On Monday, the storm was rated a Category 5 with maximum sustained winds of 165 miles per hour and gusts to 200 mph, as it reached the upper end of the storm intensity scale. Cyclone Amphan ranked as the most powerful storm in the Northern Hemisphere so far this year, and the strongest tropical cyclone to occur in the Bay of Bengal.
Even as a Category 4 storm as of Monday evening, Cyclone Amphan is capable of inflicting catastrophic damage in a heavily populated, low-lying area that has seen staggeringly high death tolls in past storms.
The storm is undergoing an eyewall replacement cycle, during which time the storm’s inner ring of thunderstorms and powerful winds loses steam as an outer ring forms and contracts, causing a temporary hiccup in storm intensity. It’s unclear how much intensity the storm will regain once this is complete, but it’s now likely it will remain an intense tropical cyclone right through landfall on Wednesday, Eastern time.
Current track forecasts show the storm crossing the coast of West Bengal, south or southeast of Kolkata, India. This would put parts of West Bengal and neighboring areas of Bangladesh on the right-hand side of the storm, where the most intense winds and highest storm surge will be.
The Joint Typhoon Warning Center is forecasting Amphan (pronounced “UM-PHUN”) to make landfall as a Category 2 or 3 storm. The forecast takes the fierce storm within 25 miles of Kolkata, which has a population of about 5 million.
The IMD, which tracks storms in this area, is predicting a storm surge to the right of the storm’s center, where onshore winds will be maximized, to reach a staggering 13 to 16 feet (four to five meters), with waves riding on top of that. The storm surge is the storm-driven rise in water above normally dry land. Sea level rise due to climate change already is making storm surge flooding more damaging in coastal areas around the world, and Bangladesh is considered to be among the most vulnerable areas for increasingly devastating storm surges.
Water, both in the form of coastal storm surge flooding and inland flooding from heavy rainfall, is the biggest killer from tropical cyclones.
The IMD has issued cyclone warnings for West Bengal and the north Odisha coasts.
Even if Super Cyclone Amphan weakens to a Category 1 or 2 storm in terms of its wind speeds before landfall, it still is likely to bring ashore a storm surge equivalent to a much stronger storm. The IMD is forecasting the surge “is likely to inundate low lying areas of south and north 24 Parganas and about 3-4 meters over the low lying areas of East Medinipur District of West Bengal during the time of Landfall.”
The shape of the Bay of Bengal maximizes storm surge at its northern end, since the region becomes narrower as storms spin farther to the north, creating a funnel effect for the movement of water.
Past storms that have struck this densely populated region have killed tens of thousands of people and displaced thousands more. A 1999 cyclone that struck Odisha killed about 10,000 people in northeast India. The deadliest storm on record globally was the 1970 Bhola Cyclone, which made landfall in Bangladesh and killed an estimated 300,000 to 500,000 people.
In recent years, India and Bangladesh have had some success in warning vulnerable coastal residents and initiating evacuations in advance of such storms. In advance of Amphan, India is evacuating 1 million people in the state of Odisha. This is on par with the largely successful evacuations ahead of Cyclone Fani, which struck Odisha last year. That storm killed 89 people and caused billions of dollars in damage.
One complicating factor this year is that India and Bangladesh are battling the coronavirus pandemic. In addition, Bangladesh is still home to around 1 million Rohingya refugees, who fled violence in neighboring Myanmar and are living in camps highly vulnerable to heavy rains and storm surge flooding.
Like many powerful storms in recent years, Tropical Cyclone Amphan underwent a period of rapid intensification Sunday night, feasting upon the warm waters of the Bay of Bengal, absence of wind shear that could’ve interfered with its circulation as well as abundant moisture surrounding the storm.
Based on data from the typhoon warning center, Cyclone Amphan intensified by 110 mph in just 36 hours. “That would certainly put it in a rare class of [rapid intensification] events globally,” said meteorologist Alex Lamers via Twitter. It also jumped in intensity from a Category 1 storm to a Category 5 monster in just 24 hours, according to Bob Henson of Weather Underground.
Rapidly intensifying storms is one of the impacts scientists have seen from human-caused global warming, with studies pointing increasingly to the dangers posed by storms that make a sudden leap in intensity categories.
Other storms that have rapidly intensified in recent years include last year’s Hurricane Dorian and Hurricane Michael in the Atlantic to numerous Pacific Typhoons and tropical Cyclones in Asia. (While these storms go by different names around the world, they are the same weather phenomena.)
The cyclone is likely to complicate efforts to contain the spread of the coronavirus in India and Bangladesh, where infections have climbed steadily. India recorded over 5,000 cases in a 24-hour period ending Monday, the most in a single day, and is nearing the 100,000 mark overall. Ganjam, a coastal district in the state of Odisha, has seen a surge in cases as migrant workers returning home due to an extended lockdown have tested positive. Its neighboring state, West Bengal, saw the highest rise in its virus death toll in early May.
With over 20,000 cases, a fresh cause of worry for Bangladesh has been the discovery of two coronavirus cases in its dense camps for the Rohingya refugees, home to more than 1 million people.
Niha Masih contributed reporting from Delhi.