Thursday, October 22, 2009

Next window for N-E monsoon from Oct 27 to Nov 4

The next window for the North-East monsoon over the Bay of Bengal and adjoining peninsula is likely to open up during October 27 to November 4 in what is an unusually delayed onset this season.

The US National Centres for Environmental Prediction sees the south-central and adjoining south Bay of Bengal and peninsular India being brought under wet cover during this period.

SUPPORT FORECAST

This outlook is more or less corroborated by the Climate Prediction Centre (CPC) of the US National Weather Services, which said that the Bay would emerge out of the grip of a suppressed convection (dry) phase of the Madden-Julian Oscillation (MJO) wave.

Stage for the launch

According to the CPC, the dry phase of the MJO will exit the Bay of Bengal by October 27, setting the stage for the north-east monsoon to launch itself over the Bay.

Simultaneously, south China, Taiwan and the Philippines are forecast to get smothered by waves of rainfall unleashed by Super Typhoon Lupit, which is seen making a landfall over the Philippines by Thursday.

The CPC attributes the delay in the onset of the northeast monsoon to this phase of the MJO wave, which triggers dry weather over the region under its footprint.

The MJO wave is an upper-level phenomenon travelling periodically east across the Indian Ocean with alternating wet and dry phases. The wet phase sets up excess rainfall, onset of monsoons, low-pressures areas and even cyclones.

Meanwhile, Super Typhoon Lupit will weaken after landfall and will slip off the Philippine archipelago to emerge into the South China Sea. Here, it will go more rounds of intensification while continuing to travel straight into west.

NEW SUPER TYPHOON

This track will take Lupit for a brush-past with Taiwan and Hong Kong before it barrels into the south China-Vietnam region for a roaring landfall and subsequent weakening.

This too is expected to happen around October 27, another reason why the nearly contiguous Bay of Bengal should be able to breathe free to get the northeast monsoon going.

Meanwhile, India Met Department satellite pictures showed cloud build up along the equator and a northwest-to-southeast banding of clouds over northeast Bay of Bengal. These patterns were being attributed to the `pull' effect of Super Typhoon Lupit.

An IMD update on Tuesday said that the remnant south-west monsoon was subdued over Arunachal Pradesh, Nagaland-Manipur-Mizoram-Tripura, West Bengal, Sikkim, Orissa, Andhra Pradesh, Tamil Nadu, Karnataka and Kerala.

The withdrawal line dipped into the peninsula as Bihar, Jharkhand, Chhattisgarh, Vidarbha, central Maharashtra, Marathawada, Konkan, entire West Bengal, Sikkim, Orissa, the North-Eastern States, parts of Telangana, north interior Karnataka and Goa were declared cleared of southwest monsoon.

MERCURY LEVEL

Maximum temperatures were above normal by 2 to 5 deg Celsius over peninsular India and by 2 to 3 deg Celsius over parts of central and east India. They were near normal over the rest of the country.

Minimum temperatures were below normal by 2 to 5 deg Celsius over parts of east and adjoining central India, parts of Uttar Pradesh, Punjab and Jammu and Kashmir.

No significant change in maximum and minimum temperatures is likely during next two to three days, the IMD said. Satellite pictures on Tuesday showed convective clouds over parts of Andaman Sea.

Outlook for the three days ending October 25 suggested isolated to scattered rain or thundershowers activity over the Andaman and Nicobar Islands.

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