Twin depression alert in Arabian Sea as monsoon draws closer

The India Meteorological Department (IMD) has issued a twin depression alert for the Arabian Sea as the latter readies to match the Bay of Bengal in terms of the build-up for a spectacular onset of the monsoon over Kerala. The monsoon had hitched a hike on an eventual super cyclone Amphan to enter the Bay almost 10 days ago.

The monsoon on Friday entered more parts of the South-East Arabian Sea and the Maldives-Comorin seas. Conditions may suit its further entry into some more parts of South Arabian Sea (around Kerala), Maldives-Comorin area, South-West and South-East Bay during the next two days.

Private forecaster Skymet Weather said on Friday that the Arabian Sea is hosting favourable conditions for pushing the monsoon over Kerala, a little before time. A facilitating trough is present over Lakshadweep and adjoining seas. A cyclonic circulation may pop up here by Saturday, later graduating to the status of a low-pressure area and sequentially as a well-marked low pressure or depression by Sunday.

Heavy rain alert

Many parts of Kerala and Lakshadweep have already starting moderate rain of up to 5 cm during the 24 hours ending on Friday morning under typically grey to dark skies. Thiruvananthapuram has been receiving heavy but short spells of rain from the previous day, which continued into Friday as well.

The IMD has forecast heavy rainfall at isolated places over parts of the South Peninsula from Friday to Sunday with isolated heavy to very heavy rainfall over Kerala, Coastal Karnataka and South Interior Karnataka during this period and over Lakshadweep from Saturday to Monday.

It is in this context that the IMD has hinted that a monsoon-driving low-pressure area may develop over the South-East and adjoining East-Central Arabian Sea (around Lakshadweep) in two days (by Sunday). It may move North-North-West and concentrate into a depression during the three days that follows.

During this phase, the system would stay parked in the neighbourhood, with associated strong bands of winds pushing the monsoon in for an onset over Kerala. The system likely dropping anchor here briefly is due to the presence of a twin but contender storm raging to the farther side of the Arabian Sea basin.

The twin system to the farther side has already become well-marked, marking the first round of intensification over the West-Central Arabian Sea, its nearest coast being Oman/Yemen. It would beat its younger sibling over Lakshadweep to reach depression strength as early as tomorrow (Saturday).

Weakening of the system in this manner would likely give a suitable window for the emerging depression over Lakshadweep to plot its track.The IMD expects it to meander towards the West Coast off Konkan-Mumbai-Gujarat and cross the coast into South-East Rajasthan and Delhi.