Gulf storm Barry was upgraded to a tropical storm Thursday morning as it moved closer to the Louisiana coastline, prompting mandatory evacuations for nearly 10,000 people in low-lying areas along the Mississippi River. The storm could be relabeled a Category 1 hurricane before it's predicted to make landfall over the weekend.
The storm has already brought more than eight inches of rain to New Orleans, causing flash flooding, and is expected to bring another 10 to 15 inches of rain in the coming days along with a three- to five-foot storm surge.
A Category 1 storm on its own isn't normally enough to threaten the levee system that protects New Orleans, but Barry's timing is terrible. The Mississippi River is currently experiencing one of its highest flood tides in history after the United States experienced its wettest 12-month period on record. Parts of the lower Mississippi River have been at flood stage for most of the year.
The river is already just four feet below the lowest point in the levee system, and while current projections from the Army Corps of Engineers in the New Orleans District suggest the levees might be just tall enough to hold back the water, a spokesman for the Corps told the New York Times it's still too early to tell.
While areas just outside the city that the Corps predict will be hit especially hard have issued mandatory evacuations, most New Orleans-area officials have held off, instead asking residents to shelter in place and stay off flooded roads.
Ghassan Korban, the executive director of the New Orleans Sewerage and Water Board, which operates the city's stormwater pumping and drainage system, said in an interview with New Orleans Public Radio that there are 118 pumps throughout the city ready to go in the event of major flooding in the city.
The city agency has spent tens of millions of dollars on back-up systems to power the pumps and Korban says they're in a better place to handle flooding than they've been in years past. But he went on to say that, if some of the predictions for rainfall this weekend play out, it's an event that would "overwhelm any system in any city in this country."
While officials are still uncertain about what Tropical Storm Barry has in store for Louisiana, what's becoming clear is the trend of wetter hurricanes coming earlier in the season and coinciding with spring flooding that will test an already strained system in New Orleans.
The U.S. National Hurricane Center describes the Atlantic hurricane season as running from the beginning of June to the end of November, but it's unusual for a hurricane to occur before mid-August in an average year. Only three hurricanes have made landfall in July in Louisiana since 1851, according to the New York Times—all in the last four decades. Barry could be the fourth.
And the foot of rainfall that meteorologists predict Barry will bring this weekend is part of a growing trend of wetter storms linked to climate change. Recent studies predict a likely increase of 10 to 15 percent in rainfall rates from hurricanes in a 2 degree Celsius global warming scenario.
New Orleans has spent the last decade solidifying the integrity of its levees so they don't experience the same catastrophic failure they did during Hurricane Katrina. But as the city braces for Barry and the wetter hurricanes of the future, the question is no longer, Are the levees strong enough? but rather: Are they tall enough?