Hur­ri­cane track­ers try to nar­row ‘cone of un­cer­tainty’

USA TODAY International Edition - - NEWS - Kristin Lam

Hur­ri­cane Michael is likely to make land­fall on the Florida Pan­han­dle by Wed­nes­day af­ter­noon, cre­at­ing po­ten­tially life-threat­en­ing con­di­tions from the Alabama-Florida state line all the way east­ward to the Suwan­nee River. Whether Michael lands near Tallahassee or closer to Panama City Beach, Dennis Felt­gen of the Na­tional Hur­ri­cane Cen­ter told USA TO­DAY, ev­ery­body in the hur­ri­cane warn­ing and watch ar­eas should be on alert. “We don’t want any­body to get hung up on, ‘Well, is the storm go­ing to go over this city or is it go­ing over that city?’ – that’s im­ma­te­rial here,” Felt­gen said. “You need to be look­ing at the over­all im­pacts of the hur­ri­cane.” Around the skinny black line used on tracker maps, rep­re­sent­ing the hur­ri­cane’s pro­jected path, the “cone of un­cer­tainty” shows the av­er­age track fore­cast er­ror in the past five years. Felt­gen said im­pacts, such as those from storm surge and in­land flood­ing, ex­tend out­side that cone. The ac­cu­racy of track fore­casts has im­proved in the past 10 to 15 years to the point where the five-day fore­cast for Hur­ri­cane Florence in Septem­ber was off by only 2 miles. “Lit­tle wig­gles” or vari­a­tions in a storm’s track by 20 or 30 miles to the left or right can change im­pacts, Felt­gen said. They can­not be pre­dicted far in ad­vance. To de­ter­mine the track fore­cast for ad­vi­sories is­sued ev­ery six hours, ex­perts at the hur­ri­cane cen­ter use com­puter-gen­er­ated mod­els to process data col­lected by re­con­nais­sance air­craft. Jets such as the NOAA G-IV sam­ple the at­mos­phere around and ahead of the hur­ri­cane. Ex­pe­ri­enced spe­cial­ists con­sider which mod­els work best for dif­fer­ent sit­u­a­tions and fac­tors, such as in­ten­sity. Hur­ri­canes can change paths be­cause sur­round­ing weather pat­terns steer them. Hur­ri­cane Florence stalled when it made land­fall be­cause weather sys­tems around it were in equi­lib­rium. For Hur­ri­cane Michael, a dis­tinct trough of low pres­sure in the mid­dle and up­per part of the at­mos­phere will push the storm, Felt­gen said. “Un­like Florence, Michael will be on the move,” he said. “This is not go­ing to be a lin­ger­ing storm. This trough of low pres­sure will ac­tu­ally help guide the storm from the Florida Pan­han­dle, up through Ge­or­gia, up through the Caroli­nas, and then push it out into the At­lantic.” The Pen­sacola News Jour­nal, part of the USA TO­DAY Net­work, re­ported Mon­day that the Na­tional Hur­ri­cane Cen­ter pre­dicted Michael to make land­fall be­tween Pen­sacola in the far west­ern Pan­han­dle and Apalachicola, di­rectly south of Tallahassee on the coast. Of­fi­cials in Bay and Wal­ton Coun­ties, both along the Pan­han­dle, are among those that is­sued evac­u­a­tion or­ders. Hur­ri­cane Opal, in 1995, was the last ma­jor hur­ri­cane to hit the two coun­ties. Not in­clud­ing tourists, 130,000 were or­dered to evac­u­ate start­ing at 6 a.m. Tues­day, Joby Smith, chief of Bay County’s emer­gency man­age­ment divi­sion, told USA TO­DAY. There were two shel­ters for gen­eral and spe­cial needs pop­u­la­tions. If the storm makes land­fall to the west, Bay County will face un­prece­dented storm surge con­cerns, par­tic­u­larly in bay sys­tem ar­eas. If Michael comes through the east, se­vere weather will be the main is­sue. Ei­ther way, Smith said, the county will be wor­ried about power out­ages and de­layed emer­gency ser­vices. Panama City Beach is iso­lated by high-rise bridges that will close be­cause of high winds. Low-ly­ing ar­eas are es­pe­cially vul­ner­a­ble.

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