Weather systems set stage for Day 3 of rain, hail in Bengaluru

Bengaluru city recorded 7 mm of rainfall on March 18-19, while the northern periphery of the city (the Bengaluru international airport region) reported 64.8 mm of rainfall. The highest single-day rainfall ever recorded in March in the city is incidentally 61 mm on March 28, 1981.

The maximum and minimum temperatures fell 3°C below normal to 30.6°C and 17.4°C, respectively, after the rainfall and hail on Wednesday. The Bengaluru international airport region saw a 4°C dip from normal in minimum temperature to 15.6°C after the hail and rainfall on March 18.

“It is not very unusual (hailstones in March in Bengaluru). The freezing level is normally at a height of 5 km or 5.5 km. As you go higher in the atmosphere, that is when you have freezing temperatures of 0°C. What is happening now is that freezing is at a lower level of about 4 km in the atmosphere,” Dr N Puviarasan, head of IMD Bengaluru, said.

“As a result, when there is convection, and the cloud goes above the freezing level, it condenses and falls as ice or hailstones. This is the reason. The moisture feeding is heightened because of two anti-cyclone effects at the surface level, which feed the moisture content,” the IMD official added.

“This moisture is collecting over Karnataka, where the temperature is around 33°C to 34°C, which is sufficient for the moisture to be carried to the freezing height of 4 km. This causes hail formation, which is why hail has been reported across much of interior Karnataka,” Dr Puviarasan explained.

“Even today, there is a possibility of hail, although there is a slight increase in the freezing height level for the clouds,” he said.

What the forecast says

The weather forecast for north interior Karnataka over the last couple of days has been “light to moderate rain/thundershowers with hail and gusty wind (50-60 kmph) likely to occur at a few places over Bidar, Kalburgi, Yadgir, Raichur and Koppal districts” as well as Ballari, Vijayanagara and Davangere districts.

The weather forecast for south interior Karnataka has been “light to moderate rain/thundershowers with gusty wind (30-40 kmph) likely to occur at a few places over Chamarajanagara, Mysuru, Kodagu, Ramanagara, Bengaluru (Rural), Bengaluru (Urban), Mandya, Hassan, Chikkamagaluru and Kolar districts.”

The meteorological conditions include a lower pressure trough “from Marathwada to Gulf of Mannar (which) now runs from above cyclonic circulation over central parts of Madhya Pradesh to North Interior Karnataka across Marathwada and Vidarbha at 0.9 km above mean sea” and “a trough (which) runs from Gulf of Mannar to South Interior Karnataka across Tamil Nadu at 0.9 km above mean sea level,” the IMD has reported.

The weather for Bengaluru over the weekend is predicted to be “generally cloudy sky towards afternoon/evening” and “light to moderate rain/thundershowers with gusty wind (30-40 kmph) likely” while “maximum and minimum temperature very likely to be around 30°C and 20°C respectively”.