All eyes turn skyward for monsoon onset; storm system active in South

Image Source ; IMD

Satellite pictures on Saturday evening showed thunderstorm activity building up over parts of the southern Peninsula even as rain clouds hovered over the Andaman Sea and the South-East Bay of Bengal.

The India Met Department (IMD) has already set up a watch during the next two days for signs of arrival of the South-West monsoon.

Friday morning’s cyclonic circulation parked over the North Andaman Sea and adjoining Malay Peninsula shifted bearing to the South Andaman Sea by the evening.

Myanmar, Sri Lanka

As reported, the Myanmar Department of Meteorology and Hydrology, the nearest national-level monitoring station, is looking for monsoon onset over its southern parts during the next 4-5 days. Sri Lanka is the penultimate station where the monsoon strikes before finally reaching Kerala on the South-West coast of mainland India. Its Met Department has forecast above-normal rainfall over most parts of the country during May-June-July except a few districts to the West.

Weak El Nino conditions prevail in Equatorial Pacific Ocean and are likely to continue through May-June-July, but with decreased intensity as time progresses. Prediction skills are limited during May and June due to strong day- to-day atmospheric variability caused by the passage of ‘low’s and depressions or intra-seasonal systems such as Madden Julian Oscillation (MJO) waves.

Meanwhile, the principal weather-setting systems live over India included a prevailing western disturbance over West Rajasthan along with a cyclonic circulation. The combo may cause fairly widespread to widespread precipitation over the hills of North-West India, and isolated to scattered precipitation over the plains, into Saturday.

Weather systems

During the same period, Rajasthan may witness dust storms/thunderstorms, but they will lose intensity by Sunday, the IMD forecast said.

A successor western disturbance is closing in, and was, on Friday, located to over Central Pakistan, with its southern flanks reaching out in into the North Arabian Sea. It may trigger isolated to scattered precipitation yet again over the hills of North-West India on Tuesday.

Towards the South-East and South, heat wave conditions may get entrenched over Vidarbha, while bringing North Interior Karnataka and Chhattisgarh under its fold from Saturday.

Elsewhere, cyclonic circulations were spotted over South Himachal Pradesh, South Interior Karnataka, and Central Assam, while a trough linked South Interior Karnataka with Comorin across Tamil Nadu.

Thunderstorm forecast

All these are potential weather-setting systems triggering a familiar pre-monsoon pattern of thunderstorms, lightning, high winds, heavy rain and even hailstorms.

The 24 hours ending on Friday morning saw thunderstorms roaming around Uttarakhand, Himachal Pradesh, Haryana, Punjab, Bihar, Rajasthan, West Uttar Pradesh, Assam, Meghalaya, hills of Bengal and Sikkim.

Forecast for Saturday said that thunderstorm and lightning accompanied with gusty winds (40 km/hr) may break out over the hills of Bengal and Sikkim, as well as Rajasthan.

Heat wave conditions are likely to persist over Vidarbha, Chhattisgarh, Coastal Andhra Pradesh, Rayalaseema, North Interior Karnataka and Telangana.

On Sunday, thunderstorm and lightning accompanied with gusty winds (50 km/hr) are forecast over South Interior Karnataka, Tamil Nadu, Puducherry and Kerala.

Heat wave conditions are likely over Vidarbha and in isolated over Chhattisgarh, Rayalaseema, North Interior Karnataka and Telangana. Heavy rainfall may lash Kerala.

Source ;BL