EXPLAINER: Ida similar to Katrina, but stronger, smaller

3 years ago 276

Hurricane Ida is looking eerily similar a unsafe and possibly scarier sequel to 2005’s Hurricane Katrina, the costliest tempest successful American history. But there's a fewer still-to-come twists that could marque Ida nastier successful immoderate ways, but not rather arsenic horrific successful others.

“The main communicative with Katrina was tempest surge damage, and implicit a immense area. The main communicative with Ida volition beryllium a operation of wind, tempest surge, and caller h2o flooding damage,” said meteorologist Jeff Masters, who flew hurricane missions for the authorities and founded Weather Underground.

Ida is forecast to marque landfall connected the aforesaid calendar date, Aug. 29, arsenic Katrina did 16 years ago, striking the aforesaid wide portion of Louisiana with astir the aforesaid upwind speed, aft rapidly strengthening by going implicit a akin spot of heavy lukewarm h2o that supercharges hurricanes.

What could beryllium antithetic is important though: direction, size and strength.

“Ida volition astir decidedly beryllium stronger than Katrina, and by a beauteous large margin,’’ said University of Miami hurricane researcher Brian McNoldy. “And, the worst of the tempest volition walk implicit New Orleans and Baton Rouge, which got the weaker broadside of Katrina.”

Ida is already a beardown Category 4 tempest with 150 mph (241 kph) winds and forecast to deed 155 mph earlier landfall, “a sneeze distant from becoming the 5th Category 5 landfall connected the continental U.S.,” McNoldy said. It could beryllium the archetypal Category 5 tempest to deed Louisiana oregon the strongest tempest to deed the state.

Katrina weakened rather a spot earlier landfall, striking Louisiana arsenic a Category 3 tempest with 127 mph (204 kph) winds.

Katrina deed Louisiana from owed south, portion Ida is coming to the aforesaid portion of the authorities from southeast. On Sunday, Ida’s hurricane-force winds extended 37 miles (about 60 kilometers) from the center, compared to Katrina’s hurricane-force winds that dispersed 98 miles (158 kilometers) from the halfway erstwhile it made landfall, McNoldy said.

“This has the imaginable to beryllium much of a earthy catastrophe whereas the large contented successful Katrina was much of a man-made one” due to the fact that of levee failures, said McNoldy. Levee failures pushed Katrina’s decease toll to 1,833 and its wide harm to astir $176 cardinal successful existent dollars, and experts don’t expect Ida to travel adjacent those totals.

DIFFERENT DIRECTION

Ida is coming to the aforesaid wide spot from a somewhat antithetic direction. Several hurricane experts fearfulness that quality successful space whitethorn enactment New Orleans much successful the unsafe tempest quadrant — the close beforehand portion of a hurricane — than it was successful Katrina, erstwhile the metropolis was much devastated by levee nonaccomplishment than tempest surge. Katrina’s northeast quadrant pushed 28-foot (8.5-meter) tempest surges successful Mississippi not New Orleans.

Ida’s “angle is perchance adjacent worse,” McNoldy said. Because it is smaller "it's not going to arsenic easy make a immense tempest surge ... but the space that this is coming in, I deliberation is much conducive to pushing h2o into the water (Pontchartrain).”

That northwestern way of Ida not lone puts New Orleans much successful the bullseye than it did successful Katrina, but it besides much targets Baton Rouge and important concern areas, Masters said. He said Ida is forecast to determination done “the conscionable implicit worst spot for a hurricane.”

“It is forecast to way implicit the concern corridor betwixt Baton Rouge and New Orleans, which is 1 of the cardinal infrastructure regions of the U.S., captious to the economy,” Masters said. “You’re astir apt going to unopen down the Mississippi River for barge postulation for aggregate weeks."

Meteorologist Steve Bowen, caput of planetary catastrophe penetration astatine the hazard and consulting steadfast Aon, said the interaction volition beryllium felt beyond coastal areas.

“We’re surely looking astatine imaginable losses good into the billions,” Bowen said.

SIZE MATTERS

The quality is size is not conscionable physically huge, but it matters for damages. Storms that are bigger successful width person larger tempest surge due to the fact that of the broader propulsion of the water.

Ida “is not going to make the immense tempest surge similar Katrina did, it’ll person much focused tempest surge similar (1969’s) Camille,” Masters said.

But larger successful size storms are often weaker, Bowen said. There’s a commercialized disconnected of aggravated harm successful a smaller country versus little damage, but inactive bad, successful a wider area. Bowen and Princeton University’s Gabriel Vecchi said they don't cognize which script would beryllium worse successful this case.

RAPID INTENSIFICATION

Ida precocious Saturday and aboriginal Sunday feasted connected an eddy of what’s called the Loop Current, going from 105 mph winds to 150 mph winds (169 kph winds to 241 kph winds) successful conscionable 8 hours. The Loop Current is this heavy spot of incredibly lukewarm water. It takes lukewarm h2o disconnected the Yucatan Peninsula does a loop successful the Gulf of Mexico and spins up the eastbound borderline of Florida into the Gulf Stream. Water supra 79 degrees (26 degrees Celsius) is hurricane fuel.

Normally erstwhile a tempest intensifies oregon stalls it takes up each of the region’s lukewarm h2o and past hits colder h2o that starts to weaken the tempest oregon astatine slightest keeps it from further strengthening. But these lukewarm h2o spots support fueling a storm. Katrina powered up this mode and truthful did Ida, gaining powerfulness implicit an country with hurricane substance much than 500 feet (150 meters) deep, “just a blistery tub,” McNoldy said.

“Running implicit these Loop Current (eddys) is simply a precise large deal. It’s truly dangerous,” said clime and hurricane idiosyncratic Kossin of The Climate Service.

In the past 40 years much hurricanes are rapidly intensifying much often and clime alteration seems to beryllium astatine slightest partially to beryllium blame, Kossin and Vecchi said. Hurricane Grace already rapidly intensified this twelvemonth and past twelvemonth Hanna, Laura, Sally, Teddy, Gamma and Delta all rapidly intensified.

“It has a quality fingerprint connected it,” said Kossin, who with Vecchi was portion of a 2019 study connected caller accelerated intensifications.

NEW EYEWALL

After a hurricane rapidly intensifies it becomes truthful beardown and its oculus truthful tiny that it often can't rather support going that way, truthful it forms an outer eyewall and the wrong eyewall collapses, Kossin said. That's called eyewall replacement.

When a caller eyewall forms, often a tempest becomes larger successful size but a spot weaker, Kossin said. So cardinal for Ida is erstwhile and if that happens. It happened for Katrina, which steadily weakened successful the 12 hours earlier it made landfall.

Ida has started the process of eyewall replacement, but McNoldy said helium doesn't deliberation it matters.

“It has tally retired of clip to bash thing that would marque a difference.”

HISTORY

Meteorologists person improved forecasts and they anticipation that Louisiana is amended prepared than successful 2005 with a stronger levee system. However, Bowen said Ida is coming a twelvemonth aft Hurricane Laura smacked Louisiana successful 2020 with 150 mph winds.

"No U.S. authorities since 1851 has ever recorded back-to-back years of 150+ mph hurricanes making landfall," Bowen said. “Following Laura’s landfall successful 2020, Louisiana is astir to marque unfortunate history.”

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Follow Seth Borenstein connected Twitter astatine @borenbears.

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