Over the last few years this blog has been in existence we have mentioned often how the transit of Sun is the driver of Monsoon seasons over Indian Sub Continent & Australia. We have also explained many a time the importance of Inter Tropical Convergence Zone (ITCZ), an active zone of convergence that follows the transit of Sun with a lag that plays a crucial role in these rainfall seasons.
With the angle of Sun’s Rays now falling over parts of Tamil Nadu on its way towards Tropic of Cancer we can look forward to the arrival of ITCZ over the Northern Hemisphere. While ITCZ moves up towards the Indian Sub Continent eventually becoming the Monsoon Trough during peak Southwest Monsoon season it plays a crucial role for Pre Monsoon & Post Monsoon thunderstorms during its transit from and towards Equator.
The wind and satellite charts indicate a certain amount of seasonal state of flux around Equator possibly in conjunction with the transition period. The ITCZ is possibly straddling the Equator though the clouding pattern appears it is may be little south of Equator. In the coming days ITCZ is expected to move further up This movement will enhance the thunderstorms as well over Peninsular India triggered by the seasonal wind change from Easterlies to Westerlies. When the trade winds reverse the Northward progress of ITCZ starts hastening as well finally culminating in the arrival of Southwest Monsoon.
On the thunderstorm front the wind instability is likely to remain along the Western Ghats consequent to the Easterlies remaining firmer than normal for this time of the year. Consequent to the Easterlies remaining firmer, especially around Sri Lanka latitude also means places like Thoothukudi are enjoying a spell or two of mid night / early morning rains once in a few days.