Wind Pattern show Seasonal Monsoon Change on the way for India

It is that time of the year when the Southwest Monsoon starts to give way for Northeast Monsoon or the retreating monsoon as most Meteorologists like to call it.  It is also the time of the year when most of Tamil Nadu looks forward to the seasonal change as well.  Being in the rain shadow region during the main monsoon season for the country it is the retreating monsoon that gives almost 60% of thee annual rainfall for the state.

In our yesterday’s post we had mentioned about the slow withdrawal of Southwest Monsoon so far this year.   Yes certainly the Southwest monsoon has been retreating slower than normal but the atmospheric indications are certainly showing the seasonal monsoon change is on the way for India.  The Southwest Monsoon season is characterized by very strong Westerly winds reaching up to 45 kmph at times in the West Coast.  During Peak Monsoon time the westerly winds reach up to 30 kmph over parts of Peninsular India as well.

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In the chart we compare the current surface level wind pattern with that seen during peak  monsoon period.   As one can observe the westerly winds have slowed down drastically with most places seeing less than 10 kmph winds in Peninsular India.  This could be corroborated with the early & strong sea breeze which Chennai has been seeing over the last few days indicating the weakening of westerlies.   While it is still some time away for the wind regime to clearly shift from Westerlies to Easterlies we can be assured the Clock is ticking for sure though slightly behind schedule for the seasonal change as expected at this time of the year.

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Today also we are likely to see mostly clear skies across Peninsular India with hot weather dominating right through the day.  Parts of North Tamil Nadu could see isolated late night / midnight rains in one or two places under the influence of wind instability at mid tropospheric level as the pattern sees different air masses converging over Peninsular India.  While it is still not clear if the coastal areas like Chennai could get benefit the wind pattern needs to be far better than the last couple of days if the storms have to reach the coast.