More than the low-pressure area in the northwest Bay of Bengal, it is Tropical Storm Rammasun in the northwest Pacific that is presiding over the heavy rainfall regime over India’s west coast.
A large chunk of the moisture is already being funnelled into the latest north Pacific storm which may cause the Bay ‘low’ to weaken slightly and break up as it enters central India.
The northwest Pacific faithfully delivered its latest storm right in the area where predecessor super typhoon Neoguri had taken birth before proving the nemesis for the Indian monsoon.
Rammasun is expected to become the next typhoon (cyclone) by Tuesday and grow into a severe cyclone (Category-2 storm as defined by the Saffir-Simpson scale in terms of intensity) by the very next day itself.
It would have closed in on the northernmost tip of the Philippines where it would barrel into on Thursday. But Rammasun would be far from being finished, as is normally expected of a storm on landfall.
It would instead wade into the adjoining South China Sea and intensify back into a Category-2 storm and head for Hong Kong/southern China coast by Friday up to when forecasts are available.
IMPACT ON MONSOON
The varying cycles of typhoon generation and regeneration would have ramifications for the Indian monsoon in alternate strengthening of flows from the Arabian Sea matched only by the draining from the Bay.
As in the case of super typhoon Neoguri, the latest typhoon is drawing on the moisture supply from the Arabian Sea along the west coast; across peninsular India; into the Bay; and then out of it.
This is what is currently causing the heavy rainfall over Konkan, Goa, Karnataka and Kerala coasts. This may variously continue into this week as well in tune with Rammasun’s antics in the Pacific.
As for the ‘low’ in the Bay, model forecasts show it may trigger the formation of a trough covering Maharashtra, Telangana, Madhya Pradesh and south Gujarat by Tuesday.
HEAVY RAIN
This will bring heavy rain into these regions, especially south Gujarat since the monsoon flows would have like to churn intensely in the small region covering coastal south Gujarat, Mumbai, and Goa.
Mumbai is forecast to remain under a wet spell while Surat, Veraval, Vadodara and Ahmedabad are also likely to be pulverised by torrents over the next couple of days.
Thereafter, the trough is shown as splitting into two with a break-away portion drifting into Uttar Pradesh to being moderate to heavy rain there.
The parent trough would remain static over south Gujarat-Mumbai-Konkan and slip out into northeast Arabian Sea from Dwarka-Bhuj-Junagadh, bringing some welcome rain to these parched areas.