10th Anniversary of Hurricane Katrina

Hurricane Katrina near its peak intensity as seen on NOAA P3's radar
Hurricane Katrina near its peak intensity as seen on NOAA P3’s radar

Early on the morning of August 29th, 2005, Hurricane Katrina made landfall on the Louisiana delta region and the Mississippi coast.  The storm surge brought enormous damage to the Gulf Coast and, when the levees around New Orleans failed, a great number of fatalities.  Coming amidst the very busy 2005 hurricane season, Katrina brought death and destruction not seen in a U.S. land-falling hurricane in decades.

Katrina formed out of a complex interaction of a tropical wave, the mid-level remnants of Tropical Depression 10, and an upper-tropospheric trough.  The disturbed weather consolidated into a circulation on Aug. 24th over the Bahama Islands.  As it moved northward through the archipelago, it strengthened into a Tropical Storm then turned westward toward Florida.  As NOAA 43 flew a reconnaissance mission into Katrina, it reached hurricane strength, then swerved to a southwesterly course as it came ashore in south Florida.  The hurricane brought drenching rains up to 14 inches (35.5 cm) to the peninsula.

Katrina diminished only slightly during its trek across Florida.  Once it reached the warm Gulf of Mexico, it quickly regained hurricane status and began to rapidly intensify.  While NOAA 49 flew a series of Synoptic Surveillance missions, dropping sondes in an effort to improve the track-forecast models, NOAA 43 flew two missions into the hurricane during its intensification stage, once on the 27th and another on the 28th when Katrina reached Category 5 status with its winds reaching a peak sustained wind speed of 170 mph (275 km/hr).

NOAA 43 landfall mission
NOAA 43 landfall mission

Thankfully, the hurricane began a rapid weakening as it approached the Gulf Coast.  A landfall flight by NOAA 43 documented this decline and tracked the center as it passed over the Mississippi delta and made final landfall near the Louisiana/Mississippi border.  The highest sustained wind speeds at landfall were estimated by NHC at 120 mph (193 km/hr).  Even though the top winds were much less than before, the water pushed inland by the storm was great. Pass Christian, MS observed nearly 28 feet of surge, and the Gulf waters intruded six miles inland.  Ninety percent of buildings within a half mile of the coast suffered substantial damage, and thousands of structures were completely destroyed.

Animated radar of Katrina's landfall (NOAA/NCDC)
Animated radar of Katrina’s landfall (NOAA/NCDC)

However, it wasn’t until the hurricane eye had passed well inland that the levees that protected New Orleans began to fail.  Over 50 breeches in the defense opened up, flooding large portions of the city that lay below sea level.  Homes and businesses were inundated and would remain so for weeks after the storm, and over a thousand people who had not evacuated either drowned in this flood or in the days afterward from exposure or lack of water and food.  Katrina caused over US$100 billion in damage and an estimated 1800 people’s deaths.

The data collected from the NOAA research flights proved extremely important to researchers.  It helped them better understand how storms form, evolve, and change in intensity. This understanding  has led to improvements  in NOAA’s hurricane models and our ability to better prepare communities.  Some papers written by Hurricane Research Division scientists using Hurricane Katrina data: