The India Meteorological Department expects a brewing depression over the Bay of Bengal to bring heavy rain to coastal Andhra Pradesh, Tamil Nadu, and Kerala early next week. The system could intensify into a deep depression, causing widespread rainfall and turbulent weather across the South Peninsula starting this coming Tuesday.
The India Meteorological Department has left the door open for intensification of the brewing depression into a deep depression that ranks only second to a cyclone in intensity
A brewing depression over the Bay of Bengal could intensify as it races towards the Andhra Pradesh coast, raising the prospect of another spell of heavy to very heavy rain over the South Peninsula. The system is expected to take shape by tomorrow (Saturday) and could strengthen further, bringing isolated very heavy rainfall of 11.5-20 cm to Coastal Andhra Pradesh and Yanam on Tuesday and Wednesday.
Scope for intensification
The rain belt is likely to lie south of the seas battered by very severe cyclone Arnab just days ago. It is not often that a very severe cyclone is followed so closely by another potentially powerful system. Yet, the India Meteorological Department (IMD) has left the door open for further intensification of the brewing depression, at least into a deep depression, the second-highest category in the hierarchy of low-pressure systems.
A combination of favourable oceanic and atmospheric conditions appears to support the possibility. The emerging system could bring isolated heavy rain to Tamil Nadu, Puducherry and Karaikal on Tuesday and Wednesday, besides Coastal Andhra Pradesh and Yanam on Monday and Tuesday. Kerala and Mahe, coastal Karnataka and South Interior Karnataka are also among regions forecast to receive heavy rain.
Rainfall outlook
The wider rainfall outlook points to an extended spell of unsettled weather across the peninsula. Isolated to scattered rainfall is forecast over Rayalaseema, Tamil Nadu, Puducherry and Karaikal, and North Interior Karnataka for six days from Friday. Kerala and Mahe, South Interior Karnataka, coastal Andhra Pradesh and Telangana could see similar activity for three days and again on Tuesday and Wednesday. Lakshadweep is likely to receive such rainfall for three days from Monday, while coastal Karnataka comes under the spell on Saturday and Sunday.
Turbulent weather seen
Rain coverage is expected to expand from Monday, with fairly widespread to widespread rainfall over coastal Karnataka, Kerala and Mahe, and South Interior Karnataka for three days. Coastal Andhra Pradesh and Yanam could see a similar spread on Monday and Tuesday, followed by Telangana on Tuesday. The weather could turn particularly turbulent in pockets. Thunder squalls with winds of 50-60 km/hr, gusting to 70 km/hr, are likely over Telangana on Sunday and Tuesday. Strong surface winds are also forecast over North Interior Karnataka, South Interior Karnataka, Coastal Andhra Pradesh and Yanam, and Rayalaseema for four days from Friday.
Thunderstorms, lightning and gusty winds are likely over coastal Andhra Pradesh and Yanam on Tuesday. Kerala and Mahe, and both North and South Interior Karnataka, could experience wind gusts on Sunday and Monday. Coastal Andhra Pradesh and Yanam are in the outlook for three days from Friday, while Rayalaseema faces a four-day spell. Tamil Nadu, Puducherry and Karaikal could see thunderstorms on Wednesday and Thursday, with coastal Karnataka also in the frame on Sunday and Monday.
Thunderstorms for North India
Meanwhile, the weather disturbance left behind by Arnab is set to interact with an incoming western disturbance, bringing another round of rain, thunderstorms, lightning and strong winds across parts of North-West, West, Central and East India over the next few days. Although the remnant has weakened into a well-marked 'low' over central Chhattisgarh, its influence need not end with the system's gradual dissipation.
Its interaction with the western disturbance, associated induced circulations and an elongated trough could keep weather conditions unsettled, including over parts of the South Peninsula. The trough provides an important link between the two weather developments. It extends from the remnant circulation over central Chhattisgarh and adjoining Odisha, through Telangana and North Interior Karnataka, towards another cyclonic circulation over south Konkan.
An elongated zone of low-level wind convergence encourages air to rise, cloud formation and precipitation along and around its axis. A weakening low does not necessarily mean an immediate let-up in rain. The larger circulation and associated trough can squeeze out showers even as the original system loses strength.