Monday, June 15, 2009

Key to monsoon revival now lies in Bay of Bengal

June 14 The monsoon has been stuck for exactly a week after it revived from the shock administered by Cyclone Aila, and is expected to stay as such for another three to four days.

This would delay its advance into major farming regions in the east, southeast and peninsular India, India Meteorological Department (IMD) said on Sunday.
TROUGH OF LOW

The only redeeming feature as on date was the presence of a trough of low pressure over north Bay of Bengal. The European Centre for Medium-Term Weather Forecasts sees some activity brewing here within the next five days.

The IMD said that increase in rainfall is likely along the west coast and over the Andaman and Nicobar Islands from Wednesday apparently as a prelude to the churn in the Bay.

To the peninsular west, a persisting offshore trough linking south Karnataka coast to Kerala coast would continue to cause fairly widespread rainfall over coastal Karnataka, Kerala and Lakshadweep.

The Regional Met Centre, Chennai, said in its update that rainfall occurred at many places over Kerala and at a few places over Lakshadweep and coastal Karnataka during the 24 hours ending Sunday morning.

Isolated rainfall occurred over Tamil Nadu, coastal Andhra Pradesh, Rayalaseema and interior Karnataka also.
MORE RAINS

Rain or thundershowers are likely at many places over Kerala and Lakshadweep, and at a few places over coastal and south interior Karnataka, coastal Andhra Pradesh, Rayalaseema and interior Tamil Nadu for two more days.

Isolated rain or thundershowers are likely over coastal Tamil Nadu, Puducherry, north interior Karnataka and Telangana.

Delay in monsoon over Bihar, Orissa, Jharkhand, Chhattisgarh, parts of Andhra Pradesh, Maharashtra, southern Gujarat, Madhya Pradesh and adjoining peninsular India has allowed heat wave conditions to develop.

On Saturday, the highest maximum temperature of 44.6 deg Celsius was recorded at Ganganagar. Severe heat wave conditions prevailed at isolated places in Vidarbha.

Meanwhile, Dr Karumuri Ashok, Senior Research Scientist at the Asia-Pacific Climate Centre, Busan, South Korea, has clarified that the forecast for a weak El Nino and positive Indian Ocean Dipole (IOD) over the next months was ‘experimental’ in nature.
MODEL DIFFERENCE

The APCC predictions for El Nino and IOD are only in research mode, produced once a season for the next six-months with collaboration from several research centres to arrive at a consensual coupled model prediction.

The APCC’s ‘operational’ prediction (based on mathematical models of atmospheric motions alone) is different from this ‘coupled’ (ocean-atmosphere) prediction, Dr Ashok informed Business Line.

“As per our operational prediction, rainfall signals for India for June-July-August are positive to near normal everywhere, unlike the coupled prediction,” he said.

The equatorial Pacific would still need to be constantly watched before any final word could be said about the development of any major weather-altering event.
‘NEUTRAL’, FOR NOW

Meanwhile, the Climate Prediction Centre (CPC) of the US National Weather Services said in its June-8 update said that ‘neutral’ conditions were present in the equatorial Pacific Ocean.

But current observations and dynamical model forecasts indicated that conditions were favourable for a transition to El Nino conditions during June-August.

Since the beginning of May 2009, positive sea-surface temperature (SST) anomalies have been observed across the equatorial Pacific.

During the last four weeks, equatorial SSTs were above-average across much of the equatorial Pacific Ocean, with the largest positive anomalies evident in the eastern and western Pacific, it said.

Original:: http://www.thehindubusinessline.com/2009/06/15/stories/2009061550490300.htm

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