The Hindu Business Line : West coast under watch as Bay throws up a whirl

Thiruvananthapuram, June 25 India Meteorological Department’s (IMD) outlook for the next few days suggests that rain or thundershowers would be fairly widespread across the country with the west coast and the northwest coming under special focus.

A significant development was an upper air cyclonic circulation that sprung up over North Bay of Bengal off the north Orissa and West Bengal coasts. This would be put under watch for signs of intensification.

The European Centre for Medium-Range Weather Forecasts (ECMWF) continued to suggest its movement to the west and growth as a likely ‘low’, which would in turn trigger a counterpart system over the Arabian Sea to represent an active monsoon phase.

According to received wisdom, the strength of the Bay system will determine the attributes of the brewing Arabian Sea system. The latter’s mandate is to hold one end of the shear zone of monsoon turbulence in place. In this manner, the shear zone gets rolled out as an elongated web of turbulence across the peninsula.

The IMD has said that the Bay system would cause fairly widespread rainfall over Orissa and Chhattisgarh during the next three days. But the ECMWF has lately marked down the strength of the two systems with a likely cascading impact on the precipitation over the peninsula.

MAJOR IRRITANT

The major irritant in monsoon performance during the past week or so has been Typhoon Fengshen in the western Pacific, a storm with destructive strength that hit Philippines first and later travelled west into the South China Sea. Fengshen has lately weakened into a tropical storm and made a landfall over mainland China. This should help the monsoon flows, which have been strong all through and well represented in the typical south to southwesterly wind pattern, to converge around peninsular India and the west coast by the weekend.

Just as an ill-timed Arabian Sea cyclone or depression affects precipitation during the onset phase of the Indian monsoon, a western Pacific typhoon too can divert the flows mid-course, especially when there is no matching system in the country’s territorial waters. But no two strong systems can co-exist in the regional or planetary-scale monsoon system either.

The biggest casualty during the lean phase has been Kerala whose hydel reservoirs have depleted and is faced with the threat of a punishing load-shedding schedule. Kerala’s latitudinal coordinates as the gateway to monsoon also subjects it to the vagaries associated with formation of west Pacific typhoon with incoming flows getting easily diverted into the typhoon feed.

The progress of monsoon into the northwest of the country too has been stalled since June 16 after hitting east Rajasthan. This is again being attributed to the absence of any big intervening surge from the Bay. The localised host monsoon circulations have been well represented to the east and northeast causing the flows to converge and precipitate in that region.

The fresh wave of rains in the northwest in two days’ time would not be able to drive the monsoon current deeper into Rajasthan. These rains would be an offshoot of remnant moisture left behind by monsoon easterlies as well as westerly troughs coming from the border. The rains would be more of a localised phenomenon playing out under the benign gaze of the larger monsoon system.

On Wednesday, the monsoon trough passed through Ganganagar, Hissar, Badaun, Fatehpur, Daltonganj, Balasore and southeastward into the east-central Bay of Bengal. Rains have been forecast for Punjab, Haryana, West Uttar Pradesh and Uttarakhand during next 24 hours with the possibility of a scale-up thereafter.

In the south, rain or thundershowers are likely at many places over north Andhra Pradesh, coastal Karnataka and Kerala. Among other places likely to receive widespread showers are Konkan, Goa, Madhya Maharashtra, Marathwada, east Rajasthan, east Madhya Pradesh, Vidarbha and Chhattisgarh.

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