Hurricane Ida is rapidly gaining strength Saturday over the unusually warm waters of the Gulf of Mexico and is predicted to hit southeastern Louisiana as an "extremely dangerous" Category 4 storm on Sunday evening, according to the National Hurricane Center.
Why it matters: This storm has the potential to cause catastrophic damage from high winds, nearly two feet of rain and up to 15 feet of storm surge inundation. New Orleans is likely to see significant impacts, including hurricane-force winds and a storm surge that could test the city's post-Hurricane Katrina flood protection system.
The latest: As of 8 a.m. ET, Hurricane Ida was located about 385 miles south-southeast of the mouth of the Mississippi River, or about 440 miles south-southeast of New Orleans. It was moving northwest at 16 mph and had maximum sustained winds of 85 mph.
Threat level: After hitting Cuba Friday night, Ida paused its intensification for a time, but resumed its alarming trends Saturday morning. Computer models, observations and forecaster intuition all show the storm explosively intensifying right up through landfall.
- In many ways, Hurricane Ida is a worst-case scenario: A storm traversing extremely warm water in an area conducive to strengthening, headed for a state that is extremely vulnerable to storm surge flooding.
- To make matters worse, Louisiana is already in the midst of a COVID-19 surge, with hospitals lacking extra capacity should serious injuries occur. For example, the state chose not to evacuate patients inland from coastal hospitals, per AP reports.
- Hurricane and storm surge warnings are in effect for the length of the Louisiana coast, with the highest surge levels — which refers to the storm-driven amount of water vaulted above normally dry land — of 10 to 15 feet occurring between Morgan City to the Mouth of the Mississippi River.
- Lower amounts, of seven to 11 feet, are predicted for New Orleans, with a 4- to 7-foot surge in Lake Ponchartrain. This would be within the design limits of the city's system of levees, flood gates and pumps built in the wake of Hurricane Katrina for about $14 billion.
- "Widespread deep inundation" is predicted to occur outside the risk reduction system.
- However, this system could be tested if a surge of 15 feet or higher materializes, and the surge depends on the precise wind direction, tide level and storm motion at the time of landfall.
- “A surge of that magnitude is close to the system’s design limits, and will be higher than any observed since the levee system was rebuilt,” wrote meteorologists Jeff Masters and Bob Henson for Yale Climate Connections.
Context: The National Hurricane Center and local Weather Service offices are not mincing words about the threat posed by this storm. The New Orleans office put out a statement Saturday morning warning of "structural damage to buildings, with many washing away" in areas that due see surge-related flooding.
- Near and just to the east of where the hurricane makes landfall, wind damage will be "potentially catastrophic," the Weather Service warns.
- Even if the strongest winds stay west of New Orleans, as currently forecast, the city is still likely to see hurricane-force winds, with downed trees and power lines and some structural damage possible.
- Widespread power outages are likely across Louisiana as the storm plows inland, with its eye wall — a ring of towering thunderstorms surrounding the near-calm center of the storm — slowly pinwheeling north.
How it works: Hurricane Ida is traversing some of the warmest waters in the Gulf, which will provide it with much-needed fuel.
- The warm waters aren't just at the surface, but extend deep into the ocean, which means as the storm's winds churn the water, cooler water won't be brought to the surface to weaken the storm.
- Atmospheric conditions are ideal for strengthening, with a high-pressure area at the upper levels that will encourage the venting of air away from the storm at upper levels.
- The lack of winds that differ in speed and/or direction with height, or wind shear, that could tilt the storm's thunderstorms and limit its peak strength.
- A lack of dry air that could cause some of the thunderstorms to wobble or sputter, instead of coiling up tightly like a snake around the eye.
Between the lines: According to the latest United Nations Intergovernmental Panel on Climate Change (UN IPCC) report, stronger hurricanes are becoming more common as the climate warms due to human emissions of greenhouse gases, and such storms are also producing more rainfall as air and sea temperatures warm.
- Scientists have also shown that rapid intensification may be linked to climate change, with more storms exhibiting such leaps in storm categories.
- Sea level rise is making such storms more damaging as well. The combination of sea level rise and land subsidence in coastal Louisiana makes such a trend particularly problematic.
Of note: The storm's formidable arsenal is expected to hit New Orleans on the 16th anniversary of Hurricane Katrina.
- Louisiana was hit by several powerful hurricanes last season, including Category 4 Hurricane Laura, which also rapidly intensified before landfall and devastated the city of Lake Charles.