“Ida is expected to be a dangerous major hurricane when it reaches the northern Gulf Coast on Sunday, and the risk of hurricane-force winds continues to increase, especially along portions of the Louisiana coast, including metropolitan New Orleans,” the Hurricane Center wrote.
Exactly when and where Ida would cross the coast is still coming into focus, but the most reliable models predict landfall southwest of New Orleans and close to due south of Lafayette, La., between Sunday night and early Monday morning. Storm impacts from wind and flooding will expand far beyond where the storm’s center crosses the coastline.
Ida’s approach comes barely a year after Lake Charles, La. was slammed by back-to-back hurricanes, including Category 4 Laura in August 2020 and Delta in October. Zeta breezed through New Orleans on Oct. 28 after striking Louisiana at Category 3 strength. The three storms caused roughly $27 billion in damage.
With the entirety of coastal Louisiana and adjacent Mississippi and Alabama under hurricane watches and a storm surge watch spanning the shores, it seems like the area can’t catch a break.
Cities such as New Orleans, Baton Rouge and Lafayette in Louisiana, Biloxi and Gulfport, Miss., and Mobile, Ala., are in line for potential direct impacts, with conditions deteriorating as early as late Saturday night. Ida’s remnants could even prove problematic far inland, dropping a swath of heavy rainfall across parts of the South, the Ohio Valley and the Mid-Atlantic.
Louisiana Gov. John Bel Edwards (D) declared a state of emergency to free up state resources ahead of the approaching tempest.
“Now is the time for people to finalize their emergency game plan, which should take into account the ongoing covid-19 pandemic,” Edwards said in a news release issued Thursday.
Ida was a strengthening tropical storm with 65 mph winds as of 11 a.m. Friday, showing signs of intensifying further based on hurricane hunter aircraft reconnaissance data. It was located 200 miles east-southeast of the western tip of Cuba, and was moving northwest at 15 mph.
A hurricane hunter aircraft found that, while the system does have a maturing structure and a closed circulation, its wind field was a bit uneven — the strongest winds, sustained around hurricane force at flight level, were relegated primarily northeast of the center.
Satellite imagery revealed a hefty “convective burst,” or outburst of thunderstorm activity, near and northeast of the center. In the coming hours, it’s likely that more convection will begin to wrap around the center and work toward making Ida’s structure a bit more symmetrical. That’s the first step in a process of marked intensification.
“Ida is now forecast to become a hurricane when it is near western Cuba and once it moves over the southeastern Gulf of Mexico a period of rapid strengthening is likely to begin,” the Hurricane Center wrote.
What’s next for Ida
Ida is forecast to cross over western Cuba late Friday. Hurricane warnings are up there, with tropical storm warnings over Little Cayman and Cayman Brac and central Cuba, where wind and rain squalls are expected through roughly midday Saturday.
A general eight to 12 inches of rainfall with up to 20 inches in some areas is expected, which could spur a few landslides or mudslides in the higher terrain.
How Ida interacts with Cuba is key in its forecast. The system is still organizing now, meaning it is vulnerable to fluctuations in intensity and structure. If the central vortex is disrupted, it could take some time to reorganize over the southern Gulf.
Even though Ida is set to pass over the Sierra del Rosario mountain range in western Cuba, which could briefly disrupt it, rapid intensification already appears to be underway. It’s improbable that the growing storm will suffer more than a fleeting hiccup before emerging over the Gulf on Saturday morning.
Likelihood of rapid intensification
All signs are pointing toward Ida strengthening rapidly, with parameters basically maxed out as a disconcerting forecast setup unfolds. Water temperatures are in the upper 80s in the Gulf of Mexico, providing Ida a seemingly limitless bathtub of fuel to gobble up as air pressures plummet and winds quickly ramp up. Some of the warmest waters are found immediately along the coastline, meaning Ida will probably continue strengthening up until the point of landfall.
Studies have shown that warming sea surface temperatures because of human-caused climate change have increased the likelihood of such rapid strengthening.
Added to the equation is a lack of disruptive wind shear, or change of wind speed and/or direction with height. That means Ida won’t be knocked off-kilter, the atmosphere largely leaving it alone to fester and spin up undisturbed.
At the upper levels, a zone of high pressure and clockwise-spinning air will help with Ida’s “outflow,” or the evacuation of exhaust-air exiting the storm. That removal of spent air will allow Ida to ingest more warm, humid air in contact with the sea surface, fueling explosive intensification.
Ida is forecast to be a Category 3 storm with maximum sustained winds of 120 mph as it approaches coastal Louisiana late Sunday. There is also some potential it could be stronger than that.
What to expect: wind speeds
The National Hurricane Center is forecasting Ida to make landfall late Sunday at major hurricane strength with winds in the eyewall gusting over 120 mph. The eyewall is a lone band of strong thunderstorms that forms a destructive doughnut around the calm eye.
The harshest and most extreme conditions are found where the eyewall intercepts the coast. In this zone, the National 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.”
While the eyewall is a relatively narrow zone of destructive winds, damaging winds exceeding tropical-storm-force (39 mph) will cover a much larger area, probably extending more than 100 miles from the center, while hurricane-force winds (topping 74 mph) could extend 50 miles away.
Even if Ida’s eyewall avoids downtown New Orleans and tracks to its west, the Big Easy could still see wind gusts to hurricane force.
Tropical storm-force winds may arrive in coastal Louisiana as early as Saturday evening in any spiral rain bands that work ashore.
Widespread power outages and tree damage are possible where the core moves ashore; there will be a drop-off in wind away from the center. Winds will still be fierce, but magnitude and impacts will decay well away from the coast as Ida penetrates inland and begins to weaken Monday.
Storm surge
A destructive and potentially deadly storm surge is possible near the coast where strong winds push water ashore. Storm surge represents an increase in water levels that inundates ordinarily dry ground. The Hurricane Center is referring to the anticipated surge as “life-threatening,” noting that a 7 to 11 foot storm surge is possible if a worst-case scenario is realized across the Mississippi River Delta from roughly Fort Morgan, La. to Ocean Springs, Miss.
Lake Pontchartrain, La. is slated to see 4 to 6 feet of storm surge, and a dangerous surge is likely all the way east to the Florida Panhandle. The most serious surge will occur east of the center.
In the hardest-hit areas, outside of Hurricane Risk Reduction System, a system of levees, pumps and flood gates, protecting metropolitan New Orleans, 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.”
It’s important to note that surge can vary significantly over short distances, and is largely dependent on wind direction, local topography and tidal cycles at the time of landfall.
Heavy rainfall and flooding
Flooding because of anticipated rainfall is probable both along the coast and far inland. “[T]otal rainfall accumulations of 8 to 16 inches with isolated maximum amounts of 20 inches are possible from southeast Louisiana to coastal Mississippi and Alabama through Monday morning,” the Hurricane Center predicts.
There will be a sharp west to east cutoff of rainfall on the left side of the system toward western Louisiana and Texas, but rainfall rates could top three inches per hour as the heaviest rain bands work through.
New Orleans is likely to see 10 to 15 inches of rain, and it’s not out of the question a few isolated communities could approach 20 inches.
Heavy rainfall with amounts topping four inches could continue all the way through the Midwest and Mid-Atlantic or Northeast midweek as Ida’s remnants weaken and unleash considerable moisture. “This is likely to result in considerable flash, urban, small stream, and riverine flooding,” the Hurricane Center cautioned.
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