- With sustained wind speeds of 75 mph, Barry has strengthened to a hurricane and has moved over land in Louisiana.
- A hurricane warning is in effect for much of Louisiana’s coastline, including New Orleans.
- The storm could be the biggest test ever for New Orleans’s river levees along the Mississippi. Forecasters warn that the river may reach levels of 19 or 20 feet — the highest since 1950.
- The National Weather Service has forecast up to 20 inches of rain in parts of Louisiana.
- As the planet and its oceans warm because of climate change, hurricanes are likely to get wetter and slower.
- Visit Business Insider’s homepage for more stories.
Barry has strengthened to hurricane level as it moves over the Louisiana coast, with wind speeds of 75 mph.
Hurricane-force winds extend outward up to 45 miles from the storm’s center, but the winds aren’t the biggest threat to the state: Heavy rains are beginning to batter coastal Louisiana, with much of the affected area expected to see between 10 and 20 inches of rainfall in the coming days. Some isolated areas could get up to 25 inches.
“The primary risk continues to remain heavy rains for the city of New Orleans,” mayor LaToya Cantrell said at a press conference on Saturday morning, adding, “we are not in any way out of the woods.”
Barry is bringing a storm surge — the wall over water above regular tide levels — of up to 6 feet. More than 46,000 people in the state are already without power.
A hurricane warning is in effect for the stretch of coast from Grand Isle to Intracoastal City. A storm-surge warning is in effect for the area between Intracoastal City and Biloxi, Mississippi, as well as Lake Pontchartrain.
Barry is the first hurricane of the 2019 Atlantic season. This is only the third time in 168 years (since researchers started keeping track) that a hurricane has hit the Gulf in July, as meteorologist Eric Holthaus wrote in the New Republic. Typically, August and September are peak hurricane season.
Louisiana Gov. John Bel Edwards declared a state of emergency in anticipation of the storm, and US President Donald Trump has also declared a state of emergency, authorizing federal agencies to coordinate disaster-relief efforts.
The biggest test of Mississippi River levees since 1927
The storm poses a significant threat to much of New Orleans, since the Mississippi River, which snakes by the city, has been abnormally high since January.
New Orleans has levees in place to keep the river from flooding its banks and swamping nearby neighborhoods, but water has already started to overtop several river levees in the Plaquemines Parish area. Mandatory evacuation orders were issued in the parish on Thursday. In a press conference on Saturday, officials expressed concern that flooding there could cut off road access for those who haven’t yet left.
As rain pummels the New Orleans area, the Mississippi River is expected to crest at a near-record height of 19 or 20 feet on Sunday or Monday — the highest level the Mississippi has reached in the area since at least 1950, according to the NWS. But river levees are only 20 feet high in some places.
In 2005, Hurricane Katrina — one of the deadliest storms in US history — killed more than 1,800 people when storm-surge levees along canals in New Orleans failed. The Mississippi River levees, which were built in 1927, stayed intact during that storm. But this week could prove to be their biggest test ever.
“The levees protect the city up to 20 feet, but 19 is close and doesn’t include waves splashing up and so on. It’s too close for comfort for us,” David Ramirez, the chief of water management for the Army Corps of Engineers’ New Orleans District, told Slate on Tuesday.
We’re likely to see slower and wetter hurricanes
This past year was the hottest on record for Earth’s oceans and the fourth warmest for the planet.
As ocean temperatures continue to increase, we’ll likely see more coastal flooding due to sea-level rise (since water, like most things, expands when heated) and more severe hurricanes. That’s because a hurricane’s wind speed is influenced by the temperature of the water below. A 1-degree Fahrenheit rise in ocean temperature can increase a storm’s wind speed by 15 to 20 mph, according to research from Yale Climate Connections.
Water temperatures in the Gulf of Mexico are at near-record levels, Holthaus wrote.
As the planet keeps warming, Earth’s atmosphere will be able to hold more moisture. That increases the likelihood of intense rainfall in already wet areas.
What’s more, storms are also getting more sluggish. Over the past 70 years, the speed of hurricanes and tropical storms has slowed about 10% on average, according to a 2018 study. A slower pace of movement gives a storm more time to lash an area with powerful winds and dump rain, which can exacerbate flood problems.
Hurricane Barry has moved very slowly and is expected to stall over land for the next 36 hours or so. Sluggishness was also the reason that Hurricane Harvey caused so much damage Houston in 2017.