Hurricane Katrina: Development and Devastation

Hurricane Katrina: Development and Devastation

Hurricane Katrina was one of the strongest storm systems to ever collide with the coastal United States in the last century. Strong winds sustained during landfall of over 140 mph combined with a very low central pressure (920 mb) to wreak havoc on many coastal communities in ways not seen before in the US (1). Despite monitoring the storms development, tracking its movement, and issuing early warnings, Hurricane Katrina has proved to be the most destructive and costliest natural disaster in the history of the United States.

Hurricane Katrina began as Tropical Depression #12 on August 23rd in the Southeastern Bahamas (1). The next day, on August 24th the storm was named Tropical Storm Katrina (1). TS Katrina picked up in strength while traveling a northwesterly then westerly path through the Bahamas (1). Shortly before landfall in southern Florida, at about 6:30 Eastern Daylight-Savings Time on August 25th, Katrina strengthened into a category 1 hurricane (windspeeds > 75 mph) (1).

Hurricane Katrina made landfall in Florida between Hallandale Beach and N. Miami Beach with windspeeds around 80 mph and gusts to 90 mph. Katrina's winds slowed while traveling over the Florida's southern tip, then regained hurricane strength while in the Gulf of Mexico due to the relatively small amount of time (> 7 hrs) spent over land (1).

Once in the Gulf of Mexico Katrina moved due west. At the same time, a mid-level ridge that was hovering over Texas weakened and moved westward (1). This cleared room for and allowed Katrina to slowly turn to the northwest and then north over the following few days (1). An upper level anticyclone over the Gulf lead to Katrina's rapid intensification. On August 27th, the storm was upgraded to Category 3 (2).

On Sunday morning at just 12:40 a.m., August 28th, Katrina was awarded Category 4 status (2). Later that morning, Katrina was recorded as having maximum winds o f 150 kts, (173 mph), reaching a status of a Vategory 5 hurricane (1). Katrina's minimum central pressure of 902 mb was the 4th lowest ever recorded for the Atlantic at that time (1), (Hurricane Rita and Hurricane Wilma both in 2005 surpassed this low pressure) (2). Although some earlier hurricanes, such as Camille in 1969 (3), have been as intense as Katrina, they were not as broad and did not impact such a large area (1).

At 6:10 a.m. Central Daylight-Savings Time, Hurricane Katrina made landfall as a Category 4 near Buras-Triumph, Louisiana (2). At this time, hurricane force winds extended 120 miles with a forward speed of 15 mph and pressure at 918 mb (2).

Hurricane Katrina worked up the eastern Louisiana coast. Many communities were severely damaged due to Katrina's storm surge. "A 10 to 30 foot (3 to 10m) storm surge came ashore on over 200 continuous miles of coastline from southeast Louisiana, including Mississippi and Alabama, through to the Florida panhandle," (2) The eyewall's strong winds including those in Plaquemines and St. Bernard Parish, Slidell in St. Tammany Parish, and even eastern New Orleans (2).

Katrina made landfall for the third time near the Mississippi/ Louisiana border with 125 mph (Category 3) sustained winds (2). "Because the storm was so large, extreme damaging eyewall winds and the strong northeastern quadrant of the storm, pushing record storm surges onshore, smashed the entire Mississippi Gulf Coast, including towns in Mississippi such as Gulfport and Biloxi," and Bayou La Batre in Alabama (2). Katrina moved inland diagonally over the state of Mississippi and left a path of destruction over most of the state (2).

Hurricane Katrina had a significant impact on the weather in many areas in the United States. Katrina generated over 5 inches of rainfall across a large portion of southeastern Florida during its initial landfall (1). "An analysis by NOAA's Climate Prediction Centre shows that parts of the region received heavy rainfall, over 15 inches in some locations, which caused localized flooding (1)." Some damage and large blackouts occurred north of Miami which experienced 80 mph (Category 1) winds (1).

Most affected by Hurricane Katrina was the Gulf Coast. On August 29th, Newton, Mississippi received over one inch of rainfall for three hours (1), and over half an inch for five hours. "Precipitation analysis from NOAA's Climate Prediction Center show that rainfall accumulations exceeded 8-10 inches along much of the hurricane's path and to the east of the track," (1).

Katrina's windspeeds were recorded over 140 mph at first landfall in southeastern Louisiana, with gusts in New Orleans recorded over 100 mph (1). At second landfall, at the Louisiana- Mississippi border, winds were recorded around 125 mph with gusts in Mobile, Alabama over 80 mph, and in Biloxi, Mississippi over 90 mph (1).

Rainfall became the major factor as the storm moved inland and weakened on the 29th (1). Amounts of rainfall exceeding 2-4 inches ranged from the Gulf Coast to the Ohio Valley (1). As a result, many areas were under a flood watch or flood warning. New Orleans experienced such sustained, extensive flooding because of its low elevation and bowl-like effect, trapping water in the region. Hurricane Katrina