Severe Cyclonic Storm Phethai to soak eastern India into Tuesday

By Eric Leister, AccuWeather senior meteorologist

By Adam Douty, AccuWeather senior meteorologist

December 16, 2018, 10:53:37 AM EST

Severe Cyclonic Storm Phethai in the Bay of Bengal is expected to move into eastern India early in the week bringing damaging winds and flooding rainfall.

The warm waters of the Bay of Bengal aided in the storm strengthening into a severe cyclonic storm (the equivalent of a strong tropical storm in the Atlantic or Pacific ocean) over the weekend.

"As the storm strengthens, seas will build across the southern Bay of Bengal and become increasingly dangerous for boaters," according to AccuWeather Senior Meteorologist Kristina Pydynowski. "Fishermen off the southeastern coast of India are encouraged to return to port."

Bathers will also be at risk due to increased surf and rip currents along the coast of Tamil Nadu and Andhra Pradesh, as well as Sri Lanka, during this time.

The cyclone may lose some wind intensity and weaken as it nears the coast, though it may still be a cyclonic storm as it moves onshore on Monday. It can still deliver flooding rainfall, damaging winds and potentially dangerous mudslides to parts of eastern India.

The outer rainbands of the storm began to bring rain to northern Andhra Pradesh and southern Orissa on Sunday.

Rainfall and winds will increase in these areas on Monday as the storm approaches.

"Northern Andhra Pradesh can receive 100-200 mm (4-8 inches) of rain with an AccuWeather Local StormMax™ of 300 mm (12 inches) from the storm," according to AccuWeather Senior Meteorologist Dave Houk.

That can lead to numerous incidents of flash flooding in cities such as Kakinada and Visakhapatnam.

Streams and rivers may overflow their banks and flood neighboring land and homes. Roads can become flooded and closed, which can cause major travel disruptions.

Despite the storm being past its peak at landfall, wind gusts of 80-95 km/h (50-60 mph) can still batter the coast of Andhra Pradesh into Monday.

"The persistent gusty winds driving the water onshore can lead to coastal flooding," Pydynowski said. "The risk will be highest in the vicinity of Kakinada and near where the storm moves onshore."

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The winds can also down trees, cause power outages and minor structural damage.

While any wind from the storm should be confined to the coast, heavy rain can spread over a larger area of eastern India.

Heavy rain can raise the risk for flash flooding in poor drainage and urban areas across Chhattisgarh and Odisha early this week.

Rainfall may also increase across West Bengal, northeastern India and Bangladesh later Monday into Tuesday. This includes Kolkata and Dhaka.

"How quick the storm continues to weaken will determine whether there will be pockets of heavier rain or a more widespread soaking over these areas," according to Pydynowski. "If the latter unfolds, localized flash flooding and travel delays may remain concerns."

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Even in the absence of any flooding, heavy rain can create hazards for motorists by dramatically reducing visibility and heightening the risk of vehicles hydroplaning when traveling at highway speeds.