"monsoon" has already been declared over mainland Thailand

India Meteorological Department (IMD) has said that below-par heating witnessed over northwest India during the pre-monsoon period need not necessarily have any adverse impact on the subsequent rainy season.

The clarification came on Sunday in the backdrop of doubts over implications of the cooling anomaly for onset and progression of monsoon, which is essentially borne out of land-sea heating contrasts.

In a special bulletin, the IMD admitted that temperatures have been below normal over north and northwestern parts of India thus far during the season.

It attributed this to the enhanced activity of seasonal western disturbances (waves of low-pressure areas) that cross into northwest India in terms of their number.

But the IMD significantly added that their increased frequency has not translated into rainfall over the region.

In fact, northwest India as a met subdivision has piled up a rainfall deficiency during the period. The less than optimum heating up is not unprecedented in the region.

There have been at least six instances of similar rollout of weather during the last 30 years but with varied impact, if at all, on the subsequent monsoon, the IMD said.

No one-to one relationship could be observed between surface heating of northwest India during the pre-monsoon period and the monsoon rainfall, it concluded. Meanwhile, as was forecast by global models, the northwest Pacific has thrown up a named cyclone, Aere, and advancing towards the Philippines for a landfall.

But unlike earlier guidance, the cyclone would not cross into adjoining South China Sea but would instead re-curve and enter East China Sea and onward to Japan.

The western disturbances currently active over India and the rest of East Asia would act in concert with the northeasterly flows around a high-pressure area of the Pacific to blow away Aere in this manner.

Going forward, however, some models indicate that the weak ‘low' over east Bay of Bengal would sustain for an extended period to evolve as a stronger weather system and churn up the waters.

The Climate Prediction Centre of the US National Weather Services has put the Bay under watch for a tropical storm during the week ending May 17.

It could also lead to the onset of monsoon over the Andaman and Nicobar Islands, which are already witnessing heavy to very heavy precipitation.

This has prompted the Thailand Meteorological Department to observe that ‘strong southwest monsoon' prevails over the Andaman Sea.

The monsoon has already been declared over mainland Thailand and the Gulf of Thailand, just across the Bay.