Tuesday, June 4, 2013

Monsoon arrives in Bangalore, heads slowly towards Goa


Based on METD WEATHER's norms ( See here for details- http://www.facebook.com/notes/metd-weather/norms-for-the-onset-of-sw-monsoon-metd-weather/216135871743180)

SW Monsoon arrived in Karnataka yesterday i.e 4th June 2013 covering a northern limit of Mangalore-Bangalore.

However, there hasn't been any significant rainfall in Tamil Nadu particularly Chennai ( excluding the thunderstorm related rainfall on 2nd June 2013) and hence the primary criterion of rainfall as per the norms is missing due to which METD WEATHER isn't considering the SW Monsoon onset in Tamil Nadu. However more analysis will be done on it today,5th June 2013.

However, IMD advanced the SW Monsoon as north as Southern Maharsahtra, North Central Andhra Pradesh.. Their onset norms are very unclear and hence its being suspected that they violated the norms which includes rainfall, wind direction as not so major rainfall was reported in the regions since June 1st 2013 nor there is an appreciable wind structure blowing from West/South West direction in all the layers of atmosphere till 600mb. Infact, the wind at lower atmospheric profiles ( like 700mb etc) is blowing from the East/South East instead of West/South West in the further lower profile like 850,925mb etc.

Here is a GFS meteogram of Panaji for the next few days

One can note that the 2m RH plot showing the surface relative humidity is still dropping to a minimum of around 50% whereas as per METD WEATHER's norms, it should be atleast/above 60% for 48hrs. Hence METD WEATHER doesn't agree with IMD's advancement

However, it can be seen from 9th June 2013 that the conditions are changing. Its very clear that all the factors are coming together including the wind direction,speed,rainfall amounts,RH etc.

As a result of which, SW Monsoon will advance into Goa during 11-12th June 2013. Before that, it will reach south of Goa i.e north of Karnataka ON TIME AS PER METD WEATHER's forecast of 8-10 June

SW Monsoon will also arrive in Chennai and subsequent Tamil Nadu around 11th June as the conditions come together

The next destination will be Pune ( As I don't see major rainfall for Hyderabad and Andhra Pradesh as the bay branch is inactive at the moment just like Chennai is not getting rains).

Parameters like wind,pressure, rains will start stabilising around 12/13 June 2013 and hence SW Monsoon will be reaching Pune on 15/16th June 2013. See the meteogram here ( http://monsoondata.org/wx/punegfs.png)

Next will be Mumbai! SW Monsoon will reach Mumbai in a day or so after reaching Pune. Hence the onset will likely be around 17/18th June 2013.

SW Monsoon will be arriving in Nagpur on 19/20th June as per the present situation.

Worrying factor -

The Madden Julian Oscillation (MJO) had a wet phase till now due to which there was enhanced rainfall in west coast of India. Heavy pre-monsoon/ system influenced rainfall will likelyinitiate in these areas after around 10th June 2013 and then the dry phase of MJO will take over. Due to this dry phase, its very likely that the monsoon's speed will be a bit slow and also will be the rainfall amounts. Hence the monsoon will taking so much time to reach the areas . 

The Arabian Sea low pressure will fizz away vey soon. It already did what one had feared off i.e pulling moist ladend winds and clouds. However IMD went forward and declared the monsoon to everyone's surprise in Southern Maharashtra! 

Central India will be getting the first heavy pre monsoon showers around 7-9th June 2013. 

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