Hurricane Otis turned from mild to monster in record time, and scientists are struggling to figure out how B次元官网网址� and why they didnB次元官网网址檛 see it coming.
Usually reliable computer models and the forecasters who use them didnB次元官网网址檛 predict OtisB次元官网网址� explosive intensification, creating a nightmare scenario of an unexpectedly strong storm striking at night. At least 27 people are dead and four missing in the destruction along MexicoB次元官网网址檚 Pacific coast, with devastation that extends for miles.
All this after Acapulco was told to expect a tropical storm just below hurricane strength. Just 24 hours later, Otis blasted ashore with 165 mph (266 kph) winds, the strongest landfall of any East Pacific hurricane.
In just 12 hours, OtisB次元官网网址� strength more than doubled from 70 mph (113 kph) winds to 160 mph (257 kph), also a record, as it neared the coast. And it got even stronger before it struck. Storms typically gain or lose a few miles per hour in 12 hours, though some outliers gain 30 to 50 mph (48 to 80 kph) in a day.
What happened with Otis was just plain nuts, said University of Miami hurricane researcher Brian McNoldy. But it coincides with a documented trend of because of warmer water connected to , scientists said.
Five different hurricane experts told The Associated Press they werenB次元官网网址檛 quite sure what set Otis off and why it wasnB次元官网网址檛 predicted, especially since meteorologists have been dramatically improving their intensity forecasts in recent years.
B次元官网网址淭he models completely blew it,B次元官网网址� said MIT atmospheric sciences professor Kerry Emanuel, a hurricane expert.
Experts point to lack of data on the storm and its surroundings and just not completely understanding what makes a storm act like itB次元官网网址檚 on steroids.
And it really matters because in OtisB次元官网网址� case, the storm was coming ashore when it muscled up.
B次元官网网址淚tB次元官网网址檚 one thing to have a Category 5 hurricane make landfall somewhere when youB次元官网网址檙e expecting it,B次元官网网址� McNoldy said. B次元官网网址淏ut to have it happen when youB次元官网网址檙e not expecting anything to happen is truly a nightmare.B次元官网网址�
For example, McNoldy, who lives in Miami, said a tropical storm forecast would prompt him to B次元官网网址渄o things like move some lightweight furniture in and take down wind chimes and things like that. ThatB次元官网网址檚 about it. YouB次元官网网址檙e not preparing for a Category 5 hurricane.B次元官网网址�
National Hurricane Center Director Michael Brennan said B次元官网网址渢hatB次元官网网址檚 a very bad scenario, populated area, rapid intensification very close to landfall, a change in the expectations about the impacts thatB次元官网网址檚 happening on a time scale that doesnB次元官网网址檛 give people a lot of time to respond.B次元官网网址�
Brennan said OtisB次元官网网址� unforeseen buildup was because B次元官网网址渋t found a much more favorable environment than we were anticipating.B次元官网网址� He said one part was warm water, another was that the winds B次元官网网址� moving in the right direction and at the right altitude B次元官网网址� allowed a somewhat raggedy storm to rapidly develop structure and strengthen.
McNoldy said there may be a mystery ingredient that scientists just donB次元官网网址檛 know right now, but water is key.
Warm water is fuel for hurricanes. Hot, deep water is like an all-you-can-eat buffet.
Globally, the worldB次元官网网址檚 oceans have been setting monthly surface heat records since April. The surface waters off the Mexican coast were warm but B次元官网网址渘ot crazy warm,B次元官网网址� said University at Albany atmospheric scientist Kristen Corbosiero. Bennan and McNoldy said those waters were maybe 1 or 2 degrees above normal.
Below that, the water was much hotter than usual B次元官网网址渁nd thereB次元官网网址檚 just a ton of fuel out there right now,B次元官网网址� McNoldy said. Still, the storm didnB次元官网网址檛 linger and feed on that, which would be expected in rapid intensification, Brennan said.
The heat content in the deeper ocean worldwide has been ItB次元官网网址檚 from human-caused climate change, McNoldy and other scientists said, as the oceans act as a sponge to absorb a lot of the excess heat caused by the burning of coal, oil and gas.
Otis and two other historically explosive cases of rapid intensification B次元官网网址� Patricia in 2015 and Wilma in 2005 B次元官网网址� all happened in the same mid- to late-October time frame, when deeper water and ocean heat content is at its highest, McNoldy said.
Numerous studies have shown globally that there are than there used to be. An official definition of rapid intensification is a gain in strength of 35 mph (56 kph) in 24 hours. , many of them just before smacking land. In 2017, two devastating hurricanes, Harvey and Maria, rapidly intensified. Last month in the Atlantic, Hurricane Lee rapidly intensified from 80 mph (129 kph) to 155 mph (249 kph), but didnB次元官网网址檛 hit anywhere.
B次元官网网址淲eB次元官网网址檙e seeing so many more cases of these just astonishing rapid intensification events,B次元官网网址� said former National Oceanic and Atmospheric Administration hurricane and climate scientist Jim Kossin, now with the First Street Foundation.
Kossin said that thereB次元官网网址檚 evidence that whatB次元官网网址檚 happening globally over a longer time frame is due in part to human-caused climate change but itB次元官网网址檚 hard to say that about an individual storm.
But, he added, B次元官网网址渢his is exactly the kind of thing we would expect to find as the climate warms.B次元官网网址�
MITB次元官网网址檚 Emanuel said it might be more than just the waterB次元官网网址檚 temperature, but its low salinity, too. Water in that area at this time of year is fresher from heavy rains at the surface, and that changes the mix of water temperature, he said. Normally a hurricane mixes the warm water on the surface with cooler water below. But when the surface water is fresher, a storm pulls up even more hot water from below, which feeds the storm more B次元官网网址渁nd before you know it, youB次元官网网址檙e in hot water,B次元官网网址� Emanuel said.
One key test of that theory is whether Otis leaves warm water in its wake. Usually, hurricanes leave behind cold water. Emanuel hopes satellite images will show it, but itB次元官网网址檚 not certain whether theyB次元官网网址檒l get the right view.
Another factor that Brennan and others mention is that perhaps forecasters underestimated OtisB次元官网网址� original strength. That would mean it didnB次元官网网址檛 intensify as much as it appears because it was stronger to begin with.
B次元官网网址淭he East Pacific in a lot of ways is a huge data void,B次元官网网址� Brennan said. B次元官网网址淭hereB次元官网网址檚 no buoys. ThereB次元官网网址檚 very few land observations. ThereB次元官网网址檚 no radars along the west coast of Mexico. So weB次元官网网址檙e really reliant almost entirely on satellite imagery.B次元官网网址�
And sometimes satellites, looking at a storm from high above, cannot get an accurate picture of whatB次元官网网址檚 going on.
Think of it like a jigsaw puzzle and forecasters at times have only 10% of the pieces, Brennan said.
Forecasters have far more tools to see whatB次元官网网址檚 happening in Atlantic storms, he said.
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Seth Borenstein, The Associated Press
