September- The wettest month of the driest regions?

Rayalseema and North Interior Karnataka are the driest regions of India apart from West Rajasthan. These regions are known for their intense heat(though with exceptions lik Hubli,Belgaum,Arogyavaram etc) and rocky & dusty atmosphere.

1.Rayalseema

Bellary is included as part of Rayalseema as it belongs historically and geographically  to Rayalseema. We see that September is the wettest month of this region barring Arogyavaram which does not fit into the geography of Rayalseema. Rather it would belong to the neighbouring South Interior Karnataka which has October as its wettest month.

2. North Interior Karnataka

Belgaum is not in a proper rain shadow area. Some rain clouds do manage to peep in. Its rainiest month is July with 306mm. Bidar is almost located in the Vidharbha region which enjoys good SWM due to land based low pressures and various other factors and hence its rainiest month too is July. Other than Belgaum and Bidar, all other stations clearly have September as their rainiest month.

Hence, September is very clearly the wettest month of these two meteorological sub divisions.

Wettest month of South Interior Karnataka- The October surprise?

South interior Karnataka is one of the top ranking meteorological sub divisions in the country in terms of average altitude. It is also known to have a fairly beautiful weather all through the year. It is particularly good in the month of May when other parts of the country reel under intense heat wave.

It is also known that the early South West Monsoon months provide little precipitation to this region. However, the weather is overcast and cool. I took the following picture at Mysore Chamundi temple during June 2009.

Also, it is widely believed that September and October are the wettest months of this region due to the convective currents formed by warming up of lower atmosphere. Let us survey some important cities all across South Interior Karnataka and  understand the wettest months of this region. For convenience, Let us ignore the ghat areas of the region where SWM is dominant in July and August.

We see that with the exception of Bangalore, all the other South Interior Karnataka's stations point out that October is the wettest month of the region with the second position going to September and May is just marginally trailing behind. This may be attributed to the combined effects of the SWM and the NEM.

A paradise called Bangalore- Part 1- The Train Journey!!

Bangalore, one of the highest altitude cities of the country is one of my personal favorites. Having grown up in Chennai, I had always detested its unbearable summer. Especially the month of May, where I was supposed to enjoy the summer holidays, on the contrary ,it was a suffering. Combined with a crazy humidity its a punishment in itself. And there came the respite, my athai(aunt) moved to Bangalore in 1995 and yippeyyy we found a place for summer :) :)

We are a set of 7 cousins and the best thing is that we are all in the same age group. In late April, my brother and myself would rush to the Madras Moore Market reservation complex and get our tickets booked for one of the day trains(Mostly the Lalbag Express).

On the D-Day in May, we get our baggage packed; ready to escape like refugees in a war zone. We grab our lunch at home as quick as possible. All of us gather at my place in Chintadripet which is 2 stops away from Central station.

We usually start from home around  1:30 PM and the weather- Freeeaking hot and sultry. But since we were all a gang, we used to have fun forgetting the crappy Madras afternoon weather.

 And the train starts from Madras Central at 3:30PM...

 As the slanting sun rays enter the coach, it was a pain. The first stop is Arakonam- we actually felt hotter *sigh*. And the next stop was Katpadi. Though it was about 5:30 PM it was still very hottt. We usually meet up with the Chennai bound Brindavan express then and we would be commenting on how unlucky the passengers in that train were ;)

And then comes Jolarpet. The stretch from Katpadi to Jolarpet is a treat to watch. Full of coconut trees and hills. We buy some bread omelet then :) The sight of Yelagiri hills in the foot hills of Jolarpet is majestic and till  that point the weather would be just ok..

And then starts the magic....

And from Jolarpet, we could realize that we were climbing a gradient and in no time(an hour or so) a soothing chillness was welcoming us and then came Kuppam. And some time after Kuppam, we had our purpose served- drizzles!!! and we couldnt wait for the train to arrive at Majestic ( Bangalore City Station)... Lalbag reaches around 9:30PM... and our mood would be upbeat..

We usually head straight to my Athai's place at Rajaji Nagar in North Bangalore.After a great dinner, we would  have a comfortable sleep that we were missing for all those days at Chennai...

That was one hell of a googly by Bangalore.. ;)

Wettest months of TN Regions!!

All of us in Tamil Nadu know that the north east monsoon(NEM) is a major contributor to the rainfall of the state. I quote the Indian Meteorological Department here-- " For Tamilnadu this is the main rainy season accounting for about 48% of the annual rainfall. Coastal districts of the State get nearly 60% of the annual rainfall and the interior districts get about 40-50%  of the annual rainfall."


