The historic rains and flooding that swamped Louisiana over the weekend are continuing to threaten the state – and there’s more rain on the way.

The torrential rain was the result of several factors, including warm Gulf waters and a stalled front, and is the type of extreme rainfall that is expected to occur more often as the world warms.

Louisiana flooding

A man surveys a flooded home in St. Amant, La.

While most of the rivers that rapidly rose – some to record levels – over the weekend have since crested and slowly begun to recede, six gauge locations in the state indicate a major flood remains in progress. More than 1,000 homes have been flooded in Baton Rouge, and 20,000 people have been rescued from their homes. The Louisiana Governor’s Mansion has been evacuated.

Through 11 a.m. ET Tuesday, six Louisiana sites had received more than 2 feet of rain since Aug. 9. Watson, La., leads that list with 31.39 inches. Another 14 sites in the state had between 1 and 2 feet of rain.
 

 

 

An increase in heavy rain events is a prime indicator of climate change. According the National Climate Assessment, released in 2014, the Southeast has had a 27 percent increase in the amount of precipitation falling in the heaviest events since the late 1950s. A report earlier this month from the EPA indicated that nine of the top 10 years for extreme one-day precipitation events in the contiguous U.S. have occurred since 1990.

The reason rising temperatures lead to more extreme rainfalls is because a warmer atmosphere coupled with warmer ocean water leads to more evaporation. This means more water is available in a storm system, potentially making for heavier precipitation.
 


 

Globally, sea surface temperature has been consistently higher during the past three decades than at any other time since reliable observations began in 1880. In recent weeks, surface temperatures in the Gulf of Mexico have been particularly high, around 90°F (32°C), which is 2°-4°F (1-2°C) above average for this time of year.

More rain is in store this week in Louisiana, though the heaviest rain is expected to shift northwestward toward Arkansas and eastern Texas. Several inches of rain are forecast in those areas.