The Louisiana Floods: What Caused Them and how much Damage has Occurred?

The flooding in Louisiana over the period from August 10 – 17 was absolutely devastating. The total damage caused by this flooding is likely to approach levels generated by some recent United States landfalling hurricanes. Recent media reports indicate that over 40,000 homes have been either damaged or destroyed, and over 20,000 people have been rescued by local emergency responders, as well as the Coast Guard. At this point, 20 parishes have been declared disaster areas by President Obama, but this number is likely to increase in the coming days. The Red Cross has declared the Louisiana flooding to be the worst natural disaster to hit the United States since Superstorm Sandy in 2012.

The meteorological conditions that led to this event included a very slow-moving subtropical low pressure area that tapped into the very warm waters of the Gulf of Mexico as a primary fuel source. Typically, the jet stream helps push storms from west to east and prevents these types of dramatic flooding situations, but during the summer months, the jet stream recedes farther toward the north, weakening the large-scale steering forcing for these types of systems. A great more in-depth discussion on the meteorology behind the Louisiana flooding has recently been written by the Washington Post’s Capital Weather Gang.

The rainfall amounts with this flooding event have been absolutely staggering. Many areas received between 10-20 inches of rain during this time with areas from Lafayette to just east of Baton Rouge hit especially hard. The highest rainfall total for the event was over 30 inches of rain reported in Watson, Louisiana. Watson is located about 10 miles northeast of Baton Rouge. While rainfall has mostly ceased in Louisiana, flood waters have continued to rise in some areas, especially south of Baton Rouge. Fortunately, while additional light rain may fall in Louisiana over the next few days, no additional heavy rain is currently in the forecast.

What's interesting is that this particular flooding event has not received as much media attention as expected given the vast amounts of devastation that have occurred. This is likely due to a combination of factors including the point that this particular storm system did not have a name (e.g., it was not a tropical cyclone). In addition, the event happened to fall during both the Summer Olympics and during a presidential election cycle.

Please remember that following a disaster, it is common to find health and safety hazards such as contaminates, debris, and unstable building structures. A good rule of thumb to follow is until local authorities announce that the public water supply is safe, it is best to assume all water is unsafe. Also make sure that only trained, licensed professionals assist you with emergency mitigation and water removal.

About the Author:
Dr. Phil Klotzbach has received national and international attention for his work in researching weather patterns and forecasting hurricanes. For the past 15 years, Dr. Klotzbach has co-authored Colorado State University's Atlantic basin hurricane forecasts with his esteemed colleague the late Dr. William Gray.