Fast, furious: How Michael grew into a 155 mph monster

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<pMoist air, warm waters in the Gulf of Mexico, and ideal wind patterns supercharged Hurricane Michaelhurricane Tuesday morning, with winds of 90 mph. A little over a day later, it had transformed into a monster. When it made landfall Wednesday afternoon, it was blowing at 155 mph. That’s a 72 percent increase in wind speed in less than 33 hours.

<p"Michael saw our worst fears realized, of rapid intensification just before landfall on a part of a coastline that has never experienced a Category 4 hurricane," University of Miami hurricane researcher Brian McNoldy said Wednesday morning.

<pHurricanes have something called a potential intensity. That's how strong a storm<pAs Michael's eye started coming ashore, it boasted the third lowest central pressure of any storm to hit the United States, behind only a 1935 Labor Day storm and 1969's Camille.

<pMeteorologists first got a sense something big could be happening by watching how Michael's eye changed shape. Early Tuesday, it was oddly shaped and ragged. Later in the morning it started to get better organized, and by Tuesday night real-time satellite imagery was showing the eye getting stronger and scarier by the minute.

<pAnother factor: Its pressure, the measurement meteorologists use to gauge a hurricane's strength. The lower the pressure, the stronger the storm. Before landfall, Michael's pressure fell so low it looked like the winds were sure to pick up fast, said Ryan Maue, a meteorologist for weather<pThat mismatch "pushes the storm over" or decapitates it, Kossin said. When the wind shear near Michael eased, the storm took off, he said.

<p"It's kind of like someone was holding on to it when it was trying to run and they let it go," Kossin said.

<pAnother huge factor was the water temperature. Warm water is the energy that fuels hurricanes, and the Gulf water is 4 to 5 degrees warmer than normal.

<pWater temperatures in the Gulf of Mexico vary along with weather, but some scientists said the warm waters are signs of human-caused climate change<pThe warm waters, Kossin said, are a "human fingerprint" of climate change.

<pKossin and others have a study out this month in the Journal of Climate with computer simulations showing that human-caused global warming will increase rapid intensification of tropical weather across the globe in the future.

<pOther studies have shown rapid intensification has already increased over past decades. One study this year in Geophysical Research Letters found that since 1986, the rate of intensification of storms like Michael has increased by about 13 mph.

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<pFollow Seth Borenstein on Twitter: @borenbears . His work can be found here .

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<pThe Associated Press Health & Science Department receives s upport from the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.

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<pFor the latest on Hurricane Michael, visit https://www.apnews.com/tag/Hurricanes .