The monsoon will likely persist with a bias to Central and Northwest India during the short-to-medium term with the La Nina signature becoming clearer.
Peninsular India would lose the Madden-Julian Oscillation (MJO) wave advantage in the higher levels of the atmosphere during this week and into the next.
WELL-ENTRENCHED
Since the country has a well-entrenched monsoon now, this may only translate into denial of incremental rain that the friendly MJO wave would have facilitated.
International models showed the MJO wave transiting Equatorial Indian Ocean to enter South China Sea and Northwest Pacific during this period.
The Climate Prediction Centre (CPC) of the US National Weather Services has therefore indicated increased chances of below average rains for parts of Indian Ocean and South India.
By the same token, it saw increased chances for above normal rainfall for areas to the east extending from Southeast Asia to Northwest Pacific.
Apart from enhanced MJO activity, developing La Nina conditions and elevated sea-surface temperatures (SSTs) would contribute to the emerging wet session here.
CYCLONE WATCH
The CPC has continued to put the seawaters surrounding the Philippines for possible tropical cyclogenesis (cyclone formation).
The warm SSTs would combine with areas of weak vertical wind shear to boost the prospects for cyclone formation, it said.
In the latest available forecast, the CPC brought a larger area to both sides of North Pacific – South China Sea to southern Japan – under cyclone watch until August 16.
But a warm pool developing lately over West Equatorial Indian Ocean (Southwest of Sri Lanka) could act as a drag on the cyclogenesis in the West Pacific, forecasts indicated.
Back home, coastal waters along Tamil Nadu and Andhra Pradesh is showing a warming trend, but the warming anomaly has not yet reached Head Bay of Bengal.
FAMILIAR PATTERN
This is why the activity is getting confined to Northwest or adjoining West-central Bay of Bengal where low-pressure areas have sprung up in recent times. The ‘low's instead wheel west-northwest into Central India and further into Gujarat or Northwest India in a pattern that has become all too familiar during the season.
East and Northeast India is left high and dry in this manner, and has showed deficit during the season logging a practically unchanged 21 per cent as on Tuesday.
Meanwhile, India Meteorological Department (IMD) has forecast the next ‘low' in the series to show up over Northwest and adjoining West-central Bay in the next two days. Once again, it would cut a path to west-northwest to roll into Central India before heading into the Gujarat/Rajasthan region.
An upper air cyclonic circulation from the previous ‘low' lay parked over Southeast Rajasthan and adjoining areas on Tuesday. The rain-driving offshore trough ran down from South Gujarat to the Karnataka coast.
The last 24 hours ending Tuesday afternoon saw widespread rainfall occurring over Saurashtra, Kutch, Konkan, Goa, Coastal Karnataka and Andaman and Nicobar Islands.
It was fairly widespread over Uttarkhand, East Rajasthan, East Uttar Pradesh, Madhya Pradesh, Vidarbha, Chhattisgarh and the Northeastern States.
Cloud imagery on Tuesday showed convective clouds over parts of Gujarat, Madhya Pradesh, the Northeastern states, Orissa, South Peninsular India, East Arabian Sea, parts of Bay of Bengal and northern Andaman Sea.
A warning valid for the next two days said that isolated heavy to very heavy rainfall is likely over Himachal Pradesh, Uttarkhand, Arunachal Pradesh, Assam, Meghalaya, Konkan, Goa, North Andhra Pradesh and Coastal Karnataka.
Outlook until Friday spoke about the possibility of widespread rain or thundershowers over West Himalayas, Konkan, Goa and Coastal Karnataka.
Fairly widespread rain or thundershowers would occur over Gujarat, Rajasthan and Interior Karnataka during the next 24 hours and decrease thereafter. But the rains may continue over Rajasthan.
Fairly widespread rain or thundershowers have been forecast over Punjab, Haryana, Chandigarh, Delhi, Uttar Pradesh, Orissa, Madhya Pradesh, Chhattisgarh, West Bengal, Sikkim, Jharkhand, North Andhra Pradesh and the Northeastern States.
Extended forecast until Sunday said that fairly widespread rainfall would occur over the plains of Northwest India, North Peninsula and adjoining Central India.
