Explained: Why do hailstorms occur in Summer?

Hyderabad: Several new weather patterns have triggered rain and hail storms in different parts of the country. Northern states were the first to experience drizzle and hail. They were followed by the eastern and northeastern states, and finally the southern and central states.

Why do hailstorms occur in warm weather?

As spring arrives, the temperature is higher than it was during the winter. Yet, this does not imply that it is likewise getting warm in the various levels of the atmosphere. Conditions become more favorable for severe weather, in our case hailstorms, When Western Disturbance/Jet Streams between 200-500hpa (Cold Air on Upper levels) clash with moisture-feeding winds, Easterlies from the Bay of Bengal and South Westerly from the Arabian Sea between 850-925 HPA (Warm Air on Surface levels) considering the factor they pass over the land with higher surface temperatures.

The confluence of climatic conditions allows cumulonimbus clouds to form, resulting in violent thunderstorms throughout North, Central, and East India. Hail forms in the thunderstorm's updraft, which is the rising heated air in the cumulonimbus clouds. It raises the water droplets higher into the atmosphere, where air temperatures are below freezing, converting the droplets into hail stones; later, the earth's gravity drags the hails down towards the land.

As it descends, it encounters numerous impediments such as strong horizontal winds, humidity levels, and temperature differences, which eventually determine the size of the falling hail. As opposed to the monsoon season, the freezing levels in the clouds are lower in spring. As a result, hail falls quickly in these months. During the monsoon, the cloud freezing level is greater and the surface temperature is very warm, thus hail melts back into water droplets or rain before reaching the surface. This explains why hail does not occur in India during the monsoon season. The India Meteorological Department (IMD) has now issued alerts for about 95% of the country for some bad weather over the next few days. Let's take a deeper look at what has been happening.

Northwest India

Western disturbances (WD) have been moving in and around the northern regions of the country, showering the region with much-needed drizzle to lift the scorching states out of heatwave-like conditions. Another WD will interact with southeasterly moist air from the Bay of Bengal to produce abundant amounts of rain in Northwest, West, and Central Indian states in the next days, as a cyclonic circulation near Iran, Afghanistan, and Rajasthan.

For the next few days, the IMD anticipates scattered to reasonably widespread mild to moderate rainfall in Jammu and Kashmir, Ladakh, Punjab, Haryana, Uttar Pradesh, Rajasthan, Himachal Pradesh, and Uttarakhand. These rains may be accompanied by lightning-filled thunderstorms and powerful winds (speed 30-40 kmph).

Hailstorms and rains lashed Shimla bringing a sharp fall in temperatures in the region. Rain and hailstorm lashed parts of Delhi on Saturday and early hours of Sunday, bringing the maximum temperature five notches below the season's average of 25.3 degree Celsius, the lowest so far this month, officials said.

Furthermore, hailstorm season has begun in Himachal Pradesh, Jammu-Kashmir Ladakh, and Uttrakhand from Thursday, and Haryana, West Uttar Pradesh, and North Rajasthan from Friday.

West and Central India

This week, Central India will bear the brunt of pre-monsoon rainfall, with many areas placed on enhanced orange alert (meaning 'be prepared') for the next few days. IMD anticipates scattered to fairly widespread light or moderate rain in Gujarat, Maharashtra, Madhya Pradesh, Vidarbha, and Chhattisgarh.

Thunderstorms with lightning and equivalent gusty winds are also possible during this period. Hailstorms are expected in East Madhya Pradesh, Vidarbha, Chhattisgarh, Madhya Maharashtra, and Marathwada.

On Thursday, Madhya Maharashtra, Vidarbha, Marathwada, and Chhattisgarh were placed under orange alert due to the severe weather. However, the severity of thunderstorms is expected to decrease and the IMD has reduced the alert level to yellow from Friday until Monday.

South India

While the southern areas of the state (particularly the peninsular region) may be beyond the WD's reach, a north-south trough flowing from North Interior Tamil Nadu to Konkan has ensured that South Indians don't miss out on the rains.

This trough will draw moisture in over the next two days, bringing scattered to fairly widespread light to moderate rainfall, thunderstorms, and gusty winds (30-40 kmph) across North Interior Tamil Nadu, Andhra Pradesh, Telangana, and Karnataka.

South India will also benefit from some of the most intense rainfall during this projected period, with the IMD forecasting substantial rainfall (64.5 mm-115.5 mm) over Telangana and Coastal Andhra Pradesh with a possibility of more hailstorms in Telangana.

All six zones in Hyderabad – Charminar, Khairatabad, Kukatpally, LB Nagar, Secunderabad, and Serilingampally – are expected to witness hailstorms towards evening or night. These zones will also witness generally cloudy skies, light to moderate rain or thundershowers, and gusty winds ranging from 40-50 kmph.

“Telangana state average rainfall was 23.9mm in the last 24hrs which is the highest in March in at least the last 10 years. An absolute record-breaking spell of unseasonal rains. We have also had hailstorms in various places like Vikarabad, Manikonda, KPBH, JNTU, we have seen similar hailstorm in 2013” said Balaji, popularly known as Telangana Weatherman on Twitter.

This region's only subdivisions not included in the weather notice are Kerala and Coastal Karnataka on the Indian mainland, as well as the Lakshadweep and Andaman & Nicobar Islands. Telangana, on the other hand, will share the orange alert with the central states at this time.

East and Northeast India

The northeastern states are infamous for receiving massive amounts of rain throughout the year, which seems appropriate given that two troughs are currently fueling precipitation in the region. A westerly trough, as well as another that flows from Sub-Himalayan West Bengal to South Odisha, will bring substantial rainfall to the region.

As a result, the eastern and northeastern states may have widespread light to moderate showers with thunderstorms, lightning, and gusty winds (speed 30-40 kmph). Hailstorms may become common over Bihar, Jharkhand, and Gangetic West Bengal, as they have in the past.

Strange meteorological activity has been observed in areas of Mizoram, with the sky turning pitch black shortly after noon. Heavy hail and dust storms have been reported. Instead of the potentially hazardous weather, Sikkim and Sub-Himalayan West Bengal have been placed under the orange alert.