DE­FY­ING LOGIC:

How did Hur­ri­cane Michael get so pow­er­ful so quickly?

The Times-Tribune - - NATION & WORLD - BY DAVID FLESHLER SUN SEN­TINEL (TNS)

storm grew very strong, very quickly.

FORT LAUD­ERDALE, Fla. — As Hur­ri­cane Michael drew strength from the warm wa­ters of the Gulf of Mex­ico, it stunned ex­perts with its abrupt trans­for­ma­tion from gar­den-va­ri­ety Oc­to­ber storm to his­tory-mak­ing mon­ster.

At the Na­tional Hur­ri­cane Cen­ter, as the storm’s grow­ing power was be­com­ing clear, one fore­caster wrote that its rapid in­ten­si­fi­ca­tion in the face of un­fa­vor­able high-al­ti­tude winds “de­fies tra­di­tional logic.”

“You could tell they were flum­moxed,” Phil Klotzbach, re­search sci­en­tist in the De­part­ment of At­mo­spheric Science at Colorado State Uni­ver­sity, said Thurs­day. “This shouldn’t be hap­pen­ing, but it is.”

The storm’s sud­den in­ten­si­fi­ca­tion to near-cat­e­gory 5 power, with winds of 155 mph when it slammed into Mex­ico Beach, un­der­lined the con­tin­ued lag in fore­cast­ers’ abil­ity to pre­dict a storm’s strength, even as they dis­play grow­ing vir­tu­os­ity in say­ing where it will make land­fall.

In the case of Michael, the storm ap­peared to be head­ing into a hur­ri­cane-snuff­ing en­vi­ron­ment of strong wind sheer, the dif­fer­ences in wind speed and di­rec­tion that can dis­rupt a hur­ri­cane’s ro­tat­ing, cone-shaped struc­ture. But these winds ap­peared to fade sooner than ex­pected, and the hur­ri­cane found it­self in a highly fa­vor­able en­vi­ron­ment, with a moist at­mos­phere and above-av­er­age wa­ter tem­per­a­tures. Gen­er­ally warm to be­gin with, the wa­ter of the Gulf of Mex­ico had a tem­per­a­ture of 2 or 3 de­grees higher than nor­mal.

“Once that sheer weak­ened, the rest of the con­di­tions were al­ready present,” said Corene J. Matyas, a hur­ri­cane ex­pert and as­so­ciate pro­fes­sor in the de­part­ment of ge­og­ra­phy at the Uni­ver­sity of Flor­ida. “It had all the en­ergy it needed, so once those winds re­laxed, it was able to use that en­ergy to the fullest.”

The Na­tional Hur­ri­cane Cen­ter de­fines rapid in­ten­si­fi­ca­tion as a gain of at least 30 knots — about 35

mph — in wind speed over a 24-hour pe­riod.

Such sud­den gains in power aren’t un­com­mon. Hur­ri­cane Pa­tri­cia, which struck Mex­ico’s Pa­cific coast Oct. 23, 2015, strength­ened from trop­i­cal storm to Cat­e­gory 5 hur­ri­cane in 24 hours. In Au­gust 2004, Hur­ri­cane Charley strength­ened from 110 mph to 150 mph in just a few hours be­fore strik­ing Flor­ida’s Gulf Coast south of Sara­sota.

Although Florid­i­ans re­mem­ber Hur­ri­cane Wilma for rak­ing the state from west to east in Oc­to­ber 2005, it’s fa­mous among me­te­o­rol­o­gists for its ex­plo­sive gain of strength over the western Car­ib­bean, shoot­ing from trop­i­cal storm to strong Cat­e­gory 5 hur­ri­cane, with 185 mph winds, in two days.

Hur­ri­cane Michael un­der­went three pe­ri­ods of rapid in­ten­si­fi­ca­tion, said Haiyan Jiang, as­so­ciate pro­fes­sor of me­te­o­rol­ogy at Flor­ida In­ter­na­tional Uni­ver­sity. Be­gin­ning Sun­day, it strength­ened from trop­i­cal de­pres­sion to Cat­e­gory 1 hur­ri­cane, gained power and, within one 24-hour pe­riod, in­creased its max­i­mum wind speed from 74 mph, or a min­i­mal Cat­e­gory 1 hur­ri­cane, to 155 mph, a strong Cat­e­gory 4.

Fore­cast­ers to­day pre­dict a storm’s path with an ac­cu­racy that would have daz­zled their col­leagues of a gen­er­a­tion ago, hav­ing nar­rowed and length­ened the fa­mous “cone of un­cer­tainty” to re­flect their abil­ity to fore­cast a storm’s track five days in ad­vance.

But in­ten­sity fore­cast­ing, while im­proved, hasn’t shown the same gains. While fore­cast­ing a storm’s path re­quires broad in­for­ma­tion on large-scale fac­tors around a storm, such as winds and air pres­sure, fore­casts of in­ten­sity re­quire de­tailed, spe­cific data from the most vi­o­lent part of a hur­ri­cane’s in­te­rior, not the eas­i­est place to do science.

“We try to fly through the storms as much as we can,” said Matyas, of the Uni­ver­sity of Flor­ida. “They make passes and they drop in­stru­ments, but some­times you don’t drop it where the strong­est winds are go­ing to go. You have to hunt around to find the ex­act spots where the strong­est winds are blow­ing, and then drop your in­stru­ments in, re­mem­ber­ing that you’re drop­ping it from, let’s say 10,000 feet, it’s go­ing to get blown side­ways as it drops to­ward the ground. So it’s very, very dif­fi­cult to mea­sure.”

PE­DRO POR­TAL / MI­AMI HER­ALD / TNS

De­struc­tion is ev­i­dent Thurs­day along U.S. Route 231, in­clud­ing a mas­sive train de­rail­ment, in Panama City, Fla., the day af­ter Hur­ri­cane Michael blew through.

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