True to forecasts, the North-East monsoon has achieved fresh momentum from the start of November under the influence of strong easterly to north-easterly winds from the Bay of Bengal to South-East Peninsular India (Tamil Nadu and Andhra Pradesh), aided by a trough of low over the South-West and adjoining West-Central Bay of Bengal, some distance away.
The short-term outlook by the India Meteorological Department (IMD) is itself instructive, providing picture-perfect settings for a flawless performance of the North-East monsoon. Fairly widespread to scattered rain is forecast for the Andaman & Nicobar Islands for the next seven days while, almost along a straight line, it would be scattered to fairly widespread to widespread over Coastal Andhra Pradesh, Telangana, Rayalaseema, Tamil Nadu, Puducherry, Karnataka, Kerala and Lakshadweep.
Easterly waves, troughs
Easterly waves, troughs, cyclonic circulations and other atmospheric features would be at work over the Bay during this period. Apart from light to moderate scattered to fairly widespread rain over South Peninsular India during the next seven days, isolated heavy rain is likely over Tamil Nadu-Puducherry-Karaikal and Kerala-Mahe from Thursday to Monday; and over South Interior Karnataka from Friday to Sunday. Isolated very heavy rain is likely over Tamil Nadu on Saturday and over Kerala on Friday and Saturday. Another productive phase of the North-East monsoon is due from Sunday, as per IMD projections.
Global models agree that the expansive phase of the North-East monsoon would be on show until November 11 with Kerala, Coastal Karnataka, North Interior Karnataka, Rayalaseema and Telangana likely going under the hammer. It would be less virulent over Tamil Nadu. But the heavy rain belt may shift towards Konkan-Mumbai, parts of Gujarat and adjoining West Madhya Pradesh from November 12. Things will quieten down over the South Peninsula from the last week of November into early December.
Western disturbances at play
Meanwhile over North-West India, a feeble western disturbance is expected to bring light rainfall or snowfall at isolated places over Jammu-Kashmir-Ladakh-Gilgit-Baltistan-Muzaffarabad and Himachal Pradesh on Thursday and Friday and over Uttarakhand on Friday. A fresh western disturbance may affect the hills early next week. Global models are of the view that both North-West and adjoining Central India will experience rain or showers through the rest of November and into early December.
A few other models say conditions may remain favourable for the overall rainfall trend to sustain over not just the South Peninsula but over Central and North-West India, though briefly deficient over North-East India. Maharashtra, Madhya Pradesh, parts of Gujarat, and North-West India are expected to make reasonable gains during most of November. The West Coast and adjoining Madhya Pradesh will be major beneficiaries during the third and fourth weeks, and to a lesser extent into early December.