalayas while most parts of West Coast sees weak monsoon conditions.  It is at this time the extreme Southern Peninsular India starts seeing thunderstorms once again.

During the next few days we could see conditions turn good for the comeback of Rains in Tamil Nadu.  The first indicator of the changing fortunes was the advent of sea breeze yesterday.  After almost a week or so we could see a strong sea breeze make its entry along the coast of Chennai. The trigger provided by sea breeze resulted in isolated rains in the city.  Today also sea breeze is expected to make a quick entry and possibly trigger thunderstorms over parts of North Tamil Nadu, depending on the support from wind we could see isolated rains in Chennai today.