Tropical-storm-force winds could reach southeast Louisiana by Sunday morning, with deteriorating conditions expected thereafter into early Monday.
“Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana,” the Hurricane Center wrote.
New Orleans is under a hurricane warning that stretches from Louisiana’s central coast to the border with Mississippi. Storm surge warnings stretch from Louisiana’s central coast to the Mississippi-Alabama border.
Forecasters are extremely concerned about Ida’s potential to explosively intensify as it passes over the extremely warm waters of the Gulf of Mexico. Some of the warmest waters in the gulf are found immediately along the coastline, meaning Ida will probably continue to strengthen until landfall.
Studies have shown that warming sea surface temperatures due to human-caused climate change have increased the likelihood of rapid strengthening of tropical storm systems.
Ida’s landfall is forecast on the 16th anniversary of Hurricane Katrina striking Louisiana, and it could be even more intense than that historic storm. However, since Katrina, a $14.5 billion flood-protection system was constructed around New Orleans that is expected to be much more effective in keeping stormwaters from inundating the city.
“There’s been a $15 billion investment in the system over the last 16 years, and we are in a far better place than we were in 2005,” said Collin Arnold, director of the New Orleans Office of Homeland Security and Emergency Preparedness, on CNN Saturday. “That being said, this is still a very dangerous storm.”
It’s also probable that Ida’s center will not pass as close to the city as Katrina did, meaning storm surge could be less intense. Katrina was also an enormous storm, which allowed it to push more water ashore. Ida is somewhat more compact.
Due to the storm’s predicted rapid strengthening, Cantrell said it was too late for a mandatory evacuation for areas inside the levee protection system. Instead, she instructed residents to voluntarily evacuate if they can or to shelter in place. “People need to be in their safe spaces by and no later than midnight tomorrow [12 a.m. Sunday],” she said.
Iconic images of Hurricane Katrina’s devastating destruction
Ida is hitting while Louisiana sees a surge in coronavirus cases: On average, more than 4,000 new cases per day have been reported over the past week, with a 10.5 percent increase in deaths.
The Biden administration is sending a surge response team of 50 FEMA paramedics to the state and prepositioning personnel, food, water and generators ahead of the storm.
The most reliable models predict Ida will make landfall Sunday evening southwest of New Orleans, nearly due south of Lafayette, La. Storm impacts from wind and flooding will expand hundreds of miles beyond the storm’s center.
In addition to New Orleans, Baton Rouge and Lafayette in Louisiana, Biloxi and Gulfport, Miss., and Mobile, Ala., are in line for potential direct impacts.
The storm could pass directly over Baton Rouge. Josh Eachus, chief meteorologist for Baton Rouge’s ABC affiliate, called for an “18 hour window of some of the worst weather our city has experienced in years.”
Ida’s remnants could even prove problematic far inland, dropping a swath of heavy rainfall and isolated tornadoes across parts of the South, the Ohio Valley and Mid-Atlantic.
Ida right now
At 8 a.m. Saturday, Ida had 85 mph peak winds as it headed to the northwest at 16 mph, centered 440 miles south-southeast of New Orleans. Its winds havestrengthened by 5 mph since the Hurricane Center’s 5 a.m. advisory.
Ida slipped over western Cuba on Friday night. But unlike past storms that encountered the island, Ida never really weakened. It passed over the Sierra de Organos mountains, a low-topped mountain range, while maintaining its strength as a Category 1 hurricane with 80 mph winds. A number of “convective bursts,” or flare-ups of thunderstorm activity, occurred shortly before midnight.
Ida is set to tap into a powder keg oceanic and atmospheric setup with virtually nothing holding it back. Satellite imagery depicted multiple impressive “hot towers,” or tall thunderstorms near Ida’s center, explosively developing and orbiting one another. In between, an eye was beginning to form. That’s a sign that rapid intensification is underway.
The storm is tapping into sea surface temperatures in the upper 80s, fueling its runaway strengthening. Weak upper-level winds will allow it to mature without interrupting its growth. Broad clockwise flow at high altitudes will assist Ida’s “outflow,” or the evacuation of exhaust air at the upper levels, allowing the storm to ingest more warm, humid air near the surface. All signs point to breakneck rates of intensification, with the likelihood of Ida reaching a high-end Category 4 storm strength by Sunday.
Surge forecast
Ida’s winds will push water up along the coast, likely resulting in devastating storm surge that will occur over a broader area and have a bigger footprint than the winds. The Hurricane Center warned the surge could reach heights of 10 to 15 feet between Fort Morgan, La., and the mouth of the Mississippi River.
A 7- to 11-foot surge is possible southeast of New Orleans, with 4 to 7 feet of inundation likely on Lake Pontchartrain. Coastal Mississippi, including Biloxi and Gulfport, could see a similar storm tide, with a few feet of surge possible all the way east in Mobile Bay.
While much of New Orleans is protected from surge by the Hurricane Storm Damage Risk Reduction System — a system of levees, pumps and flood gates — outside this system, the Weather Service warns the surge could bring “[w]idespread deep inundation,” “structural damage to buildings, many washing away,” “roads washed out or severely flooded,” “extreme beach erosion,” and “massive damage to marinas.”
Surge heights can vary significantly over small distances due to the nuances of coastal topography, landfall location and tidal effects. The worst surge ordinarily occurs east of the storm’s center, where southerly winds directly intersect the coastline.
Wind forecast
Where Ida makes landfall in central coastal Louisiana, winds gusting above 140 mph are possible. That will be the case only at the immediate shoreline where the eyewall, or inner ring of extremely strong winds surrounding the eye, crashes ashore.
Winds of 80 to 100 mph will penetrate about 40 or 50 miles inland. There is a growing chance New Orleans may only experience tropical storm force winds below 75 mph, but the city should be prepared for worse, as subtle shifts in the storm’s path could result in enormous differences in impact.
The National Weather Service will likely opt to issue extreme wind warnings where the eye tracks ashore. That’s a special alert reserved for winds topping 115 mph in major hurricane eyewalls that can cause tornado-like wind damage.
Where the eyewall intercepts the coast, the Weather Service warns of “[s]tructural damage to sturdy buildings, some with complete roof and wall failure,” and “[m]any roads impassable from large debris.”
Winds will decrease quickly with distance outside of the eyewall, but are still likely to cause widespread tree and roof damage as well as power outages across much of Louisiana.
Rain forecast
The potential exists for serious flooding due to Ida’s heavy rain as well. The Weather Service forecast 8 to 16 inches of rain in southeast Louisiana and southern Mississippi, with up to 20 inches in a few spots. “This rainfall is likely to result in significant flash and riverine flooding impacts,” the Hurricane Center wrote.
Rainfall amounts will drop off significantly on the west side of the storm, with a steep gradient through western Louisiana. For example, Shreveport, at Louisiana’s Texas border, may wind up with barely half an inch.
New Orleans is likely to see 8 to 12 inches of rain, and it’s not out of the question that a few communities see more than that. This amount of rain will test the city’s network of 99 pumps, 96 of which are currently functional.
Flash flood watches are up for much of the Deep South ahead of Ida, with widespread 4- to 8-inch totals expected for northeastern Louisiana and central Mississippi into the Tennessee Valley.
Ida could then trek northeast through the Ohio Valley and into parts of the interior Mid-Atlantic and Northeast, with a few inches of rain and isolated severe weather toward the midweek.
Caroline Anders contributed to this report.
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