Also we know that  during weak monsoon condition(September-Early October) when there is ample sunshine, the lower levels of the atmosphere are warm which gives rise to convection current. The air goes up leading to the formation of clouds, resulting in rainfall in some interior regions of the state.  Again I quote IMD here- "The rainfall over south peninsula towards the end of southwest monsoon season  is mainly in the interior districts and it generally occurs in the afternoon , evening or early part of the night. As the  season advances the rainfall is mainly in the coastal districts with the interior districts getting  less rain."


Let us walk through  distinct regions of Tamil Nadu one by one and find out more about the wettest months. The rainfall figures are in millimeters(mm). The top 2 wettest months are indicated in brackets for every region.


1. North Coastal Tamil Nadu (November--October)


This is one of the most rainiest regions of the state or even in the entire country outside West Coast and East India. It is home to the dry evergreen forests and hosts the Chennai(Madras)  metropolis. It is also known for its hot weather during summer and a wet flooding weather during the winter.  The following table gives the rainfall(in mm) for three months viz September,October and November. 


This is the region where NEM effect is more pronounced than any other region of the state and hence clearly November tops the charts followed by October throwing no surprises. September too is pretty decent but no where close to the other two months.

2. North Interior Tamil Nadu (October--November)


By north interior TN, we mean the interior places covering west of Chennai and east of Salem. This region is one of the hottest regions in Tamil Nadu. Its quite intolerable in summer, enjoyable after August, quite cold in winter. It covers districts like Tiruvallur,Kanchipuram,Vellore, Tiruvannamalai and Villupuram.


 As we can see these places are dominated by the ending  South West Monsoon and North East Monsoon with October and November being the wettest months (in that order). It is also notable that Vellore has almost equal rainfall in all the 3 months.

3. North West Tamil Nadu (October--September)


This region is a relatively pleasant region. Besides being primarily agrarian , it is also decently forested. It is  located in a relatively higher altitude giving it a reasonably salubrious climate compared to most regions of TN. However, it is not a high rainfall zone. This region is also known for a fairly wet May making it a summer destination. It hosts the non-western ghat hill stations of TN like Yercaud and Yelagiri.


This region along with neighboring Bangalore experiences a very good September-early October due to active convective currents due to warming up of lower levels of atmosphere. However the effect of NEM is limited in this region. So, the wettest months are October and September(in that order).

4. West Tamil Nadu (October--November)


One of the most prosperous regions of Tamil Nadu outside Chennai, West TN hosts municipal corporations like Coimbatore,Erode and Tirupur. It also hosts famous hill stations like Ooty,Coonoor,Kotagiri and Valparai. Although it is one of the driest regions of the state(or even the country), people get eluded by the pleasant overcast and chill weather. However the hilly regions receive good rainfall due to orographic effects and local T-storms. 


Despite its proximity to the western ghats, the rain shadow effects are more pronounced in this area virtually ruling out any heavy rain in the South West Monsoon season(including September). It has to rely highly on the NEM. Thus as with other interiors October is the wettest month followed by November.

5. Central TN (October--Indeterminate)


This region forms the central part of TN.  It is primarily drained by Kaveri and its distributeries. This region is known for its hot climate. Trichy is its principal city.


Although October is the rainiest month in this region(as always), it displays considerable variance for the second wettest month. September is the second wettest month of Trichy. October for Thanjavur and  November for Ariyalur.

6. South Tamil Nadu (October--November)


The region south of Trichy till Tirunelveli comprises of South TN. This area is primarily drained by the Vaigai.
Madurai is its principal city. It also hosts the famous hill station of  Kodaikanal.


October again tops for this region followed by November. Due to its proximity with Trichy, Karaikudi experiences Trichy like Climate with second wettest month being September. Kodaikanal has a great North East Monsoon.

7. Deep Southern Tamil Nadu (November--October)


This region comprises of Tirunelveli, Tuticorin and Kanyakumari districts. The Tirunelveli and Tuticorin districts have one of the worst South West Monsoon in the Indian Republic(worse than West Rajasthan).


If not for the North East Monsoon(NEM), these districts would be fully arid deserts. Thanks to NEM, this region is saved. This region throws an interesting information. Apart from North Coastal TN, this is the only region  where November is the wettest month followed by October.

Conclusion
We see that October and November months that coincide with the North East Monsoon season are the wettest months of Tamil Nadu state as a whole. However, it is interesting to note  that the north west part of  the state  has September as the second wettest month. 

What is this blog about?

This blog will be an account of my experiences with interesting weather data(mainly rainfall) and weather events pertaining to  South India. Also, it would contain some travel information about my trips to places in South India and the United States.