Start of Thunderstorm season & outlook for South west monsoon 2014

Thundershowers have begun over south and east India, Many places have received heavy rainfall over the last three days, thundershowers will continue for the next week or so before a break for about a week and then one more spell of thundershowers over most of peninsula India.

April and May rainfall is expected to be good over interior south of the country.


The only bad news coming in so far  from many international models is an impending el nino phase which will coincide with the onset of the south west monsoon. Rains so far are forecast to be between 70 - 80% of the LPA (long period average). Droughts are forecast for many parts of madhya maharashtra, madhya pradesh and North Andhra pradesh althought the North eastern states which missed out last year are forecast to get 100 - 110% of its LPA this year.


These numbers are based on preliminary forecasts from the meteorological departments in Australia, Europe and the US and could change as the monsoon draws near. 

South west monsoon Withdrawal phase to begin soon

The south west monsoon should begin retreating from western Pakistan from the 5th of September after the feeble western disturbance fizzles out.

according to PMD : Seasonal low lies over Northwest Balochistan and adjoining areas. Monsoon currents from the Arabian Sea are penetrating into central and upper parts of the country. A westerly wave is also prevailing over upper parts of the country.

First signs of monsoon withdrawal from the Indian mainland would occur after the 10th of September, although with the low pressure hanging around Uttar Pradesh and the axis of the trough extending all the way to Amritsar withdrawal could stand still for about a week before gathering strength again. 

The monsoon is expected to withdraw from the entire country around the 10th - 12th of October very close to its normal withdrawal date of the 15th.



The withdrawal phase is going to provide heavy rainfall to the southern states with a low pressure area forecast in the bay around the 10th of September. Heavy rainfall is forecast for the first 2 weeks of September for Karnataka, North & Coastal Tamil Nadu, Andhra pradesh and coastal Maharashtra.



Do not get carried away with dry air over Pakistan in water vapor images, a lot of other factors go in to calculating the withdrawal.

Rains to return to South India & the perseids meteor shower

Rain is forecast for North east and east India, Uttar Pradesh, Uttarkhand and West & South India in the week from 10th - 16th. With some places forecast to get extremely heavy falls. There is a high possibility of a low pressure forming in the bay of Bengal after the 13th of August. Coastal areas of south Tamil Nadu and parts of north interior Tamil Nadu and south interior Karnataka could receive heavy rainfall. 




Also don't forget to watch the sky for the perseids meteor shower which has already begun and will peak between the 10th - 13th of August. Best watched away from city lights from midnight to dawn. To view the shower look NE towards the Perseus constellation, Scientists say up to 60 falling stars can be seen an hour during these days which could get higher when it peaks. The perseids are the brightest meteor showers of the year and promise to be a spectacle weather permitting..

Monsoon active phase to continue

After 2 weeks of vigorous rainfall over most parts of the country excluding parts of Tamil Nadu, North and south interior Karnataka, the north eastern states and Northern Rajasthan,  floods have been reported from Maharashtra, Gujarat, Uttar pradesh, Jammu, Bihar, Jharkhand, Orissa, West Bengal, Andhra Pradesh, Kerala and with release of surplus water from dams in Karnataka and Tamil Nadu a possibility of floods in Karnataka and Tamil Nadu as well.

The vigorous phase has been downgraded to an active phase with extremely heavy rainfall subsiding over much of the western ghats and north and central india. After a brief lull between 4th to 7th August, rather heavy rainfall is set to commence over the southern peninsula, although the western ghats may see below normal rainfall for the period through to the third week of august, currently parched regions of tamil nadu should see some rainfall in the second week of august, as will most of interior andhra pradesh extending north, north west into maharashtra and madhya pradesh.

 The North eastern states should start seeing normal rainfall and expect big numbers from the bigwigs of mawsynram and cherrapunji from the second week of august. 

A warning here that rainfall will not be as good as it was in the second half of July. 

Apart from this, A negative IOD and neutral ENSO could prevent too much moisture building up over the bay, most long range forecasts show a neutral IOD developing by October and the neutral ENSO conditions continuing into January. 

Coming to the cities of Chennai and Bangalore, Chennai will see irregular, scattered thunder showers on approximately 2 days a week through August, maximum temperatures will remain between 31 - 36 degrees through the month and minimums between 23 - 28 degrees respectively. 

Bangalore will have thundershowers in spells of 2 - 3 days and then a break for 2 days and then rain for 2 days again. Rain should be mainly widespread but could be isolated on days. Maximum rainfall day could see around 70mm after the second week of August, considering August is the third wettest month for bangalore it needs an average of 120mm for the month. Maximum temperatures will be around the 24 - 30 degrees mark and minimum temperatures will be around the 18 - 22 degrees mark respectively. Wind speeds will begin to decrease after the 7th or 8th of August in bangalore and aid in Thunderstorm development although it will increase again after the 15th and fall again after the 23rd.

Please do visit the Stanley reservoir, it is a beautiful sight to see it full and that too with water gushing out the other side. A very rare sight indeed. Be safe and God Bless!!!

the time has come. the south west monsoon will set in over kerala tomorrow the 31st of May.  IMD will take 24 hours more and declare the onset on 1 St of  June. rain is forecast for most of southern peninsula. Bangalore will get heavy showers on 1st and 2nd. Chennai on the 3rd. onset over Bangalore is the third.

Arrival of the South West Monsoon

The South West Monsoon has arrived over the Andaman and Nicobar islands. IMD will declare its onset within the next 24 hours. 

Two low pressures are forecast to come up on either side of the  peninsula within the next 72 - 96 hours and drag monsoon winds onto the mainland. However, the Arabian sea low is forecast to end up in Oman and could cause a delay of about 2 days in the onset over Kerala. The North-West of the country is heating up considerably and the annual Low pressure area will form over parts of Rajasthan and Madhya Pradesh, further strengthening Monsoon flows on the mainland. 

Expected date of Monsoon onset over Kerala is between 29th and 31st of May.

Cyclone Mahasen and the Onset of the Monsoon

As forecasted a cyclone formed in the bay which was named Mahasen. Mahasen is expected to make landfall between bakkhali in West bengal and chittagong in Bangladesh. Expected time of landfall is estimated between the morning - evening of the 16th of May. Mahasen is expected to strengthen for another 24 hours possibly reaching a maximum strength of T4.0 by Dvorak technique or category 2 on the saffir - simpson scale before it starts to recurve towards the North-East and weaken before making landfall as a deep depression.

 Rain/Drizzles From Mahasen is Expected along the east cost of India from Nagapattiam to Machilipattinam from the Night of 12th May 2013 to the Evening of 14th May 2013. Rain will be generated from localised Thundershowers as Mahasen pulls moisture and from bands of convection breaking off from the main system and hitting the coast. rainfall will move northwards along the coast as Mahasen makes its way north.

Pre-monsoon showers will continue over interior southern peninsula after the exit of Mahasen on the 17th.

SOUTH WEST MONSOON will reach Andaman islands by the 19th/20th of May 2013 aided by a possible low pressure near the east coast of Sri lanka. Some models also predict a Low pressure in the Arabian sea dragging monsoon winds over the mainland.