The Hindu Business Line : Thunderstorms rule peninsular skies

Thiruvananthapuram, Nov 4 A pair of cyclonic circulations to the south and west of extreme south peninsula has woven together a string of thunderstorms that in turn has exploded in disparate flash rain events over the adjoining land.

These ‘hit-and-miss’ thunderstorms will rule the roost determining the local weather for two to three more days, according to an update by the India Meteorological Department (IMD).

IDEALLY PLACED

The causative circulations are located, respectively, over the southwest Bay of Bengal off the Sri Lankan and Kanyakumari coasts, and over the southeast and adjoining east-central Arabian Sea off the Kerala-Karnataka coasts and the adjoining Lakshadweep area.

An IMD forecast has said that rain or thundershowers are likely at many places over Tamil Nadu and Kerala over the two days. Wet cover has been forecast also for Lakshadweep, coastal and south interior Karnataka, Rayalaseema, north and south coastal Andhra Pradesh and Andaman and Nicobar Islands.

Apart from these, although removed to the far southeast and northeast, were two other systems over the South Andaman Sea and Assam-Meghalaya belt. Though not having an immediate say on peninsular weather, either of these two could herald the next ‘low’ in the Bay.

A likely signal is from the Tropical Storm Peipah raging in the northwest Pacific, which is about to slam shore into the Philippines. It is forecast to emerge later into the South China Sea and barrel into the Vietnamese coast as a Category-1 typhoon at the least.

‘Peipah’ is seen tracking ideally in a south-southwest direction, which would mean it would have some rub-off effect on the adjoining Bay of Bengal as well. This sequence of events should reach a logical conclusion within the next seven to eight days, if projections are anything to go by.

WESTERN DISTURBANCE

Meanwhile, arrival of a western disturbance into the northwest border is likely to switch on some wet weather north-northwest from Gujarat into Rajasthan, bringing some badly needed rain to a region left high and dry by the southwest monsoon.

This is expected to happen with eastward-moving western disturbance running into moisture seeping in from the Arabian Sea to the southwest. The warmest seawaters are confined to the Arabian Sea off the Gujarat and Konkan coasts.

According to Mr Jim Andrews of AccuWeather.com, the widely-separated rain from thunderstorms over western India – covering Mumbai, Maharashtra and Gujarat - on Friday and again Saturday has resulted from incursion of moisture in this fashion.

High pressure and abundant sun brought out by the seasonal anticyclone over the region has fostered lingering heat while allowing for tropical moisture to drift northwards. This is corroborated by the convective available potential energy (CAPE) analysis by the US-based Centre for Ocean-Land-Atmosphere Studies (COLA), too.