Mumbaikars are set to experience intense rain over the weekend. Heavy to very heavy rainfall is expected in the Mumbai and Konkan regions on Saturday and Sunday, according to a five-day forecast by the India Meteorological Department (IMD), which said on Wednesday that a low-pressure area over the Arabian Sea is likely to intensify into a depression by Friday evening. Isolated parts of Mumbai, Thane and Palghar will experience light to moderate rainfall from June 7, according to the IMD.

City in for heavy rain

“The deep depression intensified into the cyclonic storm Biparjoy over east-central Arabian Sea at 5.30 pm and is likely to move nearly northwards and intensify into a severe cyclonic storm during the next 24 hours,” said an IMD official. The cyclone is also likely to lead to rough weather in the coastal areas of Maharashtra, Goa, Karnataka and Kerala, IMD said and issued a five-day warning for the region from June 7. It warned fishermen in the region not to venture into the sea.

The wind speed in the Arabian Sea is likely to range from 80 kmph to 155 kmph over the next five days, according to the weather agency. Meteorologists, however, underlined that though the tentative track of the system is likely to be in the northward direction storms at times defy the predicted track and intensity.

Monsoon to progress slowly

Conditions have become favourable for the onset of the southwest monsoon in Kerala, because of Biparjoy, the first storm brewing in the Arabian Sea this year, according to experts. However, meteorologists predicted a “mild” onset over Kerala and “weak” progress beyond the southern peninsula. After the onset over Kerala, the monsoon is expected to remain “weak” until the storm degenerates around June 12, according to Mahesh Palawat, vice president (climate and meteorology) Skymet Weather.

“The powerful weather system in the Arabian Sea may spoil the advancement of the monsoon deep inland. Under their influence, the monsoon stream may reach coastal parts but will struggle to penetrate beyond the Western Ghats,” Skymet Weather had said on Tuesday.

Forecasting agencies said the storm has seen “rapid intensification”, escalating from just a cyclonic circulation to a severe cyclonic storm in just 48 hours, defying earlier predictions. Atmospheric conditions and cloud mass indicate that the system is likely to sustain the strength of a very severe cyclone till June 12, they said.

Climate change intensifying storms

Cyclonic storms in the Bay of Bengal and the Arabian Sea have been intensifying rapidly and retaining their intensity for a longer duration because of climate change, according to scientists.

“The oceans have become warmer already on account of climate change. A recent study shows that the Arabian Sea has warmed up by almost 1.2 degree Celsius since March. Thus, conditions are favourable for the rapid intensification of the system (Cyclone Biparjoy). So it has the potential to sustain the strength for a long period,” said Raghu Murtugudde, professor, Department of Atmospheric and Oceanic Science, University of Maryland and IIT Bombay.