Wednesday's well-marked low-pressure area over East-central Bay of Bengal intensified to become Tropical Cyclone Giri on Thursday evening.
An India Meteorological Department (IMD) outlook said that the storm might intensify further into a severe cyclonic storm before crossing North Myanmar and adjoining Bangladesh coast by Friday evening.
JTWC AGREES
The US Navy's Joint Typhoon Warning Centre tended to agree with this outlook, saying that wind speeds may already have touched 45 to 55 knots (83 to 102 km/hr).
The rapid intensification of the system is attributed to the influence of high sea-surface temperatures, low vertical wind shear (cross-winds that lop off storm heads) and reasonably good ventilation at the top helping it to ‘breathe out.'
As expected, a prevailing western disturbance impacting ocean basins across the geography is what will cause the system to track to the northeast until landfall over Myanmar.
The same western disturbance has started affecting Typhoon Megi in the South China Sea basin, forcing it to abandon a westward track and instead head to the north and northeast, apart from weakening by notches.
BUSIER PACIFIC
The storm is not seen as intensifying anymore, but the JTWC expected it to maintain typhoon strength until landfall over Southern China by Saturday morning.
The direct threat to Hong Kong seem to have been warded off, with the storm taking a more northeasterly track aiming to hit the South China coast northwest of Taiwan.
Meanwhile, the JTWC has put out fresh cyclone notification alerts for the West Pacific under the influence of a strong wet phase of the Madden-Julian Oscillation (MJO) wave. The MJO wave travels in the higher levels of the atmosphere and has periodic dry and wet phases with implications for ground weather.
The ‘pull' effect of Cyclone Giri would bring another round of fairly widespread rain or thundershowers over Konkan, Goa, Coastal Karnataka, Kerala and the Andaman and Nicobar Islands.
MONSOON WITHDRAWAL
This would effectively cause the southwest monsoon withdrawal pinned down to where it stays currently and delay the onset of the northeast monsoon over the Southeast Coast of India
The 24 hours ending on Thursday morning saw fairly widespread rainfall being reported from West Madhya Pradesh.
It was scattered over East Uttar Pradesh, Gujarat, North Madhya Maharashtra while being isolated over Meghalaya, Arunachal Pradesh, South Tamil Nadu and Kerala.
Meanwhile, the prevailing western disturbance will trigger fairly widespread rain or thundershowers over Jammu and Kashmir and Himachal Pradesh and scattered over Uttarakhand during the next two days.
IMD has indicated scattered rain or thundershowers for the Northeastern States on Friday and increase thereafter under the twin influence of Cyclone Giri and the western disturbance.
A separate heavy weather warning valid for Friday said that isolated heavy rainfall would occur over Jammu and Kashmir during the next two days and over Nagaland, Manipur, Mizoram and Tripura thereafter.
Extended forecast valid until Tuesday said that scattered rainfall would occur over South Peninsular India in what is thought to be a count-down to onset of northeast monsoon.
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