Climate Matters

Louisiana Flooding Resources

Hello Climate Matters Mets,

As you are aware, historic flooding continues in Louisiana. While most of the rivers have crested or have slowly begun to recede, six gauge locations in the state indicate a major flood remains in progress. More than 1000 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.

Increasing heavy rain is a prime indicator of climate change. According the National Climate Assessment, the Southeast has had a 27% increase in the amount of precipitation falling in the heaviest events (from 1958-2014). A report earlier this month from the EPA indicated that 9 of the top 10 years for extreme 1-day precipitation events have occurred since 1990

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.

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Additional stats on the ongoing flooding:

• Through 10am ET Monday, six Louisiana sites had received more than two feet of rain since Tuesday morning, August 9. Watson, LA leads that list with 31.39 inches.

• 14 additional sites in Louisiana had between 1-2 feet of rain.

• Sea surface temperatures in parts of the Gulf of Mexico are at 90°F, which is 2-4°F above average for the time of year.

More rain is ahead this week in Louisiana, but the heaviest rain is expected to shift northwestward toward Arkansas and eastern Texas; several inches of rain are forecast.

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Some graphical resources to help tie the weather and climate together:

The Southeast has a 27% increase in amount of precipitation falling in the heaviest events (1958-2014): http://ccimgs.s3.amazonaws.com/HeavyDownpours.jpg

Heavy precipitation trends: Local and national: http://www.climatecentral.org/climate-matters-2015#2015HeavyPrecip

When it rains, it pours: Heavy precipitation by state: http://www.climatecentral.org/climate-matters-2015#2015wirip

Online interactive with state trends: http://www.climatecentral.org/news/across-us-heaviest-downpours-on-the-rise-18989

Oceans heating up: Global sea surface temperature rise in the last century: http://www.climatecentral.org/climate-matters-2015#2015enso

Summer precipitation trends: Wetter on the Louisiana Gulf Coast: http://www.climatecentral.org/climate-matters-2015#2015SummerTrends

As always, email me or Bernadette if you have any questions.

Sean

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