There is a good chance of a Depression forming during 2nd week of May. Early forecasts call for it heading towards Andhra coast. At the moment it does not look like affecting TN.
Lets first see the postive factors
1. Dipping of Jetstreams – When a jet stream dips, it creates upper divergence and there by increasing convergence at lower levels. These rains are always intense and are associated with hails.
2. The upper trough is caught between two HPA and a valley like trough is created. The sharper the trough the more the intense the rains are.
3. CAPE – 4000 (J/kg) is available near Chennai. So we just need a TS over Chennai. The abundant energy will magnify the TS.
4. Moisture Content – No need to worry about this. You may already felt the sultry feeling. Moisture is available right from upper level to surface levels.
1. All the above are assumed factors
2. The storms should not peak too early before coming to our Bermuda triangle
3. Chennai is located southern coastal part of India. This region not known to get rains in April.
I personally feel that we have more than good chance for rains in Chennai in next two days as the postive factors cannot be ignored.
Maximum and Minimum temperature will start to rise gradually as we head towards the peak summer season. Last week was pleasant thanks to the surprise showers where Meenambakkam recorded 104 mm.
Last two days, we have seen big mass of clouds move so close to chennai only to fade away. Some of us were thrilled and even thought that it wont miss Chennai. But in the end, it never rained as expected as the wind were not supportive and when the wind was supportive there was no moisture at all levels.
Tomorrow/ Day after Tomorrow Morning satisfies all parameter for rains, there is moisture from 6 kms to surface level and we also end up in the right hand side of the upper air trough. So, as usual, a big TS will move from Vellore, but this time it will extend into Chennai and the rains may start night /late night /after mid night. To be honest, it is very difficult to predict quantum as these TS may dump cm’s of rains in minutes.
Enjoy it as April rains are very rare and Remember Rains will start only at night or after mid night as these storms have to travel to Coast. It is also one heck of a rare system.