Cyclone Chapala Threatens Yemen With Flooding Rains

Just one week after Hurricane Patricia wowed the weather world with the highest winds ever directly recorded in a storm, another tropical cyclone is making headlines. This time it’s a rare high-end cyclone in the Arabian Sea that could rival the strongest on record for that part of the world and bring considerable damage to parts of the Arabian Peninsula.

The Arabian Sea usually sees only one or two storms a year, according to a 2011 Journal of Climate study that surveyed the historical record there. Of those, not as many reach the intensities of those in more active basins, like the Pacific, even though the area has very warm waters, usually favorable to storm development.

This is because dry air from the Arabian Peninsula and monsoon winds tend to make the region unfriendly to storm formation and intensification.

Cyclone Chapala spins over the Arabian Sea, headed towards a landfall in Yemen or Oman.

Credit: UW CIMSS

Cyclone Chapala first formed on Oct. 28, before rapidly strengthening, something it was able to do because atmospheric conditions happened to be such that they actually helped intensify the convection at the center of the storm, according to the Weather Channel. This allowed Chapala to take advantage of the very warm ocean waters of the region and send its convection into overdrive.

Chapala is currently packing sustained winds of about 150 mph, according to the U.S. Joint Typhoon Warning Center, making it equivalent to a high-end Category 4 hurricane. (Tropical cyclones, hurricanes and typhoons are all names used by different regions for the same phenomena.)

The storm is expected to continue strengthening, eventually peaking at Category 5 status, before beginning to weaken as it gets closer to land and begins to suck in drier air. It is still expected to make landfall with hurricane-force winds, though, likely somewhere between the ports of Mukalla, Yemen and Salalah, Oman, the World Meteorological Organization said in a blog post.

Such winds could be extremely damaging if the storm were to directly hit a town or city, as buildings there aren’t constructed to withstand such conditions. But that part of the coast is very sparsely populated; most people and infrastructure in Yemen are in the western end of the country.

Another major concern, and not just along the coast, is the intense rainfall that Chapala could bring. The system could produce close to 20 inches of rain in some areas of the arid landscape, which usually only records about 4 inches of rain in an entire year, according to the U.K.’s Met Office, making flooding and mudslides a major concern.

A much weaker storm made landfall in Yemen in October 2008, causing widespread flooding that displaced some 22,000 people. That storm killed 180 people and caused $1 billion in damage.

“And now we are talking about a tropical cyclone that is slated to make landfall in a similar location, but with a far greater intensity and size,” Amato Evan, co-author of the 2011 study and an atmospheric scientist at the Scripps Institution of Oceanography, said in an email. “Given the war happening there right now, this is just not good. At all.”

That war, between Houthi rebels and a Saudi-led coalition on behalf of the ousted president, Abdu Rabbu Mansour Hadi, has Yemen in dire straits. The conflict has killed thousands of civilians and left the country, one of the poorest in the Middle East, with serious food security issues and dwindling medical supplies.

The war is mostly confined to the western end of the country, so the exact impacts of the storm may depend on where it hits, said Chris Funk, a research geographer at the University of California, Santa Barbara.

Expected track of Cyclone Chapala.

Credit: U.S. JTWC

Getting supplies to the area could become even more difficult as the storm’s high winds, and the waves they whip up, are likely to make it very difficult for ships to navigate the busy shipping lanes of the Gulf of Aden.

The strongest storm known to hit the Arabian Peninsula was Cyclone Gonu in 2007, according to the 2011 study. It reached a peak intensity that was equivalent to a Category 5 storm, with winds topping out around 167 mph, according to records from the JTWC. It weakened to Category 1 status before grazing the coast of Oman and then making landfall in Iran as a tropical storm. Even though it had weakened, it still resulted in the deaths of 100 people across Oman, Iran and the United Arab Emirates and caused an estimated $4 billion in damage.

Gonu was the closest a storm has come to entering the Persian Gulf, where no tropical cyclone has ever been observed. A recent study suggested, though, that as the world warms that could change, leading to extremely high storm surge events in the region.

The most recent strong Arabian Sea storm was last year’s Nilofar, which fizzled out at sea.

Some research has also suggested that a recent increase in the intensity of Arabian Sea storms could be linked to changes in aerosol emissions from human activity, though “it would be impossible to attribute one particular storm to such slowly varying climate processes,” Evan, who has contributed to that research, said.